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I Ecological Flow Assessment

Joule Africa Ltd Yiben HEP Project

Ecological Flow Assessment

Reference: ERM_Yiben_EFA_Report_Aug_2016_Draft Date: Aug 2016 Version: Final

Yiben HEP Project August 2016

2 Ecological Flow Assessment

Prepared for: Environmental Resources Management Ltd 2nd Floor Exchequer Court 33 St Mary Axe, London, EC3A 8AA c/o: Eimear Gormally Tel: +44 131 2216779 Cell: +44 (0)7889057619 Email: [email protected]

Prepared by: Ecotone Freshwater Consultants P.O Box 84, Florida, 1710 Cell: +27 84 585 7479 Tel: +27(0) 11 672 1375 Fax: 088 011 673 1192 Email: [email protected]



Report Authors

Person Qualifications Specialisation

Michiel Jonker

Ichthyofauna

Marco Alexandre Aquatic macroinvertebrates

Ryan Gray M.Sc. (Hydrology and soil)

University of Natal Hydraulic Specialist

Denis Hughes Ph.D. University College of

Hydrologist

Megan Gomes Diatomologist

Members: Michiel Jonker & Marco Alexandre- Registration no: CK 2008/027022/23

Report Status

Final



Report Checked and Signed By

_____________________________

Full Name: Michiel Jonker

Title / Position: Aquatic Ecologist and Partner

Qualification(s): M.Sc. (Aquatic Health), M.Sc. (Environmental Management)

______________________________

Full Name: Marco Alexandre


Qualification(s): M.Sc. (Aquatic Health)



Declaration of Independence

I, Michiel Jonker, as duly authorised representative of Ecotone Freshwater Consultants CC (Ecotone),

hereby confirm my independence (as well as that of Ecotone, its members, employees and sub-

consultants) as a specialist and declare that neither I nor Ecotone have any interest, be it business,

financial, personal or other, in any proposed activity, application or appeal in respect to the proposed

Yiben HEP Project, other than fair remuneration for work performed.

______________________________

Full Name: Michiel Jonker


Qualification(s): M.Sc. (Aquatic Health) M.Sc. (Environmental Management)



TABLE OF CONTENTS

TABLE OF CONTENTS ........................................................................................................................... VI

LIST OF FIGURES ................................................................................................................................ VIII

LIST OF TABLES ..................................................................................................................................... X

ABBREVIATIONS AND ACRONYMS ..................................................................................................... XII

EXECUTIVE SUMMARY ...................................................................................................................... XIII

INTRODUCTION ........................................................................................................................................ XIII

ASSUMPTIONS AND LIMITATIONS ................................................................................................................. XIII

MATERIALS AND METHODS ........................................................................................................................ XIV

RESULTS AND DISCUSSION .......................................................................................................................... XIV

1. INTRODUCTION ............................................................................................................................... 18

1.1. PROJECT BACKGROUND ................................................................................................................ 18

1.2. PURPOSE OF THE STUDY ............................................................................................................... 18

1.3. RATIONALE ................................................................................................................................ 19

1.4. DATA AVAILABILITY ...................................................................................................................... 19

1.5. SCOPE OF WORK ......................................................................................................................... 19

ASSUMPTIONS AND LIMITATIONS ............................................................................................. 21

MATERIALS AND METHODS ....................................................................................................... 23

3.1. SITE SELECTION AND FIELD ASSESSMENT .......................................................................................... 23

3.2. ECOCLASSIFICATION ..................................................................................................................... 24

3.3. DESKTOP ECOLOGICAL RESERVE MODEL .......................................................................................... 27

RESULTS AND DISCUSSION ......................................................................................................... 32

4.1. REGIONAL CONTEXT ..................................................................................................................... 32

4.2. SITE DESCRIPTIONS ...................................................................................................................... 32

4.3. SUMMARY OF ECOLOGICAL INFORMATION ....................................................................................... 35

4.4. CONFIDENCE RATINGS .................................................................................................................. 36

4.5. ECOSTATUS DETERMINATION ........................................................................................................ 37

4.6. TREND IN PRESENT ECOLOGICAL STATE ............................................................................................ 38

4.7. ECOLOGICAL IMPORTANCE AND SENSITIVITY ..................................................................................... 39

4.8. RECOMMENDED ECOLOGICAL CATEGORY ......................................................................................... 41

4.9. ECOLOGICAL RESERVE MODEL ....................................................................................................... 42

CONCLUSION ............................................................................................................................. 50

REFERENCES ............................................................................................................................... 51

APPENDIX A: IN SITU WATER QUALITY ....................................................................................... 57

6.1. MATERIALS AND METHODS ............................................................................................................ 57



6.2. RESULTS AND DISCUSSION ............................................................................................................. 57

APPENDIX B: DIATOM ASSESSMENT .......................................................................................... 59



APPENDIX C: INTERMEDIATE INDEX OF HABITAT INTEGRITY...................................................... 64



APPENDIX D: MACROINVERTEBRATE ASSESSMENT ................................................................... 70

9.1. MATERIALS AND METHODS ........................................................................................................... 70


APPENDIX E: FISH ASSESSMENT ................................................................................................. 84

10.1. MATERIAL AND METHODS ............................................................................................................ 84


APPENDIX F: TABULATED FLOW VOLUMES .............................................................................. 102

11.1. NATURAL FLOWS....................................................................................................................... 102

11.2. PRESENT DAY FLOWS ................................................................................................................. 103

11.3. LOWER FLOWS EWR ................................................................................................................. 104



LIST OF FIGURES

FIGURE 3-1: A: CHANNEL CROSS SECTION OF R2. B: STAGE DISCHARGE CURVE SHOWING THE RELATIONSHIP BETWEEN DEPTH

AND DISCHARGE FOR R2. ........................................................................................................................ 29

FIGURE 3-2: TIME SERIES OF MONTHLY STREAM FLOW DATA USED AS INPUT TO THE MODEL. ......................................... 30

FIGURE 4-1: DISCHARGE HABITAT RELATIONSHIP FOR R2. ................................................................................... 43

FIGURE 4-2: HABITAT FLOW STRESSOR RESPONSE CURVE FOR DECREASED FLOWS DURING DRY SEASON BASEFLOWS. .......... 44

FIGURE 4-3: HABITAT FLOW STRESSOR RESPONSE CURVE FOR DECREASED FLOWS DURING THE WET SEASON BASEFLOWS. ... 45

FIGURE 4-4: HABITAT FLOW STRESSOR RESPONSE RELATIONSHIPS FOR THE DRY MONTHS UNDER HIGHER FLOWS THAN NATURAL

CONDITIONS ASSOCIATED WITH HYDRO-POWER RELEASES. ............................................................................. 45

FIGURE 4-5: (A) FLOW-HABITAT STRESS RELATIONSHIPS FOR THE WET AND DRY SEASONS, (B) HABITAT STRESS FREQUENCY

CURVES FOR THE WET SEASON, (C) HABITAT STRESS FREQUENCY CURVES FOR THE WET SEASON. ........................... 47

FIGURE 4-6: EXAMPLE TIME SERIES PERIOD OF OWER FLOWS COMPARED TO NATURAL AND PRESENT DAY DOWNSTREAM

HYDRO-POWER RELEASES. ....................................................................................................................... 47

FIGURE 4-7: EXAMPLE TIME SERIES PERIOD OF IGHER FLOWS COMPARED TO NATURAL AND PRESENT DAY DOWNSTREAM

HYDRO-POWER RELEASES. ....................................................................................................................... 49

FIGURE 6-1: THE PH AND EC VALUES FOR SITES LOCATED ON THE ROKEL RIVER, JULY 2016. ........................................ 58

FIGURE 7-1: BAR GRAPHS SHOWING (A) POLLUTION TOLERANT VALUES FOR THE STUDY SITES, JULY 2016, (B) SPECIFIC

POLLUTION INDEX VALUES FOR THE STUDY SITES, JULY 2016 AND (C) BIOLOGICAL DIATOM INDEX VALUES FOR THE

STUDY SITES, JULY 2016. ....................................................................................................................... 63

FIGURE 9-1: BAR GRAPH INDICATING THE BIOTOPES AVAILABLE FOR HABITATION BY AQUATIC MACROINVERTEBRATES AT THE

STUDY SITES DURING THE JULY 2016 ASSESSMENT. (* = BIOTOPE ABSENT). ..................................................... 74

FIGURE 9-2: STACKED COLUMN GRAPH ILLUSTRATING THE PERCENTAGE DISTRIBUTION OF THE FFGS AT EACH STUDY SITE. .. 77

FIGURE 9-3: ASPT AND SASS SCORES FOR SITES ASSESSED ON THE ROKEL RIVER DURING THE JULY 2016 ASSESSMENT. .... 80

FIGURE 9-4: COLUMN GRAPH SHOWING %EPT AS EXPRESSED FROM THE TOTAL NUMBER OF TAXA SAMPLED FOR EACH SITE

DURING THE JULY 2016 ASSESSMENT OF THE ROKEL RIVER. .......................................................................... 80

FIGURE 9-5: AQUATIC MACROINVERTEBRATE INDICATOR TAXA SELECTED FOR SETTING FLOW REQUIREMENTS AND FOR

BIOMONITORING. .................................................................................................................................. 83

FIGURE 10-1: FREQUENCY DISTRIBUTION OF FISH HABITAT, (A) COVER, (B) FLOW-DEPTH AND (C) SUBSTRATE MEASURED AT

A DISCHARGE OF 43.5- 48.5M³S¯¹. .......................................................................................................... 90

FIGURE 10-2: OVERALL ABUNDANCES OF FISH SAMPLED DURING JULY 2016. ............................................................ 91

FIGURE 10-3: OVERALL ABUNDANCES OF FISH SAMPLED BY PAYNE ET AL. (2010) AT SITES BELOW CORRESPONDING WITH THE

ECOTONE 2016 ASSESSMENT. ................................................................................................................. 92

FIGURE 10-4: PERCENTAGE CHANGE FROM REFERENCE CONDITIONS FOR COMPONENTS USED IN THE FISH PES ASSESSMENT.

......................................................................................................................................................... 93

FIGURE 10-5: CLUSTERED BAR GRAPHS SHOWING THE DIFFERENCE BETWEEN NUMBER OF FISH EXPECTED AND SAMPLED WITH

A SPECIFIC PREFERENCE FOR (A) COVER, (B) SUBSTRATE, (C) VERTICAL ZONATION AND (D) VELOCITY-DEPTH CLASS.

......................................................................................................................................................... 94




SPECIFIC REPRODUCTIVE AND FEEDING REQUIREMENTS FOR (A) REPRODUCTIVE STRATEGY, (B) MIGRATION

REQUIREMENTS, (C) SPAWNING TIME AND (D) FUNCTIONAL FEEDING GROUP. ................................................. 95


SPECIFIC TOLERANCE LEVELS FOR (A) NO FLOW CONDITIONS AND (B) CHANGES IN WATER QUALITY. ...................... 95

FIGURE 10-8: FISH INDICATOR TAXA SAMPLED DURING JULY 2016. (A) LABEO PARVUS, (B) NANNOCHARAX SP., (C) RAIAMAS

SCARCIENSIS AND (D) R. STEINDACHNERI. .................................................................................................. 96



LIST OF TABLES

TABLE 0-1: HYDRAULIC CALIBRATION DATA COLLECTED JULY 2016 .......................................................................... XV

TABLE 0-2: SUMMARY OF BASELINE INFORMATION COLLECTED DURING JULY 2015 ..................................................... XV

TABLE 0-3: SUMMARY OF THE INTEGRATED ECOSTATUS RESULTS ............................................................................ XV

TABLE 0-4: SUMMARY OF EFRS EXPRESSED AS A PERCENTAGE OF THE TOTAL ANNUAL FLOWS FOR THE RESOURCE UNIT ..... XVI

TABLE 0-5: FREQUENCIES OF EXCEEDANCE FOR MODIFIED HYDRO-POWER RELEASES .................................................. XVII

TABLE 3-1: RECONCILIATION OF SITE NAMES FOR THE AQUATIC ECOLOGY SITES ASSESSED AND THE CHANNEL CROSS SECTIONS

COMPLETED FOR THE EFA....................................................................................................................... 23

TABLE 3-2: GENERIC ECOLOGICAL CATEGORIES FOR ECOSTATUS COMPONENTS (KLEYNHANS & LOUW, 2007) ................. 25

TABLE 3-3: SCORING GUIDELINES FOR EACH ATTRIBUTE CONSIDERED IN DETERMINING THE EIS (KLEYNHANS, 1999B) ....... 26

TABLE 3-4: SCORING GUIDELINES FOR EACH ATTRIBUTE CONSIDERED IN DETERMINING THE EIS (KLEYNHANS, 1999B) ....... 26

TABLE 3-5: HYDRAULIC HABITAT TYPES AND THEIR DEFINITIONS ............................................................................... 28

TABLE 4-1: SITE DESCRIPTION FOR SITE R1 .......................................................................................................... 32



TABLE 4-4: HYDRAULIC DATA COLLECTED JULY 2016 ............................................................................................ 35

TABLE 4-5: SUMMARY OF BASELINE INFORMATION COLLECTED DURING JULY 2016 ..................................................... 36

TABLE 4-6: AVAILABILITY OF INFORMATION FOR EACH SPECIALIST COMPONENT AND SOURCES OF INFORMATION, WHERE A

CONFIDENCE RATING OF 4 IS HIGH AND A SCORE OF 0 INDICATES NO CONFIDENCE .............................................. 37

TABLE 4-7: SUMMARY OF INTEGRATED ECOSTATUS RESULTS. THE IMPORTANCE SCORE REFERS TO THE IMPORTANCE AS AN

INDICATION OF THE PES WHERE 1=LOW AND 5=HIGH ................................................................................. 38

TABLE 4-8: TREND ASSESSMENT FOR EACH COMPONENT. CONFIDENCE RATINGS SCORED FROM 1= LOW CONFIDENCE TO 4=

HIGH CONFIDENCE ................................................................................................................................. 39

TABLE 4-9: ECOLOGICAL IMPORTANCE AND SENSITIVITY SCORES AND CONFIDENCE LEVELS ASSOCIATED WITH EACH SITE

ASSESSED. RATINGS VARY FROM 1 (LOW) TO 4 (HIGH) ................................................................................. 40

TABLE 4-10: RECOMMENDED ECOLOGICAL CATEGORY BASED ON PES AND EIS ......................................................... 42

TABLE 4-11: FREQUENCIES OF EXCEEDANCE FOR MODIFIED HYDRO-POWER RELEASES .................................................. 48

TABLE 0-5: FREQUENCIES OF EXCEEDANCE FOR MODIFIED HYDRO-POWER RELEASES .................................................... 50

TABLE 6-1: IN SITU WATER QUALITY PARAMETERS MEASURED ................................................................................. 57

TABLE 6-2: BENCHMARK CRITERIA FOR IDEAL, TOLERABLE AND INTOLERABLE VALUES FOR MAJOR IONS (KOTZE, 2002) ..... 57

TABLE 6-3: WATER QUALITY VALUES FOR SITES LOCATED ON THE ROKEL RIVER, JULY 2016 .......................................... 58

TABLE 7-1: CLASS VALUES USED FOR THE SPECIFIC POLLUTION SENSITIVITY INDEX AND THE BIOLOGICAL DIATOM INDEX IN THE

EVALUATION OF WATER QUALITY (ADAPTED FROM ELORANTA & SOININEN, 2002) ........................................... 60

TABLE 7-2: INTERPRETATION OF THE PERCENTAGE OF POLLUTION TOLERANT VALVES SCORES (ADAPTED FROM KELLY, 1998)

......................................................................................................................................................... 60

TABLE 7-3: ECOLOGICAL DESCRIPTORS FOR THE YIBEN DAM SITES BASED ON THE DIATOM COMMUNITY, JULY 2016 (VAN DAM

ET AL., 1994) ...................................................................................................................................... 61



TABLE 7-4: SPECIES AND THEIR ABUNDANCES FOR THE ROKEL RIVER SITES, JULY 2016 ................................................ 62

TABLE 7-5: DIATOM INDEX SCORES CALCULATED FOR ROKEL RIVER SITES, JULY 2016 .................................................. 63

TABLE 8-1: DESCRIPTIVE CLASSES FOR THE ASSESSMENT OF MODIFICATIONS TO HABITAT INTEGRITY (ADAPTED FROM

KLEYNHANS, 1996) .............................................................................................................................. 64

TABLE 8-2: CRITERIA AND WEIGHTS USED FOR THE ASSESSMENT OF HABITAT INTEGRITY (ADAPTED FROM KLEYNHANS, 1996)

......................................................................................................................................................... 65

TABLE 8-3: ECOLOGICAL CATEGORIES, KEY COLOURS AND CATEGORY DESCRIPTIONS PRESENTED WITHIN THE HABITAT

ASSESSMENT (ADAPTED FROM KLEYNHANS, 1996) ...................................................................................... 65

TABLE 8-4: RESULTS FOR THE IHI FOR ROKEL RIVER SITES DURING THE JULY 2016 ASSESSMENT .................................... 66

TABLE 9-1: INVERTEBRATE HABITAT ASSESSMENT SCORE RATINGS AND CATEGORIES (MCMILLAN, 1998) ...................... 70

TABLE 9-2: ECOLOGICAL INTEGRITY CATEGORIES (THIRION, 2016 - MODIFIED FROM KLEYNHANS, 1996 AND KLEYNHANS,

1999) ................................................................................................................................................ 72

TABLE 9-3: IHAS OF SITES ASSESSED DURING THE JULY 2016 ASSESSMENT ............................................................... 74

TABLE 9-4: AQUATIC INVERTEBRATE BIOTOPES PRESENT AT SITE R1 ......................................................................... 74



TABLE 9-7: SPECIFIC FUNCTIONAL FEEDING GROUPS FOR MACROINVERTEBRATES SAMPLED AT THE STUDY SITES ............... 76

TABLE 9-8: TABLE SHOWING THE ENVIRONMENTAL PREFERENCES AND TOLERANCES OF EXPECTED AND SAMPLED AQUATIC

MACROINVERTEBRATES (THIRION, 2016) .................................................................................................. 78

TABLE 9-9: AQUATIC MACROINVERTEBRATES SAMPLED DURING THE JULY 2016 ASSESSMENT OF THE ASSOCIATED REACH OF

THE ROKEL RIVER, WITH RELEVANT ABUNDANCE AND SENSITIVITY SCORES ACCORDING TO DICKENS & GRAHAM (2002)

......................................................................................................................................................... 80

TABLE 9-10: ECOLOGICAL CATEGORIES: BASED ON WEIGHTS OF METRIC GROUPS FOR THE ASSOCIATED RIVER REACH ......... 82

TABLE 10-1: HABITAT TYPES AND THEIR DESCRIPTIONS INCLUDED IN THE JULY 2016 AQUATIC ECOLOGY ASSESSMENT ....... 84

TABLE 10-2: HYDRAULIC UNITS USED IN MODELLING VARIATION IN FISH HABITAT UNITS ............................................... 84

TABLE 10-3: FISH SAMPLING EQUIPMENT USED AND THE SAMPLING EFFORT FOLLOWED DURING SURVEYS ....................... 85

TABLE 10-4: ECOLOGICAL CATEGORIES, KEY COLOURS AND CATEGORY DESCRIPTIONS PRESENTED WITHIN THE BIOTIC

ASSESSMENT (KLEYNHANS & LOUW, 2007) ............................................................................................... 86

TABLE 10-5: REVISED EXPECTED LIST WITH IUCN RED LIST STATUS, INDICATION OF REGIONAL ENDEMISM AND PRESENCE

DURING THE JULY 2016 ASSESSMENT ....................................................................................................... 87

TABLE 10-6: RELATIVE FISH ASSEMBLAGE INTEGRITY SCORE AND ECOSTATUS FOR THE RESOURCE UNIT ASSOCIATED WITH SITES

R1, R2 AND R3 .................................................................................................................................... 93

TABLE 10-7: ECOLOGICAL PARAMETERS FOR FISH INCLUDING SUBSTRATE PREFERENCE, VERTICAL ZONE PREFERENCE, COVER

PREFERENCE AND DIET CLASSIFICATION ...................................................................................................... 98

TABLE 10-8: ECOLOGICAL PARAMETERS FOR THE REVISED EXPECTED FISH INCLUDING REPRODUCTIVE REQUIREMENTS, BREEDING

TIME, MIGRATION REQUIREMENTS, VELOCITY DEPTH REQUIREMENTS AND FLOW AND WATER QUALITY TOLERANCES . 99



ABBREVIATIONS AND ACRONYMS

ASPT Average Score per Taxa

DLIFR Drought low flow

EC Ecological Category

EFA Environmental Flow Assessment

EFR Environmental Flow Requirement

EIS Ecological Importance and Sensitivity

EWR Ecological Water Requirement

FD Fast Deep

FDC Flow Duration Curves

FI Fast Intermediate

FL Fork Length

FRAI Fish Response Assessment Index

FROC Frequency of Occurrence

FS Fast Shallow

FVS Fast Very Shallow

HFSR Habitat Flow Stressor Response

IHI Index of Habitat Integrity

LSR Large semi-rheophilic fish species

MAR Mean Annual Runoff

MCM Million Cubic Meters

MIRAI Macro-Invertebrate Response Assessment Index

MV Marginal vegetation

MVI Marginal vegetation macroinvertebrate

PES Present Ecological State

RDM Resource Directed Measures

RDRM Revised Desktop Reserve Model

REC Recommended Ecological Category

SASS South African Scoring System

SD Slow Deep

SS Slow Shallow

SVS Slow Very Shallow

Veg Vegetation

VEGRAI Riparian Vegetation Response Assessment Index



EXECUTIVE SUMMARY

INTRODUCTION

Environmental Resource Management Ltd (ERM) as appointed by Joule Africa (Ltd) is undertaking the

Environmental Social Impact Assessment (ESIA) for the proposed Yiben HEP Project. The project will

consist of the development of a new dam and power generating facilities approximately 32km upstream

of the existing Bumbuna Dam in the Yiben area.

Ecotone Freshwater Consultants CC (Ecotone) was appointed by ERM to conduct an Environmental Flow

Assessment (EFA) for this Project. The main aim of the assessment was to identify and define the

Ecological Water Requirements (EWRs) for the study area.

ASSUMPTIONS AND LIMITATIONS

The EFR modelling was undertaken at a desktop level, with the inclusion of three hydraulic site

measurements, associated with the resource unit, between Bumbuna Falls and the confluence

of the Tonkolili River. This level of study is normally associated with planning and, typically, a

more detailed analysis would be required to refine the EFRs for implementation in the system.

The study focussed on ascertaining the EFRs for the instream aquatic community associated with

the resource unit assessed. The EFRs required for riparian vegetation and channel morphology

was not considered. However, the instream requirements for aquatic macroinvertebrates and

fish are generally more sensitive compared to those of riparian structure and channel

morphology.

The study did not consider the flow requirements associated with local fishing practices, or any

socio-economic aspect thereof.

The EFRs were determined for the resource unit between the Bumbuna Falls and the confluence

of the Tonkolili River. Data availability regarding additional catchments limited the application

of the Revised Desktop Reserve Model (RDRM) to areas downstream of the Tonkolili River

catchment.

The ecological conditions reflected by this assessment, and the subsequent environmental

inferences, are limited to a single high flow survey. Ideally the resource unit should be subjected

to a high- and a low flow assessment, in order to account for seasonal variation.

Daily operating variables, such as maximum discharge ratio, maximum ramping rate and the

degree to which discharge will be regulated, all have ecological risk implications. The total

discharge associated with the Project may well be within the broad EFRs given a mean daily or



monthly view, but daily ramping rates or discharge control may be intolerable to instream biota.

The effectiveness of mitigating impacts related to these daily operational variables has not been

well studied and is poorly documented.

Operational releases (discharge, regime etc.) are not addressed in this study. Different

operational alternatives can be measured against the output of this assessment and this in turn

can inform the ecological sustainability of releases.

MATERIALS AND METHODS

The stretch of the Rokel River between Bumbuna Falls and the confluence of the Tonkolili River

was assessed during July 2016. Three hydraulic cross-sections were made (R1, R2 and R3) and

the most representative cross-section (R2) was used in the RDRM. Site R2 was considered

representative of the river reach (resource unit) assessed.

The resource unit was subjected to an EcoClassification, consisting of an EcoStatus

determination and an assessment of its Ecological Importance and Sensitivity (EIS). EcoStatus

categories range from category A- Natural state to F- Critically modified state, while the EIS

categories range from Marginal or Low (important on a national scale) to Very Low (not

important or sensitive on any scale).

The results of the EcoClassification informed the EFA and aided in setting resource management

objectives for the resource unit.

The RDRM was applied for the environmental flow determination. The approach involves

integrating hydrological, hydraulic (channel cross-sections) and ecological habitat data to

establish a modified flow regime that is expected to achieve some level of ecological functioning

relative to the natural condition (as ascertained from the EcoClassification).

RESULTS AND DISCUSSION

SUMMARY OF AVAILABLE INFORMATION

Table 0-1 and Table 0-2 provide a summary of available information applied in this assessment. The

hydraulic calibration data was generated from cross sectional surveys completed for three cross-sections

during the July 2016 assessment. Similarly, the baseline EcoClassification and instream habitat data were

applied in the overall EcoStatus assessment (Table 0-3). The macroinvertebrate assemblages fell into a D

Ecological Category (EC) which translated into a Largely modified state, while the fish assemblages fell



into a C/D EC, inferring a Moderately to Largely modified state. Both the macroinvertebrates and fish

indicated a clear digression from reference conditions, most likely due to existing flow alterations

(increase in dry season baseflows and diurnal variation in flows). The dominant habitat units were Fast

Deep (FD) and Slow Deep (SD) associated with overhanging vegetation, mud, sand and bedrock.

Table 0-1: Hydraulic calibration data collected July 2016

Cross Section

Max. Depth (m)

Av. Depth (m)

Discharge (m³s¯¹)

Width (m) Perim. (m) Av. Velocity

(m.s¯¹) R1 4.85 3.350 44.85 51.10 54.20 0.26

R2 1.54 0.92 43.57 33.30 33.80 1.43

R3 3.769 2.465 48.244 47.490 49.390 0.410

Av.: Average, Max.: Maximum, Perim.: Perimeter

Table 0-2: Summary of baseline information collected during July 2015

Cross Section

IHI Diatoms Aquatic Macro-

invertebrates Fish

Flow-depth

Cover/ substrate

R1 C Good D C/D FD>SD Overhanging vegetation,

Mud>Sand>Bedrock


Mud>Sand>Bedrock


Mud>Sand>Bedrock FD: Fast Deep, SD: Slow Deep,

SUMMARY OF THE ECOSTATUS

The overall EcoStatus classification fell in a D category (Table 0-3). The EIS category was classified as High

and it is recommended that the resource unit be maintained within a C EcoStatus category. However, it

is recognised that the maintenance of a C EC is unlikely under present condition and the focus of the EFA

for a category C level of protection.

Table 0-3: Summary of the integrated EcoStatus results

EcoStatus % EcoStatus Category EIS Category REC

48.6% D High C

EIS: Ecological Importance and Sensitivity, REC: Recommended Ecological Category



SUMMARY OF THE FLOW HABITAT RELATIONSHIP

In the main dry season month (April) the natural flows vary from less than 2m³s¯¹ to about 14m³s¯¹. These

equate to a maximum depth of about 0.6m and a width of 40m to a depth of 1.1m and the full width of

80m, respectively. The frequency of fast habitats (mostly Fast Deep) decreases quickly over this flow

range from about 45% at the higher flow to less than 20% at the lower flow. At the lower flow it is also

evident that the Fast Intermediate (FI) and Fast Shallow (FS) habitats dominate, while the FD habitat

almost disappears. Conversely SD and FD dominate at flows exceeding 20m³s¯¹, with additional flows

translating into a steady increase in FD. The proportional representation of habitat is optimised at

approximately 11m³s¯¹.

SUMMARY OF THE HABITAT STRESSOR RESPONSE RELATIONSHIP AND ECOLOGICAL FLOW REQUIREMENTS

The resource unit yielded flow sensitive aquatic macroinvertebrate and fish taxa. Selected indicator taxa

included: Heptageniidae and Tricorythidae for the macroinvertebrates and Labeo parvus, Enteromius

sacratus, Nannocharax sp. and Raiamas sp. for the fish. Variations in the frequency distribution of these

taxa are likely to indicate a change in the resource classification (EcoStatus) associated with the resource

unit assessed.

The habitat and flow requirements of the sensitive macroinvertebrate and fish taxa primarily informed

the EFA. However, the fish requirements were weighted more as the system naturally has a high fish

diversity. A subsequent summary of the EFR proportions in relation to the mean annual flows are

provided in Table 0-4.

Table 0-4: Summary of EFRs expressed as a percentage of the total annual flows for the resource unit

Names used in this report

EFR as a portion of the total annual flows

Represents about 11% of the natural flows and a mean annual volume of

383*106m3

The present day mean annual volume is approximately 3 235*106m3,

while the EFR represents a mean annual volume of 2 711*106m3. This

translates into a 16% reduction in the volume from present day

conditions. However, given that some of

dry season would be met from the up

the reduction in release volume would be slightly less.



CONCLUSION

It should be recognised that flow is a primary determinant of the physical habitat within the resource

unit, this in turn dictates the biotic composition. Under present conditions a digression from reference

conditions have been measured for fish and aquatic macroinvertebrates with both response models

indicating a flow related stress. Under present day conditions that are dominated by the hydro-power

releases, the minimum wet season flows increase to about 70m³s¯¹ and therefore the habitat conditions

during the wet season are not changed very much. During the dry season the present day flows vary in a

fairly narrow range between 60 and 80m³¯¹ and therefore the habitat conditions are very similar to the

natural wet season and dominated by FD habitat. Habitat diversity during dry months is a key issue and

is a natural function of lower flows. A subsequent ecological stress is anticipated as minimum low flows

ersity occurs under a flow rate of about

15m³s¯¹, which is well below the rate of flows proposed for the Yiben Dam expansion. Table 0-5

summarises the frequencies of exceedance of stress for the two main dry season months (March and

April) as well as for February and May. These frequencies were designed to increase the level of habitat

diversity quite substantially during the two main dry season months and to add some additional diversity

during the other two months.

Table 0-5: Frequencies of exceedance for modified hydro-power releases

March and April February and May

Freq. (%) of Exc. Stress


Freq. (%) of Exc. Stress


80 0 11 90 4 30

20 3 21 60 5 44

0 5 44 0 7 84


1. INTRODUCTION

1.1. PROJECT BACKGROUND

ERM, as appointed by Joule Africa (Ltd), is undertaking the Environmental Social Impact Assessment

(ESIA) for the proposed Yiben HEP Project. The project will consist of the development of a new dam and

power generating facilities approximately 32km upstream of the existing Bumbuna Dam in the Yiben

area.

Ecotone was appointed by ERM to conduct an Environmental Flow Assessment (EFA) for this Project. The

main aim of the assessment was to identify and define the Ecological Water Requirements (EWRs) for the

study area.

1.2. PURPOSE OF THE STUDY

The Project and its associated activities will impact the hydrology, water quality and geomorphology of

surface water systems, which will subsequently impact the instream biota of the downstream receiving

environment. A sound understanding of baseline ecological conditions is necessary to adequately address

and mitigate ecological risks. The purpose of the study was to:

Collate and augment baseline data of ecological integrity of the downstream aquatic resources

and identify sensitive biota.

Define and classify the river reach (resource unit) associated with the study area, in terms of its

EcoStatus.

Determine the EIS of the resource unit.

Determine a REC for the resource unit based on the results of the PES and EIS.

Based on the habitat preferences and tolerances of the sampled instream aquatic communities

(macroinvertebrates and fish), determine the likely relationship between flow and habitat stress

(habitat flow stressor response relationship).

Apply the habitat flow stressor response relationship to determine the EFRs.



1.3. RATIONALE

The Project requires the assessment of baseline ecological conditions and the EFRs associated with these

conditions to inform potential impacts. An understanding of the PES and EIS of the receiving system is

pertinent in assessing potential ecological risks linked to the Project. This in turn will guide the

management of the resource unit. Currently, no official protocol for the assessment of environmental

flows for Sierra Leone rivers exists; therefore, a South African approach- the Revised Desktop Reserve

Model (RDRM) (Hughes et al., 2013)- was implemented using data from the aquatic ecology and

hydrological studies.

1.4. DATA AVAILABILITY

The fish component of the instream PES assessment was informed by studies completed by Paugy et al.

(1990), Payne at al. (2010) and more recently Hüllen (2015). No reference could be made to baseline

variation within aquatic macroinvertebrate assemblages.

Modelled hydrological information for the Rokel River was available from Annexes three and four,

obtained from the Feasibility Study Volume III-2 (2012). The modelled data consists of mean monthly

annual flows for the period 1943 to 1992 and were used to undertake a RDRM for the resource unit.

1.5. SCOPE OF WORK

The primary objectives were to:

Establish the PES of the resource unit by implementing the following methodologies:

o Index of Habitat Integrity (IHI - Kleynhans, 1999) (see Appendix C: Intermediate Index

of Habitat Integrity).

o Aquatic macroinvertebrates - Macroinvertebrate Response Assessment Index

(MIRAIV2 -Thirion, 2016) (see Appendix D: Macroinvertebrate Assessment);

o Fish -Through adapting the Fish Response Assessment Index framework (FRAI -

Kleynhans, 2007) (see Appendix E: Fish Assessment);

Extraction of an integrated PES/EcoStatus for the resource unit between the Bumbuna Falls and

the Tonkolili River confluence.

Extraction of an EIS score for the same resource unit (RDM - Kleynhans, 1999a).



Establishment of an ecological trend for the resource unit based on habitat information from

the baseline aquatic information.

Establishment of the REC based on the EcoStatus and EIS data.

Model the relationship between discharge and instream habitat.

Based on the requirements of sensitive (indicator) fish and macroinvertebrate taxa, derive the

habitat flow stressor response relationship.

Model a desktop quantity reserve from available derived average monthly flow data and habitat

flow stressor response curves for the PES.



ASSUMPTIONS AND LIMITATIONS

The section below describes the main assumptions and limitations relevant to the scope of the study:

The EFR modelling was undertaken at a desktop level, with the inclusion of three hydraulic site

measurements, associated with the resources unit, between Bumbuna Falls and the confluence

of the Tonkolili River. This level of study is normally associated with planning and, typically, a

more detailed analysis would be required to refine the EFRs for implementation in the system.

Of consideration would be:

o The feasibility of implementing the flow requirements.

o Additional hydraulic calibrations during different seasonal flows. This will increase the

confidence in the habitat frequency distribution output.

o Accounting for temporal variation within instream biota. This will further aid an

understanding of the relationship between discharge, hydraulics, habitat and instream

community.

The study focussed on ascertaining the EFRs for the instream aquatic community associated with

the resource unit assessed. The EFRs required for riparian vegetation and channel morphology

was not considered. However, the instream requirements for aquatic macroinvertebrates and

fish are generally more sensitive compared to those of the riparian structure and channel

morphology.

The study did not consider the flow requirements associated with local fishing practices, or any

socio-economic aspect thereof. Payne et al. (2010) reports that fishermen below Bumbuna Falls

stated that the colder months yielded less fish than the warmer months, while the most fish are

caught during the onset of the rainy season. The variation in catch is directly influenced by the

flow regime.

The EFRs were determined for the resource unit between the Bumbuna Falls and the confluence

of the Tonkolili River. Data availability regarding additional catchments limited the application

of the RDRM to areas downstream of the Tonkolili River catchment. This study did not consider

the flow requirements for the Rokel Estuary. The Estuary became a RAMSAR wetland of

importance in 1999.

The ecological conditions reflected by this assessment, and the subsequent environmental

inferences, are limited to a single high flow survey. Ideally the resource unit should be subjected

to a high- and a low flow assessment, in order to account for seasonal variation.

Daily operating variables such as maximum discharge ratio, maximum ramping rate and the

degree to which discharge will be regulated, all have ecological risk implications. The total



discharge associated with the Project may well be within the broad EFRs given a mean daily or

monthly view, but daily ramping rates or discharge control may be intolerable to instream biota.

The effectiveness of mitigating impacts related to these daily operational variables has not been

well studied and is poorly documented.

Operational releases (discharge, regime etc.) are not addressed in this study. Different

operational alternatives can be measured against the output of this assessment and this in turn

can inform the ecological sustainability of releases.



MATERIALS AND METHODS

This section describes the study approach and is divided into three main sections. The first section deals

with the site selection and the field assessment. The second section describes the water resource

classification applied. This relates to defining the ecological integrity, importance and sensitivity of the

resource unit included in the EFA. The third section describes the methodology applied for the RDRM.

The results from the EcoClassification informed the habitat flow stress responses for the resource unit

assessed. The future relevance of the EcoClassification is that it provides a framework in which the

resource unit can be managed. Details regarding the methods applied for the components included

within the EFA can be found in the respective appendices and is referenced here for convenience:

Water quality - Appendix A: In situ Water Quality

Diatoms - Appendix B: Diatom Assessment

Intermediate Habitat Integrity - Appendix C: Intermediate Index of Habitat Integrity

Aquatic Macroinvertebrates - Appendix D: Macroinvertebrate Assessment

Fish - Appendix E: Fish Assessment

Hydraulic Parameters - Appendix F: Tabulated Flow Volumes

3.1. SITE SELECTION AND FIELD ASSESSMENT

The names and coordinates of the three sites that were used during the July 2016 high flow assessment

are provided in Table 3-1. All three cross-sections were used to define the resource unit. The resource

unit represented the Rokel River downstream of the Bumbuna Falls up until the confluence of the

Tonkolili River.

Table 3-1: Reconciliation of site names for the aquatic ecology sites assessed and the channel cross sections completed for the EFA

Site Names Latitude Longitude

R1 9.049066 -11.743448

R2 9.055462 -11.766980

R3 9.013351 -11.805157



The tasks undertaken during the field assessment included:

A visu directly upstream and downstream of the probable EFA sites.

The selection of an appropriate EFR site which was governed by the suitability of the river

channel for accurate hydraulic modelling and flow assessment, as well as the presence of

habitats critical for ecosystem functioning, such as diversity in velocity-depth classes, cover and

substrate units. Each site was also representative of the resource unit to allow extrapolation of

the results to the resource unit.

The present condition of instream components was assessed at each site in relation to the

considered reference condition. The instream components included:

o The water quality assessed during the site visit for in situ variables.

o Inferences regarding water quality were made from the diatom community assessment

at each site assessed. The following three indices were applied, SPI (CEMAGREF, 1982),

BDI (Lenoir & Coste, 1996) and PTV (Kelly & Whitton, 1995).

o An aquatic macroinvertebrate assessment. The invertebrate specialist surveyed the

aquatic macroinvertebrates occurring within the range of habitats at each locality using

the SASS5 methodology and sampling equipment and techniques, including a

comprehensive assessment of the frequency distribution of different flow-depths and

substrate units associated with each reach assessed (Dickens & Graham, 2002).

o A fish assessment. The fish specialist sampled fish in all suitable aquatic habitats in the

vicinity of the EFR site using an electro-fish shocker and nets (Kleynhans, 2007).

Three cross-sectional profiles were surveyed by the hydraulic specialist, hydraulic data for

calibration purposes was collected and the river flow was determined.

3.2. ECOCLASSIFICATION

EcoClassification refers to the determination and categorisation of the PES of various biophysical

attributes of the aquatic resource unit in relation to a perceived reference condition (Kleynhans & Louw,

2007). The integration of the various PES categories (in this case aquatic macroinvertebrates and fish)

results in the EcoStatus. The EcoClassification process followed in this study was based on the EcoStatus

level III (Kleynhans & Louw, 2006). The level of investigation is subject to time, budget and data

availability. The EcoClassification involves the following steps:



Determining the PES for aquatic macroinvertebrates and fish components using the rule-based

EcoStatus models (Appendix D: Macroinvertebrate Assessment and Appendix E: Fish

Assessment).

Determining the EcoStatus, which involves integration of the individual Ecological Category (EC)

values of the abovementioned components to obtain an overall EcoStatus category.

Determining of the anticipated trend of the EcoStatus within a medium term (five years).

3.2.1. ECOSTATUS

The implementation of the following EcoStatus protocols for aquatic macroinvertebrates and fish were

undertaken during the high flow aquatic ecology survey (July 2016):

Macroinvertebrate Response Assessment Index (MIRAI) (Thirion, 2007).

Adapted version of the Fish Response Assessment Index (FRAI) (Kleynhans, 2007).

The results of these models provide a PES of each component based on the change from reference

(historical) conditions. Results for each response component were provided as ECs and percentages

ranging from Natural (Category A) to Critically modified (Category E or F) (Table 3-2). The individual

results were then combined according to Kleynhans & Louw (2007) to provide a single integrated

EcoStatus for the reach assessed.

Results from the population of the Index of Habitat Integrity (IHI) were used as a surrogate for driver

information (Kleynhans, 1996). Detailed methodology for the response and driver metrics used is

provided in Appendix A: In situ Water Quality to Appendix E: Fish Assessment.

Table 3-2: Generic ecological categories for EcoStatus components (Kleynhans & Louw, 2007)

Category Description

A Unmodified No impacts, conditions natural.

B Largely Natural Small changes in community characteristics, most aspects natural.

C Moderately Modified Clear community modifications, some impairment of health evident.

D Largely Modified Impairment of health clearly evident. Unacceptably impacted state.

E Seriously Modified Most community characteristics seriously modified, unacceptable state.

F Critically Modified Extremely low species diversity. Unacceptable state.



3.2.2. ECOLOGICAL IMPORTANCE AND SENSITIVITY

The ecological importance is defined by Kleynhans (1999a), and is regarded as an expression of the water

ability to maintain the ecological diversity and functioning on local and wider scales. The

ty to recover from disturbance. The EIS scores were

calculated using the Resource Directed Measures (RDM - Kleynhans, 1999a) method (Table 3-3; Table

3-4). Information from the baseline aquatic ecology assessment was taken into account when populating

the EIS scores. The EIS was used in conjunction with the integrated EcoStatus category to set the

Recommended Ecological Category (REC).

Table 3-3: Scoring guidelines for each attribute considered in determining the EIS (Kleynhans, 1999b)

EIS Scores

Very High 4

High 3

Moderate 2

Marginal/Low 1

None 0

Confidence Score

Very high confidence 4

High confidence 3

Moderate confidence 2

Marginal/low confidence 1

Table 3-4: Scoring guidelines for each attribute considered in determining the EIS (Kleynhans, 1999b)

EIS Categories Range of EIS

score Very high: Rivers that are considered ecologically important and sensitive on a national or even international level. The biodiversity of these systems is usually very sensitive to flow and habitat modifications. They play a major role in moderating the quantity and quality of water of major rivers.

>3 and <=4

High: Rivers that are considered to be ecologically important and sensitive. The biodiversity of these systems may be sensitive to flow and habitat modifications. They play a role in moderating the quantity and quality of water of major rivers.

>2 and <=3

Moderate: Rivers that are considered to be ecologically important and sensitive on a provincial or local scale. The biodiversity of these systems is not usually sensitive to flow and habitat modifications. They play a small role in moderating the quantity and quality of water of major rivers.

>1 and <=2

Low/marginal: Rivers that are not ecologically important and sensitive at any scale. The biodiversity of these systems is ubiquitous and not sensitive to flow and habitat modifications. They play an insignificant role in moderating the quantity and quality of water of major rivers.

>0 and <=1



The EIS was also informed by indicator species. These species are particularly responsive to changes in

river flow. Fluctuations in flow cause depth and velocity fluctuations, and a subsequent change in habitat.

Usually, the first habitat to be impacted with a change in the flow regime is the fast-shallow (FS), white

water (rheophilic) habitat, which will cause a decrease in rheophilic fish and macroinvertebrate taxa. Data

on the aquatic community composition from the baseline data collected during July 2015 surveys was

used to pin-point sensitive taxa that may be used as indicators for application within the EFA. Rheophilic

taxa were selected based on a combination of scores assigned in the FRAI and MIRAI EcoStatus models

(Kleynhans, 2007; Thirion, 2007), ecological information collected for each fish species (Paugy et al., 1990;

Skelton, 2001; Paugy et al., 2003; Payne et al., 2010 and IUCN, 2014) and expert opinion. Refer to Table

10-7 and Table 10-8 in Section 10 for a list of species sampled, and their associated habitat preferences

and tolerances.

3.3. DESKTOP ECOLOGICAL RESERVE MODEL

The approach used is the so- et al., 2014) that

has been developed for environmental flow determinations (referred to as the ecological reserve) in

South Africa. The approach involves integrating hydrological, hydraulic (channel cross-sections) and

ecological habitat data to establish a modified flow regime that is expected to achieve some level of

ecological functioning relative to the natural condition. It is always assumed that the level of ecological

functioning is determined through a combination of ecological objectives (e.g. preservation of sensitive

habitats) and water use and development objectives.

The hydrological data typically consists of time series of natural (unmodified) monthly flows that may

either be obtained from observations or from hydrological models or a combination of both. The model

can also make use of hydrological data that represents present day (or some future possible scenario)

flow conditions for comparative purposes.

The channel cross-sections and hydraulic data can be generated within the model using regionalized

parameters or the model can make use of surveyed channel cross-sections and some sample gauging

data to establish the necessary hydraulic parameters that include the water energy gradient and the

hydraulic roughness. The hydraulic habitat types are based on a combination of velocity and depth and

are shown in Table 3-5. The hydraulic sub-model calculates the frequency distribution of different

hydraulic habitats based on a combination of depth and velocity (slow-very shallow (SVS), slow-shallow

(SS), slow-deep (SD), fast-very shallow (FVS), fast-shallow (FS), fast-intermediate (FI) and fast-deep (FD)

for all possible flow rates in m³s-1).



The ecological sub-model for low flows uses a combination of the hydrological and hydraulic data to

estimate relationships between flow rates (discharge) and an index of ecological stress (based on a scale

of 0 10, where 0 is no stress and 10 is equivalent to zero flow conditions), which is based on the relative

loss of the fast flowing habitats as the flow reduces. These analyses are performed separately for two key

months representing the main wet and dry seasons. The model calculates and graphs the frequency of

exceedance of different stress levels under natural hydrological conditions (and present day if such flow

data is included). The model user is able to adjust a set of parameters to establish stress frequency curves

that are considered appropriate given the ecological objectives and the type of biota present in the river

(typically based on ecological surveys by a set of specialists). The modified stress frequency curves are

then transformed into environmental flow requirement assurance curves and compared graphically to

the natural flow duration curves for the two key months. The low flow requirements for the remaining

10 months of the year are calculated using an interpolation process.

The ecological requirements for high flows are estimated in a much more simplistic manner and related

to the expected proportions of the total natural flow that are considered to be infrequent or seasonal

high flows compared with more continuously varying low flows (typically referred to as baseflows). The

high and low flows are then combined to generate the output as a time series of monthly flow volumes

that represent the environmental flow requirements for the specific channel cross-section.

Table 3-5: Hydraulic habitat types and their definitions

Habitat Type Depth (m) Velocity (m s-1) Fast Deep (FD) >0.3 > 0.3

Fast Intermediate (FI) > 0.2; > 0.3 Fast Shallow (FS) > 0.1; > 0.3

Fast Very Shallow (FVS) > 0.3 Slow Deep (SD) >0.5

Slow Shallow (SS) Slow Very Shallow (SVS)

3.3.1. CHANNEL CROSS-SECTION SELECTION

A total of three channel cross-sections were surveyed in the field. All three cross-sections were located

below the Bumbuna Falls, but upslope from the Tonkolili River confluence. After careful consideration of

the hydraulic characteristics of the sites, it was decided to make use of cross-section R2 as a suitably

representative site for the environmental flow determinations (see Table 3-1 for site coordinates). The

characteristics of the cross-section are illustrated in Figure 3-1 and the channel dimensions are

represented by Figure 3-1A, while the stage discharge curve (Figure 3-1B), showed the respective

relationship between discharge and depth for the preferred hydraulic cross section. Table 3-5 includes



the discharge stage (depth) rating curve shown in the lower part of the diagram (Figure 3-1B). This

curve approximately passes through the single gauging observation that was available from the July 2016

field survey (43.6m³s¯¹ at a depth of 1.54m).

Figure 3-1: A: Channel CROSS section of R2. B: Stage discharge curve showing the relationship between depth and discharge for R2.

Table 3-5: Input data for the RDRM hydrological sub-model

Hydraulic Parameter Value

Geomorphological zone 5

Flood region 7

Hydrological variability 2.31

Valley slope fraction 0.002

Catchment area (km²) 3999

Width v Qc power 0.75

Width v Qc constant 0.30

Maximum depth (m) 4.4

Maximum width (m) 648.12

Bed width (fraction) 0.6

Macro roughness (m) 1.32

Micro roughness (m) 0.002

Maximum gradient 0.005

Minimum gradient 0.002

Gradient shape factor 11

Maximum Manning n 0.151

Minimum Manning 0.07

n Shape factor 21



3.3.2. HYDROLOGICAL DATA

Modelled hydrological information for the Rokel River was available from Annexes three and four,

obtained from the Feasibility Study Volume III-2 (2012). The available hydrological data consist of

simulated flows for a period of some 50 years for both the assumed natural flow regime as well as for the

hydro-power release regime under present day conditions (Figure 3-2).

Figure 3-2: Time series of monthly stream flow data used as input to the model.

3.3.3. SPECIALIST WORKSHOP (ECOCLASSIFICATION WORKSHOP)

The results of the field assessments of the various habitat and biotic components to obtain the EcoStatus

and the REC were compiled after the completion of the site visit. This assessment took place during the

EcoClassification workshop. This process included the determination of the following:

Reference conditions: Are conditions that occur under natural conditions before anthropogenic

impacts.

PES or EcoStatus: The determination of the current state of the reach through rule-based models

for the biological response components (FRAI and MIRAI). A rule-based model is used to derive

the EcoStatus or overall condition or health of the resource unit by integrating the driver and

response status.



Trends: This is the reaction of the components to changes in the catchment and can be stable,

positive or negative.

The EIS: The EIS model (Kleynhans, 1999, updated 2002) was used to determine the EIS.

The IHI (Kleynhans, 1996) was used to evaluate the habitat integrity of both the instream and

riparian components. This assessment model is based on the qualitative assessment (allocation

of scores) for various impact criteria on both the instream and riparian zones.

The REC: The PES and EIS were used in the classification of the REC.

Habitat flow stressor response curves for different discharges for aquatic macroinvertebrates

and fish.



RESULTS AND DISCUSSION

4.1. REGIONAL CONTEXT

The study area falls within the Northern Upper Guinea aquatic ecoregion. The Northern Upper Guinea

ecoregion lies on the western side of the Guinean range, extending from the foothills of the Fouta Djalon

-Bissau

and Liberia. The relatively short rivers of the ecoregion descend from the Guinean Dorsale and cross the

coastal plain adjacent to the Atlantic Ocean. The climate of the ecoregion is tropical and wet, with rainfall

influenced by the moist southwest trade winds. The ecoregion receives heavy but seasonal precipitation

with concentrated rain during August to September. Approximately 30% of the fish fauna described for

this ecoregion is endemic to it.

The Rokel/Seli River drains the uplands of northern Sierra Leone at altitudes of 300-400m amsl.

Payne et al. (2010) highlights the falls as an important feature marking the transition from the upper to

the lower parts of the River.

4.2. SITE DESCRIPTIONS

Aerial views and bank photographs illustrating the location and general bank features at each site, are

provided in Table 4-1, Table 4-2 and Table 4-3. Hydraulic data are summarised in Table 4-4. The spatial

and temporal variation within the channel profiles illustrate heterogeneity within channel bed and banks.

The variation in bed and bank conditions translate into habitat availability.

Table 4-1: Site description for site R1



Location

Site is located downstream of Bumbuna Falls but upslope of Bumbuna bridge. The channel cross-section includes run rapid sequence to the centre and left bank, with a bedrock pool associated with the right bank.

Habitat type River Channel morphology Bedrock, gravel sand and mud.

Canopy cover Dense cover within marginal zone, approximately 5m of overhanging riparian vegetation, measured

Channel Dimensions

Macro-channel width (m) 200m Active-channel width (m) 150m Water surface width (m) 105m Bank height (m) 4m Cross Sectional Features

High terrace Present Terrace Present Flood bench Present Dominant Physical Biotope

Habitat Bedrock, gravel, sand and mud. Velocity depth classes FD and SD Discharge (m³s) 44.846m³s¯¹


Location Site is located 2.3km downstream of Bumbuna bridge.

Habitat type River

Channel morphology Bedrock, gravel sand and mud.

Canopy cover

Dense cover within marginal zone, approximately 7m of overhanging riparian vegetation, measured from approximately 44m³s¯¹.

Channel dimensions

Macro-channel width (m) 110m

Active-channel width (m) 87m

Water surface width (m) 78m

Bank height (m) 4m



Cross Sectional Features

High terrace Present

Terrace Absent

Flood bench Present

Dominant Physical Biotope

Habitat Bedrock, gravel, sand and mud.

Velocity depth classes FD and SD

Discharge (m³s) 43.576m³s¯¹


Location Site is located 8.23km downstream of R2.

Habitat type River

Channel morphology Bedrock, gravel sand and mud.

Canopy cover Dense cover within marginal zone, approximately 6m of overhanging riparian vegetation, measured

pproximately 48m³s¯¹. Channel dimensions

Macro-channel width (m) 100m

Active-channel width (m) 87m

Water surface width (m) 80m

Bank height (m) 4m

Cross Sectional Features

High terrace Present

Terrace Absent

Flood bench Present

Dominant Physical Biotope

Habitat Bedrock, gravel, sand and mud.

Velocity depth classes FD and SD

Discharge (m³s) 48.244m³s¯¹



Table 4-4: Hydraulic data collected July 2016

Cross Section

Max. Depth (m)

Av. Depth (m)


Width (m) Perim. (m) Av. Velocity

(m.s¯¹) R1 4.85 3.350 44.85 51.10 54.20 0.26

R2 1.54 0.92 43.57 33.30 33.80 1.43

R3 3.769 2.465 48.244 47.490 49.390 0.410

Av.: Average, Max.: Maximum, Perim.: Perimeter

4.3. SUMMARY OF ECOLOGICAL INFORMATION

A summary of the results of the EcoStatus models and driver variables (in situ water quality) assessed is

provided in Table 4-5, and is discussed below:

Water quality: The pH values, observed during July 2016, varied from 7.54 and 8.6, while the

perature varied

between 24.5 and 28.5°C (see Table 6-3 in Appendix A: In situ Water Quality). These

observations compare well with those of Payne et al. (2010) who measured pH values between

6.8 and 7.8, with electrical conductivity values ranging from 14 and 55µS-

temperatures ranged between 21 - 32°C.

Diatoms: The diatom assemblages were generally comprised of species characteristic of

circumneutral, fresh waters with high oxygen levels. The diatom communities at each site

indicated oligo-to mesotrophic conditions. All sites had low %PTV scores and the ecological

water quality was Good, indicating that there was no evidence of organic pollution entering the

system (see Table 7-5 in Appendix B: Diatom Assessment).

Intermediate Index of Habitat Integrity: The IHI score fell within a C EC which translates to a

Moderately modified state, where clear alteration to the natural instream and riparian habitat

has occurred but the basic habitat structure and functions are still present. The main driving

variables responsible for the decline in habitat integrity include flow modification, alteration in

the extent of inundation and vegetation removal from the non-marginal riparian zone (see Table

8-4 in Appendix C: Intermediate Index of Habitat Integrity).

Macroinvertebrate Response Assessment Index: The resource unit fell in a D EC, based on

invertebrate assemblages, inferring a Largely modified state, where the alteration within

invertebrate assemblages is clearly evident. The MIRAI model highlighted flow modification,

alteration in instream habitat and change in seasonality as the driving variables responsible for

the decline in ecological integrity of the system (see Table 9-10 in Appendix D:

Macroinvertebrate Assessment).



Fish Response Assessment Index (adopted from Kleynhans, 2007): The EcoStatus of the resource

unit, as indicated by the fish assemblage, fell into a C/D category which translates into a

Moderately to Largely modified state, with clear alteration within the fish assemblage (see Table

10-6 and Figure 10-4 in Appendix E: Fish Assessment). The status assessment is a function of

the difference in the frequency of occurrence of expected and sampled fish. The main reasons

for the loss of ecological integrity primarily relate to an alteration in the natural flow regime of

the system. This is most notably expressed by the digression in flow related metrics between

expected and sampled fish. Metrics reflecting the most digression, include a loss of fish with

specific requirements for: (1) vertical zonation (benthic and benthopelagic), (2) migration

(potamodromous), (3) velocity depth (units related to FS and SS), (4) spawning times and (5) fish

with specific reproductive strategies.

Table 4-5: Summary of baseline information collected during July 2016

Cross Section

IHI Diatoms MARAI FRAI Flow-depth Cover/

substrate

R1 C Good D C/D FD>SD

Overhanging vegetation,

bedrock, sand and

mud



bedrock, sand and

mud



bedrock, sand and

mud

4.4. CONFIDENCE RATINGS

The available information for the EFR sites is summarised in Table 4-6. The summary is linked to Reserve

Determination levels for the various scores (Kleynhans & Louw, 2006). Data availability on a Rapid

Reserve level has a score of 0-2, the Intermediate level a score of 3 and the Comprehensive level a score

of 4. Note that a Comprehensive level requires four biomonitoring assessments over different seasons

and four hydraulic calibrations. Reasons informing the confidence scores are provided in the comments

column of Table 4-6, but the main limiting factor influencing the confidence score is the lack of

information regarding seasonal variation and only a single hydraulic calibration done during the July 2016

assessment. The overall confidence of the EFA should be improved prior to creating operating rules.



Table 4-6: Availability of information for each specialist component and sources of information, where a confidence rating of 4 is high and a score of 0 indicates no confidence

Component Confidence Level

Comments

Water Quality 2 No long term monitoring data available. Inferences regarding water quality was further aided by the diatom assessment during July 2016.

Habitat Integrity 2

Single high flow assessment. Low level habitat survey (IHI on a site level). Satellite image (Google Earth). Site photos.

Aquatic macroinvertebrates

2

Single high flow assessment. Ecological preferences from MIRAI (Thirion, 2007) (refer to Table 9-8 in Appendix D: Macroinvertebrate Assessment).

Fish 3

High flow assessment restricted access and decreased sampling efficiency. IUCN (2014) information on ecology and threats for 50% of the expected fish. Ecological inferences were aided by information from Paugy et al. (1990), Paugy et al. (2003), Payne et al. (2010) and Skelton (2001). Ecological preferences were compiled and partially informed by the FRAI (Kleynhans, 2007; Payne et al., 2010) (see Table 10-7, Table 10-8 in Appendix E: Fish Assessment). Fish data from four sampling seasons obtained for relevant reach from Payne (Personal communication).

Hydrology 2 Only modelled flow available. Only one calibration for modelled flow during high flow conditions.

Hydraulics 2 Single hydraulic calibration during high flows only. Low flow rating curve had to be adjusted and carries a low confidence.

4.5. ECOSTATUS DETERMINATION

A Level III EcoClassification was completed for the resource unit by combining the field data for sites R1,

R2 and R3 (Kleynhans & Louw, 2006). The EcoStatus percentage and categories along with a short

justification is provided in Table 4-7. The overall EcoClassification for the resource unit is a D category

and relates to a Largely modified state. The EcoClassification thus infers that under current catchment

uses and present day flow conditions the system is in an impaired state. Note that the classification is

based on a comparison of the July 2016 field observations and constructed reference conditions.



Table 4-7: Summary of integrated EcoStatus results. The importance score refers to the importance as an indication of the PES where 1=Low and 5=High

Instream Biota Importance Score

Weight EC% EC

Aquatic Invertebrates Natural diversity of invertebrate biotopes 2 70% Natural diversity of invertebrate taxa with different velocity requirements

2 70%

Natural diversity of invertebrate taxa with different tolerances to modified water quality

3 100%

Aquatic Invertebrate Ecological Category

7 240 42.2 D

Fish Natural diversity of fish species with different flow requirements

5 100%

Natural diversity of fish species with a preference for different cover types 3 90%

Natural diversity of fish species with a preference for different flow depth classes

5 80%

Natural diversity of fish species with various tolerances to modified water quality

4 80%

Fish Ecological Category 11 350 58.0 C/D Instream Ecological Category (No Confidence)

590 48.6 D

4.6. TREND IN PRESENT ECOLOGICAL STATE

A trend assessment of the EcoStatus trajectory is provided in Table 4-8. The trend assessment considers

the current state of the catchment and existing stress experienced by the resource unit, and comments

on the resilience of the resource unit under these conditions. The confidence is Moderate to Low due to

uncertainties related to possible increases in use of the resource unit within the medium term. However,

provided that catchment conditions and existing use of the resource unit remain the same, within the

medium term, it is expected that the habitat and invertebrate assemblages will remain stable while fish

assemblages may decrease further (Table 4-8).



Table 4-8: Trend assessment for each component. Confidence ratings scored from 1= low confidence to 4= high confidence

Component Trend Confidence Reason

Habitat Stable 2

The resource unit is likely to remain intact over the medium term (five years), although some modification due to catchment scale, river bank cultivation and deforestation may impact on the instream and riparian integrity within the long term.

Aquatic macroinvertebrates

Stable 2

69% of the expected and sampled aquatic macroinvertebrates reflect a tolerance or moderate tolerance to changes in water quality, while 67% of the expected and sampled species are tolerant and moderately tolerant to flow variation.

Fish Negative 2

Although the sampled fish assemblage reflected a Moderate to Large digression from the reference assemblage, a number of sensitive fish remained. Nine of the twenty-two species sampled reflected an intolerance or moderate intolerance to alteration in water quality and flow (see graphs in Figure 10-5 and Figure 10-6 in Appendix E: Fish Assessment). A long term loss in habitat diversity associated with an increase in dry season baselflows is likely to further impact on fish assemblages. Prolonged decreases within intra-annual flow variation is likely to impact on fish requirements, such as migration and spawning cues, flushing of eggs and larva and the quality of spawning habitat. Without consideration of these aspects a further decrease in fish assemblage integrity is expected over the medium term.

4.7. ECOLOGICAL IMPORTANCE AND SENSITIVITY

The EIS scores for the resource unit is Moderate to High (Table 4-9). The resource unit is considered to

be ecologically important and sensitive. The biodiversity of these systems are sensitive to flow and habitat

modifications. Table 4-9 provides details of the different components included within the EIS and a

justification for the scores assigned to each component.



Table 4-9: Ecological Importance and Sensitivity scores and confidence levels associated with each site assessed. Ratings vary from 1 (low) to 4 (high)

Determinant Score Confidence Reason

Primary Determinants

Rare and endangered species

4 3

The revised expected list reflects the possible occurrence of five NT fish species: (1) Leptocypris guineensis, (2) Ichthyborus quadrilineatus, (3) Raiamas nigeriensis, (4) Synodontis tourei and (5) Petrocephalus levequei (see Table 10-5 in Appendix E: Fish Assessment).

Populations of unique species

3 2

17 out of the revised expected 45 fish species are regional endemic species. Six of these (Tilapia louka, R. steindachneri, S. thysi, Hippopotamyrus paugyi, Marcusenius thomasi and P. levequei) have been sampled during July 2016. While five species, namely Petrocephalus levequei, Leptocypris guineensis, Raiamas scarciensis, Clarias laeviceps and Synodontis thysi are endemic to Sierra Leone and South west Guinea.

Species/taxon richness

3 2

A relatively high number of species in relation to catchment size (Payne et al., 2010). In this relatively small river basin eight species of true tilapia have been recorded previously, compared to four in the Nile basin (Payne & Collinson, 1983) and six in the Niger basin.

Diversity of habitat types or features

2 3

Dominated by overhanging vegetation, undercut banks and root wads associated with SD and FS velocity-depth units. Large intra-annual variation in discharge result in some increase in FS and SS units associated with suitable substrate. Flood plains or large annual flood benches are generally poorly developed or absent.

Migration/breeding and feeding for instream species

3 2

65% of revised expected species are potamodromous and require upstream migration and associated flow and spawning ques (see Figure 10-5 and Appendix E: Fish Assessment).

Sensitivity to changes in the natural hydrological regime

3 2

The resource unit is highly responsive to rainfall and reflects large intra-annual variation in flows. During the main dry season month (April) the natural baseflow varies from less than 2m3s-1 to about 14m3s-

1, while during the main wet season month (October) baseflow varies from slightly less than 50 m3s-1 to over 100m3s-1. Habitat units related to FS, FI are FVS are optimally represented during lower flows (<11.5m3s-

1). These units are thus hydraulically sensitive and play an important role in sustaining the dynamics within fish and



Determinant Score Confidence Reason

macroinvertebrate community assemblages.

Sensitivity to water quality changes

3 2

33% of expected species reflect an intolerance or moderate intolerance for alteration in water quality. Nine of the 22 species sampled reflected an intolerance or moderate intolerance to alteration in water quality and flow (see graphs in Figure 10-5 and Figure 10-6 in Appendix E: Fish Assessment).

Flood storage, energy dissipation and particulate/element removal

2 2

Under natural conditions the wet season baseflow varies from 50m3s-1 to over 100m³s¯¹, while for the dry season they vary from about 2m³s¯¹ to 14m³s¯¹. The large difference between wet and dry season flows indicate that flow in the river responds rapidly to rainfall and flood storage and baseflow augmentation is subsequently relatively limited.

Baseflow augmentation; dilution

2 3 See above, the resource unit reflects low dry season baselflows.

Modifying Determinants

Protected status area 0 4

The resource unit does not fall within any category of protected status that reflects its importance for the conservation of ecological diversity at any scale. However, the system does run into the Rokel Estuary which is a RAMSAR site.

Ecological importance (rarity of size/type/condition) local, regional or national context

3 3

The resource unit provides a relatively diverse instream habitat template with well-developed and utilised riparian features. The unit is considered important on a regional scale.

TOTAL 28 28 MEDIAN 3

4.8. RECOMMENDED ECOLOGICAL CATEGORY

In theory, if the EIS of a system is rated as High, the ecological aim should be to improve the river, and

the PES is usually adjusted up a category as per the rule-based process in the Reserve Determination

(IWR, 2004). If the EIS is Moderate or Low, the ecological aim should be to maintain the river in its

assessed PES. This management approach is based on the premise that the ability of the resource to

continue its ecosystem services is directly linked to its ecological integrity, which is expressed within the

REC. (Table 4-10). The PES of the resource unit fell into a D category, while the EIS was considered as



High. The management of the resource should thus aim to improve the system to a C category and if not

possible maintain it in a D category. Note that the focus of the EFA primarily fell on the protection of

category C level of protection.

Table 4-10: Recommended Ecological Category based on PES and EIS

EcoStatus EIS Category REC

D High C

4.9. ECOLOGICAL RESERVE MODEL

4.9.1. DISCHARGE (FLOW) HABITAT RELATIONSHIPS

One of the key outputs from the hydraulic analysis component of the model is the habitat frequency

diagram that shows the frequency of available habitats for the different discharges (Figure 4-1). The

different habitats are defined as slow very shallow (SVS), slow shallow (SS), slow deep (SD), fast very

shallow (FVS), fast shallow (FS), fast intermediate (FI) and fast deep (FD). From the available hydrological

data, it is apparent that natural low flows during the dry season can be as low as about 2m³s¯¹ at which

point the maximum depth would be about 0.6m and the wetted channel width some 40m. There is very

little (10% of wetted width) fast flowing habitat available at this discharge. As the flows increase the

habitat diversity increases until at about 12m³s¯¹. At flows exceeding 12m³s¯¹ the fast deep and slow deep

habitats dominate and the full width (about 80m) of the main channel is occupied by flow.



Figure 4-1: Discharge habitat relationship for R2.

4.9.2. FLOW (HABITAT) AND STRESS ASSESSMENT

Ascertaining the instream flow requirements is a function of the hydraulic response of the resource unit

to variation in discharge. The hydraulic variation directly influences the habitat availability. The Habitat

requirements and ecological parameters for macroinvertebrates are noted in Table 9-8 in Appendix D:

Macroinvertebrate Assessment and for fish in Figure 10-5A-D and Figure 10-6A-D in Appendix E: Fish

Assessment, while a detailed discussion on the flow sensitive indicator species/ taxa selected for the flow

(habitat)-stress assessment is provided in Section 9.2.4 for invertebrates and in Section 10.2.4 for fish.

The following section provides details of the habitat stress and responder assessment. Figure 4-2 and

Figure 4-3 provide the habitat flow stressor response curves for decreased flows associated with the dry

season baseflows and wet season baseflows respectively, while Figure 4-4 indicates the stress

relationship for increased baseflows during the dry season. Based on the habitat frequency distribution

(Figure 4-1), the proportional representation of habitat is optimised at approximately 11m³s¯¹. At this

discharge the system is experiencing zero habitat stress. The representation of FD, FS and SD habitats

were considered important (based on the flow requirements of indicator species), and a steady reduction

in FD and SD are noted between 11m³s¯¹ and 3.8m³s¯¹. At discharges below 3.8m³s¯¹ there is a rapid

decrease in both hydraulic units and a subsequent increase in stress levels.



Wet season baseflows allow for a more dramatic reduction in flows (from approximately 90m³s¯¹ to

22m³s¯¹) between a stress level of zero and three. This is due to the dominance of FD and SD habitats at

flows in excess of 20m³s¯¹.

The stress curve for an increase in dry season baseflows reflect the rapid loss in FS, FI and SS habitat units

at flows in excess of 15m³s¯¹ (Figure 4-4). The intra-annual variation in flow provides important habitat

variations. This variation is more pronounced during the dry season period (discharge < 11m³s¯¹) (Figure

4-1). An increase in FS and FI during dry season baseflows are important for spawning, fry nursing and

juvenile recruitment (Kraft, 1972; Kingsford, 2000). These flow conditions are also associated with a

higher macroinvertebrate diversity which is required to sustain the fish community (Faragher & Harris,

1994). The decrease in FD and SD habitats (within the natural limits) results in a natural stress that acts

as a primary control for the fish and macroinvertebrate dynamics. Maintaining this control mechanism

has also been shown to impede the invasion of alien species (Kroger, 1973; Bun et al., 2002).

Figure 4-2: Habitat flow stressor response curve for decreased flows during dry season baseflows.



Figure 4-3: Habitat flow stressor response curve for decreased flows during the wet season baseflows.

Figure 4-4: Habitat flow stressor response relationships for the dry months under higher flows than natural conditions associated with hydro-power releases.

4.9.3. ECOLOGICAL FLOW REQUIREMENTS

It is recognized that under future conditions the hydro-power releases will be returned to the channel of

the Rokel River approximately 2.5km below the dam wall and that within this channel reach there are

some ecologically important areas (rapids and waterfalls). The key environmental flow requirement issue

in this channel reach is therefore to ensure that some flow is maintained in the channel through releases

directly from the Bumbuna Dam into the channel. This is referred to in th



EF -power releases are returned to the

channel the key issue is the loss of habitat diversity due to elevated low flows. Establishing the EFR for

these channel areas involves quantifying the seasonal pattern of reductions in hydro-power releases that

are required to ensure some habitat diversity and this is referred to in this report

EF

LOWER FLOWS ECOLOGICAL FLOW REQUIREMENTS

The basic principles of the approach used for the lower flows EFR is to establish appropriate relationships

between ecological habitat stress (between 0 and 10) and discharge for the main wet and dry season

months and then to identify the frequency with which key stress levels should be equalled or exceeded

within an acceptable flow regime (see Figure 4-2). The natural flow regime variations are then used to

determine a future flow regime that will satisfy these stress requirements. Figure 4-5A-C illustrates the

approach as well as the flow-stress relationships and stress frequency curves that were used in this

analysis. In Figure 4-5B and C the black line represents natural stress conditions, the grey line the present

day and the blue line the stress conditions adopted as the required EFR for this study (the other lines can

be ignored as no attempt was made to quantify EFRs for different levels of environmental protection).

The EFR stress frequency curves (blue lines) are then used together with the flow-stress relationships and

the natural flows to generate time series of EFR flows (with interpolation from the main wet and dry

months for the remaining months of the year). In this study no allowance has been made for additional

high flow releases as the so-called baseflow requirements are seen as adequate for the desired habitat

diversity. Figure 4-6 illustrates a 20-

of the natural flows and a mean annual volume of 383*106m3. The full time series of all monthly flow

volumes are tabulated in Appendix F: Tabulated Flow Volumes.



Figure 4-5: (A) Flow-habitat stress relationships for the wet and dry seasons, (B) Habitat stress frequency curves for the wet season, (C) Habitat stress frequency curves for the wet season.

Figure 4-6: Example time series pedownstream hydro-power releases.



The approach for the higher flows EFR started with the ecologists specifying a flow-stress relationship

that is the reverse of the type of relationship used in the previous section, i.e. increasing stress with

increasing flows to reflect the problem of reduced habitat diversity with increasing flows during the dry

season months. This relationship is shown in Figure 4-4. The next step was to fit a non-linear equation to

the curve and the most appropriate equation was found to be:

Discharge = 0.68 * Stress2.4 + 11.5 or Stress = ((Discharge 11.5) / 0.68)0.417

The non-linear equation was used to convert the monthly time series of present day mean monthly

discharge into a time series of habitat stress, after which the stress values for the dry season months of

February to May were ranked (separately for each month). The ecology specialists provided a table of

frequencies of exceedance of stress for the two main dry season months (March and April) as well as for

the other two months (Table 4-11). These frequencies were designed to increase the level of habitat

diversity quite substantially during the two main dry season months (hence lower stress and therefore

lower flows) and to add some additional diversity during the other two months.



Freq. (%) of Exc. Stress Freq. (%) of Exc. Stress

80 0 90 4

20 3 60 5

0 5 0 7

The stress values in Table 4-11 were used to create an alternative ranking of stress values for each of the

months and the two rankings (present day stress and EFR stress) were used as lookup tables in excel to

modify the present day time series of stress into a time series of required stress values for the EFR. The

stress to flow conversion equation was then used to create the

in Figure 4-7. The present day mean annual volume is some 3 235*106m3, while the EFR represents a

mean annual volume of 2 711*106m3, a 16% reduction in the volume of water released for hydro-power.

However, given that stream

volume would be slightly less. Note that no other

months of the year apart from February to May have been changed and the green lines in Figure 4-7 are

over the red lines for the non-dry season months. The extra flow derived from the upstream releases



during the wet season would have no negative ecological consequences as the present day flows are

already well below the natural wet season flows.

Figure 4-7: Fdownstream hydro-power releases.



CONCLUSION

It should be recognised that flow is a primary determinant of the physical habitat within the resource

unit, this in turn dictates the biotic composition. Under present conditions a digression from reference

conditions have been measured for fish and aquatic macroinvertebrates with both response models

indicating a flow related stress. Under present day conditions that are dominated by the hydro-power

releases, the minimum wet season flows increase to about 70m³s¯¹ and therefore the habitat conditions

during the wet season are not changed very much. During the dry season the present day flows vary in a

fairly narrow range between 60 and 80m³¯¹ and therefore the habitat conditions are very similar to the

natural wet season and dominated by FD habitat. Habitat diversity during dry months is a key issue and

is a natural function of lower flows. A subsequent ecological stress is anticipated as minimum low flows

about 15m³s¯¹, which is well below the rate of flows proposed for the Yiben Dam expansion. Table 5-1

shows the frequencies of exceedance of stress for the two main dry season months (March and April) as

well as for February and May. These frequencies were designed to increase the level of habitat diversity

quite substantially during the two main dry season months (hence lower stress and therefore lower flows)

and to add some additional diversity during the other two months.



Freq. (%) of Exc.

Stress Discharge

(m³s¯¹) Freq. (%) of

Exc. Stress


80 0 11 90 4 30

20 3 21 60 5 44

0 5 44 0 7 84



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Niokolo Koba National Park, Senegal: a unique example of an undisturbed West African

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Albania using Benthic Macroinvertebrates as Bio-indicators of Water Quality. Balwois

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and their breeding behaviour in the Blyde and Spekboom rivers. Unpublished M.Sc Thesis,

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APPENDIX A: IN SITU WATER QUALITY

6.1. MATERIALS AND METHODS

In situ physico-chemical variables were measured during the aquatic surveys using a pre-calibrated multi-

parameter water quality meter (Table 6-1). The water quality results were compared to benchmark

criteria compiled by Kotze (2002) consisting of Target Water Quality Ranges (TWQRs - DWAF, 1996) and

source water quality guidelines used by Rand Water (Steynberg et al., 1996; Rand Water, 1998) (Table

6-2).

Table 6-1: In situ water quality parameters measured

In situ parameters Abbreviation Units

pH pH [H¹+ ions]

Temperature Temp °C

Electrical Conductivity EC µS-

Total Dissolved Solids TDS ppm

Time T 24h

Table 6-2: Benchmark criteria for Ideal, Tolerable and Intolerable values for major ions (Kotze, 2002)

Parameter Ideal Tolerable Intolerable

EC <450* 450 - 1000* >1000*

pH 6.5-8.5# 5-6.5 & 8.5-9# <5 & >9#

* = µS- # = [H¹+ ions]

6.2. RESULTS AND DISCUSSION

The Rokel River system has low mineralization with a low buffering capacity as shown in a study carried

out in 2010, which took place over a 12-month period (Payne et al., 2010). Over this period the pH values

varied from 6.8 - 7.8 with EC values ranging from 14 - 55µS- ile temperatures ranged between

21-32°C.

In general, the in-situ water quality associated with the study sites during the July 2016 assessment were

characterised by circumneutral pH values with very low salt loads (Table 6-3). The main points are briefly

discussed below:



With the exception of site R1, both the pH and EC values for the most part fell within the ideal

range for the protection of aquatic ecosystems (Table 6-3). The pH value at site R1 was elevated

and fell just outside the ideal range (> 8.5) and was considered Tolerable according to benchmark

criteria (Table 6-2).

The pH values ranged from 7.54 to 8.66 at the upstream site (R1), while the EC values varied

between 27-34 µS- Figure 6-1).

The EC values during the July 2016 assessment fell within the range recorded by Payne et al.

(2010) however, the pH value at site R1 was elevated and fell outside this range.

Table 6-3: Water quality values for sites located on the Rokel River, July 2016

Variable Abb. Unit R1 R2 R3

pH pH [H¹+ ions] 8.66 7.54 7.80 Electrical Conductivity EC µS- 34.3 27.0 30.0 Total Dissolved Solids TDS ppm 22.4 19.5 22.8 Temperature Temp. °C 24.5 26.0 28.5 Time T 24h 08:46 10:08 11:50 Tolerable (Kotze, 2002)

Figure 6-1: The pH and EC values for sites located on the Rokel River, July 2016.

0

5

10

15

20

25

30

35

40

6.87

7.27.47.67.8

88.28.48.68.8

R1 R2 R3

EC (

µS-

pH [

H¹+

ions

]

Electrical Conductivity pH



APPENDIX B: DIATOM ASSESSMENT


Diatom laboratory procedures were carried out according to the methodology described by Taylor et al.

(2005). Diatom samples were prepared for microscopy by using the hot hydrochloric acid and potassium

permanganate method. Approximately 300 to 400 diatom valves were identified and counted to produce

semi-quantitative data for analysis. Prygiel et al. (2002) found that diatom counts of 300 valves and above

were necessary to make correct environmental inferences. The taxonomic guide by Taylor et al. (2007)

was consulted for identification purposes. Where necessary, Krammer & Lange-Bertalot (1986, 1988,

1991 a, b) were used for identification and confirmation of species identification. Environmental

preferences were inferred from Taylor et al. (2007) and various other literature sources as indicated in

the discussion section to describe the environmental water quality at each site.

Two indices, namely the Specific Pollution Index (SPI; CEMAGREF, 1982) and the Biological Diatom Index

(BDI; Lenoir & Coste, 1996) were used in the diatom assessment. The SPI has been extensively tested in

a broad geographical region and integrates impacts from organic material, electrolytes, pH, and nutrients.

In addition, the Percentage of Pollution Tolerant Valves (%PTV; Kelly & Whitton, 1995) was used to

indicate organic pollution. The overall ecological water quality classes were determined using the SPI and

BDI in conjunction with the %PTV scores. All calculations were computed using OMNIDIA ver. 4.2 program

(Lecointe et al., 1993).

The limit values and associated ecological water quality classes adapted from Eloranta & Soininen (2002)

were used for interpretation of the SPI and BDI scores (Table 7-1). The SPI and BDI indices are based on

a score between 0 20, where a score of 20 indicates no pollution and a score of zero indicates an

increasing level of pollution or eutrophication. The %PTV has a maximum score of 100, where a score

above 0 indicates no organic pollution and a score of 100 indicates definite and severe organic pollution

(Table 7-2).



Table 7-1: Class values used for the Specific Pollution Sensitivity Index and the Biological Diatom Index in the evaluation of water quality (adapted from Eloranta & Soininen, 2002)

Index Score Class >17 High quality

13 to 17 Good quality 9 to 13 Moderate quality 5 to 9 Poor quality

<5 Bad quality

Table 7-2: Interpretation of the Percentage of Pollution Tolerant Valves scores (adapted from Kelly, 1998)

%PTV Interpretation

<20 Site free from organic pollution.

21 to 40 There is some evidence of organic pollution.

41 to 60 Organic pollution likely to contribute significantly to eutrophication.

>61 Site is heavily contaminated with organic pollution.


Diatoms are the unicellular algal group most widely used as indicators of river and wetland health as they

provide a rapid response to specific physico-chemical conditions in water and are often the first indication

of change. The presence or absence of indicator taxa can be used to detect specific changes in

environmental conditions such as eutrophication, organic enrichment, salinization and changes in pH.

They are therefore useful for providing an overall picture of trends within an aquatic system.

7.2.1. ECOLOGICAL DESCRIPTORS

The ecological classification for water quality according to Van Dam et al. (1994) and Taylor et al. (2007)

is recorded in (Table 7-3). The diatom assemblages mainly comprised of species with a preference for

circumneutral (pH 7), fresh brackish (>500 -

bound nitrogen was N-autotrophic tolerant, indicating a tolerance of very small concentrations of

organically bound nitrogen. The oxygen saturation requirements were high (>75%) for all sites. The

-mesosaprobic).



Table 7-3: Ecological descriptors for the Yiben Dam sites based on the diatom community, July 2016 (Van Dam et al., 1994)

Site

pH Salinity Nitrogen uptake

Oxygen Requirements

Saprobity Trophic State

R 1 Circumneut

ral Fresh

brackish

N-autotrophic

tolerant High (>75%)

-mesosaprobic

Eutrophic

R 2 Circumneut

ral Fresh

brackish

N-autotrophic


-mesosaprobic

Eutrophic

R 3 Circumneut

ral Fresh

brackish

N-autotrophic


-mesosaprobic

Eutrophic

R 4 Circumneut

ral Fresh

brackish

N-autotrophic


-mesosaprobic

Tolerant

7.2.2. COMMUNITY ASSEMBLAGE

A total of 39 diatom species were recorded at the four study sites in August 2016, with R2 having the

highest number of species (Table 7-4). The two dominant species, Nitzschia palea and Achnanthidium

minutissimum, were recorded at all the sites (Table 7-4). The former is a taxon known to occur in

eutrophic, moderate to high electrolyte, very heavily polluted waters; whereas, the latter occurs in well

oxygenated, clean, fresh waters (Taylor et al., 2007). The ecological water quality for all the sites was

relatively Good and there was no evidence of organic pollution (Table 7-4; Table 7-5). Additional

information is provided for the other dominant/sub-dominant species in order to make ecological

inferences for the four sites (Taylor et al., 2007):

R1: This site was dominated by Fragilaria capucina which occurs in circumneutral, oligo-to

mesotrophic waters with moderate electrolyte content (Table 7-4). The subdominant

Gomphonema parvulum and Tabularia fasciculata occur in a range of waters and are generally

considered to be tolerant of extremely polluted conditions (Table 7-4). The presence of A.

minutissimum points to well oxygenated, clean, fresh waters. The %PTV score was low,

indicating that there was no evidence of organic pollution at this site (Table 7-5).

R2: The diatom community was dominated by F. capucina and A. minutissimum which indicates

oligotrophic, clean conditions (Table 7-4). The subdominance of G. parvulum, T. fasciculata and

N. palea all point to eutrophic, fresh waters. According to the low %PTV score the ecological

water quality was considered Good (Table 7-5). This site appears to be free from organic

pollution.

R3: The diatom community at this site indicated oligotrophic conditions. The dominance of F.

capucina and A. oblongella pointed to oligotrophic, clean waters (Table 7-4). However, the



presence of N. palea and N. veneta suggests that there may be some form of nutrient inputs at

this site. The %PTV was low and the ecological water quality was considered Good (Table 7-5).

According to the diatom community structure, the overall ecological water quality of the three

sites was considered Good (Table 7-5). Overall, the %PTV was higher for sites R1 and R2

compared to site R3 (Figure 7-1A) however, the scores were still considered low, indicating that

the sites were free from organic pollution. The SPI and BDI values for all the sites were

comparable and relatively high, suggesting that the water quality was Good (Figure 7-1B; Figure

7-1C).

Table 7-4: Species and their abundances for the Rokel River sites, July 2016

Taxa R 1 R 2 R 3 Achnanthes oblongella Oestrup 0 6 24 Achnanthes standeri Cholnoky 3 4 0 Achnanthes subaffinis Cholnoky 0 3 0 Achnanthidium crassum (Hustedt) Potapova & Ponader 0 6 16 Achnanthes eutrophila Lange-Bertalot 2 10 0 Achnanthidium exiguum (Grunow) Czarnecki 0 2 4 Achnanthidium minutissimum (Kützing) Czarnecki 17 34 13 Amphora veneta Kützing 0 4 7 Brachysira neoexilis Lange-Bertalot 15 15 15 Craticula vixnegligenda Lange-Bertalot 5 0 0 Encyonema mesianum (Cholnoky) D.G. Mann 3 6 0 Encyonema minutum (Hilse in Rabh.) D.G. Mann 3 5 11 Eolimna subminuscula (Manguin) Moser Lange-Bertalot & Metzeltin 0 3 0 Eunotia bilunaris (Ehr.) Mills var. bilunaris 0 5 0 Fragilaria capucina Desmazieres var.capucina 57 41 45 Fragilaria capucina Desmazieres var.vaucheriae(Kützing)Lange-Bertalot 24 24 0 Fragilaria ulna (Nitzsch.) Lange-Bertalot var. ulna 3 5 0 Frustulia crassinervia (Breb.) Lange-Bertalot et Krammer 0 3 0 Frustulia vulgaris (Thwaites) De Toni 0 0 3 Gomphonema angustatum (Kützing) Rabenhorst 0 0 9 Gomphonema gracile Ehrenberg 28 19 18 Gomphonema lagenula Kützing 25 16 0 Gomphonema parvulius Lange-Bertalot & Reichardt 22 0 13 Gomphonema parvulum (Kützing) 46 30 13 Lemnicola hungarica (Grunow) Round & Basson 0 5 0 Luticola mutica (Kützing) D.G. Mann 5 3 13 Navicula antonii Lange-Bertalot 0 0 18 Navicula cryptocephala Kützing 5 0 5 Navicula cryptotenella Lange-Bertalot 0 0 13 Navicula radiosa Kützing 6 15 0 Navicula rostellata Kützing 0 0 13 Navicula veneta Kützing 5 3 18 Navicula viridula (Kützing) Ehrenberg 0 0 10 Navicula zanoni Hustedt 0 25 0 Nitzschia palea (Kützing) W.Smith 13 16 19 Pinnularia subcapitata Gregory var. subcapitata 18 0 8 Pinnularia viridis (Nitzsch) Ehrenberg var. minor Cl. 6 18 0 Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot 0 3 10 Tabularia fasciculata (Agardh)Williams et Round 39 21 32 TOTAL 350 350 350 Nutrients Salinity Organics Dominant



Table 7-5: Diatom index scores calculated for Rokel River sites, July 2016

Site No. of Species

%PTV SPI BDI Ecological Water Quality

R 1 22 16.9 10.6 13.5 Good R 2 29 14 11.2 14.1 Good R 3 24 9.1 10.6 13.8 Good

Figure 7-1: Bar graphs showing (A) Pollution Tolerant Values for the study sites, July 2016, (B) Specific Pollution Index values for the study sites, July 2016 and (C) Biological Diatom Index values for the study sites, July 2016.



APPENDIX C: INTERMEDIATE INDEX OF HABITAT INTEGRITY


The severity of the impact of the modifications is based on six (6) categories. These categories comprise

rating scores ranging from 0 to 25: where 0 (no impact), 1 to 5 (small impact), 6 to 10 (moderate impact),

11 to 15 (large impact), 16 to 20 (serious impact) and 21 to 25 (critical impact Table 8-1).

Table 8-1: Descriptive classes for the assessment of modifications to habitat integrity (adapted from Kleynhans, 1996)

Impact Category

Description Score

None No discernible impact, or the modification is located in such a way that it has no impact on habitat quality, diversity, size and variability.

0

Small The modification is limited to very few localities and the impact on habitat quality, diversity, size and variability is also very small.

1 - 5

Moderate The modifications are present at a small number of localities and the impact on habitat quality, diversity, size and variability is also limited.

6 - 10

Large The modification is generally present with a clearly detrimental impact on habitat quality, diversity, size and variability. Large areas are, however, not influenced.

11 - 15

Serious The modification is frequently present and the habitat quality, diversity, size and variability in almost the whole of the defined area are affected. Only small areas are not influenced.

16 - 20

Critical The modification is present overall with a high intensity. The habitat quality, diversity, size and variability in almost the whole of the defined section are influenced detrimentally.

21 - 25

The habitat integrity assessment is based on two different components of a river: (1) the instream

channel, and (2) the riparian zone. Separate assessments are done for both aspects, however, the data

for the riparian zone is interpreted primarily in terms of the potential impact on the instream component

(Kemper, 1999). The rating system is based on different weights for each criterion (Table 8-2).



Table 8-2: Criteria and weights used for the assessment of habitat integrity (adapted from Kleynhans, 1996)

Instream Criteria Weight Riparian Zone Criteria Weight

Water abstraction 14 Bank erosion 14

Water quality 14 Indigenous vegetation removal 13

Bed modification 13 Water abstraction 13

Channel modification 13 Water quality 13

Flow modification 13 Channel modification 12

Inundation 10 Exotic vegetation encroachment 12

Exotic macrophytes 9 Flow modification 12

Exotic fauna 8 Inundation 11

Solid waste disposal 6

TOTAL 100 TOTAL 100

The methodology classifies habitat integrity into one of six classes, ranging from Natural (Category A) to

Critically Modified (Category F), for both instream and riparian habitat (Table 8-3).

Table 8-3: Ecological categories, key colours and category descriptions presented within the habitat assessment (adapted from Kleynhans, 1996)

Category Description Score (%)

A Natural Unmodified, Natural. 90-100

B Largely Natural

Few modifications. Small change in natural habitats and biota may have taken place but the ecosystem functions are essentially unchanged.

80-89

C Moderately Modified

A loss and change of natural habitat and biota occurred but the basic ecosystem functions are still predominantly unchanged.

60-79

D Largely Modified

Large loss of natural habitat. Biota and basic ecosystem functions occurred.

40-59

E Seriously Modified

The losses of natural habitat, biota and basic ecosystem functions are extensive. 20-39

F Critically Modified

Modifications have reached a critical level and the lotic system has been modified completely with an almost complete loss of natural habitat and biota. In the worst instances, the basic ecosystem functions have been destroyed and the changes are irreversible.

<20




The intermediate Index of Habitat Integrity (IHI) was applied on a site level basis in order to ascertain the

change of instream and riparian habitat from natural conditions (Kemper, 1999). The habitat integrity

assessment provides a tool for assessing instream and riparian habitat by incorporating factors and

potential impacts (Kleynhans, 1996). The IHI scores and categories per site with justifications for the

various metrics are shown in Table 8-4. The main aspects are briefly discussed below:

Overall the associated reach of the Rokel River was classed in a C category, inferring a

Moderately modified state, where alteration to the natural habitat has occurred but the basic

ecosystem functions are still predominantly unchanged (Table 8-4).

The main driving variables responsible for the decline in habitat integrity include flow

modification, alteration in the extent of inundation and vegetation removal (Table 8-4).

The riparian zone is more impacted when compared to the instream habitat, mainly as a result

of flow modification and vegetation removal (Table 8-4).

Table 8-4: Results for the IHI for Rokel River sites during the July 2016 assessment

Criterion Relevance Score Cat. Description

Instream Habitat Integrity

Water abstraction

Direct impact on habitat type, abundance and size. Also implicated in flow, bed, channel and water quality characteristics. Riparian vegetation may be influenced by a decrease in the supply of water.

0 None Existing water abstraction relates to local application and relatively small scale agricultural practices.

Flow modification

Consequence of abstraction or regulation by impoundments. Changes in temporal and spatial characteristics of flow can have an impact on habitat attributes such as an increase in duration of low flow season, resulting in low availability of certain habitat types or water at the start of the breeding, flowering or growing season.

20 Serious

Current operations of the Bumbuna HEP resulted in an increase in low flow baseflows. Mean flows during Feb to May naturally range between 6.3 and 20m³s¯¹ this compares to Bumbuna operations at 20 to 24.5m³s¯¹ for the same period. Similarly, HEP releases during Jun and Jul are less comparable to the natural mean flows for the same period. Mean natural flows during Jun and Jul range between 65.2 and 137.8m³s¯¹, while for the same period the flow has been reduced to 12.9 and 8.2m³s¯¹, respectively.

Channel modification

May be the result of a change in flow, which may alter channel characteristics causing a change in marginal instream and riparian habitat. Purposeful channel modification to improve drainage is also included.

0 None Channel is bedrock controlled and appears stable under current conditions.




Water quality

Originates from point and diffuse point sources. Measured directly or agricultural activities, human settlements and industrial activities may indicate the likelihood of modification. Aggravated by a decrease in the volume of water during low or no flow conditions.

10 Moder

ate

According to the diatom community structure, the overall ecological water quality of the three sites was considered Good. However, the turbidity of the water is high and this may have a knock-on impact on trophic status and nutrients loads. The increase in turbidity suggests active erosion within the upslope catchment. Current agricultural practices and vegetation clearing are considered primary reasons for increased erosion rates.

Inundation

Destruction of riffle, rapid and riparian zone habitat. Obstruction to the movement of aquatic fauna and influences water quality and the movement of sediments (Gordon et al., 1992).

15 Large

The increase in low flow baseflow is associated with a decrease in habitat diversity, particularly habitat units related to riffle and rapid sections (FS and FI hydraulic units).

Bed modification

Regarded as the result of increased input of sediment from the catchment or a decrease in the ability of the river to transport sediment (Gordon et al., 1993). Indirect indications of sedimentation are stream bank and catchment erosion. Purposeful alteration of the stream bed, e.g. the removal of rapids for navigation (Hilden & Rapport, 1993) is also included.

0 None The majority of the resource unit is bedrock controlled and bed conditions appears stable.

Exotic macrophytes

Alteration of habitat by obstruction of flow and may influence water quality. Dependent upon the species involved and scale of infestation.

0 None None observed during July 2016.

Exotic fauna

The disturbance of the stream bottom during feeding may influence the water quality and increase turbidity. Dependent upon the species involved and their abundance.

0 None None observed during July 2016

Solid waste

A direct anthropogenic impact which may alter habitat structurally. Also a general indication of the misuse and mismanagement of the river.

10 Moderate

Some solid waste associated with the Bumbuna Urban centre. This is mostly concentrated at access points were people wash clothes, bath and take water from the River.

Instream Habitat Integrity Score 67 % Integrity Class C Riparian Habitat Integrity

Water Abstraction

Direct impact on habitat type, abundance and size. Also implicated in flow, bed, channel and water quality characteristics. Riparian vegetation may be influenced by a decrease in the supply of water.

10 Moderate

Relatively large non-riparian areas have been cleared of vegetation and is under cultivation.




Flow Modification

Consequence of abstraction or regulation by impoundments. Changes in temporal and spatial characteristics of flow can have an impact on habitat attributes such as an increase in duration of low flow season, resulting in low availability of certain habitat types or water at the start of the breeding, flowering or growing season.

11 Large

Alteration in runoff characteristics due to changes in surface roughness caused by vegetation clearing effects the lateral flow of water from the valley slopes into the River.

Channel Modification

May be the result of a change in flow which may alter channel characteristics causing a change in marginal instream and riparian habitat. Purposeful channel modification to improve drainage is also included.

5 Small

Some isolated lateral head cuts noted. Some marginal riparian areas have also been effected by artisanal gold mining, but is generally limited in extent.

Water Quality

Originates from point and diffuse point sources. Measured directly or agricultural activities, human settlements and industrial activities may indicate the likelihood of modification. Aggravated by a decrease in the volume of water during low or no flow conditions.

11 Large

Lateral inflow drains areas cleared for cultivation and some urban infrastructure, this results in sediment laden water entering the system. Particularly the right bank riparian zone is effected by a decrease in water quality.

Inundation Season inundation of flood benches, terraces and plains

15 Large

The Bumbuna Dam is a flood control on the system. This is naturally mitigated due to the absence of well-developed floodplain features. However, the majority of the resource unit assessed (R1, R2 and R3) reflected the presence of an annual flood bench with associated riparian features.

Vegetation Removal

Impairment of the buffer the vegetation forms to the movement of sediment and other catchment runoff products into the river (Gordon et al., 1992). Refers to physical removal for farming, firewood and overgrazing. Includes both exotic and indigenous vegetation.

20 Serious Relatively extensive clearing on both banks for agricultural purposes.

Exotic Vegetation

Excludes natural vegetation due to vigorous growth, causing bank instability and decreasing the buffering function of the riparian zone. Allochtonous organic matter input will also be changed. Riparian zone habitat diversity is also reduced.

5 Small Alien woody component is limited.

Bank Erosion

Decrease in bank stability will cause sedimentation and possible collapse of the river bank resulting in a loss or modification of both instream and riparian habitats. Increased erosion can be the result of natural vegetation removal, overgrazing

5 Small

No notable lateral headcuts observed. Banks on both sides of the River was observed as stable for the resource unit assessed.



Criterion Relevance Score Cat. Descriptionor exotic vegetation encroachment.

Riparian habitat integrity % 62

Riparian habitat integrity Class C Over all IHI % 64.36 Over all IHI catergory C



APPENDIX D: MACROINVERTEBRATE ASSESSMENT

This section deals with spatial variation within the aquatic macroinvertebrate community structures

linked to the sites assessed during July 2016. The sensitivity of each community is represented based on

the known preferences and tolerances (Thirion, 2016) of invertebrates sampled and the ecological

category inferred from the present invertebrate assemblages. Table 9-8 provides details on the habitat

preferences and tolerances of the invertebrate communities sampled at each site, while the

macroinvertebrate abundances sampled is summarised in Table 9-9. The results of the invertebrate

assessment informed the habitat stress curves applied in the EFA.


9.1.1. INVERTEBRATE HABITAT ASSESSMENT SYSTEM

Macroinvertebrate habitat availability was assessed using the IHAS version 2 methodology (McMillan,

1998). The IHAS is a quantitative and comparable description of habitat availability for aquatic

macroinvertebrates. The IHAS reflects the quantity, quality and diversity of biotopes available for

habitation by aquatic macroinvertebrates. The quantity and quality of various sampling biotopes were

assessed in terms of potential habitat for invertebrates and were expressed as a percentage score. The

scores for each biotope were then summed up to give a total habitat score and class (Table 9-1). The

IHAS, in this context, purely provides a relative measure of habitat availability between sites and does

not reflect the ecological state of the system in any way.

Table 9-1: Invertebrate Habitat Assessment Score ratings and categories (McMillan, 1998)

IHAS score % Description Category

>80% Habitat is considered to be more than

adequate and able to support a diverse invertebrate fauna.

Good

<80>70% Habitat is considered to be adequate and able to support invertebrate fauna.

Adequate

<70% Habitat is considered to be limited and unable to support diverse invertebrate fauna.

Poor



9.1.2. SOUTH AFRICAN SCORING SYSTEM (VERSION 5)

Aquatic macroinvertebrates were collected using the SASS5 sampling protocol (Dickens & Graham, 2002).

The protocol is divided amongst three biotopes: (i) Vegetation (VEG), (ii) Stones in Current (SIC) and (iii)

Gravel, Silt, Mud (GSM). Samples are collected in an invertebrate net with a pore size of 1000 microns on

a 30cm x 30cm frame by kick sampling of SIC and GSM, and sweeping of VEG for a standardised time or

area. Macroinvertebrates were identified to family level in the field according to the SASS5 protocol and

using relative reference guides (Dickens & Graham, 2002; Gerber & Gabriel, 2002). The SASS5 score,

Number of Taxa and the Average Score per Taxa (ASPT) were the indices calculated using the sensitivity

scores and presence of taxa in each sample.

9.1.3. MODIFIED % EPHEMEROPTERA, PLECOPTERA AND TRICHOPTERA INDEX

Community data collected in the field was used to populate the M%EPT based on the EPT method (MACS,

1996) to assess macroinvertebrate integrity. This metric measures the abundance of the generally

pollution-sensitive insect orders of Ephemeroptera, Plecoptera and Trichoptera. Taxa from these orders

are sensitive to environmental alterations and occur in clean and well oxygenated waters (Keci et al.,

2012). The EPT assemblages are commonly considered good indicators of water quality (Rosenberg &

Resh, 1993). Changes in these assemblages indicate possible pollution and disturbance.

9.1.4. MACROINVERTEBRATE RESPONSE ASSESSMENT INDEX

Abundance data collected from the implementation of the SASS5 protocol at each site was used to

populate the updated MIRAI v2 (Thirion, 2016). The MIRAI is a rule-based index that makes use of a rating

approach comprised of four different metric groups that measure the change in present

macroinvertebrate assemblages from the reference assemblage. The MIRAI is the change in assemblage

in terms of four different metric groups:

flow modification; habitat modification; water quality modification, and system connectivity and seasonality.

Abundances obtained during the survey were compared to the reference condition in order to establish

the present state of the sites. The MIRAI approach is based on rating the degree of change from natural

on a scale of 0 (no change from reference condition) to 5 (maximum change from reference condition)



for a variety of different metrics (Thirion, 2016). An increase or decrease in abundance is considered as a

change compared to natural conditions.

The final outcome of the model is to derive an Ecological Category by combining the four metric groups

and expressing it as a percentage of similarity to reference conditions (Table 9-2).

Table 9-2: Ecological Integrity Categories (Thirion, 2016 - modified from Kleynhans, 1996 and Kleynhans, 1999)

Ecological Category

Generic Description of Ecological Conditions

Arbitrary Guideline Score (% of Maximum

Theoretical Total)

A

Unmodified/natural, close to natural or close too predevelopment conditions within the natural variability of the system drivers: hydrology, physico-chemical and geomorphology. The habitat template and biological components can be considered close to natural or to pre-development conditions. The resilience of the system has not been compromised.

>92 - 100

A/B The system and its components are in a close to natural condition most of the time. Conditions may rarely and temporarily decrease below the upper boundary of a B category.

>88 -

B

Largely natural with few modifications. A small change in the attributes of natural habitats and biota may have taken place in terms of frequencies of occurrence and abundance. Ecosystem functions and resilience are essentially unchanged.

>82 -

B/C Close to largely natural most of the time. Conditions may rarely and temporarily decrease below the upper boundary of a C category.

>78 -

C

Moderately modified. Loss and change of natural habitat and biota have occurred in terms of frequencies of occurrence and abundance. Basic ecosystem functions are still predominantly unchanged. The resilience of the system to recover from human impacts has not been lost and it is ability to recover to a moderately modified condition following disturbance has been maintained.

>62 -

C/D The system is in a close to moderately modified condition most of the time. Conditions may rarely and temporarily decrease below the upper boundary of a D category.

>58 -

D

Largely modified. A large change or loss of natural habitat, biota and basic ecosystem functions have occurred. The resilience of the system to sustain this category has not been compromised and the ability to deliver ecological goods and services has been maintained.

>42 -

D/E

The system is in a close to largely modified condition most of the time. Conditions may rarely and temporarily decrease below the upper boundary of an E category. The resilience of the system is often under severe stress and may be lost permanently if adverse impacts continue.

>38 -

E

Seriously modified. The change in the natural habitat template, biota and basic ecosystem functions are extensive. Only resilient biota may survive and it is highly likely that invasive and problem (pest) species may dominate. The resilience of the system is severely compromised as is the capacity to provide ecological goods and services. However, geomorphological conditions are largely intact but extensive restoration may be required to improve the system's hydrology and physico-chemical conditions.

>20 -

E/F

The system is in a close to seriously modified condition most of the time. Conditions may rarely and temporarily decrease below the upper boundary of an F category. The resilience of the system is frequently under severe stress and may be lost permanently if adverse impacts continue.

>18 -



Ecological Category

Generic Description of Ecological Conditions

Arbitrary Guideline Score (% of Maximum

Theoretical Total)

F

Critically/Extremely modified. Modifications have reached a critical level and the system has been modified completely with an almost complete change of the natural habitat template, biota and basic ecosystem functions. Ecological goods and services have largely been lost This is likely to include severe catchment changes as well as hydrological, physico-chemical and geomorphological changes. In the worst instances the basic ecosystem functions have been destroyed and the changes are irreversible. Restoration of the system to a synthetic but sustainable condition acceptable for human purposes and to limit downstream impacts is the only option.


9.2.1. INVERTEBRATE HABITAT

Habitat availability (quality and quantity) is an important part of an ecosystem as it forms a template for

the biotic communities. If the habitat quality is low, it will have an effect on the biotic assemblages noted.

When the habitat diversity is high and un-impacted, the biotic community structures tend to be in a

relatively good condition. Habitat availability and diversity are major determinants in the overall

community structure of aquatic macroinvertebrates. For this reason, it is important to evaluate habitat

quality and quantity when applying biomonitoring methodologies and assessing ecosystem health. The

main points are briefly discussed below:

The site located furthest upstream (R1), obtained the highest scores and indicated Good habitat

availability for macroinvertebrate colonization. The habitat and reach is considered to be more

than adequate and able to support a diverse macroinvertebrate assemblage (Table 9-3). Site R1

was the only site to reflect adequate SIC habitat (Figure 9-1). The invertebrate habitat template

at site R1 is only partially representative of the resources unit, while R2 is more consistent with

the general river reach.

Located further downstream, site R2 indicated Poor habitat availability (Table 9-3) for the

colonization of aquatic macroinvertebrates, with the lack of the SIC biotype resulting in the low

overall IHAS score (Figure 9-1).

Poor habitat availability was also recorded at site R3 (Table 9-3). SIC habitat was present to a

limited extent and marginal vegetation was limited mainly to roots and stems, lacking leafy

vegetation (Figure 9-1).

The abundance of the specific biotopes present at each site was scored in Table 9-4 to Table 9-6

using a scale ranging for 0 (absent) to 5 (entire). It is evident in these tables that relatively diverse



biotopes were present at site R1 (Table 9-4) with the habitat template of the lower reaches

being dominated by sand, mud and clay (Table 9-5; Table 9-6).

Table 9-3: IHAS of sites assessed during the July 2016 assessment

System Rokel River Sites R1 R2 R3 Total IHAS (%) 82.43 44.59 55.41 Class Good Poor Poor

Figure 9-1: Bar graph indicating the biotopes available for habitation by aquatic macroinvertebrates at the study sites during the July 2016 Assessment. (* = biotope absent).

Table 9-4: Aquatic Invertebrate Biotopes present at site R1

Summarised river make up:

Pool run Riffle/rapid 2 mix 3 mix

SASS Biotope Rating Rating Rating Rating

Stones in current 4 Riffle 2 Run 2 Boulder rapid 4

Chute 3 Cascade 3 Bedrock 4

Stones out of current

2 Backwater 0 Slackwater 2 Pool 0

Bedrock 3

Marginal vegetation in current

3 Grasses 0 Reeds 3 Shrubs 0

Sedges 2

Marginal vegetation out of current 3

Grasses 0 Reeds 3 Shrubs 0

Sedges 0

Aquatic vegetation 2 Sedges 2 Moss 0 Fil. algae 0

Gravel 2 Backwater 0 Slackwater 2 In channel 1

Sand 4 Backwater 4 Slackwater 3 In channel 2

Silt/mud/clay 4 Backwater 4 Slackwater 2 In channel 1

0 = absent; 1 = rare; 2 = sparse; 3 = common; 4 = abundant; 5 = entire; Fil = Filamentous

0.00

5.00

10.00

15.00

20.00

25.00

R1 R2 R3

Stones in Current Vegetation Other Habitat

*





Pool Run Riffle/rapid 2 mix 3 mix




Stones out of current 0

Backwater 0 Slackwater 0 Pool 0

Bedrock 0



Sedges 2

Marginal vegetation out of current

2


Sedges 2

Aquatic vegetation 1 Sedges 1 Moss 0 Fil. algae 0







Pool Run Riffle/rapid 2 mix 3 mix




Stones out of current 1

Backwater 0 Slackwater 0 Pool 0

Bedrock 1



Sedges 2

Marginal vegetation out of current

2


Sedges 2

Aquatic vegetation 0 Sedges 0 Moss 0 Fil. algae







9.2.2. INVERTEBRATE COMMUNITY ANALYSES

FUNCTIONAL FEEDING GROUPS

There are two main approaches to using macroinvertebrates as indicators of ecosystem health, namely

the taxonomic approach, with the focus on diversity or taxa richness and the functional approach which

focuses on the ecological functions (traits) of the taxa that makeup a given community and is more useful

in determining the ecological condition of a system (Cummins et al., 2005). Although it has been

suggested that identification of invertebrates to species level has many benefits the functional approach

is more rapid. The latter approach is based on Functional Feeding Groups (FFGs) that provide information

on the balance of feeding strategies (food acquisition and morphology) in the benthic assemblage. The

FFGs are divided into five groups, namely scrapers, shredders, gatherers, filterers, and predators. The

FFGs for taxa sampled during the July 2016 survey are provided in Table 9-7.

Table 9-7: Specific Functional Feeding Groups for macroinvertebrates sampled at the study sites

Taxon FFG References Baetidae Collector (gatherer) Merritt et al. (2008)

Heptageniidae Generally, a Scraper / Facultative Collector (gatherer) Merritt et al. (2008)

Leptophlebiidae Collector (gatherer) Merritt & Cummins (1996) Tricorythidae Collector (gatherer) Bouchard (2004) Coenagrionidae Predator Merritt et al. (2008) Platycnemidae Predator Deemool & Prommi (2015) Libellulidae Predator Merritt et al. (2008) Corixidae* Generally, piercers Merritt et al. (2008) Nepidae* Predator Cummins et al. (2005) Notonectidae* Predator Domínguez & Fernández (2009)

Veliidae* Predator Domínguez & Fernández (2009) Leptoceridae Collector (gatherer) / Predator Nhiwatiwa et al. (2009) Dytiscidae* Predator Cummins et al. (2005) Elmidae Scraper Cummins et al. (2005) Chironomidae Collector (gatherer) Cummins et al. (2005) Simuliidae Collector (filterer) Cummins et al. (2005)

Overall, the macroinvertebrate community assemblages within the resource unit were largely

dominated by predators and gatherers, with a low proportion of filterers and the absence of

shredders (Figure 9-2).



Specialized feeders, such as scrapers, piercers, and shredders, are the more sensitive organisms

and usually represent healthy streams. Generalists, such as collectors (gatherers and filterers)

have a broader diet range compared to specialists (Cummins & Klug, 1979), and thus are more

tolerant to pollution that might alter availability of certain food.

Temporal changes in the proportion of the FFGs may provide useful data monitoring to assess

the impact of flow alteration, as alterations in flow may impact on the nutrition resource base

of the system; thereby altering the relative proportion of FFGs ratio (Cummins et al., 2005).

Figure 9-2: Stacked column graph illustrating the percentage distribution of the FFGs at each study site.

INVERTEBRATE SENSITIVITY

The sensitivity assessment used preferences and tolerances of sampled aquatic macroinvertebrates to

infer likely sensitivity to alterations in hydrology, substrate composition and water quality. The

macroinvertebrate sensitivity took the following three aspects into account:

i. ASPT - this index is based on the principle that different aquatic macroinvertebrates have

different tolerances to pollutants. The sensitivity scores are derived from the tolerances of

macroinvertebrates to pollution as used in the SASS5 scoring system, ranging from a high

tolerance to a very low tolerance to pollution (Dickens & Graham, 2001).

ii. Ephemeroptera, Plecoptera and Trichoptera since EPT taxa are pollution sensitive taxa, using

the %EPT will therefore be a good indication of impacts related to land use activities on the

diversity and abundance of macroinvertebrates and changes in community structure.

iii. Presence of sensitive taxa - This provides a measure of relative sensitivity between the different

sites assessed. The assessment is based on the macroinvertebrates sampled and not

macroinvertebrates expected to occur (Table 9-9).

50.042.9

37.5

66.742.9

0%

20%

40%

60%

80%

100%

R1 R2 R3

Scrapers Shredders Gatherers Filterers Predators



Table 9-8 shows the sensitivity of sampled and expected aquatic macroinvertebrates to alteration in flow,

presence of a specific preference. The following main aspects were identified with regards to the

expected and sampled macroinvertebrate community assemblage:

Several taxa with a high preference for fast flow water (>0.6 m/s) are expected to occur within

the study area sites, these include taxa from the following families: Oligoneuridae,

Hydropsychidae, Simuliidae, Tricorythidae and Elmidae. When referring to the existing

community assemblages, no taxa from the family Oligoneuridae or Hydropsychidae were

sampled.

Taxa with a preference for good water quality, expected to occur at the study sites include taxa

from the following families: Oligoneuridae, Heptageniidae, Perlidae, Hydropsychidae (>2spp),

and Baetidae (>2spp). However, only Heptageniidae and Baetidae were sampled during the July

2016 assessment.

The above mentioned points highlight the fact that the associated reach of the Rokel River is

experiencing alteration in both water quality and flows.

Table 9-8: Table showing the environmental preferences and tolerances of expected and sampled aquatic macroinvertebrates (Thirion, 2016)

Taxon Flow Requirement (ms¯¹) Substrate Water

Qual. <0.1 0.1-0.3 0.3-0.6 >0.6 Cob Veg GSM WC Oligoneuridae 0 0 3 5 4.5 3.5 1 0 H Hydropsychidae >2spp 1 2.5 4 4.5 4.5 1 1.5 0 H

Ceratopogonidae 4.5 3 2.5 4.5 3.5 2 4 0 L Simuliidae 1.5 2 3.5 4.5 4.5 1.5 0.5 0 L Trichorythidae 0.5 2 3.5 4.5 4.5 1 0.5 0 M Elmidae 1.5 3 4 4.5 4 1 3.5 0 M Potamonautidae 4 4.5 4.5 4.5 4.5 0.5 4 0 VL Chironomidae 4.5 4.5 4.5 4.5 3.5 3 3.5 0 VL Baetidae >2spp 3 3.5 4 4 4 4 4 0 H Tipulidae 2.5 4 4 4 3.5 0.5 4 0 L Ancylidae 3.5 4 4.5 4 4 2 2 0 L Psephenidae 2.5 3.5 4.5 4 4.5 0.5 1 0 M Perlidae 0.5 3 4 3.5 4 0.5 1.5 0 H Libellulidae 3 3.5 4 3.5 4.5 3.5 2.5 0 L Leptoceridae 4 4 4 3.5 3.5 4 4 0 L Gyrinidae 3.5 3.5 3.5 3.5 3 3.5 2 4 L Hydrophilidae 3.5 3.5 3.5 3.5 2.5 4.5 1.5 1 L Leptophlebiidae 2 3.5 4.5 3.5 4 1 3.5 0 M Oligochaeta 4.5 4 3.5 3.5 4 3 4.5 0 VL Heptageniidae 1 4 4.5 3 4.5 0.5 1.5 0 H Caenidae 4.5 3.5 3 3 3 3 4.5 0 L Hydracarina 3 3 3 3 3 2.5 2.5 0.5 M Gomphidae 4.5 4 3 2.5 2.5 1 4.5 0 L Tabanidae 1 4.5 4 2.5 4 1 3 0 L



Taxon Flow Requirement (ms¯¹) Substrate Water

Qual. <0.1 0.1-0.3 0.3-0.6 >0.6 Cob Veg GSM WC Aeshnidae 2.5 3.5 4 2.5 4 3 3 0 M Coenagrionidae 4.5 3.5 2 2 0.5 4.5 0.5 0 L Veliidae 4 2.5 2 2 2.5 3.5 1.5 4.5 L Naucoridae 3 4 3 1.5 3.5 3.5 3.5 3 L Porifera 3 4.5 3 1 4.5 1 0 0 L Chlorolestidae 3 3 1 1 3 4 1 0 M Platycnemidae 2 3 1 1 4 3 0 0 M Corixidae 4.5 3 1.5 1 3 2.5 3.5 2 VL Physidae 4.5 2 1 0.5 1 4.5 4 0 VL Gerridae 4 3.5 2.5 0 1 3 0 4 L Dytiscidae 4.5 1.5 0.5 0 2 4 3.5 0 L Haliplidae 4.5 1 0 0 4 3.5 2 0 L Corduliidae 4 1 0.5 0 0.5 0.5 4.5 0 M Belostomatidae 4 1 0 0 0 4.5 0.5 0 VL Nepidae 4.5 0.5 0 0 0 5 0 0 VL Notonectidae 4 3 0.5 0 0 4 0 3.5 VL Culicidae 4.5 2 0 0 0 4 0 3.5 VL Muscidae 4.5 1 0 0 0.5 2.5 3.5 4 VL Sampled during the July 2016 assessment Cob = Cobbles; Veg = Vegetation; GSM = Gravel, Sand and Mud, WC = Water Column; H= High; M = Medium; L = Low; VL = Very Low.

A total of 16 taxa were sampled on the Rokel River during the July 2016 assessment across the three

study sites (Table 9-9). The main points are briefly discussed below:

Overall, all the study sites showed low species diversity and richness which was mostly

dominated by tolerant and moderately tolerant taxa (Table 9-9) despite Good habitat availability

in the upper part of the resource unit.

There are several factors that influence the presence and distribution of aquatic

macroinvertebrates, with the most important of these being: current velocity (Bunn &

Arthington, 2002; Donohue et al., 2006; Hussain, 2011), temperature (Lessard & Hayes, 2003;

Sullivan et al., 2004; Worthington et al., 2015), the substratum (Courtney & Clements, 2002;

LeCraw & Mackreth, 2010, Hussain & Pandit, 2012), vegetation (Subramanian &

Sivaramakrishnan, 2005; Kleynhans et al., 2007), and dissolved substances (Sorensen et al., 1977;

LeCraw & Mackreth, 2010; Xu et al., 2014).

It is believed based on the absence of expected taxa, that alteration in flow and water quality

(possibly temperature) are the driving variables responsible for the loss of sensitive taxa.

Spatially, the ASPT decreased along the longitudinal profile of the Rokel River (Figure 9-3). Site

R1, located furthest upstream obtained an ASPT of 6.22, compared to 5.13 recorded at site R3.

This decrease in ASPT is most likely associated with the decline in habitat diversity in the lower

reaches of the river. A large majority of the expected taxa have a preference for cobbles habitat,

which was limited to absent in the lower reaches (refer to Section).



A similar trend was observed in the EPT, with the upstream site (R1) obtaining the highest overall

score, with representatives from two of the EPT orders (Figure 9-4). Only taxa from the order

Ephemeroptera were sampled at site R2 and R3.

Figure 9-3: ASPT and SASS scores for sites assessed on the Rokel River during the July 2016 assessment.

Figure 9-4: Column graph showing %EPT as expressed from the total number of taxa sampled for each site during the July 2016 assessment of the Rokel River.

Table 9-9: Aquatic macroinvertebrates sampled during the July 2016 assessment of the associated reach of the Rokel River, with relevant abundance and sensitivity scores according to Dickens & Graham (2002)

Taxon Sensitivity

Score R1 R2 R3

Baetidae 2 sp. 6 A A Baetidae > 2 sp. 12 A Heptageniidae 13 1

0

1

2

3

4

5

6

7

0

10

20

30

40

50

60

R1 R2 R3

ASPT

SASS

Sco

re

ASPT SASS Score

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

R 1 R 2 R 3

%EP

T

Ephemeroptera Plecoptera Trichoptera



Taxon Sensitivity

Score R1 R2 R3

Leptophlebiidae 9 1

Tricorythidae 9 1 Coenagrionidae 4 A Platycnemidae 10 A Libelluilidae 4 1 Corixidae* 3 1 A Nepidae* 3 A 1 Notonectidae* 3 A Veliidae* 5 A A A Leptoceridae 6 1 Dytiscidae* 5 1 Elmidae* 8 1

Chironomidae 2 B 1

Simuliidae 5 B Number of Taxa 9 6 8 Score 56 34 41 ASPT 6.22 5.67 5.13

Very low tolerances to pollution Moderately tolerant to pollution High tolerance to pollution

* = Air breathing 1 = single individual A = 2-10 individuals B = 11-100 individuals C = 101-1000 individuals

9.2.3. MACROINVERTEBRATE ECOLOGICAL INTEGRITY

The MIRAI provides a measure of the residual ecological integrity of a system based on the deviation of

the present community in relation to an expected (reference) community. The variation in the

preferences and tolerances between the expected and the sampled community also indicates the likely

contribution of different drivers (changes in flow, substrate and water quality) to the decrease in

ecological integrity. The main aspects with regards to the aquatic macroinvertebrate assemblages are

briefly discussed below:

The resource unit fell in a D category, based on invertebrate assemblages, inferring a Largely

modified state, where the impairment of ecosystem health is clearly evident (Table 9-10).

The MIRAI model highlighted, flow modification, instream habitat and change in seasonality as

the driving variables responsible for the decline in ecological integrity of the system (Table 9-10).



At present the system is experiencing severe flow alteration due to discharges from the

upstream Bumbuna dam, and it is believed to be the main contributing factor responsible for

the decline in ecological integrity of the associated reach of the Rokel River.

Table 9-10: Ecological Categories: based on weights of metric groups for the associated river reach

Invertebrate EC Metric Group

Metric Group

Calculated Score

Calculated Weight

Weighted Score of Group

Rank of Metric Group

%Weight for

Metric Group

Flow Modification 37.6 0.278 10.44 1 100 Habitat 36.0 0.250 9.00 2 90 Water Quality 53.9 0.278 14.96 1 100 Connectivity & Seasonality 40.0 0.194 7.78 3 70

Invertebrate EC 42.18% Invertebrate EC Category D

9.2.4. AQUATIC MACROINVERTEBRATE- INDICATOR SPECIES

Following from the sensitivity description provided in Sections 9.2.2 and for the purposes of the

generating flow requirements suitable to sustain aquatic macroinvertebrate communities, two flow and

water quality sensitive invertebrates have been selected: Tricorythidae and Heptageniidae (Figure 9-5).

Both taxa fall within the order Ephemeroptera. The habitat requirements for both species are briefly

discussed below:

Tricorythidae: nymphs from the family Tricorythidae, commonly referred to as Stout Crawlers

are generally found under rocks with moderate to fast-flowing currents and also tend to be

found among vegetation in slower currents (de Moor et al., 2003). An assessment carried out by

Thirion (2016) indicated that Tricorythidae have a preference for very fast flowing (>0.6m/s)

water (with the greatest response at 1 m/s) at depths between 10-30cm, associated with

cobble/pebble substrate.

Heptageniidae: nymphs form the family Heptageniidae, or Flat-headed Mayflies occur at a wide

range of different altitudes and under stones in riffle/rapid areas where they feed on periphyton

(organisms that live attached to underwater surfaces) (de Moor et al., 2003). As with

Tricorythidae this family also prefer a depth range between 10-30cm over cobbles but have a

preference for fast flowing (0.3 - 0.6 m/s) water, with the greatest response at 0.6 m/s (Thirion,

2016).

The above mentioned families were present at sites R1 and R2, respectively; however, only single

specimens were sampled during the July 2016 assessment. These sites are most likely to be affected by



further alteration in flow, during construction and operational phases of the proposed Project. It is

anticipated that both taxa may provide a meaningful indication of the ecological consequences that may

arise due to the Project implementation. The indicator taxa can be applied in terms of monitoring the

significance of flow alteration and altered water quality induced by the implementation of the proposed

Project. Note that any monitoring efforts should remain holistic and all-inclusive and should not be

reduced to only focus on spatial and temporal variation within indicator species. Rather, as part of a

holistic monitoring regime, variation outside of a meaningful statistical variation of these two taxa will be

best applied as an early warning for potential loss in ecological integrity.

Figure 9-5: Aquatic macroinvertebrate indicator taxa selected for setting flow requirements and for biomonitoring.



APPENDIX E: FISH ASSESSMENT

This section describes the fish community associated with the resource unit assessed. It provides details

of available fish habitat, the community structure, PES and indicator species. Where relevant reference

is made to the flow and related habitat requirements of the fish assemblage.

10.1. MATERIAL AND METHODS

10.1.1. FISH HABITAT ASSESSMENT

The fish habitat assessment was adopted from Kleynhans (2007). The frequency of different habitat units

was expressed based on the number of occurrences measured for the cross-section assessed. The

different habitat units and their descriptions are provided in (Table 10-1 and Table 10-2). The frequency

distribution of the substrate and flows were also applied within the EFA to create the stress curves for

aquatic macroinvertebrate and fish communities.

Table 10-1: Habitat types and their descriptions included in the July 2016 aquatic ecology assessment

Habitat Type Description

Overhanging Vegetation Marginal riparian zone, canopy forming just above the surface of

the water Aquatic Vegetation Aquatic macrophytes

Undercut banks and root wads Marginal zone cover provided by cavities within the bank and

inter-root wad spaces Bedrock >1.5m

Boulders >256mm

Cobbles >64-256mm

Pebbles >4-64mm

Gravel >2-4mm

Sand >0.05-2mm

Mud >0.002-0.05mm

Table 10-2: Hydraulic units used in modelling variation in fish habitat units

Habitat Type Depth (m) Velocity (m s-1)

Fast Deep (FD) >0.3 > 0.3

Fast Intermediate (FI) > 0.2; > 0.3

Fast Shallow (FS) > 0.1; > 0.3

Fast Very Shallow (FVS) > 0.3

Slow Deep (SD) >0.5



Habitat Type Depth (m) Velocity (m s-1)

Slow Shallow (SS)

Slow Very Shallow (SVS)

10.1.2. FIELD SAMPLING

Fish survey methodology was undertaken according to Kleynhans (2007). Fish sampling effort was site

specific and based on habitat type and accessibility. Several sampling techniques were used and included:

(i) electro-fishing, (ii) gill nets, (iii) fyke nets, and (iv) cast nets. Electro-fishing was undertaken at sites

where conductivity was suitable and gill nets were used at sites where adequate depth was available.

Where depth and habitat allowed, fyke nets were placed at sites overnight. A description of the

equipment used and the fish sampling effort per unit are listed in Table 10-3.

Table 10-3: Fish sampling equipment used and the sampling effort followed during surveys

Sampling type Unit Unit Sampling Effort Mesh Size Depth Length/Size

Electro-shocking 1 45 min N/A <0.5m NA

Gill net 4 Over night Multi Mesh >1.5m 50m

Cast net 1 10 casts 20mm >0.5m Diameter = 3m

Fyke net 1 Over night 20mm <0.5m Mouth size = 50cm

10.1.3. EXPECTED FISH LIST AND REFERENCE CONDITIONS

The expected fish list was primary informed by Paugy et al. (1990), Paugy et al. (2003) and ARC GIS

Freshwater Biodiversity Browser 10.1. While Payne et al. (2010) and Hüllen (2014) was referenced to

refine the expected list further. The expected list was readjusted to consider habitat availability.

10.1.4. FISH PRESENT ECOLOGICAL STATE ASSESSMENT

The FRAI model calculates the residual ecological integrity based on the difference between the expected

and the sampled fish assemblages (Kleynhans, 2007). The model also indicates likely reasons for the

digression from references conditions based on the difference in habitat preferences and tolerances

between the expected and sampled fish communities. Main components included within the model are:

Velocity-depth preferences;

Cover preferences;



Tolerance to conditions of no flow;

Tolerance to alteration in water quality;

Migration requirements; and

Alien and invasive species.

Additional components included within the assessment are:

Dietary requirements;

Reproductive strategy; and

Breeding time.

Abundances and frequency of occurrence obtained during the survey were compared to the reference

condition in order to establish the present state of the sites. An increase or decrease in

abundance/frequency of occurrence is considered as a change compared to natural conditions. The final

outcome of the model is the Ecological Category expressed as a percentage of similarity to reference

conditions (Table 10-4).

Table 10-4: Ecological categories, key colours and category descriptions presented within the biotic assessment (Kleynhans & Louw, 2007)

Category Description

A Unmodified No impacts, conditions natural.

B Largely natural Small changes in community characteristics, most aspects natural.

C Moderately modified Clear community modifications, some impairment of health evident.

D Largely modified Impairment of health clearly evident. Unacceptably impacted state.

E Seriously modified Most community characteristics seriously modified, unacceptable state.

F Critically modified Extremely low species diversity. Unacceptable state.


The resource unit provides potential refuge for 45 indigenous species representing 15 families (Table

10-5). Note that the expected list has been adjusted based on the habitat available during July 2016. Of

the expected species 34 species reflect an IUCN Red List status of LC, one is DD (Raiamas scarciensis),

four have not been assessed (Vericorhinus wurtzi, Awaous lateristriga, Malapterurus leonensis and

Mormyrus cf. rume), and five have a Near Threatened (NT) status (Leptocypris guineensis, Raiamas

nigeriensis, Ichthyborus quadrilineatus, Synodontis tourei and Petrocephalus levequei). Three of the five

species with a NT status have been sampled during July 2016. The section below provides a brief summary

of the NT and DD species:



Raiamas scarciensis (DD): This species is endemic to Sierra Leone and no information on the

species and its threats are available. Therefore, pending further information, it is categorised as

DD (Bousso & Lalèyè, 2010).

Leptocypris guineensis (NT): It is qualified as NT due to its restricted range. The known range is

relatively free of threats and therefore any threats within the distribution range would cause

the species to be assessed as threatened (Bousso & Lalèyè, 2010).

Raiamas nigeriensis (NT): This species is relatively widely distributed. However, there is an

ongoing decline in habitat in the River Cross due to oil exploration. In Ghana, the main threats

posed to this fish species include effluents from mining activities. Due to these threats the

species is qualified as NT as it is close to meeting the requirements for a Vulnerable classification

(Awaïss et al., 2010.).

Ichthyborus quadrilineatus (NT): This species is a regional endemic with widespread threats,

particularly from drought, deforestation, overfishing, and dams. It is therefore assessed as NT

(Bousso & Lalèyè, 2010).

Petrocephalus levequei (NT): Deforestation and mining, especially in the Upper Guinean zone,

threaten the habitat of the species. Its extent of occurrence and area of occupancy are close to

meeting the thresholds for a Vulnerable status and is found in fewer than 10 locations. The

species is assessed as Near Threatened (Entsua-Mensah, 2010).

Table 10-5: Revised expected list with IUCN Red List status, indication of regional endemism and presence during the July 2016 assessment

Family Genus & Species IUCN Red

List Regional Endemic

Jul-16

Anabantidae Ctenopoma kingsleyae LC

Bagridae Auchenoglanis occidentalis LC

Chrysichthys johnelsi LC

Chrysichthys nigrodigitatus LC x

Centropomidae Lates niloticus LC

Characidae Brycinus macrolepidotus LC

Brycinus longipinnis LC x

Cichlidae Hemichromis fasciatus LC x

Pelvicachromis humilis LC x

Sarotherodon caudomarginatus LC x

Tilapia brevimanus LC x

Tilapia louka LC x x

Tylochromis leonensis LC x

Claridae Clarias buettikoferi LC x

Clarias laeviceps djalonensis LC x

Heterobranchus isopterus LC x

Cyprinidae Barbus ablabes LC



Family Genus & Species IUCN Red

List Regional Endemic

Jul-16

Barbus sacratus LC x

Labeo coubie LC

Labeo parvus LC x

Leptocypris guineensis NT x

Raiamas nigeriensis NT x

Raiamas scarciensis DD x

Raiamas steindachneri LC x x

Vericorhinus wurtzi NA

Distichodontidae Ichthyborus quadrilineatus NT x

Neolebias unifasciatus LC

Nannocharax cf. fasciatus LC x

Gobidae Awaous lateristriga NA x

Malapteruridae Malapterurus leonensis NA x

Mastacembelidae Mastacembelus liberiensis LC x

Mochokidae Synodontis tourei NT x

Synodontis thysi LC x x

Synodontis waterloti LC x

Mormyridae Hippopotamyrus paugyi LC x x

Marcusenius thomasi LC x x

Marcusenius sp. x

Mormyrops anguilloides LC x

Mormyrops breviceps LC

Mormyrus tapirus LC x

Mormyrus cf. rume NA x

Petrocephalus levequei NT x x

Petrocephalus pellegrini LC x

Notopteridae Papyrocranus afer LC x

Schilbeidae Schilbe micropogon LC



10.2.1. FISH HABITAT

FORAGING

The frequency distributions of cover units, substrate and velocity-depth classes are provided in Figure

10-1A, Figure 10-1B and Figure 10-1C, respectively. The habitat was measured at a discharge ranging

between 43.5 and 48.5m³s¯¹ during July 2016. The frequency distribution provided here include all

habitats measured at the three sites assessed (R1, R2 and R3) and are considered representative of the

resource unit.

The most dominant cover unit is overhanging vegetation, followed by undercut banks and root wads, leaf

litter and substrate. The function of submerged aquatic vegetation, emergent vegetation, aquatic

macrophytes and algae are limited, as these units reflect the lowest frequency distributions. The main

cover units (overhanging vegetation and undercut banks) are associated with FD and SD velocity depth

classes. At the time of sampling other hydraulic units were limited. However, the representation of FI, FS,

SS and SVS during periods of low flow remains important for maintaining the natural fluxes in fish

assemblages (for example the relative representation of different Mormyrid and Cichlid species) and the

recruitment of species with specific flow requirements (examples include, Barbus sacratus, Labeo parvus,

Leptocypris guineensis and the Raiamas species).

The dominance of sand and mud as substrate is consistent with the preferences of the expected and

sampled fish communities (Figure 10-1A). The instream ecology of the resource unit is marked by

benthopelagic species feeding over marginal sediment associated with overhanging vegetation, undercut

banks and root wads.



Figure 10-1: Frequency distribution of fish habitat, (A) Cover, (B) Flow-depth and (C) Substrate measured at a discharge of 43.5- 48.5m³s¯¹.

REPRODUCTION

Unlike the habitat requirements for foraging, reproductive requirements are generally seasonal and more

intensely associated with a season flow regime. The intra-annual variation in the habitat template, due

to the variation in dry and wet season flows, is an important driver of fish reproduction within the system.

Section 10.2.2 provides a discussion on the reproductive strategies, migration requirements and

spawning times of the expected and the sampled fish assemblages, but in summary, the most

represented reproductive strategy is non-guarding open substrate spawners, with an annual upstream

migration requirement and spawning during April and November. Some examples include the Characids

(Brycinus macrolepidotus, B. longipinnis and Hydrocynus forskahlii); Cyprinids (Labeo parvus, Barbus

sacratus, Leptocypris guineensis and Raiamas sp.) and Mochokids (Synodontis thysi, S. tourei and S.

waterloti). The typical habitat requirements for open substrate spawners include a riffle rapid pool

sequence with varying depths of fast flowing water over suitable substrate. The onset of migration and

spawning is cued by changes in discharge and temperature. A notable feature of the Rokel River in this

regard is the Bumbuna Falls, which marks a natural transition within the river ecology and poses a

migration barrier. It is thus likely that migrating fish will accumulate below the falls, highlighting this area

as an important spawning and fish nursery area. Payne et al. (2010) reports that local fisherman

confirmed this notion during his 2010 surveys of the Rokel River.



10.2.2. FISH COMMUNITY ANALYSES

The total fish yields for sites R1, R2 and R3 were combined for the community assessment. The July 2016

assessment yielded a total of 116 specimens. Figure 10-2 shows the abundance distributions over the 21

confirmed species sampled, while Figure 10-3 reflects comparative abundances sampled by Payne et al.

(2010). During July 2016 Marcusenius thomasi was the most represented species followed by

B. longipinnis and the NT Petrocephalus levequei. The Mormyrid and Synodontis diversity were highest

during this period. The results of the July 2016 assessment partially compare to the findings of the Payne

et al. (2010) study on the following basis:

Members from the family Mormyridae were dominant during both studies. However, some

species differed. The 2016 study was dominated by M. thomasi while the 2010 assessment

yielded more Hippopotamyrus paugyi.

Members from the Synodontis family were better represented during the 2016 study compared

to the 2010 study, although other catfishes such as Chrystichtys nigrodigitatis yielded higher

abundances during the 2010 study.

Another notable difference is the near absence of Cyprinids during the 2016 assessment, despite

a sub-dominance of this family during the 2010 assessment. Species such as Vericorhinus wurtzi,

Labeo parvus and Barbus sacratus yielded higher abundances during the 2010 assessment.

Figure 10-2: Overall abundances of fish sampled during July 2016.



Figure 10-3: Overall abundances of fish sampled by Payne et al. (2010) at sites below corresponding with the Ecotone 2016 assessment.

10.2.3. FISH ECOLOGICAL INTEGRITY

The PES, as indicated by the fish assemblage, fell into a C/D category and translates into a Moderately to

Largely modified state, with clear alteration within the fish assemblage (Table 10-6). The PES assessment

is a function of the difference in the frequency of occurrence of expected and sampled fish. The

assessment considered the variation between expected and sampled species for 10 metric groups. The

metric groups and the percentage change measured within each group are provided in Figure 10-4, while

variations for each metric are illustrated in Figure 10-5A-D, Figure 10-6A-D and Figure 10-7A-B.

Main reasons for the loss of ecological integrity primarily relate to an alteration in the natural flow regime

of the system. This is most notably expressed by the digression in flow related metrics between expected

and sampled fish. Metrics reflecting the most digression include: a loss of fish with specific requirements

for; vertical zonation (benthic and benthopelagic), migration (potamodromous), velocity depth (units

related to FS and SS), spawning times and fish with specific reproductive strategies.



Table 10-6: Relative fish assemblage integrity score and EcoStatus for the resource unit associated with sites R1, R2 and R3

Resource Unit Relative Fish Assemblage (%) Fish Assemblage Integrity Category

Rokel: R1, R2 and R3 58 C/D

Figure 10-4: Percentage change from reference conditions for components used in the fish PES assessment.



Figure 10-5: Clustered bar graphs showing the difference between number of fish expected and sampled with a specific preference for (A) Cover, (B) Substrate, (C) Vertical Zonation and (D) Velocity-depth class.



Figure 10-6: Clustered bar graphs showing the difference between number of fish expected and sampled with specific reproductive and feeding requirements for (A) Reproductive strategy, (B) Migration requirements, (C) Spawning Time and (D) Functional Feeding group.

Figure 10-7: Clustered bar graphs showing the difference between number of fish expected and sampled with specific tolerance levels for (A) no flow conditions and (B) changes in water quality.

10.2.4. FISH- INDICATOR SPECIES

The fish assemblage was considered within its entirety when the flow habitat stressor response curves

were determined (see Figure 4-2 and Figure 4-4). However, the fish in general and specifically the species

sensitive to flow and water quality alteration have been weighted more relative to more sensitive taxa.

The ecological parameters associated with all fish are provided in Table 10-7 (substrate, flow and cover)



and Table 10-8 (reproductive strategies, migration and spawning requirements). From the environmental

parameters the notable rheophilic and semi-rheophilic species (flow dependant) species include:

Barbus sacratus

Labeo parvus* (Figure 10-8A)

Leptocypris guineensis

Nannocharax cf. fasciatus* (Figure 10-8B)

Raiamas scarciensis* (Figure 10-8C)

Raiamas steindachneri*(Figure 10-8D)

Vericorhinus wurtzi

Figure 10-8: Fish indicator taxa sampled during July 2016. (A) Labeo parvus, (B) Nannocharax sp., (C) Raiamas scarciensis and (D) R. steindachneri.

The * indicates species sampled during the July 2016 assessment. The section below provides a brief

description of the ecological requirements of the indicator species:

Barbus sacratus: This is migratory species, running up river to spawn in suitable gravel beds. Barbus

sacratus prefers flowing habitats, in pools below cascades and rapids. It probably breeds in flowing water

over rocky or gravel substrates following the onset of the rainy season (Harrison, 1977; Roux, 2006). Ripe

adults congregate downstream of suitable spawning sites until ready to spawn. This occurs when groups

of ripe male fishes move into the site and are then joined by individual females who are attended to



closely and pressured by the males, the ova being released and fertilized over the gravel or rocky bed.

Breeding activity may extend over several days, and after spawning the adults return downstream. The

eggs hatch and the larvae and young fish move downstream into nursery areas where they form cohort

schools in slow shallow and fast shallow portions.

Labeo parvus: is a strong swimming fish, adapted for flowing water. Labeo parvus migrate upstream in

numbers to breed on rocky habitats of small and large rivers. As with most other Labeos sp. it occurs in

shoals and feeds by grazing algae from the surface of the rocks and woody debris. During the July 2016

assessment, Labeo parvus (Fork Length (FL): 21cm) was sampled at mean velocity of 0.3ms¯¹ and focal

point velocities >0.5ms¯¹. The occurrence of the species was associated with bedrock and substrate.

Labeo parvus is sensitive due to the combination of a high instantaneous total mortality and one breeding

season per year which makes it highly susceptible to the failure of the annual hydrological cycle

(Montchowwui et al., 2009). This species is particularly vulnerable to changes in environmental

conditions that influence its reproductive strategy (Skelton et al., 1991). The eggs, embryo and larvae of

Labeo are sensitive to sudden flooding and to associated silting up that can significantly reduce the larvae

survival and recruitment (Skelton et al., 1991).

Nannocharax sp.: little information is available regarding the biology of this species, although it is

commonly associated with rocky substrate of fast shallow flowing waters (Welcomme, 1986). We

sampled a number of specimens with a FL ranging from 5.5 to 7cm. All specimens were sampled in

velocities exceeding 0.4ms-1, while focal point velocities ranged between 0.5 and 1.0ms-1. All specimens

were associated with cobbles, pebbles, rocks, emergent and overhanging vegetation.

Raiamas sp.: available information on this genus indicates a preference for streams and rivers with good

water quality and rocky beds associated with a variety of velocity depth classes. Juveniles are likely to

seek cover and feed close to interstitial spaces in fast shallow flowing parts of pool, riffle and rapid

sequences. Olaosebikan, (2010) reported a negative association with water depth suggesting preference

for shallow habitats. The principal variable that affected the habitat use of Raiamas sp. maturation stages

was the flow velocity. All maturation stages preferred areas with non-zero flow velocity, though the flow

strength was positively related to maturation stage. We sampled Raiamas steindachneri (FL:11) and R.

scarciensis (FL: 14cm) at velocities less than 0.3ms¯¹ and a focal point depth of approximately 0.8m.

Varicorhinus wurtzi: did not yield species specific literature on flow requirements, but general inferences

from this sensitive genus suggest species occur in a fast deep and fast shallow flowing streams, associated

with suitable substrate. Environmental conditions associated with this genus suggest that they occupy

riffles and pools. Payne et al. (2010) suggests that this species occupy the same ecological role as B.

sacratus and acts as a substitute for B. sacratus downstream of the Bumbuna Falls. They forage during

the day and aggregate in crevices between rocks at night. Juveniles are likely associated with shallow



sandy-pebble flats by pools where the flow is generally more constant. The species feed primarily on the

periphyton growing on the rocks, and leave unique scars after grazing. The peak of juvenile recruitment

is often observed during the onset of the dry season when water levels decrease and suitable habitat

becomes available.

As noted, most of the indicator species belong to the Cyprinid family, and are either directly or indirectly

dependent on fast flowing water for most of their life stages. The Raiamas group are micropredators

which prefer to occupy slower flowing zones next to fast focal point riffle and rapid sections. Of the two

Labeo species, L. parvus was more frequently observed during the 2010 survey (Figure 10-3). As with

L. parvus, Payne et al. (2010) also observed more V. wurtzi than B. sacratus downstream of Bumbuna

Falls. Neither of the latter species have been sampled during July 2016. All of the listed indicator species

have specific habitat and flow requirements and are likely to respond to impacts. However, the baseline

data is not sufficient to identify a single indicator species and it is recommended that the spatial and

temporal variation of most or all of these species be considered in drawing conclusions regarding flow

related impacts.

Table 10-7: Ecological parameters for fish including Substrate preference, Vertical zone preference, cover preference and diet classification

Genus & Species Substrate Vertical zone Cover Diet

Ctenopoma kingsleyae Gravel, Sand & Mud Benthopelagic

Submerged stream bank vegetation Invertivore

Auchenoglanis occidentalis Mud Demersal No Data Benthic macrophagic omnivore

Chrysichthys johnelsi Mud Demersal No Data Benthic macrophagic omnivore

Chrysichthys nigrodigitatus Mud Demersal No Data Benthic macrophagic omnivore

Lates niloticus Gravel, Sand & Mud

Demersal No Data Piscivore

Brycinus macrolepidotus No Data Pelagic Water column Macrophagic omnivore

Brycinus longipinnis No Data Pelagic Water column Macrophagic omnivore

Hemichromis fasciatus Rocky Benthopelagic Substrate Invertivore and piscivore

Pelvicachromis humilis Mud & Sand Demersal No Data Benthic macrophagic omnivore

Sarotherodon caudomarginatus Mud & Sand Demersal Macrophytes Microphagic detritus/algae

Tilapia brevimanus Gravel, Sand & Mud Benthopelagic

Water column & Overhanging Vegetation

Benthic macrophagic omnivore

Tilapia louka Gravel, Sand & Mud

Benthopelagic Water column & Overhanging Vegetation

Benthic macrophagic omnivore

Tylochromis leonensis Sand Benthopelagic No Data Benthic macrophagic omnivore

Clarias buettikoferi Mud & Sand Demersal No Data No Data

Clarias laeviceps djalonensis

Mud & Sand Demersal No Data No Data

Heterobranchus isopterus No Data Benthic Water column Benthic generalist

Barbus ablabes No Data Benthopelagic No Data Benthic herbivore

Barbus sacratus Rocky Benthopelagic Substrate Benthic macrophagic omnivore



Genus & Species Substrate Vertical zone Cover Diet

Labeo coubie No Data No Data No Data No Data

Labeo parvus Pebble Benthopelagic Substrate Benthic herbivore

Leptocypris guineensis Sand & Gravel Benthopelagic Water column Invertivore

Raiamas nigeriensis Sand & Gravel Benthopelagic Water column Invertivore

Raiamas scarciensis Sand & Gravel Benthopelagic Water column Invertivore

Raiamas steindachneri Sand & Gravel Benthopelagic Water column Invertivore

Vericorhinus wurtzi No Data No Data No Data No Data

Ichthyborus quadrilineatus No Data Pelagic No Data No Data

Neolebias unifasciatus No Data Pelagic No Data No Data

Nannocharax cf. fasciatus No Data No Data No Data No Data

Awaous lateristriga Sand Benthic No Data Benthic Invertivore

Malapterurus leonensis Mud & Sand Benthic Substrate Piscivore

Mastacembelus liberiensis Rocky Benthopelagic Substrate Benthic Invertivore

Synodontis tourei No Data Demersal Substrate Benthic macrophagic omnivore

Synodontis waterloti No Data Demersal Substrate Benthic macrophagic omnivore

Hippopotamyrus paugyi Mud Benthopelagic Overhanging Vegetation & undercut banks Invertivore

Marcusenius thomasi Mud Benthopelagic Overhanging Vegetation & undercut banks

Invertivore

Mormyrops anguilloides Mud & Sand Demersal Overhanging Vegetation Invertivore and piscivore

Mormyrops breviceps Mud & Sand Demersal Overhanging Vegetation Invertivore and piscivore

Mormyrus tapirus Mud Demersal Overhanging Vegetation & undercut banks

Invertivore

Mormyrus cf. rume Mud Demersal Overhanging Vegetation & undercut banks Invertivore

Petrocephalus levequei Mud Demersal Overhanging Vegetation Invertivore

Petrocephalus pellegrini Mud Demersal Overhanging Vegetation Invertivore

Papyrocranus afer No Data Demersal Macrophytes Piscivore

Schilbe micropogon No Data No Data Emergent aquatic vegetation

Invertivore

Table 10-8: Ecological parameters for the revised expected fish including reproductive requirements, breeding time, migration requirements, velocity Depth requirements and flow and water quality tolerances

Genus & Species

Reproduction

Breeding Time

Migration Velocity-Depth Flow intolerance Water quality

Ctenopoma kingsleyae

Guarding eggs attached to vegetation

May-Dec Resident Slow Shallow Tolerant Tolerant

Auchenoglanis occidentalis

Guarding eggs laid in nest

May-Oct

Potamodromous

Slow Deep to Slow Shallow Tolerant Intolerant

Chrysichthys johnelsi

No Data Apr-Aug

Potamodromous

Slow Deep to Slow Shallow

Tolerant No Data

Chrysichthys nigrodigitatus

No Data Apr-Aug

Potamodromous


Tolerant No Data



Lates niloticus

Non-guarding open substrate spawner

Feb-Aug

Potamodromous


Tolerant No Data

Brycinus macrolepidotus


May-Dec

Potamodromous


Moderately Tolerant

Moderately Tolerant

Brycinus longipinnis


May-Dec

Potamodromous


Moderately Tolerant

Moderately Tolerant

Hemichromis fasciatus


Apr-Nov

Potamodromous

Slow Deep & Slow Shallow Tolerant Intolerant

Pelvicachromis humilis

Cave spawner

No Data

No Data Slow Deep & Slow Shallow

Tolerant Intolerant

Sarotherodon caudomarginatus


May-Oct

Potamodromous

Slow Deep & Slow Shallow

Tolerant Tolerant

Tilapia brevimanus


No Data

Potamodromous


Tolerant Moderately Tolerant

Tilapia louka Guarding eggs laid in nest

No Data

Potamodromous

Slow Deep & Slow Shallow Tolerant

Moderately Tolerant

Tylochromis leonensis


No Data

No Data No Data No Data No Data

Clarias buettikoferi No Data

No Data

Potamodromous

Slow Deep & Slow Shallow Tolerant Tolerant

Clarias laeviceps djalonensis

No Data No Data

Potamodromous


Tolerant Tolerant

Heterobranchus isopterus

Non-guarding eggs broadcast on vegetation

No Data

Potamodromous


Barbus ablabes

No Data No Data

Potamodromous

No Data No Data No Data

Barbus sacratus


May-Oct

Potamodromous

Fast Deep & Slow Deep

Moderately Intolerant


Labeo coubie No Data No Data


Labeo parvus


May-Dec

Potamodromous

Fast Deep & Fast Shallow



Leptocypris guineensis


May-Oct

Potamodromous


Intolerant Intolerant

Raiamas nigeriensis


May-Oct

Potamodromous



Raiamas scarciensis

Non-guarding open

May-Oct

Potamodromous





substrate spawner

Raiamas steindachneri


May-Oct

Potamodromous



Vericorhinus wurtzi

No Data No Data


Ichthyborus quadrilineatus No Data

No Data No Data No Data No Data No Data

Neolebias unifasciatus No Data


Nannocharax cf. fasciatus No Data


Awaous lateristriga No Data

No Data

Amphidromous


Malapterurus leonensis

Nest associated

No Data

No Data Slow Deep & Slow Shallow

Tolerant Tolerant

Mastacembelus liberiensis

No Data No Data

No Data Fast Shallow Moderately Intolerant


Synodontis tourei


May-Dec

Potamodromous



Synodontis waterloti


May-Dec

Potamodromous



Hippopotamyrus paugyi

No Data May-Dec

Potamodromous


Moderately Tolerant


Marcusenius thomasi

No Data May-Dec

Potamodromous


Moderately Tolerant


Mormyrops anguilloides

Fractional spawner

May-Dec

Potamodromous


Moderately Tolerant


Mormyrops breviceps

Fractional spawner

May-Dec

Potamodromous


Moderately Tolerant


Mormyrus tapirus

No Data May-Dec

Resident Slow Deep & Slow Shallow


Mormyrus cf. rume

No Data May-Dec

Resident Slow Deep & Slow Shallow


Petrocephalus levequei

No Data May-Dec

Potamodromous



Moderately Tolerant

Petrocephalus pellegrini

No Data May-Dec

Potamodromous



Moderately Tolerant

Papyrocranus afer

No Data No Data


Schilbe micropogon


May-Dec

No Data Slow Deep Tolerant Tolerant



APPENDIX F: TABULATED FLOW VOLUMES

11.1. NATURAL FLOWS

Start month is October (10) 1943 837.536 304.560 155.615 58.121 27.060 11.517 13.738 56.514 142.560 411.402 645.494 789.523 1944 646.298 263.606 118.117 73.388 32.417 16.070 23.587 48.479 105.754 371.762 690.492 745.459 1945 674.421 301.450 147.580 76.067 34.353 17.142 12.960 35.087 102.643 318.997 661.029 926.640 1946 867.534 311.558 154.812 59.193 26.369 11.249 11.923 32.944 134.266 343.371 637.191 848.880 1947 715.936 261.274 120.528 62.942 29.316 12.588 12.960 40.712 130.118 293.820 639.334 718.243 1948 730.132 279.677 129.367 76.067 33.143 16.606 18.144 46.872 86.832 254.984 559.250 893.722 1949 805.127 312.854 155.615 75.531 34.111 16.874 9.590 22.766 107.309 260.608 510.771 1030.838 1950 869.409 340.589 151.062 82.763 36.772 19.017 14.256 65.085 239.242 403.099 663.975 757.382 1951 1198.584 438.307 164.454 80.084 37.333 18.213 10.627 38.569 129.600 371.226 658.083 808.186 1952 673.350 328.406 159.633 77.406 35.078 17.945 18.144 28.391 200.880 465.506 711.651 738.461 1953 746.738 302.486 158.561 132.313 59.270 29.195 34.992 91.066 191.030 391.582 682.992 824.515 1954 897.800 391.910 236.235 79.013 35.804 18.481 38.102 96.690 350.179 409.260 647.369 765.158 1955 968.509 341.107 161.508 71.781 33.324 15.803 12.701 45.801 139.968 318.194 577.731 821.923 1956 608.800 281.232 147.580 79.281 35.804 18.213 25.920 27.320 103.939 373.905 606.122 757.642 1957 884.408 347.587 156.954 164.722 73.060 34.284 32.918 109.011 257.126 267.304 537.555 883.613 1958 987.258 430.790 270.786 141.152 63.383 33.212 17.366 90.530 288.749 342.032 551.215 890.611 1959 894.050 390.355 244.002 69.638 32.573 15.267 14.515 44.461 238.205 394.796 603.444 847.843 1960 959.403 296.784 143.294 64.549 28.788 13.124 13.997 46.068 112.234 733.078 710.847 758.419 1961 610.675 283.046 133.384 162.311 72.818 36.694 36.547 92.673 320.890 468.184 708.973 701.395 1962 626.210 334.109 268.108 65.889 29.272 13.660 17.626 45.265 158.112 357.566 669.868 912.125 1963 952.171 308.707 136.063 70.174 32.823 15.535 5.962 21.695 82.685 313.908 639.334 723.946 1964 622.460 279.677 139.545 70.174 31.933 15.535 9.850 31.873 122.083 344.174 606.390 881.798 1965 834.322 320.630 144.634 79.013 34.836 17.677 11.405 44.461 227.837 311.230 642.012 756.605 1966 776.200 342.662 161.508 80.084 36.046 18.749 14.515 47.943 165.370 374.976 696.920 831.254 1967 997.704 382.320 163.650 81.423 38.085 19.017 15.811 102.851 169.517 429.615 692.366 662.515 1968 790.128 340.070 162.579 73.924 33.143 16.338 22.550 43.658 205.805 412.474 696.652 701.395 1969 938.243 312.595 152.133 72.852 36.772 20.892 15.811 58.389 106.790 334.532 567.553 1180.397 1970 678.171 334.627 154.544 89.459 38.465 18.749 46.915 50.086 121.306 255.252 682.456 751.680 1971 572.910 288.749 181.060 76.334 34.577 18.749 22.032 53.836 412.128 476.220 660.226 965.520 1972 1147.159 319.594 151.597 69.103 32.417 16.070 11.664 75.263 230.947 335.871 647.101 781.488 1973 741.917 377.136 142.491 59.460 26.127 10.446 10.109 31.605 125.712 403.635 658.619 781.229 1974 959.671 304.042 122.403 56.782 24.918 9.107 12.182 27.855 138.672 344.442 546.661 1068.422 1975 887.622 289.526 121.332 109.279 51.615 25.980 20.995 91.333 421.978 357.299 471.934 775.786 1976 1161.354 571.795 204.630 58.657 27.337 14.196 12.182 22.766 93.830 225.253 653.530 746.237 1977 735.221 249.869 109.279 76.602 31.692 12.321 23.328 61.603 232.762 465.238 594.605 849.917 1978 684.599 295.229 147.044 78.745 33.869 16.874 4.147 29.195 111.197 484.255 700.937 664.848 1979 890.300 363.658 159.633 79.281 37.333 18.481 14.774 42.051 160.704 410.331 590.319 847.584 1980 707.365 341.626 160.972 66.960 29.756 13.928 17.107 72.317 165.629 449.168 708.705 651.110 1981 866.998 287.453 137.402 67.228 30.240 14.196 16.070 49.550 138.413 404.974 666.118 743.904 1982 1000.918 313.891 138.473 57.586 25.402 10.178 23.328 52.229 297.821 509.164 649.244 770.861 1983 549.340 262.570 117.314 59.996 28.564 11.785 15.034 65.889 165.629 372.030 552.554 1196.208 1984 867.802 277.603 122.939 57.318 25.644 10.446 5.184 16.070 61.171 283.643 603.176 977.443



1985 723.704 267.754 116.510 62.675 28.063 12.321 13.997 67.496 146.448 301.588 657.279 828.922 1986 594.337 288.749 128.563 75.531 33.385 16.874 16.070 42.051 142.301 378.994 594.337 944.784 1987 968.242 325.037 153.740 56.246 26.058 9.642 9.850 27.855 147.226 214.540 640.941 876.614 1988 687.813 264.902 113.832 67.228 30.240 14.196 10.627 40.176 117.677 325.158 599.962 939.600 1989 762.273 317.002 138.205 56.246 35.078 10.981 6.480 21.159 88.128 139.545 631.299 911.606 1990 658.083 282.528 128.831 45.265 26.853 9.374 4.406 19.820 44.842 220.968 450.507 465.782 1991 646.030 264.902 101.511 72.852 36.582 19.017 6.221 31.873 123.120 669.332 1183.049 925.862

11.2. PRESENT DAY FLOWS

Start month is October (10) 1943 384.886 286.416 222.039 191.506 170.882 209.183 222.394 256.323 238.723 253.377 252.305 383.357 1944 384.350 241.056 222.575 199.809 164.748 208.647 222.653 242.663 252.720 245.609 251.234 416.534 1945 460.685 240.278 212.129 220.164 184.343 220.700 222.134 256.055 266.717 245.074 250.966 396.835 1946 409.527 271.642 222.039 191.506 164.989 198.469 223.430 231.949 252.461 241.324 251.234 334.627 1947 399.082 240.538 222.575 180.256 170.631 208.915 211.766 231.949 236.131 245.877 251.502 317.520 1948 424.259 235.613 212.665 203.291 173.699 209.451 234.317 231.949 255.571 236.235 250.163 357.178 1949 462.560 251.424 233.021 222.307 194.504 242.395 222.653 255.252 284.083 302.124 267.572 402.278 1950 602.104 264.643 222.575 215.076 203.455 241.860 222.653 253.644 262.570 256.323 250.966 398.390 1951 394.796 400.982 235.164 203.023 191.678 220.700 222.134 243.199 264.125 277.214 264.626 421.459 1952 417.295 256.349 233.021 222.843 213.373 241.324 254.794 277.750 282.269 291.142 265.697 432.086 1953 524.699 261.014 232.753 233.289 203.213 242.663 242.870 276.411 310.781 303.195 268.376 451.008 1954 565.142 355.622 247.484 213.201 205.632 221.236 234.317 256.323 265.162 263.287 251.234 349.661 1955 363.727 307.930 233.021 189.095 170.631 208.915 211.248 231.414 235.872 257.394 250.966 346.291 1956 461.220 236.131 212.129 212.933 224.018 243.199 255.571 279.893 277.344 303.731 252.305 379.987 1957 533.537 268.013 233.289 245.074 242.404 253.912 242.093 276.411 306.115 298.909 261.680 414.202 1958 534.876 393.725 268.644 231.414 205.390 231.146 242.611 261.948 284.861 298.374 262.751 414.202 1959 535.412 354.067 252.037 211.861 190.927 220.432 234.576 257.394 250.128 292.749 339.621 446.602 1960 388.636 272.160 222.307 222.039 223.776 241.592 254.794 277.750 287.194 329.979 294.624 426.643 1961 387.564 263.347 222.575 231.949 205.632 231.682 243.389 263.822 270.605 267.036 252.305 427.162 1962 555.768 299.117 255.519 211.861 184.343 231.949 210.989 255.519 251.424 245.877 251.234 325.555 1963 362.120 281.750 222.307 189.363 159.356 197.130 210.989 232.217 226.541 245.074 251.234 359.510 1964 450.775 236.131 212.397 201.416 184.343 231.682 223.171 245.341 274.752 275.607 252.305 362.621 1965 430.151 258.682 222.307 203.023 185.069 220.164 234.058 255.787 278.640 254.448 252.305 409.795 1966 558.446 266.198 233.021 215.076 203.455 241.860 234.058 252.037 285.638 284.446 265.697 376.877 1967 432.294 346.550 233.824 212.933 212.725 221.772 233.539 255.519 270.346 289.535 257.126 392.947 1968 506.485 264.384 233.021 222.575 194.746 232.485 221.875 265.697 265.162 242.931 250.966 468.893 1969 430.419 285.120 222.307 224.450 203.213 241.860 232.762 262.215 279.418 251.770 250.163 351.994 1970 345.514 302.746 222.307 191.238 164.748 208.647 211.248 230.878 280.454 331.586 275.875 518.918 1971 609.604 238.205 222.575 220.164 190.676 242.395 223.430 255.519 283.565 291.410 252.037 387.504 1972 417.295 290.563 222.307 212.129 195.471 209.719 234.576 245.341 249.610 265.697 252.037 392.947 1973 509.700 277.603 222.843 200.076 175.876 220.700 222.912 242.931 265.939 244.270 250.966 445.046 1974 518.806 278.122 222.575 203.826 213.857 243.199 233.798 265.697 297.821 332.657 262.215 366.250 1975 593.801 267.235 222.575 224.986 210.721 232.217 234.317 243.734 266.458 237.306 250.163 298.598 1976 400.153 497.664 242.663 179.185 164.748 208.915 211.507 231.146 261.274 286.053 253.377 405.648



1977 397.742 240.278 191.773 201.416 184.343 231.682 223.430 233.021 249.350 279.089 258.733 367.805 1978 471.131 249.350 222.039 212.933 205.148 231.949 234.058 254.180 277.344 268.376 252.305 380.246 1979 405.778 328.147 233.556 204.898 200.448 220.968 222.653 267.304 275.530 277.214 256.859 385.690 1980 457.739 265.421 233.021 209.987 185.069 220.968 222.653 253.109 276.566 253.109 252.037 381.283 1981 531.662 263.606 222.307 211.861 184.827 220.700 222.653 254.180 281.750 317.123 282.839 453.600 1982 358.370 285.898 222.307 188.827 164.748 209.183 211.766 256.055 249.869 258.466 250.966 486.518 1983 573.445 240.797 222.843 191.506 181.907 220.700 222.653 244.538 232.502 247.216 251.234 375.062 1984 413.813 261.014 222.575 191.506 164.989 198.469 210.989 254.984 252.720 263.019 251.234 375.581 1985 364.262 242.352 222.575 180.256 164.748 208.915 211.766 232.485 250.906 253.109 252.305 428.976 1986 535.680 237.427 212.397 220.432 184.585 220.968 222.912 242.931 262.310 250.163 250.163 361.066 1987 395.868 294.970 222.307 179.185 170.631 210.790 213.581 219.361 253.238 241.860 250.966 401.760 1988 425.866 233.280 201.951 199.809 175.392 231.682 223.171 232.485 237.686 225.789 250.430 325.814 1989 376.315 257.386 222.575 169.007 164.506 208.647 211.766 235.164 187.661 229.003 250.163 243.648 1990 251.770 236.390 212.397 168.471 164.989 198.469 212.285 117.314 120.010 257.662 440.061 502.330 1991 557.643 214.618 191.773 220.432 201.701 231.949 221.616 264.894 275.530 254.180 252.305 407.722

11.3. LOWER FLOWS EWR

Start month is October (10) 1943 28.228 37.628 45.506 29.303 16.327 7.491 8.030 16.431 21.680 51.495 39.732 52.941 1944 24.109 34.608 32.669 35.195 17.016 10.659 16.141 14.751 13.362 37.407 62.984 52.745 1945 24.249 35.709 37.497 39.097 20.856 12.860 7.661 9.773 12.662 28.958 51.999 58.157 1946 30.705 39.174 44.469 29.315 16.315 7.486 6.508 9.291 19.117 33.100 35.906 53.071 1947 24.542 34.591 32.676 29.340 16.366 7.511 7.661 11.053 18.593 25.719 36.631 52.103 1948 24.685 34.649 32.717 39.097 18.222 11.447 12.216 13.975 12.221 25.675 35.356 53.169 1949 26.046 41.321 45.506 37.190 20.435 11.816 4.466 6.167 14.065 25.692 35.290 72.206 1950 33.526 54.492 38.992 50.715 25.118 14.610 8.672 18.077 40.387 45.026 53.715 52.810 1951 87.914 85.219 59.454 49.218 26.585 13.620 5.357 10.205 18.075 36.615 47.870 52.957 1952 24.200 48.690 49.678 42.112 22.067 13.415 12.216 7.234 31.519 56.656 76.798 52.712 1953 24.935 36.415 48.343 50.715 30.687 17.428 16.670 22.493 30.376 43.062 61.258 52.990 1954 42.474 73.166 60.526 44.078 22.877 14.230 16.858 22.550 41.713 48.585 42.193 52.859 1955 58.405 56.228 54.604 33.398 18.865 10.426 7.492 13.169 20.552 28.142 35.382 52.973 1956 23.924 34.665 37.497 46.601 22.877 13.620 16.479 6.378 12.920 39.712 35.473 52.826 1957 35.082 61.305 47.157 50.715 30.704 17.481 16.574 22.550 41.289 25.701 35.303 53.137 1958 61.860 78.554 63.931 50.715 30.687 17.429 11.529 22.237 41.611 32.233 35.329 53.153 1959 40.431 68.192 61.018 31.714 17.670 9.687 8.911 12.377 38.816 44.132 35.460 53.055 1960 49.551 34.986 35.751 29.346 16.353 7.698 8.231 13.558 15.064 58.337 73.435 52.843 1961 23.957 34.682 32.724 50.715 30.704 17.566 16.764 22.550 41.713 56.657 71.117 52.075 1962 24.029 49.766 62.313 29.352 16.359 8.007 11.865 12.888 24.111 35.912 57.316 53.513 1963 47.019 38.374 32.731 32.367 17.941 9.965 3.936 6.096 12.180 27.443 36.631 52.116 1964 23.992 34.649 34.348 32.367 16.595 9.965 4.668 8.413 16.607 33.933 35.487 53.120 1965 27.103 46.342 36.283 44.078 21.753 13.192 5.896 12.377 34.054 26.724 38.797 52.794 1966 25.128 59.828 54.604 49.218 23.938 14.561 8.911 14.380 26.022 40.912 66.339 53.022 1967 65.624 63.359 59.006 50.715 28.693 14.610 10.015 22.550 29.150 54.517 64.551 52.048 1968 25.234 52.831 57.762 36.159 18.222 11.121 14.231 12.120 32.661 53.195 65.924 52.075 1969 44.665 40.105 41.244 33.937 25.118 16.319 10.015 16.940 13.683 30.575 35.369 78.262



1970 24.301 51.225 43.412 50.715 29.620 14.561 17.056 15.450 16.089 25.684 59.184 52.777 1971 23.862 34.698 59.464 40.848 21.323 14.561 13.628 16.030 41.713 56.684 50.664 65.409 1972 74.341 45.099 40.070 30.994 17.016 10.659 6.193 21.598 35.665 31.380 40.814 52.924 1973 24.846 63.003 35.067 29.321 16.308 7.471 5.112 7.949 17.546 45.903 49.327 52.908 1974 52.278 36.988 32.690 29.285 16.283 7.451 6.844 6.620 20.058 34.580 35.316 75.056 1975 36.745 34.715 32.683 50.715 30.534 17.322 13.043 22.550 41.713 35.237 35.277 52.892 1976 79.598 92.198 59.931 29.309 16.334 8.678 6.844 6.167 12.657 25.666 45.121 52.761 1977 24.763 34.583 32.641 41.494 16.391 7.501 14.853 17.520 37.204 56.467 35.421 53.088 1978 24.356 34.723 36.856 43.058 19.899 11.816 3.500 7.544 14.517 56.793 66.498 52.062 1979 38.525 62.568 49.678 46.601 26.585 14.230 9.433 11.476 24.896 50.015 35.395 53.039 1980 24.476 58.189 52.689 29.358 16.372 8.345 11.208 20.886 27.126 55.612 68.861 48.684 1981 29.427 34.690 32.738 29.566 16.378 8.678 10.610 15.121 19.556 47.176 55.500 52.728 1982 69.754 42.636 33.642 29.297 16.289 7.466 14.853 15.734 41.713 56.883 43.663 52.875 1983 23.834 34.599 32.662 29.328 16.346 7.496 9.716 19.094 27.126 38.507 35.342 81.006 1984 32.070 34.640 32.697 29.291 16.295 7.471 3.781 5.985 12.054 25.710 35.447 68.972 1985 24.611 34.632 32.655 29.334 16.340 7.501 8.231 20.022 22.477 26.079 46.450 53.006 1986 23.892 34.698 32.703 37.190 19.356 11.816 10.610 11.476 21.108 41.956 35.408 62.963 1987 55.222 47.595 42.413 29.272 16.302 7.461 4.668 6.620 23.309 25.648 37.938 53.104 1988 24.414 34.616 32.648 29.566 16.378 8.678 5.357 10.632 15.545 29.768 35.434 60.742 1989 25.028 43.945 32.973 29.272 22.067 7.481 4.278 6.095 12.455 24.227 35.500 53.186 1990 24.153 34.673 32.710 29.266 16.321 7.456 3.636 6.093 10.718 25.657 35.264 42.485 1991 24.068 34.616 32.634 33.937 24.474 14.610 4.101 8.413 17.096 57.544 80.259 55.770

Higher Flows EWR

Start month is October (10) 1943 384.900 286.400 222.000 191.500 79.300 30.800 35.000 195.000 238.700 253.400 252.300 383.400 1944 384.400 241.100 222.600 199.800 73.600 30.800 37.700 150.100 252.700 245.600 251.200 416.500 1945 460.700 240.300 212.100 220.200 87.500 33.000 34.600 191.000 266.700 245.100 251.000 396.800 1946 409.500 271.600 222.000 191.500 75.500 30.800 41.200 133.800 252.500 241.300 251.200 334.600 1947 399.100 240.500 222.600 180.300 78.400 30.800 30.700 133.800 236.100 245.900 251.500 317.500 1948 424.300 235.600 212.700 203.300 80.300 30.800 65.400 133.800 255.600 236.200 250.200 357.200 1949 462.600 251.400 233.000 222.300 96.500 72.900 37.700 179.100 284.100 302.100 267.600 402.300 1950 602.100 264.600 222.600 215.100 107.400 60.500 37.700 171.500 262.600 256.300 251.000 398.400 1951 394.800 401.000 235.200 203.000 95.300 33.000 34.600 155.300 264.100 277.200 264.600 421.500 1952 417.300 256.300 233.000 222.800 132.500 51.200 109.700 222.900 282.300 291.100 265.700 432.100 1953 524.700 261.000 232.800 233.300 104.900 81.500 94.900 218.500 310.800 303.200 268.400 451.000 1954 565.100 355.600 247.500 213.200 112.600 34.200 65.400 195.000 265.200 263.300 251.200 349.700 1955 363.700 307.900 233.000 189.100 78.400 30.800 30.200 129.200 235.900 257.400 251.000 346.300 1956 461.200 236.100 212.100 212.900 149.900 87.800 113.700 225.200 277.300 303.700 252.300 380.000 1957 533.500 268.000 233.300 245.100 193.300 105.500 88.200 218.500 306.100 298.900 261.700 414.200 1958 534.900 393.700 268.600 231.400 110.000 43.100 91.500 199.200 284.900 298.400 262.800 414.200 1959 535.400 354.100 252.000 211.900 94.200 32.100 76.000 197.100 250.100 292.700 339.600 446.600 1960 388.600 272.200 222.300 222.000 148.300 52.800 109.700 222.900 287.200 330.000 294.600 426.600 1961 387.600 263.300 222.600 231.900 112.600 45.600 98.500 203.300 270.600 267.000 252.300 427.200 1962 555.800 299.100 255.500 211.900 87.500 47.600 30.000 185.000 251.400 245.900 251.200 325.600 1963 362.100 281.800 222.300 189.400 73.600 30.800 30.000 135.400 226.500 245.100 251.200 359.500 1964 450.800 236.100 212.400 201.400 87.500 45.600 39.600 162.300 274.800 275.600 252.300 362.600 1965 430.200 258.700 222.300 203.000 91.900 32.000 53.600 187.000 278.600 254.400 252.300 409.800



1966 558.400 266.200 233.000 215.100 107.400 60.500 53.600 167.800 285.600 284.400 265.700 376.900 1967 432.300 346.600 233.800 212.900 131.000 34.500 48.900 185.000 270.300 289.500 257.100 392.900 1968 506.500 264.400 233.000 222.600 97.600 49.000 34.000 209.700 265.200 242.900 251.000 468.900 1969 430.400 285.100 222.300 224.500 104.900 60.500 48.100 201.200 279.400 251.800 250.200 352.000 1970 345.500 302.700 222.300 191.200 73.600 30.800 30.200 126.200 280.500 331.600 275.900 518.900 1971 609.600 238.200 222.600 220.200 93.000 72.900 41.200 185.000 283.600 291.400 252.000 387.500 1972 417.300 290.600 222.300 212.100 98.800 30.900 76.000 162.300 249.600 265.700 252.000 392.900 1973 509.700 277.600 222.800 200.100 82.300 33.000 38.600 153.500 265.900 244.300 251.000 445.000 1974 518.800 278.100 222.600 203.800 134.000 87.800 50.400 209.700 297.800 332.700 262.200 366.300 1975 593.800 267.200 222.600 225.000 128.100 48.300 65.400 157.000 266.500 237.300 250.200 298.600 1976 400.200 497.700 242.700 179.200 73.600 30.800 30.300 127.700 261.300 286.100 253.400 405.600 1977 397.700 240.300 191.800 201.400 87.500 45.600 41.200 140.200 249.400 279.100 258.700 367.800 1978 471.100 249.400 222.000 212.900 108.700 47.600 53.600 175.300 277.300 268.400 252.300 380.200 1979 405.800 328.100 233.600 204.900 101.200 34.000 37.700 211.900 275.500 277.200 256.900 385.700 1980 457.700 265.400 233.000 210.000 91.900 34.000 37.700 169.700 276.600 253.100 252.000 381.300 1981 531.700 263.600 222.300 211.900 89.700 33.000 37.700 175.300 281.800 317.100 282.800 453.600 1982 358.400 285.900 222.300 188.800 73.600 30.800 30.700 191.000 249.900 258.500 251.000 486.500 1983 573.400 240.800 222.800 191.500 83.400 33.000 37.700 158.800 232.500 247.200 251.200 375.100 1984 413.800 261.000 222.600 191.500 75.500 30.800 30.000 177.200 252.700 263.000 251.200 375.600 1985 364.300 242.400 222.600 180.300 73.600 30.800 30.700 138.600 250.900 253.100 252.300 429.000 1986 535.700 237.400 212.400 220.400 88.600 34.000 38.600 153.500 262.300 250.200 250.200 361.100 1987 395.900 295.000 222.300 179.200 78.400 30.900 32.200 110.700 253.200 241.900 251.000 401.800 1988 425.900 233.300 202.000 199.800 81.300 45.600 39.600 138.600 237.700 225.800 250.400 325.800 1989 376.300 257.400 222.600 169.000 73.600 30.800 30.700 143.400 187.700 229.000 250.200 243.600 1990 251.800 236.400 212.400 168.500 75.500 30.800 30.800 81.500 120.000 257.700 440.100 502.300 1991 557.600 214.600 191.800 220.400 102.400 47.600 33.700 205.500 275.500 254.200 252.300 407.700

Documents

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