The Detection of Flood Characteristics Alteration Induced by the Danjiangkou Reservoir at Han River, China

As one of the most common natural phenomena, floods can bring both risks and benefits for human beings. They can pose a risk of inundation to a human habitat but can also be utilized as a resource with hydraulic engineering. Improving the knowledge of flood characteristics is the basis and premise of improving water resources management and ecological environmental protection. Presently, the quantitative evaluation of flood characteristics needs to gradually evolve from a single indicator to a systematic one. In this paper, by introducing the concepts of ecohydrology on magnitude, frequency, and duration, a set of flood characteristics indicators evaluation system is constructed based on the hydrological characteristics for the section where Danjiangkou Reservoir is located at the middle reach of the Yangtze in China. The results showed that the Danjiangkou Reservoir has changed the flood characteristics to a great extent both of seasonal or annual floods, and the mean degree of the flood characteristic alteration indicators is about 19%. The changing trend of the flood indicators upstream showed an increasing trend from the 1970s to 2010s, while downstream were divided into two periods by the year of about 1975. The methodological system provided by this paper can effectively evaluate flood characteristics quantitatively, provide technical guidance and a useful reference for flood process analysis, and provide support for flood management and river ecosystem protection.