Preliminary hydrological modelling for Kerang ... - Goulburn Murray … · A 19/08/2012 Project Reference Group C. Gippel 19/08/2012 Draft B 11/09/2012 Project Reference Group C

Dr Christopher J Gippel

For

Goulburn-Murray Water

September 2012

Preliminary hydrological modelling for Kerang Lakes bypass

investigation project

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Preliminary hydrological modelling for Kerang Lakes bypass investigation project


by Dr Christopher J Gippel

Fluvial Systems Pty Ltd

Please cite as follows:

Gippel, C.J. 2012. Preliminary hydrological modelling for Kerang Lakes bypass investigation project. Fluvial Systems Pty Ltd, Stockton. Goulburn-Murray Water, Shepparton, September.

Document history and status

Revision Date issued Reviewed by Approved by Date approved Revision type

A 19/08/2012 Project Reference Group C. Gippel 19/08/2012 Draft

B 11/09/2012 Project Reference Group C. Gippel 11/09/2012 Draft

C 15/09/2012 Project Reference Group C. Gippel 15/09/2012 Draft

D 21/09/2012 Project Reference Group C. Gippel 21/09/2102 Final

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B 1 1 Peter Roberts, Pat Feehan

C 1 1 Peter Roberts, Pat Feehan

D 1 1 Peter Roberts, Pat Feehan

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File location: C:\...\12002_NVIRP_Kerang Lakes\Reports\Preliminary modelling of water regime options and water savings for Kerang Lakes.docx

Author: Dr Christopher J Gippel

Project manager:

Chris Gippel

Name of organisation:


Name of project: Kerang Lakes and Gunbower Lagoons Bypass Investigation Project

Name of document:

Report on water balance modelling

Document version:

Final

Fluvial Systems Pty Ltd PO Box 49 Stockton NSW 2295 [email protected] Ph/Fax: 02 49284128; Mobile: 0404 472 114

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Disclaimer

Fluvial Systems Pty Ltd prepared this report for the use of Goulburn-Murray Water, and any other parties that may rely on the report, in accordance with the usual care and thoroughness of the consulting profession. It is based on generally accepted practices and standards at the time it was prepared. No other warranty, expressed or implied, is made as to the professional advice included in this report. It is prepared in accordance with the scope of work and for the purpose outlined in the Proposal.

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This report should be read in full. No responsibility is accepted for use of any part of this report in any other context or for any other purpose or by third parties. This report does not purport to give legal advice. Legal advice can only be given by qualified legal practitioners.

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Table of Contents

Disclaimer _______________________________________________________________ ii Copyright ________________________________________________________________ ii 1 Introduction _________________________________________________________ 1

1.1 Background to this study _____________________________________________ 1

1.2 Objectives of this report ______________________________________________ 2

1.3 Previous investigations_______________________________________________ 3 1.3.1 Net Evapotranspiration (current regime)____________________________________ 3 1.3.2 Seepage ____________________________________________________________ 3 1.3.3 Potential for water savings ______________________________________________ 4

2 Method _____________________________________________________________ 4

2.1 SWET model structure _______________________________________________ 4 2.1.1 Model concept ________________________________________________________ 4 2.1.2 Model algorithm _______________________________________________________ 5 2.1.3 Model parameters, data sources and scenarios ______________________________ 5 2.1.4 Modelling platform _____________________________________________________ 7

2.2 Bathymetry data ____________________________________________________ 8

2.3 Inflow data ________________________________________________________ 8

2.4 Inflow/outflow hydraulics _____________________________________________ 8

2.5 Climate data _______________________________________________________ 8

2.6 Groundwater exchange ______________________________________________ 9

2.7 Irrigation demand ___________________________________________________ 9

2.8 Lake management regime options ______________________________________ 9 3 Results ____________________________________________________________ 10

3.1 Summary of potential losses and savings _______________________________ 10

3.2 First (Reedy) Lake _________________________________________________ 11 3.2.1 Current regime ______________________________________________________ 11 3.2.2 Episodic regime ______________________________________________________ 13 3.2.3 Intermittent regime ___________________________________________________ 14 3.2.4 Semi-permanent regime (8 in 10) ________________________________________ 15 3.2.5 Semi-permanent regime (9 in 10) ________________________________________ 16

3.3 Middle (Reedy) Lake _______________________________________________ 17 3.3.1 Current regime ______________________________________________________ 17 3.3.2 Episodic regime ______________________________________________________ 18 3.3.3 Intermittent regime ___________________________________________________ 19 3.3.4 Semi-permanent regime (8 in 10) ________________________________________ 20 3.3.5 Semi-permanent regime (9 in 10) ________________________________________ 21

3.4 Third (Reedy) Lake _________________________________________________ 22 3.4.1 Current regime ______________________________________________________ 22 3.4.2 Episodic regime ______________________________________________________ 23 3.4.3 Intermittent regime ___________________________________________________ 24 3.4.4 Semi-permanent regime (10 in 10) _______________________________________ 25

3.5 Little Lake Charm (including Scott’s Swamp) _____________________________ 26 3.5.1 Current regime ______________________________________________________ 26 3.5.2 Episodic regime ______________________________________________________ 27 3.5.3 Intermittent regime ___________________________________________________ 28 3.5.4 Semi-permanent regime (8 in 10) ________________________________________ 29 3.5.5 Semi-permanent regime (9 in 10) ________________________________________ 30

3.6 Racecourse Lake __________________________________________________ 31 3.6.1 Current regime ______________________________________________________ 31 3.6.2 Episodic regime ______________________________________________________ 32 3.6.3 Intermittent regime ___________________________________________________ 33 3.6.4 Semi-permanent regime (9 in 10) ________________________________________ 34

3.7 Comparison with previous estimates of losses and savings _________________ 35

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3.7.1 Net Evapotranspiration (current regime)___________________________________ 35 3.7.2 Seepage ___________________________________________________________ 35 3.7.3 Potential for water savings _____________________________________________ 36

3.8 Inter-annual variability of savings ______________________________________ 36 4 Sensitivity of savings estimates to model parameters_________________________ 37

4.1 Sensitivity of savings estimates to inherent model parameter values __________ 37 4.1.1 Evapotranspiration estimate: Pan versus physical model _____________________ 38 4.1.2 Evapotranspiration estimate: wind speed assumption in physical model _________ 38 4.1.3 Initial loss parameters _________________________________________________ 39

4.2 Sensitivity of savings estimates to management regime parameter values _____ 39 4.2.1 Maximum rate of filling ________________________________________________ 40 4.2.2 Date of beginning the filling phase _______________________________________ 40 4.2.3 Duration of the filling phase ____________________________________________ 40

4.3 Summary of variability of savings and model sensitivity ____________________ 41 5 Conclusion _________________________________________________________ 42 6 References _________________________________________________________ 42 7 Appendix – Bathymetry data ____________________________________________ 45

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1 Introduction

1.1 Background to this study

The Kerang Lakes are part of an extensive wetland system of over 100 wetlands that

occurs within the Loddon-Murray Region (DSE, 2004). The Kerang Lakes Ramsar

Site, listed in 1982, consists of 23 wetlands which receive water from the Murray

River via the Torrumbarry Irrigation System, the Avoca River and the Loddon River.

These wetlands, which include both regulated and unregulated wetlands, are used

for a variety of purposes including as part of the irrigation supply, as salt disposal

lakes and as natural feature reserves receiving Environmental Water Allocations

(DSE, 2010) (Figure 1).

Figure 1. Torrumbarry Irrigation Area, showing location of Kerang Lakes. Map modified from North Central CMA (2007).

The Kerang Lakes bypass investigation project is investigating the feasibility of a

concept to construct bypass channels around five of the Kerang Lakes (NVIRP,

2012). First Reedy, Middle Reedy and Third Reedy lakes, Little Lake Charm and

Racecourse Lake (Figure 1 and Figure 2) have had permanent water regimes since

the 1920s when they were filled to become part of the TIA. The altered regimes

reduced or resulted in the loss of biodiversity (DSE, 2004, p. 16). The bypass would

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provide the opportunity to implement alternative hydrological regimes in the lakes.

Alternative regimes could lead to improvements in the ecological values of the lakes.

Also, by periodically lowering the lake levels during summer months, water savings

would be achieved through reduced evaporation losses.

Figure 2. Sketch of possible options under investigation in the Kerang Lakes bypass investigation project. Map modified from NVIRP (2012).

1.2 Objectives of this report

The key objective of this hydrological modelling component of the investigation is to

develop numerical models of 5 Kerang Lakes that can be used to:

estimate long term losses under existing conditions and possible future

operational regimes, so that water savings potential of the bypass intervention

can be estimated, and

predict long-term daily water level regimes under a range of possible

operational regimes so that their potential for ecological rehabilitation can be

evaluated, and the regimes refined accordingly.

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This hydrologicial modelling component of the Kerang Lakes bypass investigation

project was undertaken in two Stages:

Stage I.

Preliminary estimates of losses and savings potential for five Kerang Lakes

wetlands under a wide range of possible water regimes, from existing

(permanent) to dry (episodic wetting). The focus is on model development,

model sensitivity and broad-scale estimation of water savings potential.

Stage II.

Pending the outcome of Stage I, refine a narrow set of water balance models

that have the highest potential for conjointly achieving sufficiently high water

savings, and potential for improving ecological values.

This report documents the methods and outcomes of Stage I.

1.3 Previous investigations

North Central CMA (2011) reviewed previous estimates of losses and potential for

water savings at Kerang Lakes. The various estimates are outlined below in terms of

evapotranspiration, seepage and potential for savings.

1.3.1 Net Evapotranspiration (current regime)

Evapotranspiration (ET) is a term that covers both evaporation from wet surfaces

(evaporation), and vegetation (transpiration), so it can be applied to wetlands whether

vegetated or not. Net evapotranspiration (net ET) is the sum of evapotranspirative

losses and precipitation gains.

North Central CMA (2011) listed estimates of average annual evapotranspiration

losses from the five Kerang lakes that were attributed to Lugg et al. (1989). These

were expressed as net ET estimates by subtracting long term (1889 – 2012) average

annual rainfall of 352 mm (from DataDrill) (Table 1). SKM (2010) estimated average

annual net ET (in ML) for the five Kerang lakes using the Pan coefficient method

(applying an annual Pan factor of 0.78) and Morton’s shallow lake method (Table 1).

The Kerang Lakes REALM model also uses the Pan coefficient method (Table 1).

These data show that estimates of water loss are highly dependent on the method

used, and the input data used (lake surface area and climate data).

1.3.2 Seepage

SKM (2010) estimated that under the current regime, seepage loss from First, Middle

and Third Reedy lakes would total up to 500 ML/year under dry climate conditions,

and 320 ML/year for medium conditions. North Central CMA (2011) listed the degree

of groundwater interaction for the lakes, attributed to Lugg et al. (1989), as “minor

intrusion: nil”, except for Little Lake Charm which was a possible source of

groundwater recharge (i.e. loss from the lake to groundwater).

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Table 1. Previous estimates of average annual net evapotranspiration (net ET) for five Kerang lakes. Lugg et al. (1989) estimated ET and net ET was calculated by subtracting long term (1889 – 2012) average annual rainfall of 352 mm (from DataDrill). Kerang Lakes REALM model data provided by Seker Mariyapillai (pers. comm., DSE, Melbourne.

19/09/2012).

Lake Lugg et al. (1989) SKM (2010) REALM model

ET (ML/yr)

Net ET (minus

352 mm rainfall) (ML/yr)

Net ET, Pan

coefficient method (ML/yr)

Net ET, Morton’s method (ML/yr)

Net ET, Pan

coefficient method (ML/yr)

Reedy (First) 2,500 1,802 1,883 1,921 1,460

Middle (Reedy) 2,700 2,019 1,883 1,642 1,460

Third (Reedy) 3,000 2,190 2,131 2,002 1,825

Little Lake Charm 1,580 1,101 565 n/a n/a

Racecourse 3,300 2,456 2,182 2,341 1,825

TOTAL (excl. L’t. Lake Charm)

8,467 8,079 7,906 6,570

1.3.3 Potential for water savings

RMCG (2009) estimated net savings from two Bypass options: Little Lake Charm and

Racecourse Lakes Bypass (815 ML/year) and Reedy Lakes Bypass (1,250 ML/year).

The total was 2,065 ML/year.

SKM (2010) estimated that the total savings for the entire Kerang Lakes Bypass

system ranged from 4,200 – 12,400 ML/year, and an alternative operating regime

with different ecological values would save 1,400 – 9,600 ML/year. The range in

savings estimates relates to differences in wet and dry years. Middle (Reedy) was

assessed to have no potential for savings, and Little Lake Charm had potential for

only a small volume of savings. SKM (2010) were of the view that the savings

actually achieved would be on the low end of the estimated range.

2 Method

2.1 SWET model structure

2.1.1 Model concept

SWET is not a particular computer program (although originally a template did exist),

but an approach to wetland water balance modelling that incorporates all of the water

balance components, uses best available data, runs on a daily time step, and has

standard way of defining and calculating the “savings” under alternative operating

scenarios.

The SWET water balance modelling concept was initially developed to accurately

predict water savings potential at individual wetlands in the River Murray System

(Gippel 2005a, Gippel 2005b, Gippel 2005c). After development of the SWET

modelling approach was completed in 2005, it was reviewed by technical

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representatives of state and commonwealth agencies responsible for management of

the River Murray System, and then endorsed as a suitable modelling procedure for

listings on The Living Murray Developmental Register (the first stage of approval for a

water recovery measure).

A model run based on current conditions returns a value of current losses of water

from the system to the wetland. Run for a future scenario (i.e. current hydrology or

hydrology with climate change assumptions, but with a regulating structure to control

flows to and from the wetland to achieve the ecologically desirable hydrological

regime in the wetland), the model returns a value of future losses of water from the

system to the wetland. The value of current losses minus the value of future losses is

the volume of water that can potentially be recovered from the system. As well as

estimating losses, the water balance produces a daily time series of wetland water

level. Run for a pre-regulation scenario, the model characterises a wetland’s natural

hydrological regime. This can be used to guide development of a future water level

management regime for a wetland. Run for a current scenario, the model

characterises the wetland’s current hydrological regime, enabling identification of

aspects of the hydrology that may be ecologically limiting.

Although the SWET approach was originally devised mainly for the purpose of

estimating the potential for water savings at river-connected wetlands, the

hydrological principles are equally applicable to the problem of modelling the time

series of wetland water levels to assist ecological research (e.g. Catford et al., 2011),

or development of ecologically-appropriate wetland water management regimes (e.g.

Ecological Associates, 2008; Gippel, 2010).

2.1.2 Model algorithm

The SWET model attempts to estimate all the components of the hydrological cycle

that influence daily water level in a wetland (cf. Dooge, 1975; Gosselink and Turner,

1978; Winter, 1981; Duever, 1988; U.S. Army Corps of Engineers, 1993; Gippel,

1993; LaBaugh, 1996; Woo and Rowsell, 1993). The daily water budget is described

by:

ΔV = [Qir + (a Alo R) + (b Aexp R) – (Qor + Qox + Qp)] – [I] + [Gi - Go] + [Awet (R – ET)]

where: ΔV = daily change of water quantity stored in the wetland (m3); Qir = volume of

surface water spilling into the wetland from the source (m3); a = a local catchment

runoff coefficient; Alo = wetland local catchment area (m2); R = local precipitation (m);

b = a runoff coefficient for the exposed part of the wetland bed; Aexp = area of the

exposed part of the wetland bed (m2); Qor = volume of surface water flowing out of the

wetland back to the source (m3); Qox = volume of surface water flowing out of the

wetland external of the river-wetland system (permanently lost) (m3); Qp = volume of

pumped extraction (m3); I = volume of initial loss of inflowing surface water to voids in

the dry wetland bed (m3); Gi = volume of groundwater gained by the wetland (m3); Go

= volume of water lost by the wetland to groundwater (m3); Awet = wet surface area of

wetland (m2); and ET = evapotranspiration from the wet surface of the wetland (m).

2.1.3 Model parameters, data sources and scenarios

The wetland volume (V), surface area (Awet and Aexp) and water elevation (Hw) are

interchanged in the SWET model through bathymetric relationships derived from a

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digital elevation model of the wetland (generated from ground and hydrographic

survey data). The direction and rate of flow of water between the wetland and the

inflow determine the net losses from the inflow source, ΔQr = Qir – Qor – Qox. The

values of Qir, Qor, and Qox are calculated daily within the model, as determined by the

relationship between the elevation of the wetland water surface (Hw), the adjacent

source river water surface (Hr) (a model input value), and the sill separating them (a

model input value derived from survey), and also by the hydraulics of the inflowing

and outflowing connections. The hydraulics are described by standard equations for

open channel flow, pipe flow or weir flow, as appropriate. Source river water surface

elevation (Hr) is converted from river flow records (either gauged or modelled) on the

basis of a local hydraulic model of the river. For a terminal or in-line wetland (such as

Kerang Lakes) with a direct connection between the inflow source and the wetland,

these calculations are simpler. Runoff coefficients a and b are set using appropriate

values for the surface characteristics and can be made variable according to rainfall

intensity. Wetland local catchment area is determined from topographic analysis.

Precipitation data are obtained from local gauges or from a modelled source. In

Australia, modelled climate daily time series data (with records from the late 1800s

up to the present day) are available for any location from the SILO DataDrill service

provided through the Department of Environment and Resource Management,

Queensland Government. The DataDrill accesses grids of data derived from

interpolation of point station records. Pumped extraction data are obtained from local

records.

Evapotranspiration is a critical component of the water budget and should be

carefully considered. Early SWET models used the time series of modelled Class A

Pan evaporation from SILO DataDrill, factored using empirical monthly pan to open

water coefficients derived for a wetland near Griffith, western NSW (Hoy and

Stephens, 1979). More recently applied SWET models incorporated a combination

physical method recommended for the Murray-Darling Basin by McJannet et al.

(2009) that uses the Penman-Monteith method with a deBruin adjustment to the

amount of energy available for evaporation based on changes in heat storage within

the water body. The key assumption of this physical model is that the water body is

well mixed and that no thermal stratification develops. The Kerang Lakes vary in

maximum depth from 1.4 to 2.6 m. While stratification might develop under calm,

warm and sunny conditions, wind and nocturnal heat loss would normally disrupt the

stratification at the sub-daily time scale. The combination physical method requires

an estimate of daily wind speed. While the factored pan and physical model

approaches produce different estimates of evaporation at the daily time scale

(McJannet et al., 2009), at the scale of annual estimated wetland water savings, the

differences tend to be systematic, as determined by the selected pan factor/s.

Initial losses of water to bed sediments as the wetland fills represent a permanent

loss of water, because the water is ultimately evaporated from the bed sediments as

the wetland draws down. The initial loss is calculated as the percent of the bed

material that is void space multiplied by the depth of the bed layer (these values are

determined by field sampling). Most riverine wetlands in the lowland areas of the

River Murray have a clay bed that cracks upon drying and seals upon wetting. The

groundwater component in SWET models the daily flux between river and wetland

using Darcy’s Law. The hydraulic conductivity value is selected on the basis of local

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soil type. The daily time series of hydraulic head is determined from the relative

levels of the adjacent source river (SWET model input data) and the wetland

(predicted within SWET). In the lowland part of the River Murray System,

groundwater exchange is not normally a large component of wetland water budgets

due to low hydraulic conductivity of the wetland bed, and low head differences

between the adjacent river and wetland. Any wetland with strong connectivity to the

groundwater system would be a poor candidate for obtaining water savings, as a

regulating structure would be ineffective in disconnecting the wetland from the river

inflow source.

Including a regulating structure in the water balance model under a future scenario

alters the pattern of water transfer between the wetland and the inflowing river. The

height of the structure is a variable in the model, which allows for iterative trade-off of

water savings and wetland water level regime. Draft operating rules for the structure

are ideally set by a panel of scientific experts, managers and stakeholders, but these

remain flexible within the model to allow for iterative trade-off of the joint objectives of

maximising savings and generating an ecologically desirable water level regime. The

final operating rules might represent a compromise, or could favour either the

ecological or water savings objectives, depending on the local priorities.

Water savings, S, are calculated by subtracting the net long-term exchange of water

between the inflowing river and the wetland under a future (f) scenario, ∑ΔQr(f), with

that under the current (c) scenario, ∑ΔQr(c). The exchange of water between the

inflow source and wetland can be episodic. Water can flow to or from the wetland, so

on a daily basis the exchange can be positive or negative. The long-term exchange is

usually expressed as a distribution of values of annual total exchange over the

modelled period. Thus, the long-term savings is expressed as a distribution of annual

savings over the modelled period. Savings can be expressed as a single value using

the mean or median of the modelled annual values, supported by an expression of

dispersion (such as standard deviation or inter-quartile range). In most applications to

date, the SWET models have been run over 100 years or longer, because long-term

modelled climate and river flow data have usually been available.

2.1.4 Modelling platform

Most SWET models have been developed within Microsoft Excel™. The main reason

for this is that the widespread availability of, and familiarity with, Microsoft Excel™

allows for the possibility of river managers being able to use the model with very little

training. While there is no commercial or public domain software that has been

specifically designed for this purpose, commercial hydrodynamic models could

potentially be used. However, such models are normally relatively costly to run (due

to high set-up costs and long model run times), and operate at the event or sub-

annual time-scale, while the problem addressed by the SWET model requires:

(i) analysis of a long time series (to fully characterise the wetland water level regime,

and assess the potential for water savings under the full range of natural hydrological

conditions), (ii) capacity to vary water level operational regimes inter-annually, or

dependent on antecedent conditions, and (iii) inexpensive modelling costs due to the

large number of wetlands that have potential for water savings and environmental

benefits.

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2.2 Bathymetry data

The five lakes were professionally surveyed using standard techniques. Bathymetric

data were provided for each lake as a digital file of water surface area and volume for

a range of water levels (see Appendix – Bathymetry data). In addition, bathymetric

survey plans were provided. Where the lowest elevation (zero area and volume) was

not provided, this was assumed to be 0.01 m lower than the lowest provided

elevation.

2.3 Inflow data

Daily inflows to First (Reedy) Lake under the baseline (existing conditions) were

obtained from a water resource allocation model (REALM) of the Kerang Lakes

system (SKM, 2007). The modelling period is 1/01/1891 to 1/07/2010.

The REALM inflows comprise regulated and unregulated inflow. The preliminary

SWET models described here do not distinguish between these two flow types. The

future scenario models assume only controlled inflows, sufficient to just achieve the

desired water levels. However, in reality, flood flows will continue to occur in the

future, and these will disrupt some drying cycles. In one sense, these food inflows will

interfere with the expected pattern of water savings, but in another sense, the

unregulated water is low cost water compared to regulated water, so filling the lakes

from flood events, although perhaps untimely, could be viewed as a windfall. It is

likely that in Stage II of this hydrological modelling project the distinction between

regulated and unregulated will be made, and flood inflows will occur during the future

scenarios.

2.4 Inflow/outflow hydraulics

The preliminary SWET models described here have no hydraulic constraints on the

inflows and outflows. In baseline (existing condition) models, inflows to the system

are specified by the REALM model. Outflows to the next downstream lake are

calculated each day using the SWET algorithm as the surplus after losses. In reality,

there would be noticeable attenuation of inflows at times of floods due to the storage

effect of the lake itself. The effect of reducing the flood inflow peak, and extending the

duration, is apparent from gauged lake water level records. This effect would have

only a minor influence on water savings potential (because it is an infrequent event).

However, this flood inflow attenuation effect will be simulated in the models

developed in Stage II of this hydrological modelling project.

2.5 Climate data

Separate DataDrill climate files were obtained for First, Middle, Third and Lake

Charm and Racecourse lakes. The DataDrill grid is 0.05 x 0.05 degrees of latitude

and longitude, and the centre of Lake Charm and Racecourse lakes fell within the

same grid. The climate series was obtained for the period 1/01/1891 to 1/07/2010.

The Kerang Lakes SWET models retain the option of using factored Pan evaporation

data. Pan coefficients are usually borrowed from a similar water body (i.e. similar

depth and area) in a similar latitude and altitude where the Pan coefficient has been

measured. It is not uncommon practice to apply a single Pan coefficient throughout

the year, although the Pan coefficient is known to vary seasonally in nearly all

situations. The default Pan coefficients in the LMWP model are monthly variable

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values from Lake Wyangan (Griffith, NSW) (Hoy and Stephens, 1979), which are

considered the most appropriate values for wetlands in this region.

In the original application of the combination evaporation method by McJannet et al.,

(2009), the water body surface area and depth were assumed constant, but this was

clearly inappropriate for the application to management of water bodies with highly

variable water levels. Thus, in the SWET model, the estimated surface area and

depth at the end of a day become input data for the estimate of evaporation rate for

the next day. Wind speed data were obtained from the Bureau of Meteorology for

Kerang meteorological station, with a start date of 1962. Data were daily-read wind

speed at 9 AM and 3 PM. Average wind speed was assumed to be the average of

these two readings. Although this is only an approximation, it is consistent with the

way mean daily temperature is derived for the CSIRO evaporation model. In this

case, mean daily temperature is estimated from the average of maximum and

minimum daily readings. The lack of measured wind speed data prior to 1962 was

overcome by assuming a value of 2 m/s, which is the same assumption made by the

Department of Environment and Resource Management (QLD) when they estimate

reference crop evapotranspiration using the Penman-Monteith method for the SILO

DataDrill. The estimates of water use by water bodies are better if measured or

modelled wind speed data are used, but the assumption of 2 m/s does not

compromise the integrity of the model.

2.6 Groundwater exchange

The preliminary models reported here did not include groundwater exchange. This

would require generation of a daily time series of the local water table elevation, and

while possible, would not be trivial. Stage II of this hydrological modelling project will

consider the inclusion of groundwater exchange.

2.7 Irrigation demand

The Kerang Lakes have a relatively small irrigation demand that was not included in

the preliminary models reported here. This demand is not expected to have any

impact on water savings estimates, because it does not have a significant impact on

lake water levels. However, for completeness, irrigation demands will be included in

the baseline models developed in Stage II of this hydrological modelling project.

2.8 Lake management regime options

The lake future management regime options were provided by North Central CMA

(2012). The process for developing alternative wetland water regime scenarios was

informed by consideration of: (i) ecological values previously recorded at the

wetlands, (ii) wetland water regime definitions and classifications and (iii) previous

work to define water regimes for the wetlands.

At each wetland four alternative water regime scenarios were developed:

no change

episodic

intermittent

semi-permanent

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These alternative scenarios were developed for planning purposes and no particular

scenario has been selected or recommended for future management purposes.

The management scenarios modelled here were intended as preliminary regimes for

the purpose of estimating the magnitude of savings possible for the four water regime

scenario types. Any regimes that show potential will be refined in Stage II of this

hydrological modelling project.

Some assumptions were made for these preliminary models:

Lake filling began on 1 August

Maximum rate of rise from inflows was set at 50 mm per day

There was no local catchment area

The capacity to supply water to meet the desired water level was unlimited

When the lake bed dried it was assumed to develop a cracked bed to a depth

of 0.3 m with 25% void space

Some of these assumptions might be altered in later versions of the management

scenarios. The sensitivity of the estimated water savings to the potential range of

values of these parameters was tested in this report.

3 Results

3.1 Summary of potential losses and savings

The SWET model was used to calculate net losses (net evapotranspiration plus initial

losses) from the lakes over a daily time step. These losses were summed over

periods of one year or longer, depending on the management regime. The baseline

regime is the same every year, so the losses were reported for every year. The

potential future management regimes involved multi-year cycles of filling and drying,

so the losses were highly variable from year to year depending on the stage of the

cycle. In these cases the losses were reported for the period of each complete cycle.

Water savings were calculated over each cycle. For each scenario, average annual

savings represent annualized values of the savings estimated over all the completed

cycles of the modelled period. The maximum length of the modelled period was 118

years. The losses reported for the baseline (Current) scenario were calculated over

118 years, but shorter baseline periods were used for some future scenarios (in

cases where an incomplete management cycle occurred at the end of the modelled

period).

The potential water savings from alternative management of the lakes varies

significantly depending on the regime type (Table 2). The smaller Little Lake Charm

has a smaller surface area than the other lakes, so for an alternative management

regime that is mostly dry, it has lower potential for savings (Table 2). However, this

lake is shallower than the others, so its surface area reduces more rapidly during

draw down. Thus, for alternative management regimes that involve partial or less

frequent drying, it can produce savings that are comparable with or greater than

those of the others (Table 2).

Page 11

The preliminary estimates made here of total (for the five lakes) mean annual savings

were:

6,123 ML/yr for the episodic regime,

3,095 ML/yr for the intermittent regime, and

1,553 ML/yr for the semi-permanent regimes with the greatest savings.

It would not be necessary to operate all five lakes according to the same regime type,

so the above total savings represents the potential range.

Table 2. Estimated average annual net losses and potential savings from a range of

management options for five Kerang Lakes. Net loss is equivalent to the water that needs to be artificially supplied to maintain the water level regime.

Lake Scenario Period of average

(years, from 1895)

Average annual net

loss (ML/yr)

Average annual

savings* (ML/yr)

First (Reedy) Current 118 2,238 198.28 ha Episodic 115 768 1,456 Intermittent 116 1,698 531 Semi-permanent (8/10) 110 1,947 258 Semi-permanent (9/10) 110 2,130 75

Middle (Reedy) Current 118 2,235 193.40 ha Episodic 118 1,541 694 Intermittent 116 1,624 602 Semi-permanent (8/10) 110 1,854 349 Semi-permanent (9/10) 110 2,033 169

Third (Reedy) Current 118 2,652 230.13 ha Episodic 116 1,278 1,364 Intermittent 117 2,203 443 Semi-permanent (10/10) 110 2,580 34

L’t. Lake Charm Current 118 1,559 136.05 ha Episodic 116 385 1,170 Intermittent 115 423 1,127 Semi-permanent (8/10) 110 871 668 Semi-permanent (9/10) 110 975 563

Racecourse Current 118 2,812 239.65 ha Episodic 116 1,363 1,440 Intermittent 117 2,400 407 Semi-permanent (9/10) 110 2,529 244 * Savings is not always the given 118 year average current loss minus future scenario loss, as

the benchmark (current) loss was re-calculated over the same period of each future scenario;

the length of the scenario periods varied because they always ended on a complete cycle.

3.2 First (Reedy) Lake

3.2.1 Current regime

The Current regime was used as the benchmark against which future scenarios were

compared. The Current regime is based on a relatively constant water level held at

full supply level (FSL) of 74.88 m. The level is not actually constant, as, on any day,

Page 12

inflows may not be sufficient to account for evapotranspirative losses. The inflows

were as determined by the REALM model estimates for Wandella Creek and

Washpen Creek flows. The SWET model does not exactly reproduce the gauged

water levels, measured from 1986. The reasons are:

In the SWET model the outflows are unconstrained, when in reality, there will

be attenuation at times of very high inflows. Thus, the recorded flood peak

lake levels are not predicted.

The REALM model assumes current operation rules, and these many not

have applied throughout history. The data suggest that this was the case.

The recorded level of the lake would vary depending on where it is gauged.

The SWET model calculates an average lake level.

The differences between the gauged and modelled lake levels are relatively small.

Model parameter Model setting

Supply of inflows According to REALM assumptions

Controlled filling frequency and levels Not applicable

Durations of filling phases Not applicable

Assumed maximum rate of rise Not applicable

Start of filling Not applicable

Assumed local contributing area None

Water use calculation period From 1 August

Estimated long-term mean annual net losses were 2,238 ML.

Figure 3. Predicted water levels and percentage of bed dry for Current (baseline) regime, First (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 13

3.2.2 Episodic regime


Supply of inflows Assumed unlimited capacity to supply Controlled filling frequency and levels

1 in 5 years to 74.88 m

Durations of filling phases Alternating 4 then 3 months (includes filling phase)

Assumed maximum rate of rise 50 mm/day

Start of filling 1 August



Estimated long-term mean annual net losses were 768 ML, and mean annual water

savings were 1,456 ML.

Figure 4. Predicted water levels and percentage of bed dry for Episodic regime, First (Reedy) Lake.

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 14

3.2.3 Intermittent regime



3 in 4 years; Year 1 to 74.88 m; Years 2 and 3 to 73.6 m

Durations of filling phases Alternating 10, 8 then 7 months (includes filling phase)*




Water use calculation period From 1 August * The filling durations were set to give the best chance of achieving full drawdown.

Estimated long-term mean annual net losses were 1,722 ML, and mean annual water

savings were 516 ML.

Figure 5. Predicted water levels and percentage of bed dry for Intermittent regime, First (Reedy) Lake.

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

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f b

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are

a e

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sed

Page 15

3.2.4 Semi-permanent regime (8 in 10)



8 in 10 years to 74.88 – 74.28 m. Drawdown over a 2 year period.

Durations of filling phases

2 months (including filling time) at 74.88 m then draw down to 74.28 mm for remaining months of the year

Assumed maximum rate of rise

50 mm/day


Assumed local contributing area

None

Water use calculation period

From 1 August


savings were 258 ML.

Figure 6. Predicted water levels and percentage of bed dry for Semi-permanent regime (8 in 10), First (Reedy) Lake.

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

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Page 16


This regime is the same as the Semi-permanent regime (8 in 10), except that the full

drawdown occurs over only one year instead of two. The savings for a regime that

varied between 8 in 10 and 9 in 10 full would lie between the two estimates.

Model parameter Model setting Supply of inflows Assumed unlimited capacity to supply

Controlled filling frequency and levels



2 months (including filling time) at 74.88 m then draw down to 74.28 mm for remaining months of the year*


50 mm/day



None


From 1 August

* The duration of 2 months always allows for filling to the maximum level

The lake does not fully draw down under this regime.


savings were 75 ML.

Figure 7. Predicted water levels and percentage of bed dry for Semi-permanent regime (9 in 10), First (Reedy) Lake.

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.50

72.00

72.50

73.00

73.50

74.00

74.50

75.00

75.50

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 17

3.3 Middle (Reedy) Lake






were as determined by the modelled outflows from the Current SWET model for First

(Reedy) Lake. The SWET model does not exactly reproduce the gauged water levels,

measured from 1986. The reasons are the same as noted for First (Reedy) Lake.


Supply of inflows According to REALM assumptions, SWET modelled losses from First (Reedy), and no hydraulic constraints


Not applicable


Not applicable


Not applicable



None


From 1 August

Estimated long-term mean annual net losses were 2,235 ML

Figure 8. Predicted water levels and percentage of bed dry for Current (baseline) regime, Middle (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 18




1 in 2 years to 74.85 m*

Durations of filling phases Alternating 2, 3, 4 then 5 months (includes filling phase)




Water use calculation period From 1 August * For these scenarios, the FSL was given by North Central CMA (2012) as 74.85 m, but First

(Reedy) FSL is 74.88 m, and the lakes are connected. An elevation of 74.85 m was modelled

for the future scenarios, and 74.88 m for the Current scenario.

The lake does not always fully draw down under this regime.

Estimated long-term mean annual net losses were 1,541 ML. Estimated long-term

mean annual savings were 694 ML.

Figure 9. Predicted water levels and percentage of bed dry for Episodic regime, Middle (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 19




3 in 4 years; Year 1 to 74.85 m; Years 2 and 3 to 73.85 m*

Durations of filling phases Yr 1 is 10, Yrs 2 and 3 are 12 months (includes filling phase)†




Water use calculation period From 1 August * For the scenarios, the FSL was given by North Central CMA (2012) as 74.85 m, but First

(Reedy) FSL is 74.88 m, and the lakes are connected. An elevation of 74.85 m was modelled

for the future scenarios, and 74.88 m for the Current scenario

† The duration at FSL was not specified by North Central CMA (2012), so 10 months was

assumed



Figure 10. Predicted water levels and percentage of bed dry for Intermittent regime, Middle (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 20








50 mm/day



None


From 1 August


This regime is allows for near complete drawdown once every 10 years.



Figure 11. Predicted water levels and percentage of bed dry for Semi-permanent regime (8 in 10), Middle (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 21











50 mm/day



None


From 1 August





Figure 12. Predicted water levels and percentage of bed dry for Semi-permanent regime (9 in 10), Middle (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 22

3.4 Third (Reedy) Lake






were as determined by the modelled outflows from the Current SWET model for

Middle (Reedy) Lake. The SWET model does not exactly reproduce the gauged

water levels, measured from 1986. The reasons are the same as noted for First

(Reedy) Lake.

Model parameter Model setting Supply of inflows According to REALM assumptions, SWET modelled losses

from Middle (Reedy), and no hydraulic constraints


Not applicable


Not applicable


Not applicable



None


From 1 August


71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 23



Supply of inflows Assumed unlimited capacity to supply Controlled filling frequency and levels 1 in 4 years to 74.56 m

Durations of filling phases 10 months (includes filling phase)






mean annual savings were 1,364 ML.

Figure 13. Predicted water levels and percentage of bed dry for Episodic regime, Third (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 24




2 in 3 years; Year 1 to 74.85 m; Year 2 to 74.2 m

Durations of filling phases Alternating 10, 9, 8 then 7 months (includes filling phase)







Figure 14. Predicted water levels and percentage of bed dry for Intermittent regime, Third (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 25






12 month; exception is 2 consecutive years of fill for 2 months at 74.56 m, then draw down to 73.74 m for remainder of year*


50 mm/day



None


From 1 August

* The frequency of the two consecutive years of drawdown to 73.74 m was not specified by

North Central CMA (2012). It was set to once every 10 years.




Figure 15. Predicted water levels and percentage of bed dry for Semi-permanent regime, Third (Reedy) Lake.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 26

3.5 Little Lake Charm (including Scott’s Swamp)






were as determined by the modelled outflows from the Current SWET model for Third

(Reedy) Lake.


Supply of inflows According to REALM assumptions, SWET modelled losses from Third (Reedy), and no hydraulic constraints


Not applicable


Not applicable


Not applicable

Start of filling Not applicable Assumed local contributing area

None


From 1 August


Figure 16. Predicted water levels and percentage of bed dry for Current (baseline) regime, Little Lake Charm.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 27





Durations of filling phases Alternating 2 and 5 months (includes filling phase)





Estimated long-term mean annual net losses were 385 ML. Estimated long-term


Figure 17. Predicted water levels and percentage of bed dry for Episodic regime, Little Lake Charm.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 28




4 in 5 years; Year 1 to 73.95 m; Year 2, 3 and 4 to 72.75 m

Durations of filling phases 4 months (includes filling phase)







Figure 18. Predicted water levels and percentage of bed dry for Intermittent regime, Little Lake Charm.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 29








50 mm/day



None


From 1 August




Figure 19. Predicted water levels and percentage of bed dry for Semi-permanent (8 in 10) regime, Little Lake Charm.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 30











50 mm/day



None


From 1 August




Figure 20. Predicted water levels and percentage of bed dry for Semi-permanent (9 in 10) regime, Little Lake Charm.

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

71.5

72.0

72.5

73.0

73.5

74.0

74.5

75.0

75.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 31

3.6 Racecourse Lake






were as determined by the modelled outflows from the Current SWET model for Little

Lake Charm Lake.


Supply of inflows According to REALM assumptions, SWET modelled losses from Little Lake Charm, and no hydraulic constraints


Not applicable


Not applicable


Not applicable

Start of filling Not applicable Assumed local contributing area

None


From 1 August


Figure 21. Predicted water levels and percentage of bed dry for Current (baseline) regime, Racecourse Lake.

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 32












Figure 22. Predicted water levels and percentage of bed dry for Episodic regime, Racecourse Lake.

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 33




2 in 3 years; Year 1 to 73.93 m; Year 2 to 72.57 m






The lake fully draws down infrequently under this regime.



Figure 23. Predicted water levels and percentage of bed dry for Intermittent regime, Racecourse Lake.

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 34








50 mm/day



None


From 1 August





Figure 24. Predicted water levels and percentage of bed dry for Semi-permanent (9 in 10) regime, Racecourse Lake.

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Wat

er

leve

l (m

AH

D)

70.5

71.0

71.5

72.0

72.5

73.0

73.5

74.0

74.5

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Wat

er

leve

l (m

AH

D)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/2

00

0

1/0

7/2

00

0

1/0

1/2

00

1

1/0

7/2

00

1

1/0

1/2

00

2

1/0

7/2

00

2

1/0

1/2

00

3

1/0

7/2

00

3

1/0

1/2

00

4

1/0

7/2

00

4

1/0

1/2

00

5

1/0

7/2

00

5

1/0

1/2

00

6

1/0

7/2

00

6

1/0

1/2

00

7

1/0

7/2

00

7

1/0

1/2

00

8

1/0

7/2

00

8

1/0

1/2

00

9

1/0

7/2

00

9

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1/0

1/1

93

4

1/0

1/1

93

8

1/0

1/1

94

2

1/0

1/1

94

6

1/0

1/1

95

0

1/0

1/1

95

4

1/0

1/1

95

8

1/0

1/1

96

2

1/0

1/1

96

6

1/0

1/1

97

0

1/0

1/1

97

4

1/0

1/1

97

8

1/0

1/1

98

2

1/0

1/1

98

6

1/0

1/1

99

0

1/0

1/1

99

4

1/0

1/1

99

8

1/0

1/2

00

2

1/0

1/2

00

6

1/0

1/2

01

0

Pe

rce

nta

ge o

f b

ed

are

a e

xpo

sed

Page 35

3.7 Comparison with previous estimates of losses and savings

3.7.1 Net Evapotranspiration (current regime)

The average values estimated by SKM (2010) were compared with estimates made

on the basis of SILO DataDrill climate data from First (Reedy) Lake (assume at FSL)

for the 10 year period 1/7/200 to 30/6/2010. The three estimates made here were

based on rainfall combined with evapotranspiration estimated by: (i) factored Pan

evaporation (using a factor of 0.78), (ii) FAO56 Reference Crop PET (Penman-

Monteith), and (iii) a combination method of Penman-Monteith with deBruin

adjustment for changes in heat storage of the water body, as recommended by

McJannet et al. (2008) for use in estimating evaporation from open water in the

Murray Darling Basin. This comparison shows that the combination method produces

a significantly higher estimate of evapotranspiration that the other methods (Table 2).

The difference is mostly associated with higher estimated summer season

evapotranspiration (Figure 25). Despite the combination method appearing to be the

odd one out, it remains the preferred method for this purpose (McJannet et al., 2008),

and it has the advantage of sensitivity to the depth of the water body.

Table 3. Estimated average annual net evapotranspiration from First (Reedy) Lake at Full

Supply Level (FSL).

Pan coefficient Morton’s FAO56 PET Combination

SKM (2010) 1883 1921 - -

This study 1903 - 2096 2645

Figure 25. Estimated evapotranspiration using three methods for First (Reedy) Lake over a 10 year period, based on SILO DataDrill data. Pan data are not factored.

3.7.2 Seepage

The SWET model did not attempt to estimate groundwater exchange. This would

require generation of a daily time series of the local water table elevation, and while

0

2

4

6

8

10

12

14

16

18

20

Dail

y e

vap

otr

an

sp

irati

on

(m

m)

Penman-Monteith with deBruin adjustment (water bodies)

Class A Pan

FAO Reference Crop PET (Penman-Monteith)

Page 36

possible, it would not be trivial. However, a standard feature of SWET is an estimate

of initial losses, which is the water lost to cracks in the dry bed upon re-wetting. Initial

losses are not relevant to the current regime, but future regimes involving draw

downs will incur initial losses.

For First (Reedy) Lake, under the episodic regime, the dry lake is filled every five

years. The average initial loss for the wetting episodes was estimated to be 107 ML.

While these initial losses were accounted for in the SWET modelling, there could also

be losses to groundwater of the order of a few hundred ML, with the volume

dependent on the management scenario.

3.7.3 Potential for water savings

The estimates of potential savings made previously by RMCG (2009) and SKM

(2010) are of the same order as those estimated here, but the figures cannot be

compared directly due to differences in assumptions regarding operating regimes.

3.8 Inter-annual variability of savings

The losses and savings were shown to be highly sensitive to the management

regime. The savings also varied from year to year, or from one management cycle to

the next. This is illustrated using the example of First (Reedy) Lake (Figure 26). While

savings are normally expressed as an annual average, when the management

regime extends over a number of years, this represents the average annualised

value. In this case, the water savings are not realised every year, but can be

calculated at the end of each cycle, and then expressed as an annual average over

the cycle. In First (Reedy) Lake the annualised savings for the four management

options varied across a fairly wide range as a function of climatic variation (Figure

26).

Page 37

Figure 26. Time series of annualised savings (averaged over the management cycle) for four management regime options for First (Reedy) Lake.

4 Sensitivity of savings estimates to model parameters

4.1 Sensitivity of savings estimates to inherent model parameter values

The losses and savings were highly sensitive to the management regime type and to

a lesser extent natural climatic variability (Figure 26). The estimates were also

dependent on inherent model parameter values. The sensitivity of the water savings

estimate to SWET model parameter values was tested for a single scenario at one

site: First (Reedy) lake for the Intermittent regime. Stage II of this hydrological

modelling project will investigate the sensitivity of all models to model parameter

values.

0

1000

2000

1892

1896

1900

1904

1908

1912

1916

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

2004

2008

An

nu

alis

ed s

avin

gs

(ML

/yr)

Episodic

0

500

1000

1892

1896

1900

1904

1908

1912

1916

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

2004

2008

An

nu

alis

ed s

avin

gs

(ML

/yr)

Intermittent

0

200

400

1892

1896

1900

1904

1908

1912

1916

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

2004

2008

An

nu

alis

ed s

avin

gs

(ML

/yr)

Semi-permanent (8/10)

0

50

100

150

1892

1896

1900

1904

1908

1912

1916

1920

1924

1928

1932

1936

1940

1944

1948

1952

1956

1960

1964

1968

1972

1976

1980

1984

1988

1992

1996

2000

2004

2008

An

nu

alis

ed s

avin

gs

(ML

/yr)

Semi-permanent (9/10)

Page 38

4.1.1 Evapotranspiration estimate: Pan versus physical model

The combination physical model approach of McJannet et al. (2009) produced higher

estimates of water savings than did the factored Pan evaporation approach (Table 4).

This is because the evapotranspiration rates estimated by the physical model were

higher than for the Pan method (Figure 25).

Table 4. Estimated average annual water savings from First (Reedy) Lake for the Intermittent

regime using two different methods of evapotranspiration estimation.

Scenario Mean annual savings (ML/yr)

Factored Pan evaporation Physical model

First (Reedy) Intermittent (1891-2009) 398 531

4.1.2 Evapotranspiration estimate: wind speed assumption in physical model

The combination physical model approach of McJannet et al. (2009) uses local wind

speed data if available. Such data are available for Kerang from 1962 onwards,

although there were gaps in the data. A wind speed of 2 m/s was assumed for the

period 1891 to 1961.

The first test of sensitivity to wind speed data was to run the Current (baseline) and

Intermittent models for the period 1962 to 2009 with measured wind speed data, and

then with the assumption of 2 m/s for each day (Table 5). All other parameter values

were maintained at their default values.

The measured wind speed data gave a higher saving than the assumption of 2 m/s

every day (Table 5). This is explained by the measured wind speed being generally

higher than 2 m/s, and higher wind speed increases the evaporation rate.

Table 5. Estimated average annual water savings from First (Reedy) Lake for the Intermittent regime using the physical model evapotranspiration estimation with measured wind

speed and constant 2 m/s wind speed. Estimate for the period 1962 – 2009 only.


Assume 2 m/s Measured wind speed

First (Reedy) Intermittent (1962–2009) 535 622

The second test of sensitivity to wind speed was to run the model for the entire

modelled period using a constant wind speed, and varying the wind speed over the

range 1 – 4 m/s (Table 6). All other parameter values were maintained at their default

values.

The higher the wind speed, the higher was the saving (Table 6), because high wind

speed increases the evaporation rate.

Page 39


regime using the physical model evapotranspiration estimation with a range of constant wind speeds.


1 m/s 2 m/s 3 m/s 4 m/s

First (Reedy) Intermittent (1891-2009) 401 496 567 623

4.1.3 Initial loss parameters

The default parameter values for initial loss used here were 25% void space and

300 mm depth of voids. This refers to the properties of the bed of the lake after drying

out. The greater the total void space, the higher is the initial loss. These parameters

were varied over the range 20% void space and 200 m depth to 30% void space and

400 mm depth (Table 7). All other parameter values were maintained at their default

values.

Varying the initial loss parameter values over a reasonable range had only a small

effect on savings (Table 7). The larger was the total void space, the higher was the

initial loss, which had the effect of decreasing savings.


regime using a range of initial loss parameter values.


20% and 200 mm

25% and 300 mm

30% and 400 mm

First (Reedy) Intermittent (1891-2009)

543 531 515

4.2 Sensitivity of savings estimates to management regime parameter values

The losses and savings were highly sensitive to the management regime type. The

estimates were sensitive to parameter values selected for the regimes. The key

variables are:

Maximum rate of rise of lake levels while filling

Date of beginning the filling phase

Duration of the filling period

The sensitivity of the water savings estimate to these regime parameter values was

tested for a single scenario at one site: First (Reedy) lake for the Intermittent regime.

Stage II of this hydrological modelling project will investigate the sensitivity of all

models to regime parameter values.

Page 40

4.2.1 Maximum rate of filling

The default maximum rate of rise while filling was set at 50 mm/day, which

corresponds with the upper limit of the range normally acceptable for ecological

reasons. This parameter was varied over the range 10 – 1,000 mm/day (Table 8). All

other parameter values were maintained at their default values.

The way the scenarios were configured, the total duration of being full included the

period of filling. Thus, the low range of filling rate increased savings (Table 8),

because this reduced the duration that the lake was at its maximum target level.

There was no benefit in water saving by increasing the rate of rise beyond

50 mm/day, because although the lake was at the maximum level for slightly longer,

this increase in duration occurred during August, which is a month of low evaporation.


regime using a range of maximum fill rates.


10 mm/d 20 mm/d 50 mm/d 100 mm/d 1,000 mm/d

First (Reedy) Intermittent (1891-2009)

599 536 531 531 531

4.2.2 Date of beginning the filling phase

The default start of the filling phase was 1 August. This parameter was varied over

the range 1 July to 1 September (Table 9). All other parameter values were

maintained at their default values.

A later start date for filling had the effect of reducing the savings (Table 9), mainly

because this delayed the start of the draw down. Thus, the lake was full for a longer

period of time over the summer when evaporation rates are high.


regime using a range of filling start dates.


1/July 1/August 1/September

First (Reedy) Intermittent (1891-2009) 597 531 488

4.2.3 Duration of the filling phase

The default filling cycle durations were successively, 10, 8 and 7 months. This

parameter was varied by reducing and increasing the duration by one month (Table

10). All other parameter values were maintained at their default values.

Increasing the duration of the fill reduced the savings, and decreasing the duration of

the fill increased the savings (Table 10). Increasing the fill duration meant that the

lake was full for a longer time through summer, when evaporation rates are high.

Decreasing the duration had the opposite effect.

Page 41


regime using a range of filling cycle durations.


9, 7 and 6 months

10, 8 and 7 months

11, 9 and 8 months

First (Reedy) Intermittent (1891-2009) 601 531 474

4.3 Summary of variability of savings and model sensitivity

The sensitivity testing undertaken for Phase I of this hydrological investigation was

limited to one lake and one scenario. While the results (Table 11) are specific to that

case, some of the results can be generalised to the other four lakes and other

scenarios.

Table 11. Summary of sensitivity of long-term mean annual savings estimates to model

parameters, based on testing of First (Reedy) Lake Intermittent regime.

Parameter/factor Variability/sensitivity of savings

Natural climate variation over time High variability [±50% in annualised

saving from cycle to cycle; will affect

some scenarios more (±80%) and some

less (±25%)]

Evaporation estimate method Mod. sensitivity (25% lower for Pan

method than physical method; will affect

all scenarios to a variable degree)

Assumed wind speed relative to

assumed 2 m/s

Mod. sensitivity (19% lower for 1 m/s,

14% higher for 3 m/s, 26% higher for

4 m/s; will affect all scenarios)

Measured relative to assumed 2 m/s

wind speed

Mod. sensitivity (14% lower for 2 m/s; will

affect all scenarios)

Date of beginning filling Low – mod. sensitivity (±12%, but

depends on whether duration of being full

is fixed)

Duration of the filling phase for a given

regime type

Low – mod. sensitivity (±13%, but highly

scenario specific)

Groundwater exchange Low – mod. sensitivity (estimate - not

quantified)

Initial loss parameters Low sensitivity (±3%)

Maximum lake filling rate Low sensitivity (but could be moderate if

duration of being full is fixed)

Page 42

5 Conclusion

Preliminary hydrological (water balance) models were developed for five Kerang

Lakes. Even though the models were based on the best available understanding of

the hydrology of the lakes, there is uncertainty with input data and with a number of

model parameters. This uncertainty was explored by undertaking sensitivity analysis.

This revealed that the estimate of savings was quite sensitive to the method of

estimating evaporation, but it was not very sensitive to initial loss parameters.

The physical combination method of estimating evaporation from the lakes produced

estimates of mean annual net evapotranspiration that were 17% higher than the

method used by Lugg et al. (1989), 23% higher than the factored Pan method used

by SKM (2010), 26% higher than Morton’s method used by SKM (2010) and 51%

higher than the factored Pan method used in the Kerang Lakes REALM model. It is

not clear which method produces the most accurate estimate of evaporation, so it will

be necessary in Phase II of this hydrological investigation project to test the methods

against local measured lake level data.

As well as being sensitive to inherent model parameter values, the estimate of

savings was sensitive to the management regime parameter values. While it was

obvious that frequency of filling cycles would have a major impact on potential for

savings, other important variables were the date of the beginning of filling and the

duration of the filling cycle. The rate of filling had only a minor impact on the savings.

The estimates of savings made here are of the same order as those estimated in

previous investigations, but the estimates cannot be compared directly due to

differences in assumptions regarding operating regimes.

The total savings possible from alternative management of the Kerang Lakes varies

across a wide range, depending on how frequently, for how long, and how far the

lakes would be drawn down. It would be technically possible to devise a set of refined

management scenarios involving intermittent and episodic regimes that would

together achieve a long term average annual savings of at least 4 GL.

6 References

Catford, J., Downes, B., Gippel, C.J. and Vesk, P. 2011. Flow regulation reduces native plant cover and facilitates exotic invasion in riparian wetlands. Journal of Applied Ecology 48(2): 432-442. DOI: 10.1111/j.1365-2664.2010.01945.x.

Dooge, J.C.I. 1975. The water balance of bogs and fens. In Hydrology of Marsh-Ridden Areas, Proceedings of the Minsk Symposium, 1972, The UNESCO Press, Paris, pp. 233-271.

Duever, M.J. 1988. Hydrologic processes for models of freshwater wetlands. In Mitsch, W.J., Straskraba, M. and Jorgensen, S.E. (Eds) Wetland Modelling, Developments in Environmental Modelling, Vol. 12, Elsevier, Amsterdam, pp. 9-39.

DSE 2004. Kerang Wetlands Ramsar Site, Strategic Management Plan. Parks Victoria. The State of Victoria, Department of Sustainability and Environment, East Melbourne. URL: http://www.dse.vic.gov.au/__data/assets/pdf_file/0010/100135/Kerang_Wetlands_Ramsar_Site_Strategic_Management_Plan.pdf (accessed 9 September 2012).

http://www.dse.vic.gov.au/__data/assets/pdf_file/0010/100135/Kerang_Wetlands_Ramsar_Site_Strategic_Management_Plan.pdf

http://www.dse.vic.gov.au/__data/assets/pdf_file/0010/100135/Kerang_Wetlands_Ramsar_Site_Strategic_Management_Plan.pdf

Page 43

DSE 2010. Kerang Wetlands Ramsar Site, ecological character description. Arthur Rylah Institute for Environmental Research, Heidelberg. The State of Victoria, Department of Sustainability and Environment, East Melbourne.

Ecological Associates. 2008. Determination of environmental water requirements for Mosquito Creek Catchment and Bool and Hacks Lagoon. Final Report. South East Natural Resources Management Board, Mount Gambier, South Australia, August.

Gippel, C.J. 1993. Hydrological management of a lake with floating islands near Pirron Yallock, Victoria, Australia. Journal Environmental Management 37: 219-238, DOI: 10.1006/jema.1993.1018.

Gippel, C.J. 2005a. Operational procedure to calculate water recovery from wetlands and lakes at the source (individual wetlands). Fluvial Systems Pty Ltd, Stockton, NSW. The Living Murray, Murray-Darling Basin Commission, Canberra, Australian Capital Territory.

Gippel, C.J. 2005b. Model to calculate water recovery from wetlands and lakes at the source (individual wetlands) - Example application to Euston Lakes and Edward Gulpa wetlands. Fluvial Systems Pty Ltd, Stockton, NSW. The Living Murray, Murray-Darling Basin Commission, Canberra, Australian Capital Territory.

Gippel, C.J. 2005c. SWET (Savings at Wetlands from Evapotranspiration daily Time-Series). A model to calculate water recovery from wetlands and lakes at the source (individual wetlands). Model Manual. Fluvial Systems Pty Ltd, Stockton, NSW. The Living Murray, Murray-Darling Basin Commission, Canberra, Australian Capital Territory.

Gippel, C.J. 2010. Modeling the conjoint provision of ecological water requirements and generation of water savings at wetlands. Proceedings, ISE 2010 - the 8th International Symposium on ECOHYDRAULICS (ISE 2010), September 12-16, 2010, Seoul, South Korea, International Association for Hydraulic Engineering and Research (IAHR).

Gosselink, J.G. and Turner, R.E. 1978. The role of hydrology in freshwater wetland ecosystems. In Good, R.E., Whigham, D.F., Simpson, R.L. and Jackson, Jr, C.G. (Eds) Freshwater Wetlands: Ecological Processes and Management Potential, Proceedings of the Symposium on Freshwater Marshes: Present Status, Future Needs, February 1977, Rutgers University, New Brunswick, New Jersey. Academic Press, New York, pp. 63-78.

Hoy, R.D. and Stephens, S.K. 1979. Field study of lake evaporation – analysis of data from phase 2 storages and summary of phase 1 and phase 2. Australian Water Resources Council Technical Paper No. 41. Department of National Development, Australian Water Resources Council. Australian Government Publishing Service, Canberra, Australian Capital Territory.

LaBaugh, J.W. 1986. Wetland ecosystem studies from a hydrologic perspective. Water Resources Bulletin 22: 1-10, DOI: 10.1111/j.1752-1688.1986.tb01853.x.

Lugg, A., Heron, S., Fleming, G., and O’Donnell, T. 1989. Conservation value of the wetlands in the Kerang Lakes area, Report to Kerang Lakes Area Working Group, Department of Conservation Forests & Lands, Bendigo, October.

McJannet, D.L., Webster, I.T., Stenson, M.P. and Sherman, B.S. 2008. Estimating open water evaporation for the Murray Darling Basin. A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project. CSIRO, Australia. 50pp.

Page 44

North Central CMA 2007. Loddon and Campaspe Irrigation Region, Land and Water Management Plan. The State of Victoria, North Central Catchment Management Authority, Huntley.

North Central CMA 2011. Kerang Lakes Water Savings Project Investigation: Literature Review. Prepared for the Northern Victoria Irrigation Renewal Project, North Central Catchment Management Authority, Huntly.

North Central CMA 2012. Environmental Watering Scenarios for Kerang Lakes Bypass Investigation Project – Phase 1. Prepared for the Goulburn-Murray Water Connections Project, North Central Catchment Management Authority, Huntly

NVIRP 2012. Kerang lakes bypass investigation project. Newsletter No. 1, May. Northern Victoria Irrigation Renewal Project.

RMCG 2009. TRAMS Update Final Report, prepared for NVIRP, RMCG, Bendigo, Victoria.

SKM 2007. Kerang Lakes REALM modelling for refinement of the MDBC BSMS register. Sinclair Knight Merz. Goulburn-Murray Water, Shepparton.

SKM 2010. Environmental water regime requirements of the Kerang Lakes. Review of system losses, identification of environmental water regimes, and potential water savings. Goulburn-Murray Water, March.

U.S. Army Corps of Engineers 1993. Wetland water surface processes. Wetlands Research Program (WRP) Technical Note HY-EV-2.1. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, January.

Winter, T.C. 1981. Uncertainties in estimating the water balance of lakes. Water Resources Bulletin 17: 82-115, DOI: 10.1111/j.1752-1688.1981.tb02593.x.

Woo, M.K. and Rowsell, R.D. 1993. Hydrology of a prairie slough. Journal of Hydrology 146: 175-207, DOI: 10.1016/0022-1694(93)90275-E.

Page 45

7 Appendix – Bathymetry data

Area and volume table for First (Reedy) Lake.

Elevation (m AHD)

Area (ha)

Volume (ML)

Elevation (m AHD)

Area (ha)

Volume (ML)

72.69 0.00 0.00 74.20 189.03 1996.69

72.70 0.01 0.01 74.30 190.45 2186.43

72.80 1.44 0.36 74.40 191.83 2377.57

72.90 39.86 14.93 74.50 193.14 2570.06

73.00 85.85 79.07 74.60 194.40 2763.84

73.10 109.36 177.78 74.70 195.70 2958.87

73.20 128.93 297.17 74.80 197.14 3155.29

73.30 141.96 432.99 74.88 198.28 3313.48

73.40 152.27 580.09 74.90 198.55 3353.16

73.50 161.96 737.53 75.00 200.23 3552.46

73.60 169.53 903.46 75.10 203.69 3754.28

73.70 175.54 1076.03 75.20 206.64 3959.61

73.80 180.48 1254.11 75.30 208.28 4167.12

73.90 184.04 1436.55 75.40 209.77 4376.17

74.00 185.99 1621.60 75.50 210.79 4586.51

74.10 187.56 1808.39

Page 46

Area and volume table for Middle (Reedy) Lake.

Elevation (m AHD)

Area (ha)

Volume (ML)

Elevation (mAHD)

Area (ha)

Volume (ML)

71.77 0.000 0.000 73.40 112.1 302.85

71.80 0.001 0.000 73.45 115.8 359.84

71.85 0.003 0.001 73.50 119.1 418.59

71.90 0.007 0.004 73.55 121.9 478.84

71.95 0.01 0.01 73.60 124.5 540.44

72.00 0.04 0.02 73.65 126.9 603.31

72.05 0.1 0.04 73.70 129.1 667.34

72.10 0.1 0.08 73.75 131.1 732.40

72.15 0.1 0.13 73.80 133.1 798.45

72.20 0.1 0.20 73.85 135.1 865.49

72.25 0.2 0.27 73.90 137.1 933.52

72.30 0.2 0.37 73.95 139.1 1002.55

72.35 0.2 0.48 74.00 141.2 1072.62

72.40 0.3 0.61 74.05 143.7 1143.80

72.45 0.3 0.75 74.10 147.9 1216.66

72.50 0.3 0.92 74.15 152.3 1291.66

72.55 0.4 1.10 74.20 159.9 1369.53

72.60 0.4 1.30 74.25 169.3 1451.06

72.65 0.5 1.52 74.30 175.5 1537.30

72.70 0.5 1.76 74.35 178.8 1626.03

72.75 0.5 2.02 74.40 180.6 1715.89

72.80 0.6 2.30 74.45 181.7 1806.49

72.85 1.0 2.68 74.50 182.5 1897.56

72.90 2.0 3.40 74.55 183.3 1989.02

72.95 5.1 4.96 74.60 184.1 2080.87

73.00 15.3 9.66 74.65 184.8 2173.09

73.05 30.1 20.88 74.70 186.5 2265.87

73.10 48.1 40.04 74.75 188.7 2359.69

73.15 66.4 68.82 74.80 191.1 2454.66

73.20 79.8 105.56 74.85 193.4 2550.80

73.25 91.3 148.35 74.90 195.4 2648.01

73.30 99.8 196.29 74.95 197.0 2746.13

73.35 107.1 247.97

Page 47

Area and volume table for Third (Reedy) Lake.

Elevation (m AHD)

Area (ha)

Volume (ML)

Elevation (m AHD)

Area (ha)

Volume (ML)

72.89 0.00 0.00 74.30 221.63 1872.03

72.90 0.02 0.01 74.40 224.86 2095.28

73.00 0.05 0.04 74.50 228.10 2321.76

73.10 0.12 0.12 74.56 230.13 2459.23

73.20 11.11 2.67 74.60 231.50 2551.56

73.30 76.53 38.61 74.70 233.67 2784.18

73.40 124.59 135.01 74.80 235.63 3018.84

73.50 152.59 272.63 74.90 237.51 3255.41

73.60 174.32 435.64 75.00 239.21 3493.79

73.70 187.41 616.31 75.10 240.67 3733.75

73.80 199.02 809.59 75.20 241.97 3975.08

73.90 206.59 1012.64 75.30 243.17 4217.65

74.00 211.51 1221.77 75.40 244.29 4461.39

74.10 215.21 1435.18 75.50 245.35 4706.21

74.20 218.42 1652.00

Area and volume table for Little Lake Charm.

Elevation (m AHD)

Area (ha)

Volume (ML)

Elevation (m AHD)

Area (ha)

Volume (ML)

72.25 0.00 0.00 73.40 77.88 520.73

72.30 0.47 0.08 73.45 81.36 560.52

72.35 2.10 0.63 73.50 84.88 602.08

72.40 7.08 2.79 73.55 88.73 645.44

72.45 16.01 8.44 73.60 93.91 691.10

72.50 24.21 18.77 73.65 98.54 739.22

72.55 29.86 32.30 73.70 103.21 789.64

72.60 34.88 48.52 73.75 112.24 843.52

72.65 39.17 67.08 73.80 119.94 901.66

72.70 42.91 87.59 73.85 125.73 963.11

72.75 46.69 110.00 73.90 130.79 1027.25

72.80 50.34 134.27 73.95 136.05 1093.97

72.85 53.15 160.19 74.00 141.55 1163.35

72.90 55.23 187.30 74.05 147.32 1235.56

72.95 57.35 215.42 74.10 153.35 1310.97

73.00 60.79 245.02 74.15 156.73 1388.52

73.05 63.09 276.03 74.20 159.43 1467.59

73.10 65.60 308.30 74.25 161.46 1547.84

73.15 67.16 341.48 74.30 162.84 1628.95

73.20 68.87 375.48 74.35 163.82 1710.62

73.25 70.49 410.34 74.40 164.62 1792.73

73.30 72.19 446.00 74.45 165.31 1875.21

73.35 74.45 482.61

Page 48

Area and volume table for Racecourse Lake.

Elevation (m AHD)

Area (ha)

Volume (ML)

Elevation (m AHD)

Area (ha)

Volume (ML)

71.20 0.00 0.00 73.50 227.50 3680.59

71.30 5.28 1.14 73.60 230.63 3909.73

71.40 46.73 26.73 73.70 233.88 4141.84

71.50 81.54 91.92 73.80 236.33 4376.94

71.60 103.04 185.23 73.90 238.73 4614.48

71.70 123.02 297.07 73.93 239.65 4686.25

71.80 139.24 428.60 74.00 241.26 4854.60

71.90 149.90 573.43 74.10 243.00 5096.68

72.00 157.14 727.09 74.20 244.28 5340.33

72.10 163.90 887.61 74.30 245.50 5585.22

72.20 169.54 1054.34 74.40 246.68 5831.34

72.30 175.13 1226.69 74.50 247.76 6078.57

72.40 180.17 1404.36 74.60 248.82 6326.88

72.50 185.17 1587.03 74.70 249.81 6576.19

72.60 190.50 1775.17 74.80 250.73 6826.46

72.70 196.11 1968.25 74.90 251.58 7077.62

72.80 201.66 2167.07 75.00 252.56 7329.75

72.90 207.04 2371.54 75.10 253.26 7582.67

73.00 211.35 2580.79 75.20 253.83 7836.22

73.10 215.72 2794.08 75.30 254.33 8090.31

73.20 218.66 3011.32 75.40 254.75 8344.85

73.30 221.45 3231.38 75.50 255.14 8599.80

73.40 224.60 3454.55

Documents

Preliminary hydrological modelling for Kerang ... - Goulburn Murray … · A 19/08/2012 Project Reference Group C. Gippel 19/08/2012 Draft B 11/09/2012 Project Reference Group C