EUTROPHICATION ANALYSIS OF LAKES OF KUMAUN REGION

Abstract

The earth is dotted with about 3 million lakes which contain 95% of the earth's fresh liquid water. Most of the lakes are facing the most obvious, significant and worldwide water quality problem of lakes i.e. eutrophication. Lakes in such condition loose much of their beauty, their attractiveness for recreation, their usefulness and safety as industrial and domestic supplies. This work deals with the eutrophication analysis of lakes of Kumaun region which are located in the north eastern border of the Indian subcontinent. The excessive deforestation, cultivation on the hills, building of roads and mushroomed growth of hotels, buildings and industries have created various kinks of ecological problems in these lakes. Till the recent past there were 60 lakes in Kumaun region but at present only 5 lakes (Nainital, Bhimtal, Sattal, Naukuchiatal and Khurpatal) are present. Out of these Naukuchiatal is the most voluminous and deepest lake where as Khurpatal is the smallest and shallowest. There is a considerable variation in the degree and extent of human interference in the Kumaun lakes. Keeping this in view, water samples from all the 5 lakes have been collected and analyzed for various water quality parameters. A comparative study of the water quality of the lakes have been made and indicated a significant variation on a quantitative scale. The comparative study revealed that Nainital lake has the highest concentration of both cations and anions and is also rich in phosphorus and nitrogen; and lake Sattal and Naukuchiatal have lower concentrations of cations, anions and nutrients. Utilizing the results of the present analysis, relationships between total phosphorus, chlorophyll — a, and secchi depth have been developed. An attempt has been made to compare the present findings with the relationships developed by various investigators for different lakes of the world. Based on the developed relationships, a norirgram combining the eutrophication variables has been made. From the nonogram, knowing one of the eutrophication variables (SD, TP and chlor) the other two variables together with the tropic status can be determined. The tropic status of the lakes have been determined based on specific boundary values of total phosphorus using descriptive terms namely oligotropic, mesotrophic and eutrophic. Numerical Tropic State Index (TSI) was also used to determine the tropic status of the lakes. From all the evaluations it was found that among the lakes Nainital is the most polluted and hypereutrophic lake and the lakes can be arranged in decreasing level of eutrophication as Nainital, Bhimtal, Khurpatal, Sattal and Naukuchiatal. In addition, the tropic status of Indian lakes have been studied based on available water quality data collected by CPCB. The evaluation of the data revealed that most of the lakes are hypereutrophic.