ASSESSMENT OF ECOLOGICAL HEALTH OF TILYAR LAKE

Abstract

India is facing a severe water related problems. The demand is increasing whereas the quality and quantity of water is degrading. The main source of water is rivers, lakes and ground water. The ground water is somewhere contaminated and at some places the water level is going down. Rivers and lakes are polluted with various point and non-point sources. It is necessary to assess the quality of water to estimate the level of degradation so that conservative measures can be used to improve the quality. The health of the water body gives the level of degradation of the lake, nutrients in the lake and biodiversity in the lake. The ecological health of the aquatic ecosystem is assessed with main three components (I) water quality assessment, (2) water quality indices and (3) biotic indices. During the study, it is found that the lake water is not suitable for drinking as per the NSF guidelines and Weighted Arithmetic Method. Both methods show that the lake water can be used for irrigation purpose, Carlson's Trophic State Index gives that the lake is in Eutrophic condition having high algal biomass. Macro-invertebrates were collected and indentifled. They belong to pollution tolerant species which shows that the lake is in degraded condition. The riparian vegetation of the lake was observed and diversity is observed using Simpson's Diversity Index (SDI). It was found that the diversity is very low. Lake water also affects the riparian vegetation and hence it reflects the quality of water in lake. Based on Water Quality Assessment (WQI), Simpson's Diversity Index (SDI), Trophic State Index (TSl) ecological Health Index of the lake is calculated. The ecological health index found to be 2.82. It means that ecological health of the lake belongs to average range but it is approaching towards bad condition. Excessive nutrients lead to heavy growth of algae. The status is due to the lack of management activities by lake authorities. Heavy load of tourists is polluting the lake & its catchment. The Eutrophic state is causing death of fishes in lake due to low DO. Sedimentation is also reducing its depth. So, conservative measures are suggested to prevent degradation of the lake such as evacuation and dc-silting of the lake followed by refilling with fresh water, management of tourist activities, prevent direct flow of nutrients from the catchment may also be checked by constructing a channel around the lake and by creating public awareness.