Some studies on the changes in the freshwater ecosystem during the impoundment of the Kali river (Karnataka state, India)

Abstract

Dams are constructed across the rivers to stock water for generating electric power, irrigating the land, providing water for domestic and industrial uses, fish culture and for taming the rivers in spate and using them as water ways for transport. Considerable amount of research has been carried out on the limnology of river impoundments in a span of 40 years. It has been now realized that dams and reservoirs do cause environmental hazards. Time has come to now to realize that the construction of dams should be undertaken only after an accurate prediction is made about its impact on the environment and socio-economy. Construction of dams accounts to creation of a new biotope in place of an old one, in a sense; it is a reservoir ecosystem undergoes succession of 4 phases, namely pre-impoundment, filling, post-impoundment and stability phase. In the present study, an opportunity was availed to investigate the hydrobiological status of Supa reservoir during its filling phase when the dam was commissioned and the stocking of water began in 1985. Monthly survey of physico-chemical factors, net phytoplankton, zooplanktonic composition, productivity of the Supa reservoir during its filling phase was investigated for a year from December 1985 to November 1986 and the interrelationship between these parameters and the seasonal variations amongst them is statistically evaluated.