Due to climate change and human activities, drought frequency and its corresponding impact have intensified in many regions across China. Reservoirs are key in regulating streamflow and mitigating a drought's impact. Therefore, it is vital to analyze their drought mitigation ability. In this study, the drought adaptation capacity and drought resistance capacity of the reservoir are selected as two drought mitigation ability metrics to measure the effectiveness of a reservoir when facing a drought. The drought adaptation capacity represents the ability of a reservoir to prevent and mitigate damage caused by drought. It is assessed from two viewpoints, one reflecting the reservoir scale and layout reasonability, while the second reflecting the engineering operation and management. The drought resistance capacity refers to the ability of a reservoir to meet the water demand under a certain level of a drought (i.e. drought joint return period, which is defined later), and is calculated based on the reservoir's 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 metrics in the downstream of the Yellow River for a group of reservoirs. The results show that: 1) the ability of reservoirs in the downstream of the Yellow River for prevention and mitigation of damage caused by drought rates in the normal grade; and 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 the joint return period is over 6 years. Overall, the basin's drought adaptation and resistance capacity need to be improved. Management and operation of current water conservancy projects still need to be enhanced.
Keywords: Drought adaptation capacity; Drought mitigation ability; Drought resistance capacity; Reservoir; Water supply.
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