2. Study area |
Varthur Lake is one of the largest lake located in the Bangalore South taluk of the Bangalore District in Karnataka. Bellandur tank of the Bangalore south taluk (Figure.2) is interconnected to the surrounding wetlands which drain into Varthur and finally into the Dakshina Pinakini river. It has a large surface area and is the main irrigation source to the nearby agricultural fields This lake has played an important role in maintaining water resources for irrigation since its construction over the centuries (Government of Karnataka 1990), it has developed into a complex ecosystem that provides habitat for a wide variety of flora and fauna, including resident and migratory waterfowl. The lake also endows the local community with a pleasant microclimate and considerable aesthetic appeal. The lake is surrounded by small farms that grow rice, ragi, coconut, flowers, and a variety of fruits and vegetables, which are grown using the lake water. The total land irrigated by the lake water amounts to 625 hectares. The largest town in the immediate area is Varthur, which had a population of 5,431 as per 1981 census (Census of India, 1981). Several smaller villages are also located near the periphery of the lake. Figure 3 presents a view of southeastern Bangalore and Varthur Lake’s catchment area as surveyed in 1970 to 1974. Human settlements and the roadways are marked in red; the outskirts of Bangalore city proper can be seen in the upper left-hand corner. The loss in lake interconnectivity in Bangalore district is attributed to the enormous increase in population and the reclamation of tanks for various developmental activities.
Varthur Lake is part of a system of interconnected tanks and canals that receive virtually all the surface runoff, wastewater, and sewage from the Bangalore south taluk (Figure 2 and 4). Rapid development and population expansion, both within Bangalore and in the surrounding towns and villages, have taken a heavy toll on many of the tanks in the area, and Varthur is no exception. Analyses of Varthur lake drainage network revealed that the drainage network between Bellandur and Ulsoor in Varthur lake drainage network is lost due to conversion of Chelgatta tank into a golf course (Figure 4). Varthur lake finally joins the Dakshina Pinakini river The Bangalore South taluk alone has experienced a surge in its population from 2,84,556 to 4,45,581 between 1971 and 1981 (Census of India, 1981). Contamination of water supplies is having a negative effect on the quality and quantity of crops produced using the lake water. This poses a threat to the primary source of income for people living near the lake.Pollution loading has exceeded the lake’s ability to assimilate contaminants, leading to visible degradation of the quality of water in the lake. Examining the current ecological status and economic value of the lake is crucial for developing appropriate remedial measures.
