Impact of Gem Mining in Kantale Reservior

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Impact of Gem Mining in Kantale Reservoirs Tank Bed

In Eastern Province, SRI LANKA

Concise report of the study

By

Eng. WLN Buddika, Bsc(Eng)

Irrigation Engineers Office

Irrigation Department

Kantale

November 2012


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Concise report of the studyImpact of Gem Mining in Kantale Reservoirs Tank Bed

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Contents Page

1. Executive Summery..32. Introduction ...33. Location..44. Impacts of Gem mining on the tank bed..55. Summary of the damage on the ecosystems and biodiversity

due to gem mining...6

5.1 Vegetation ...6

5.2 Animals6

5.3 Ecosystem stability.6

5.4 Water quality...6

6. Conclusion .77. Recommendation ..8


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1.0Executive SummaryThis report summarizes the findings of the study conducted by Irrigation Engineers

Office, Kantale on behalf of the Irrigation Department, Sri Lanka on impact of Gem

mining in Kantale reservoirs Tank Bed on environment and ground water-body.

Soil is to being removed from the reservoir bed and hence Kantale reservoir is under

immense pressure.

2.0 Introduction

Sri Lanka has reasonable endowments of mineral resources. Gems have been the

most economically valuable resource accounting for more than 90% of all mineral

exports in Sri Lanka. Despite the relatively high economic and social benefits gem

mining cause significant environment damages.

All over the last few years Kantale area is being deemed as popular for Gems. But

now a day the case is finding gems in the vicinity of the Kantale Tank. According to

the past records there was several times at which found the gems in the tank bed.

However at the all situations Irrigation Department had taken suitable action with

the help of Police to ban the mining of the tank bed.

But again the fact arises with the gossip hanging around the Medias over Sri Lanka

in the day on 4th Nov. 2012 or some close to the date as some person finding with a

gem in the Kantale tank bed, so most of the people tend to find the Gem at the tank

bed.

While the situation is being, the National Gem and Jewelry Authority is awaiting for

auctioning the land near the bund of the tank, for gem mining.

However as the owner of this tank, it is Irrigation Departments responsibility to

make sure that this sudden mining in the tank bed could cause any effect to the dam

or the dependents under the tank.

This repot summarizes the studying of impact due to gem mining of the Kantale

reservoir bed.


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3.0 The Location

The Kantale Reservoir, owned by the Irrigation Department, is located south-west of

Trincomalee in Eastern province of Sri Lanka.

The tank of ancient origin controls a large catchment over more than 10,200ha by

bearing a capacity of 114,000 Acft of water. As well the tank is significant water

recourse for drinking. It facilitates for the people who are living in Trincomalee

District, Eastern Province.

The above Topo-Insert shows the Kantale reservoir & Vendrasan tank. This twin

tank is separated by the bund in between Kantale & vendrasan tanks calledConnecting bund which can be seen from left hand side to the Vendrasan tank and

right hand side to the Kantale reservoir in the map shown.

The founded gem location is close to this bund at the up-stream side and upper most

regions to the Kantale reservoir.


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4.0 Impacts of Gem mining on the tank bed

Soil erosion, deforestation, and pollution of water and soil often occur as a result of

gem mining. Deforestation results from clearing land to mine; erosion and

epidemic results from abandoned mining pits; and pollution is due mainly to

washing schist near streams and scattering debris from the schist into soils.

The dredging of reservoir or river beds for gems has several significant negative

impacts on the environment, like

i) Damage to natural vegetative cover, plantations and rice fields

ii) Degradation of the land and damage to stream and reservoirs banksiii) Health hazards to miners

iv) Destruction of fauna

v) Sedimentation and water pollution

The most immediate of which is the destruction of the natural watercourse by bank

erosion and over deepening of the riverbed (often resulting in concomitant shall

owing downstream). This has several knock on effects including enhancing the

effects of flooding during the monsoon by breaking down the bank and removing

vegetation, in particular mature trees, which help reduce the extent of flooding andmaintain the integrity of the reservoirs bank.

Such erosion of the reservoirs bank also makes it hazardous for the local community

to access what is in many instances the main supply of water for many domestic

activities.

The constant agitation of the tank bed with the resulting release of fine grained

particulate material into the tank can significantly reduce the quality and portability

of the water.

This contamination can also impact on the ecology of the flora and fauna of the

reservoir system by reducing the amount of light reaching the bed of the tank and by

obscuring and coating surfaces in the reservoir system. This can affect fisheries by

degrading the water and impacting on the invertebrate food supply for fish. Then

this has an obvious knock on effect on other fauna which use the tank as a food

supply.


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5.0 Summary of the damage on the ecosystems and biodiversity due to gem

mining

5.1 Vegetation

Uprooted plants, damaged to plant parts such as branches, loss of tree species,

disturbances to survival, habitat loss

5.2 Animals

loss of aquatic habitats (specially for fish), loss of fish species , decreased species

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

species and reservoirs bank dwelling species, disturbances to food webs, habitat lossfor bank dwelling species such as aquatic birds, reptiles, amphibians

5.3 Ecosystem stability

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

and transportation network, obstacles to natural water causes.

5.4 Water quality

Pollution by sedimentation, silt loads, vehicular discharge, solid waste dumping byhumans, visible impairment of water quality, decreased dissolved oxygen

concentration.


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6.0 Conclusion

The Irrigation Department is mainly controlling and maintaining the large scale

tanks & reservoirs in Sri Lanka for the benefits of farmers and also by supplying

water for drinking. The department is a non-profitable institute which helps farmers

for their cultivation and well-being.

Kantale tank is a twin tank with Vendrasan tank which are separated by an earthen

dam called connecting bund. The most effect could be to the connecting bund due to

mining close to the bund toe level, as it caused to instability of the earthen banks by

developing seepages.

Due to this reason a huge amount of water can flow to the Vendrasan tank that

cannot bearable more than at least its full capacity because still Vendrasan dam is

under instability due to heavy seepages occurring even to date.

Apparently this caused damage the Vendrasan earthen dam and gets sever damages

to the humans living under downstream of the Vendrasan tank bund.

Further the Kantale reservoir is under catchment of 188.8 Sq.miles where there are so

many natural water courses. The mining can obstacle to the natural water causes andcan be get polluted. Furthermore some silt can flow through the water courses and

get deposited in the tank bed. This may cause to the amount water that can retain at

the tank maximum.

When the bed is going to excavate, it may arise the rate of percolation and

infiltration to the ground. Therefore it takes hundreds of years to stabilize the tank

bed to retain the water.

Normally this tank fills by the NE monsoon rains and cannot be expected as much

on the Mahaweli water. Therefore we have to keep as much as possible amount of

water for the use of Yala season with the drinking demand for the Trincomalee

district. So if the percolation rate will increase due to sudden mining, which may

cause to the availability of the water for the usage of Yala season. This originate a

sever problem to the farmers and their dependents in the Trincomalee district.


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7.0 Recommendations

When considered the above impacts on gem mining in the Kantale reservoir,

It may cause;

Severe damages to the connecting bund in between Kantale & Vendrasantanks

Impact to the ecology of the flora and fauna of the reservoir system. Reduce the quality and portability of the water. Sedimentation & water pollution Degradation of the land and damage to stream and reservoirs banks Destruction of the natural watercourses Fisheries under the tank Ecosystem stability

Therefore obviously, Irrigation Department does not agree with the National Gem

and Jewelry Authority or any other party interests with this for gem mining, due to

the above mentioned impacts can be caused.

Eng. WLN Buddika

Irrigation Engineer

Kantale

Documents

Impact of Gem Mining in Kantale Reservior