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Understanding the hydropower exploitation’s hydrological impacts through a len of change in flow-sediment relationship: A case study in the Han River Basin, China

Jiang, Chong, Wang, Jun, Li, Congying, Wang, Xinchi, Wang, Dewang
Ecological engineering 2019 v.129 pp. 82-96
anthropogenic activities, case studies, climate, conservation programs, dams (hydrology), rivers, runoff, sediment yield, sediments, soil, sustainable development, water conservation, water power, watersheds, China, Yangtze River
The water and sediment yields of rivers are changing substantially under the impacts of climate variability and anthropogenic activities, which are increasingly becoming an important research topic in the field of hydro-environmental science. This study presents a comprehensive investigation of the changes in runoff depth (h), specific sediment yield (SSY), and flow-sediment relationship at multi-temporal scales in the Han River Basin (HRB). The effects of climate variability and anthropogenic activities on SSY were quantified by employing double cumulative curve analysis. The results are as follows: (1) The annual and flood season h and SSY in the midstream (Huangzhuang Station) during the past six decades presented declining trends. The detected change points (i.e., 1968 and 1984) in SSY were linked to the reservoir and dam construction and soil and water conservation programs. The Danjiangkou (DJK) Reservoir impounded water in the flood season and supplied water in the non-flood season, which made the intra-annual distributions of h and SSY more even and the intra-annual variations more moderate in the comparisons between the pre- and post-change periods. (2) The annual and flood-season flow-sediment relationships were fitted with the power function and the sediment productive ability of runoff in the flood season was much greater than that in the non-flood season. The construction and operation of the DJK Reservoir intercepted a significant quantity of sediment; thus, the sediment transported by unit runoff largely declined. (3) The estimated relative contributions of climate variability and anthropogenic activities to the changes in SSY suggested that the anthropogenic activities played a more substantial role in the SSY decline after the transition years. Sustainable development of the HRB will face many challenges as the water and sediment discharges decrease further from the Han River into the Yangtze River. These results will provide a reference for better soil and water resource conservation and draw more attention to strengthen the river basin management.