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

Sanjoy Deka¹

The Institute of Chartered Financial Analysts of India University, Sadar,

Kamalghat, Tripura (West), 799210

Abstract

Wetlands are often described as "kidneys of the landscape" (Mitsch & Gosselink 1986) but unfortunately wetlands are one of the most threatened habitats of the world.

According to the Annual Report (2005-2006) of Ministry of Environment and Forest Govt. of India, Rudrasagar Lake is listed in the LIST OF WETLANDS IDENTIFIED UNDER NATIONAL WETLAND CONSERVATION PROGRAMME and was mentioned in THE LIST OF WETLANDS OF INTERNATIONAL IMPORTANCE UNDER RAMSAR CONVENTION (INDIA). But the study carried out by the author in the Rudrasagar Lake reveals that the condition of the lake is very disappointing and pathetic with the observation of turbid water, excessive growth of algal blooms and water hyacinth, dumped garbage, construction material in the bank of the lake, and so on. It happened due to the discharge of domestic and industrial sewage, runoff from livestock feedlots and pastures, agricultural run-offs as fertilizers, insecticides and habitat construction which slowly fills in the water body with sediments and organic matter and finally makes the ecosystem unhealthy to live for diversity of flora and fauna of the lake. For this investigation, Sampling and data collection were done for one year and water quality assessment was performed adopting the method of APHA (1995).

Key words: Water quality; eco-zoning; eutrophication; soil erosion; siltation; pollutants

1. INTRODUCTION

Wetlands are defined as 'lands transitional between terrestrial and aquatic eco-systems where the water table is usually at or near the surface or the land is covered by shallow water (Mitsch & Gosselink 1986). Under the Convention on Wetlands (Ramsar, Iran, 1971) "wetlands" are defined as, 'For the purpose of this convention wetlands are areas of marsh. fen, peat land, or water , whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water depth of which at low tide does not exceed six metres."(Article 1.1) and "may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water deeper than six metres at low tide lying within the wetland."(Article 2.1). Lakes retain water during dry periods, thus keeping the water table high and relatively stable. During periods of flooding, they mitigate flood and to trap suspended solids and attached nutrients. Thus, streams flowing into lakes by way of wetland areas will transport fewer suspended solids and nutrients to the lakes than if they flow directly into the lakes. The removal of such wetland systems because of urbanization or other factors typically causes lake water quality to worsen. As with any natural habitat, wetlands are important in supporting species diversity and have a complex of wetland values. Tripura is blessed with a large number of natural and artificial lakes throughout the state. Main lakes of the state are Dumboor Lake, Rudrasagar Lake, Kamala Sagar and Khowra Lake. Govt. of India, Ministry of Environment and Forest identified Rudrasagar as one of the wetlands of National Importance for conservation and sustainable use based on its bio-diversity and socio economic importance. Secretary General, convention on wetlands, Ramsar site has declared Rudrasagar Lake as wetland of international importance and it has been included in the list of wetlands of International Importance. This certificate has been communicated by ministry of environment and forest, govt. of India on 29-02-2007.

Except a fist of project work done by forest department, fishery department and nodal department, PWD (WR), accountability of the ecosystem diversity, conservation, restoration and management works of the lakes is still scanty & under mystery. Peoples are still not aware about the conservation aspect of the lake and its genetic diversity. During preliminary survey, majority of the people inhabiting nearby the Rudrasagar Lake told that they were not aware that the lake is declared as Ramsar site. Looking view of this fact of very limited awareness and study on the Rudrasagar Lake, present study has been carried out with an aim at providing in a nutshell on 'Conserving lake ecosystem- A case study of Rudrasagar Lake (Ramsar Site), Tripura'.

2. MATERIALS AND METHODS

The methodologies that have been used primarily include several primary, secondary and public opinion surveys along with personal observations, site visits which were conducted in order to get data related to various aspects of wetland degradation of the lake and to understand the existing conditions.

To identify the impact of different natural and human activities on the lake eco-system, studies were basically conducted at the Catchments Level and the Lake Level. In addition to this, tourism related data has also been analyzed to understand the eco-tourism prospects. The water quality parameters included Water Conductivity, Dissolve Oxygen, Free Carbon Dioxide, Water pH, Turbidity, and Total Alkalinity were studied through standard method (APHA, 1995).

3. RESULTS

3.1 Lake profile

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 23^°29^° N and 90^°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 37^°C to 5^°C and rainfall during May 15 to October 15.

Table I: Present position of land and lake in Rudrasagar and adjacent panchayats areas

Source: Agenda Note on Neermahal (2007)

Table II: Public interaction data-Survey for primary data collection during January, 2010.

Source: Compiled by author

3.2 Water quality

Table III: Physicochemical parameters of Surface Water Samples of Rudrasagar Lake, Melaghar Block, West Tripura during January- 2010.

Source: Compiled by author

Locations:

Sampling site 1: North east side of the Rudrasagr Lake near neermahal palace.

Sampling site 2: south east side of the Rudragar Lake near the entry gate to the lake.

3.3 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.

3.4 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.

3.5 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.

3.6 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.

3.7 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.

3.8 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.

3.9 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..

3.10 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

3.11 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.

3.12 Promotion of ecotourism

Rudrasagar Lake is famed as one of the most beautiful place in the state from tourism point of view. A palace was also constructed by the then Tripura king Maharaja Bir Bikram Kishore Manikya Bahadur in between 1935-1938 as summer resort.

The palace is known as Neermahal (Water Palace) and is situated near the north-east bank of the lake. All these represent a hotspot for ecotourism promotion. However development of tourism has been unplanned and spontaneous. Growing urbanization and unplanned tourism development activities around the lake in absence of inadequate infrastructural facilities have negatively affected the lake's recreational values.

4. DISCUSSION

In most parts of the world anthropogenic impacts on lakes are spreading geographically and becoming more intense in quantity and quality due to human population increases and the globalization of trade, which has increased deforestation and the use of pesticides and fertilizers, and has spurred the spread of invasive species (Ayres et al. 1996, French 2000).

Increased population growth in the lakeshore and wider catchment coupled with an increase in human activity is threatening the sustainability of the lake as a rich resource base. Fishing pressure, sedimentation and pollution are threatening the lake's biodiversity to a great extent in Rudrasagar Lake.

Seven major threats to lakes of the world include: accelerated eutrophication, invasive species, toxic contamination, over fishing, water diversion, acidification, and climate change. Institutions and institutional arrangements for addressing these issues and for implementing a watershed approach is just beginning to emerge on lakes around the world (Borre at al., 2001).

The dissolved oxygen level can be an indication of how polluted the water is and how well the water can support aquatic plant and animal life. The minimum permissible limit of D.O. prescribed by Indian standard is 6 mg/L. As per the data given in the Table III, the dissolved oxygen levels at sampling site 1 (9.84 mg/L) and sampling site 2 (10.56 mg/L) are at the desirable limit level. Hardness of the water is ranging from 6 mg/L to 8 mg/L. According to the U.S E.P.A (2003) categorization of the lakes on the basis of alkalinity the Rudrasagar Lake is not sensitive with the alkalinity ranging from 34mg/L to 36 mg/L in different sampling site. pH of the lake is ranging from 6.7 to 6.8 in different sampling points. Turbidity is a measure of the cloudiness of water. The higher the turbidity, the harder it is to see through the water. The water of the Rudrasagar Lake is moderately cloudy in most of the part and is a bit clear near the agricultural land but that part is full of algae and water hyacinth. The turbidity level ranges from 40 NTU to 50 NTU and the Secchi depth was greater near agricultural land (20.1 cm) in comparison to the secchi depth (18.7 cm) by the side crowded with the picnic parties and the boating path to Neermahal.

Turbidity can also stimulate the growth of bacteria (WHO, 2004). Along with E. coli, pH, and chlorine residual, turbidity is one of the key parameters of microbial water quality (WHO, 2004). Drinking water should have a turbidity of ≤ 5 NTU (Davis, 2002). If pathogens are to be destroyed through UV irradiation whether from the sun or a lamp, turbidity must be <30 NTU (Laurent, 2005).

As per conservation guideline, 10-30m strip of land along the Lake Shoreline and next 90m is recommended for buffer zone and controlled development zone with horticultural/agro forestry activities respectively (IUCN, 1995b). The shoreline was disturbed with number of malpractices in Rudrasgar Lake. Restructuring of the littoral zone provides a balanced approach to lake restoration and multiple uses of the lake, thereby integrating management practices with planning (Engel, 1987).

Observation of uncontrolled growth of water hyacinth, excessive algae and Cultural Eutrophication in the lake considered to be the major parameter for poor water quality management in Rudrasagar Lake. Virtually irreversible accelerated eutrophication of a lake is similar to "diabetes" in humans (Nakamura, 1997).

5. 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.

The restoration program with an eco-system perspective through best management practices (BMPs) help in correcting point and non-point sources of pollution. This along with regulations and planning for wildlife habitat and fishes helps in arresting the declining water quality and the rate in loss of wetlands. These restoration goals require intensive planning, leadership and funding with active involvement from all levels of organization through interagency and inter governmental processes instrumental in initiating and implementing the restoration programs. A wetland conservation strategy should therefore have an extensive bias of participatory process (Choudhury, 2000).

Apart from governmental regulations, better monitoring mechanism is needed to increase the knowledge of the physical, chemical and biological characteristics of wetland resources, their values and a better understanding of wetlands dynamics. Management based on accurate knowledge and increased awareness of wetland issues involving all stakeholders and all components of ecosystem help in long term sustenance involving restoration and conservation.

The Rudrasagar Lake holds scope for development of eco-tourism. The optimality of the present resource appropriation in light of its sustainability needs to be worked out through further ecological assessments and definite regulatory frame work should be in place.

6. ACKNOWLEDGEMENTS

The researcher wish to express his deepest gratitude and warmest appreciation to Dr. R. K Patnaik, Dr. S. P. Gupta and Dr. A. Ranganath, who, in any way have contributed and inspired the researchers to the overall success of the undertaking

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