Analysis of variation characteristics of runoff at multi-time scales under the influence of reservoir

Reservoirs play a significant role in changing the natural hydrological conditions. This paper studies the change characteristics of runoff fluctuation caused by the Gangkouwan Reservoir in Shuiyangjiang River, and collects the hourly flow data from two hydrological stations upstream and downstream of the reservoir. Through the comparison of the uneven coefficient (CV ) and concentration degree (Cd ) of the two stations, reflect the impact of the reservoir on runoff changes at two-time scales of intra-annual and intra-month. The results shown the Gangkouwan Station has significant changes in runoff distribution at intra-annual and intra-month scales, affected by the reservoir. For the intra-month runoff, the runoff process at Gangkouwan Station is more uniform than Hulesi station in the flood season, because the reservoir has to store water. In the dry season, the opposite is realized, because the reservoir needs to discharge water to generate electricity. This paper is more conducive to deepening the understanding of the impact of reservoir operations on hydrological processes.