The combined impact of historical climate change and human activities on reservoir flood control risk

Abstract

Study area: The Chengbi River Basin (CRB,106°21′ ∼106°48′ E, 23°50′ ∼24°45′ N) and the Chengbi River Reservoir (CRR) in Southwest China. Study focus: To quantitatively assess the combined impact of historical climate change and human activities (HCCHA) on flood control risk (FCR), this study proposes a framework including a characteristics analysis of the HCCHA, a more reasonable determining of the benchmark period and the influence period, and an evaluation of the combined impact of the HCCHA on the flood control risk with bi-variate flood frequency analysis. New hydrological insights for the region: Findings show that: (i) The annual rainfall (44.342 mm/10a) and annual average temperature (0.5796 ℃/10a) increased significantly, while the potential evaporation decreased(‐44.342decreased(−44.342 mm/10a). In the land use change that characterizes human activities, woodland and cropland showed upward trends while a decreasing trend in grassland. (ii) The starting time of climate change (1985) in the CRB is earlier than that of human activities (1988), thus the demarcation time of the benchmark period and influence period is 1985. (iii)As for bivariate flood frequency analysis, the G-H Copula function outperformed the other Copula functions with the error ranges of −0.1654 to 0.0965. (iv) Influenced by HCCHA, the FCR under the design condition decreased by 0.11211–0.05419%, and the corresponding flood control standard (FCS) increased from 892a to 1845a.

Keywords

• Climate change
• Human activities
• Reservoir flood risk
• Copula function
• Bivariate flood frequency analysis