Impact of River Sand Mining in Ratnapura District in Sabaragamuwa

8/12/2019 Impact of River Sand Mining in Ratnapura District in Sabaragamuwa

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IMPACT OF RIVER SAND MINING IN RATNAPURA DISTRICT IN SABARAGAMUWA

PROVINCE

Concise report of the study done by Volunteer team of Net water


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Executive Summary

This report summerises the findings of the study conducted by NetWwater on behalf of

the Sri Lanka Water Partnership in Ratnapura District on impact of sand mining on

environment and ground water-body. Sand is being removed from rivers, rivers mouths,

banks and at inland sand deposits and hence rivers in our country are under immense

pressure.

1. Introduction

Like many other minerals sand has become a scare resource in Sri Lanka, due to high

demand for constriction and developmental activities. Traditional sites for sand mining

are rivers and beaches. But alternatively sand is being removed from river mouths,

banks and even at inland sand deposits. Rivers in Sri Lanka are under immense pressure

due to various kinds of human activities among which indiscriminate extraction of sand

is the most disastrous one. The situation is rather alarming in certain major rivers

including Kalu Ganga , Walawe ganga , Kelani ganga , Nilwala ganga , Deduru Oya, Ma

Oya and Kirindi Oya.

Some of the above rivers traverse through Ratnapura district. In July 2010, on therequest of NetWwater, the District Secretary organized an awareness meeting with

officials in Ratnapura area (Divisional Secretaries, Agricultural officers, Samurdhi

officers, Environmental officers, Grama Niladahries, Officers from GSMB, Forest

Department, SL Police)with members of NetWwater as resource persons. This meeting

is a follow up of a series of workshops and discussions conducted by the NetWwater in

Sabaragamuwa Province earlier. According to the participants, there is a tremendous

increase in removing sand from rivers, waterways and old river beds. It has beenreported that severe damages are evident in Walawe ganga and Kalu ganga specially in

the areas including Elapatha, Kotamulla- Dambemulla, Diwulwala, Kahawatte and

Galnewa.


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NetWwater was invited to conduct a scientific study in Ratnapura District on this aspect

by the District Secretary, since policy decisions on controls of removing sand within the

district to be taken with sound information. NetWwater members attached to

University of Colombo thus volunteered to conduct a pilot study with the support of

undergraduate students. This report is the outcome of the field study conducted by this

team.

2. Impacts of sand mining

Although often neglected, sand mining could cause severe environmental, social and

economic issues that are not reversible. The impacts are of several folds: Due to

removal of sand, ground water table in the vicinity of the river will drop, affecting the

moisture content in the soils. Due to the drop in river water levels, quantity and quality

of water intakes for drinking water will be affected badly specially during the dry season.

The reduction of the bed level slope due to river sand mining also results in a reduction

of the sand discharge to the coast, when water bodies end up at the sea. Salt water

intrusion is a direct result of lowering of bed levels. Widening of river mouths and

reduction of sand available for the beach nourishment of the coastal system due to

mining from the coast also can be observed as a result. Due to increased levels of seawater penetration in to the rivers, salinity level of fresh water will increase. Salt water

intrusion is a potential problem at water intakes, especially during the dry season. Sand

mining has destroyed river banks leading to instability in the ecosystem. Water scarcity

will affect livelihoods of people- agriculture and commercial activities and cause decline

in water availability for dependent plants and animals. In extreme cases it can cause

species decline and extinction.

The exposure of the riverbed to solar radiation following deep mining has resulted in its

drying up. This has decreased the water volume and caused salt water intrusion in to

rivers and ground water. Continued sand mining has led to obstruction in the free flow

of water in the rivers.


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3. Objectives of the study:

The present study was carried out by the volunteers in NetWwater (Specialists in Water

resources and Ecosystem management) with the help of undergraduates, all from

University of Colombo.

The objectives were to:

a. Identify the areas with moderate-high sand mining

b. Investigate the nature and extent of damage (on ground water resources ,

biodiversity and ecosystem functioning)

c. Recommend actions to be taken to manage RSM problem

The study area is shown in the map below;

The study was conducted in the eastern slope of the Rathnapura District of Sabaragamuwa

Provincial Council.

Fig 1;Map of Sabargamuwa Provincial Council Fig 2; Study area

Study was conducted in the 4 different locations in the eastern slope of the Rathnapura District

covering two rivers viz Kaluganga and Walawe Ganga .

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4


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Overall damage to biodiversity and ecosystem functioning

0

0.5

1

1.5

2

2.5

3

3.5

1 2 3 4 5 6 7

site

damage/rank

damage

6.0 Results of Survey on the impact on biodiversity and ecosystem functioning

In all sites studied, there were some sort of damage caused by RSM activities. Out of the

7 sites four ranked as highly damaged and the rest as moderately damaged. There were

no sites ranked as limited or zero damage.

The summary of the damage on the ecosystems and biodiversity is as follows.

Table 1: Summary of the damage on the ecosystems and biodiversity

Parameter Nature of damage

vegetation Moderate- severe damage: uprooted plants, damaged to plant

parts such as branches, loss of tree species, disturbances tosurvival, habitat loss

Animals Moderate- severe damage: loss of aquatic habitats (specially for

fish), loss of fish species (Koraliya), decreased species diversity

due to loss of sensitive species, loss of spawning grounds for

aquatic species and river bank dwelling species, disturbances to

food webs, habitat loss for bank dwelling species such as aquatic

birds, reptiles, amphibians

Ecosystem stability Moderate- severe damage: soil erosion, loss of fertile soil, bank

instability and collapse, loss of protective structures provided by

trees, changes to topography due to temporary foot paths andtransportation network, obstacles to water flow

Water quality Pollution by sedimentation, silt loads, vehicular discharge, solid

waste dumping by humans, visible impairment of water quality,

decreased dissolved oxygen concentration

Graph 1: Graph of overall damage to biodiversity and ecosystem functioning in study

sites


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Damage/ rank ; 2- moderately damaged, 3- severely damaged

(1-7 locations included)

7.0 Survey on the impact on ground water resources.

7.1 Methodology

In order to identify the affect of the sand mining (in river bed and inland) to the groundwater

resources, a monitoring study was conducted in open shallow dug wells. Locations of the dug

wells were identified with aGPS. Dug wells monitoring were conducted using the questionnaire

and the collected informations on Electrical Conductivity (EC) and Total Dissolved Solids (TDS)

were measured using the portable EC/pH. GISpackage arc-view was used to prepare maps. The

dug wells which are constructed in the river basins in the alluvium sandy to sandy clay

unconfined aquifer. The study was conducted in the 4 different locations in the eastern slope of

the Rathnapura District.

7.2 Observations

The underground water table in the Walawa river basins is related to the surface water

level in rivers and irrigation channel system in the Walawa project. River sand mining

and inland sand mining along the river during the past two decades has deepened the

riverbed by an average three to four metres, while there are some points where it has

dropped by more than six metres in the river Walawa. Consequently, the water

table in the wells in the catchment areas and the river basin has also fallen sharply to

the surface water levels in the rivers (figure 1). The study revealed that presently

groundwater levels depend on irrigation water canal system and not from the river due

the river bed deepening.


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The field study reveled that in stream sand mining in the Walawa ganga bank area

resulted in channel bed degradation and erosion, deepening the river bed, head cutting,

and stream bank erosion. All these changes adversely affect water resources balance of

the area either directly by damage to organisms or through habitat degradation.

Further, effects on stream geomorphology (e.g., channel incision) can result in

infrastructure damage and Irrigation water supply intake to the Welangahawela anicut

constructed in the British period. As a result of the deepening of the Walawa river, the

water table within the valley is directly affected. When the riverbed level falls, the

hydraulic gradient of the groundwater is increases leading to higher velocity.

Study area in the Walawa River area and distribution of dug wells

According to the study, it was revealed that close to the river bank groundwater table

has been lowered up to 11 metres from 2 metres during the last decade. Most of the

ground water levels in this area stabilized in 4 to 6 meters during the cultivation period

but during the dry periods (post harvesting period) its going down up to above 9.0

meters.

Ground water level before sand minin

Ground water level after sand minin

Dug well

River


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Inland and river sand mining areas surrounding Walawa ganga

(Sooriyawewa road)

Total depth variation in the study area after sand mining

Salinity of the river water 260 micro siemens/ cm but groundwater salinity most of

the wells were more than 500 and some time its increased up to 3500 micro

siemens/ cm. Salinity variation depends on the deepening of the river bed because

more deeper soil formations are exploiting to wells and dissolve the soil salinity.

People complained this groundwater salinity increased recent past years due to riversand mining.

Inland sand

mining

Riversand

mining areas

Water Quality Variation

0

500

1000

1500

2000

2500

3000

3500

4000

A1

A2

A3

A4

A5

A6

A7

B1

B2

B3

B4

B5

B6

B7

C1

C2

C3

C4

C5

C6

C7

Well number

ECvalue/s

0

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8

10

12

14

A1 A2 A3 A4 A5 A6 A7 B1 B2 B3 B4 B5 B6 B7 C1

C2

C3

C4

C5

C6

C7

Well number

Totaldepth(m)


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0

1

2

3

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7

8

G1 G2 G3 G4 G5 G6

Well no

Totaldepth(m)

TD(m)

Groundwater salinity distribution in the study area

Kuda oya and surrounding area in the Galpaya area (Pallebeddera)

In the Galpaya area the sand mining was conducted along the Kuda oya river bank

deposits. Morphologically the sand deposit area is highly meandering and vulnerable for

mining. According to the field study revealed that groundwater is the only source for

domestic and drinking purposes. But due to the sand mining, most of the Galpaya area

groundwater level were decreased up to 7.5m. Most of the open dug wells total depth

in between 4.7 to 7.5m. Salinity of the groundwater varies from 400 to 800 micro

siemens/ cm.

Impact on infrastructure in the Weganga along the Hunuwela to Kahawatta road

Destruction of roads, damages to bridges (bridge) is a nother result of rampant sand

mining ; damage to Hunuwela to Kahawatta road and the Bridge crossing the Weganga

is observed. Another concern is that the sand mining in river bed has bared the bases of

the pillars of the bridges to the extent that the foundation that are supposed to remain

under the riverbed are now exposed. Along the Weganga River bank erosion directly

impacts to the loss of bank stability, destruction of ecosystems, spreading of mosquito

related diseases and pollution of river water. A detailed study was not conducted due

the damage to road.


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8. Discussion and recommendations

Ratnapura area consists of natural vegetation such as forests, shrubs and cultivation

such as tea, rubber, paddy. According to published records a. 20 % of the total area is

under utilization, b. 25 % of the total area is misused c. 05 % of the total area is over

utilized and c. Continuous loss of land due to the natural disasters in Ratnapura. Due to

its location in rain forest areas in the South Western wet zone of Sri Lanka this area is

gifted with a wealth of biodiversity including a variety of endemic and threatened plants

and animals. The famous Sinharaja Man And Biosphere reserve and Sri Pada are also

situated in Ratnapura. This area is famous for the gem industry and frequently face

natural disasters including floods and landslides. All these contribute to increased

environmental sensitivity.

On top of this, river sand mining has caused severe environmental problems that has

links to various social, health and economic problems. These problems need integrated

approaches to mitigate and manage to achieve sustainable development.

As per the results of the present study with anecdotal evidence and other literature

sources we would like to submit the following recommendations.

Recommendations:

i. Establish a high level action committee to control RSM activities which

should include the District Secretary, Politicians, representatives of divisional

secretariats, police, officials from GSMB, CEA and members of community

organizations

ii. Establish a mechanism to observe and follow up whether permit procedure is

efficient and controlled

iii. Ban RSM in sensitive and vulnerable areas

iv. Enforce law in an efficient and unbiased way


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v. Restore damaged and affected natural environment using natural barriers

such as tree plantations

vi. Stop political and other interferences when issuing permits and enforcing law

vii. Raise public awareness and strengthen community organizations to combat

illegal RSM activities

Documents

Impact of River Sand Mining in Ratnapura District in Sabaragamuwa