Assessing the Drought Mitigation Ability of Reservoir in the downstream of the Yellow River

Due to climate change and human activities, drought frequency and corresponding impact have been intensified in many regions. Reservoir is a key measure to regulate streamflow and mitigate drought negative impact. Therefore, it is vital to analyze the drought mitigation ability of reservoir. In this study, drought adaptation capacity and drought resistance capacity of reservoir are selected as two drought mitigation ability metrics to measure the reservoir effect when facing droughts. Drought adaptation capacity of reservoir represents the ability of prevention and reduction of drought negative impacts. It is assessed from two aspects, one reflecting the reservoir scale and layout reasonability, while another one reflecting the engineering operation and management level. Drought resistance capacity of reservoir refers to the ability to meet the water demand under a certain drought degree (drought joint return period). It is computed based on the reservoir water supply and water demand. These two drought mitigation ability metrics can be applied not only for a single reservoir, but also for a group of reservoirs. This study applies these two drought mitigation ability metrics in the downstream of the Yellow River for a group of reservoirs. Results show that: 1) the ability of reservoirs in the downstream of the Yellow River for prevention and reduction of drought negative impacts is in the normal grade; 2) the reservoirs can better resist the drought whose joint return period is smaller than 2 years while the drought resistance capacity is weak when joint return period is over 6 years. The basin drought adaptation and resistance capacity need to be improved. Management and operation of current water conservancy projects still need to be enhanced.