Assessment of Instream Hydrologic Regime Alteration Induced by Hydraulics

The indicator of hydrologic alteration (IHA) and coupled with the range of variability approach (RVA) are usually used to evaluate the alteration of the long-term hydrologic flow regime for instreams, which is widely recognized and applied both in China and abroad. This study is intended to assess the hydrologic regime alteration of Hanjiang River induced by Danjiangkou Reservoir. In which, the record period from 1946 to 2006 was divided into two by 1967, the impoundment time of Danjiangkou Reservoir; and methods of IHA and RVA were employed to assess the hydrologic alteration degree of Hanjiang River at Xiangyang Station. Results show that, the degree of hydrologic regime alteration of Hanjiang River is 33.4% and classified as the moderate alteration category, which provides references of ecological water requirements and ecological protection for Hanjiang River, and is helpful for ecological regulation of Danjiangkou Reservoir.