Abstract:
Results of the study indicated that Pelang Ganga and its tributaries carry less water. Some tributeries near water outfall are almost dry (eg. Dangolla Ela, near water outfall). Therefore, addition of 48m3/sec of water will increase erosion, sediment load of water. The aquatic faunal composition will be disturbed. It is necessary to construct re-regulation ponds and flood protection facility there. Water in Kukule Ganga is slow moving and carries mote water. The river morphology does not show the need to have a re-regulation ponds. The river morphology and the volume of water carried in the river will buffer the addition of 46 m 3/ see of water during plant operation.
Fauna of Kukula Ganga is less affected compaired to that of Pelang Ganga.
Both rivers sustain endemic (to Sri Lanka) and threatened species of fish and other
fauna. These are also present in other river basins of the wet zone. There are migratory fish and prawn species in both rivers. therefore, a fish pass will help them
in their annual migration. Thus., they will sustain in Kukule Ganga basin. However,
in the absence of this facility, migratory species will eliminate from the region and
not from the wet zone. Out of the six alternative routes studied, Kukule-Kule Run of River (R-K ROR) has the least impact on the aquatic fauna. Under a weir any excess water over 46 m3/sec, will be naturally released. Butno water at all will be eleased under low and high dam. Further, more tributaries will be innundated under low and high dam. This badly affects riverine species of fish and other fauna. Therefore, Kukule-Kukule weir and its reservoirs has the least impact on aquatic fauna. Therefore, it is the most appropriate out of six project alternatives. In view of the above it is recomended to be implemented.
