Health Diagnosis of River System in the Yellow River Basin Under Changing Environment

The Yellow River is the “mother river” of the Chinese nation.The unbalanced relationship between water and sediment and frequent flood disasters have always been the main challenges in the governance of the Yellow River Basin or YRB.In recent years, the Yellow River channel have undergone major changes caused by the fluctuated water-sediment relationship, meanwhile, along with frequent extreme weather events, the social economy in the basin has developed rapidly.Under this changing environment, a river health diagnosis for the YRB becomes essential.In this study, methods such as information entropy and entropy weight method are adopted to study the characteristics of the healthy development and evolution of the Yellow River Basin through a new index “River Health Index”,shortly RHI.The study results indicate:(1) A health analysis of the river system shows that the YRB was in a healthier state from 1980 to 1986 and was generally unhealthy from 1987 to 1999;and from 2000 to 2019,the river system developed towards a healthy and well-aligned direction.(2) An analysis of the trend of the RHI finds that the river system developed better from 1980 to 1984,showed an increasingly unhealthy trend from 1984 to 1999,and a positive trend from 2000 to 2019;(3) The sensitive factor of the river system was the flood capacity of the main channel of the Ningxia-Inner Mongolia river section before 1986;from 1987 to 1999,the sensitive factors were the flood capacity of the main channel of the Ningxia-Inner Mongolia river section and the total water volume of Huayuankou; since the 21st century, the sensitive factors are the total scouring and silting as well as the incoming sediment of the lower reaches of the Yellow River.For the entire period, the sensitive factors are the total scouring and silting of the lower Yellow River and the flood capacity of the main channel of the Ningxia-Inner Mongolia river section.These results can provide support for the ecological conservation and high-quality development of the YRB.