Abstract

The East River is the main fresh water sources for Hong Kong, Shenzhen, Dongguan, Huizhou, Guangzhou, so concerns for keeping its ecosystem health are growing. There are over 6000 reservoirs within the East River Basin. On the one hand, reservoirs are built for gaining safety and economic benefits, on the other hand, reservoirs affect the ecological functions of rivers. This paper discusses various effects of reservoirs on river ecology and environment. Stream flow, substrate, and physical morphology are important ecological and environmental factors for biota. Due to impoundment of the reservoirs, variations of monthly discharge and flow fluctuations are reduced, meanwhile sediment load decreases, and aggradations upstream of the reservoirs and degradation downstream of the dams are found in the stream channels, therefore the habitats of aqua-animals are impaired, which have caused remarkable disturbance to benthic macro-invertebrates. The density, density of bio-mass, and richness of benthic macro-invertebrate in the downstream river channel of the reservoir are much lower than those in the upstream.

Keywords: Reservoir, Ecology and Environment, Hydrology, macro-invertebrate