This study was carried out in a catchment area to assess impacts due to implementation of river valley project and from the proposed operation, in combination with other existing and anticipated operations.

Study Area:

The Sharavathi is one of the important west flowing rivers of Karnataka, which takes its origin in Western Ghats near Ambutirtha in Tirthahalli Taluk of Shimoga district. The river Sharavathi flows in northwest direction and is mainly utilized for generation of hydro-electric power. Its length is about 128 km and has a total drainage area of 2,771 km2. The river along with its tributaries flows along the rugged terrain of Western Ghats of southwest Shimoga and southeast Uttar Kannada. The river drops to a vertical fall of about 253 m near Jog and it joins the Arabian sea at Honavar in Uttar Kannada (Karnataka State Gazetteer Part I, 1982). This region, by virtue of its geographical sketch, varied terrain and climate supports a rich diversity of flora and fauna

The Karnataka Power Corporation Limited has constructed a dam across the river in 1964 near Linganamakki, which is at present one of the oldest Hydro electric power projects in India. The dam is located at about 14O41'24'' N latitude and 74O50'54'' E longitude with an altitude of 512 m. The total capacity of the reservoir is 152 TMC (Thousand Million Cubicfeet). It has a catchment area of nearly 1991.71 It receives water mainly from rainfall and also from the Chakra and Savahaklu reservoirs, which are linked through Linganamakki through a canal. The water from Linganamakki dam flows to Talakalale Balancing Reservoir through a trapezoidal canal with a discharge capacity of 175.56 cumecs. The length of this channel is about 4318.40 m with a submersion of 7.77 sq. km. It has a catchment area of about 46.60 The gross capacity of the reservoir is 129.60 cu m.

The construction of the Linganamakki dam has caused submersion of a large area along with loss of biodiversity. The aquatic and soil ecosystems are the major resources under threat. Thus it would be important to assess the cumulative impact of the construction of the dam on the river ecosystem.