Healthy River:Essence and Indicators

Healthy river is a river whose social functions and natural functions can be balanced or compromised in corresponding periods. The symbols of healthy river should be favorable riverbed,acceptable water quality and favorable river ecosystem,when river's social functions and natural functions perform in a balanced way. The river health indicators should reflect the river's natural function status which includes the riverbed,water quality,river ecosystem and runoff. But,the variety and quantity would be different for different rivers because of different natural features and social background. The quantized indicators should be decided according to the requirement of maintaining river's normal natural functions and the extent whether the social functions and the natural functions could perform in the balanced way,and also the indicators should be adjusted according to the change of the natural features and social background. The key to river health is the abundant and clean flow,as the environmental flows are very important to safeguard the river health. The human activities would hurt the river health which include the over water diversion and over power generation from the river,improper regulation of flood and sediment,and over sewage discharge into the river and excessive change of the environmental flows relating to key species habitat. Taking the Yellow River as a case,this paper also explained the method to identify the river health indicators.