Analysis of water quality variation along a regulated stream in Sri Lanka

Man modifies water quality not only directly through discharges but also indirectly through such activities as adjusting flow regimes, impounding and abstracting. The Mahaweli Development Scheme in Sri Lanka comprises of a complex network of reservoirs, diversion structures, canals, tunnels, hydropower plants etc. The paper presents an analysis of water quality m one of its subsystems, the system from the Polgolla barrage to the Kalawewa reservoir Water passes through tunnels, hydropower plants, reservoirs, canals and natural streams in this stretch. The investigation is limited to physical and chemical parameters of water quality. The results indicate that some water quality parameters depend on the quantity of water, which could be controlled by the various structures in the subsystem. However, the quality of water is observed to be within the acceptable limits with respected to the investigated quality parameters.