Analysis of Hydrologic Regime Changes Caused by Dams in China

Dam construction has significantly altered natural flow regimes and caused various environmental problems. This study analyzes hydrologic changes on a national scale using indicators of hydrologic alteration (IHA) and the range of variability approach (RVA) with data from 35 monitoring stations in China. The majority of these stations see reductions in extreme maximum flows, flood flows, low pulse duration, high pulse number and duration, and rise and fall rates, while the extreme minimum flow, flows from December through March, low pulse number, and number of reversals increase. In general, river hydrologic regimes in China are moderately altered by reservoir impoundment, with an average overall alteration degree of 52%. The mean alteration degree of IHAs ranges from 36% to 63%. Reservoir impoundment has a large impact on the number of reversals, the change rate, and extreme minimum flows, which have significant environmental effects and should be analyzed. These change characteristics could help provide a reference for scientific decision-making concerning water resource management in China.