Conserving Lake Ecosystem- A case study of Rudrasagar Lake (Ramsar Site), Tripura

Introduction:

The Rudrasagar Lake falls in the Melaghar Block under Sonamura Sub-Division in the West Tripura District and at a distance of about 50 km from the state capital of Tripura. Geographically the lake is situated in between 23⁰29^’ N and 90⁰ 01^’ E.

Hydromorphologically, Rudrasagar Lake is a natural sedimentation reservoir, which receives flow from three perennial streams namely, Noacherra, Durlavnaraya cherra and Kemtali cherra. After settling the sediment from the received flow, clear water discharges into the river Gomati through a connective channel namely Kachigang. The lake bed has been formed by silt deposition. As such no rock formation is found with 50m is silt (Clay loam) and below formation is sandy. Surrounding hillocks are of soft sedimentary formation. Annual rainfall is of the order of 2500 mm. Spread over the months of June to September with 4/5 flood peaks. Substantial base flow in streams rounds the year. The soil in lake area is silty clay loam to clay loam. Lake water is fresh with insignificant pollution with a depth varies from 2 m to 9m. Fluctuation in water level varies from EL 9m to 16m.The downstream area of the lake is 750 ha with a temperature variation from 37⁰C to 5⁰C and rainfall during May 15 to October 15. 

Present Threats of the lake:  

1. Eco-zoning of Lake Shoreline

The non-point sources of pollutant such as agricultural run off, anthropogenic introduced solid and semisolid pollutants was observed to be greater than those of point sources of pollution. The shoreline was disturbed with number of malpractices such as anthropogenic dumped garbage, deposition of solid waste and construction materials along the shoreline etc.

2. Eutrophication

Uncontrolled growth of alien invasive species such as water hyacinth, excessive algae was observed in the lake which caused loss of aquatic biodiversity. Cultural Eutrophication which was observed to a great extent is considered to be the major parameter for poor water quality management in Rudrasagar Lake.

3. Soil erosion and Siltation in the lake

Major soil erosion in catchment area of the lake is one of the major problems to decrease the lake area and to decrease the depth of the lake also. Such degradation in catchment area and siltation in the lake has the effect since long time in the lake. For such reason and others, the area of Rudrasagar Lake has been decreased drastically from 1000 ha. Prior to 1950 to more or less 100 ha. at present. Silting of lakes on account of increased erosion as a result of expansion of urban and agricultural areas, deforestation, flood, immersion of idols by the religious activity and such other land disturbances taking place in the drainage basin of the lake.  

4. Agricultural activity

As the water area has been decreased, the society used to use out the adjacent area of the lake to the members for agriculture purpose. It is observed that the good numbers of members of the society are more interested for agriculture than to fisheries activities. In our survey it was clear that a good number of farmers use pesticides and fertilizes in their paddy field.

5. Deforestation, filling, draining and degradation of wetland areas

 Clearing and removal of native vegetation due to the rapid unplanned urbanization, rural or industrial development was observed in our study. This not only reduces native vegetation biodiversity, but also reduces fauna biodiversity through the loss of habitat for breeding, nesting, and feeding and increased competition for existing habitat areas. Clearing further fragments remnant bush land and reduces wildlife corridors.

6. Lack of awareness, scientific knowledge and negligence in protection by law

Lack of awareness was observed during the survey among landowners about conserving biodiversity on their land. Many bush land remnants, including many high conservation communities, are on privately owned land, so conserving biodiversity is partly the responsibility of landowners.

Again it was observed that nearby peoples are exploiting the areas in numbers of way just because of lack of knowledge about ecosystem requirements and the needs of individual species. Due to lack of scientific knowledge, and the complexity of ecosystems, it is often hard to predict what impacts certain activities will have on certain species or ecosystems, or what factors are causing individual species decline.

Every year during November to April, peoples from different parts of the state as well as from out side, coming to the place for picnic purpose. But during our survey it was surprising to see the solid waste dumped by the picnic parties in the lake shoreline as well as in the lake water itself. Not even a single step has been taken by the concerned authority to protect these polluting activities by the picnic parties. Even a single signboard or banner has not been hanged in the areas to prevent the lake to be contaminated by these anthropogenic activities. 

7.Lack of perfect scientific database

A perfect database with regard to their present status, sustainable use management and conservation including a detailed scientific database on aquatic biota of the lake was not maintained so far as till present time so to formulate the strategies for long term management of lakes..

8. Pollution source of the lake

 During the survey it was observed that Pollutants which are entering to the lake from fixed point sources are;

• Nutrients from wastewater from domestic effluents

• Polluted Runoff water.

Again Pollutants entering from non- point sources are;

• Nutrients through fertilizers, toxic pesticides and other chemicals, mainly from agriculture runoff

• Organic pollution from anthropogenic activities and human settlements spread over areas along the periphery of the lakes and reservoirs

9. Other causes of impairment of the lake

·         Competition for using lake water such as for drinking, irrigation, fishing etc.,

·         Untreated or inadequately treated domestic and industrial effluents from point sources located all over the basin

·         Cultural siltation in the form of immersion of Idols during specific festivals, an annual feature in India, has been a source of serious metallic pollution of lakes.

·         Not having a definite wetland Authority, Special Purpose Vehicles (SPVs) for Lake Management and conservation with a unified mandate have not been set up.

·         Lack of community toilet facilities around periphery of the lake

·         Ownership and legal status of the lake and the inhabitants around the lake are not clearly defined.

CONCLUSION

Conservation of natural resources through sustainable ecosystem management and planned development is the key to our secured future. The human settlements, negligence of the concerned authority and public effluent sources are the chief factors for the degradation of Rudrasagar Lake. The anthropogenic pressures in the catchment itself has resulted in degradation of the catchment area due to deforestation, extensive agricultural use and consequent erosion and increased silt flows, which have vitiated the quality of water stored in this natural reservoir of the state.