River Basin Environments and Ecological Succession in Danjiangkou Reservoir

Abstract

Danjiangkou Reservoir is one of largest reservoirs in China, with a storage capacity of 174.5 × 10⁸ m³, located at the starting point of the middle route project, and functions as the water source of the project. The middle route of the south-to-north water transfer project is a large project for allocating water to northern China. The water quality and health status of the reservoir have received much attention from the public and the Chinese government. In the present study, limnological features of Danjiangkou Reservoir and their long-term succession are explored on the basis of historical investigations. For half a century since its first filling, the reservoir has become transformed from a river to a lake-style reservoir. In the last decade, it has received increasing amounts of nutrients and it currently shows a trend toward eutrophication and water quality deterioration. The standing crop of phytoplankton has substantially increased, while large zooplankton crustaceans decreased. Oligochaeta and chironomidae account for a large part of the benthos. Although fish resources have recovered to some extent through a fishing moratorium and artificial fish breeding and restocking, many problems still remain in the fishery management. Long-term monitoring and limnological studies keep being required for the management of the water quality of the reservoir.