Evolution of hydrological regime in middle and lower reaches of Han River driven by water conservancy project and countermeasures

Abstract

The Han River is not only an important water supply source in China, but also a treasure trove of water resources for the economic and social development of Hubei Province. In this paper, the evolution characteristics of hydrological regime in the middle and lower reaches of the Han River (MLHR) under the influence of numerous water conservancy projects were studied, and the related problems of resource and environment were analysed, and then corresponding countermeasures were proposed. The results showed that the mean annual flow in Huangjiagang and Huangzhuang section decreased by 20.3% and 5.5%, respectively, during the four years before and after the operation of the Middle Route of South-to-North Water Diversion Project (MRP). Meanwhile, there were a decrease in the duration of the medium and high runoff and an increase in the duration of low runoff, leading to an enhancement of the attenuation effect of the annual runoff process. Moreover, a pattern formed that natural rivers and reservoirs appeared alternately after the construction of cascade reservoirs. Furthermore, with the variation of hydrological regimes in the MLHR, there were some problems of the contradiction between water supply and water demand, the evolution of river regime, the reduction of suitable aquatic habitats and others. In these regards, for providing technical support for the construction of the Han River Ecological Economic Belt, some countermeasures and suggestions were proposed, such as rational allocation of water resources, the promotion of the construction of the follow-up water supplement project and the implementation of ecological regulation in the MLHR.