水库影响下的山区洪水态势演变研究OA

In recent years,extreme flash flood events in mountainous watersheds under the combined influence of cli-mate change and human activities have occurred more frequently.Characterized by sudden onset and high destructive potential,these events pose significant challenges to China's disaster prevention and mitigation efforts.This study employs the spatiotemporally-variable-source distributed hydrological model(SKY-HydroSAT),independently developed by the China Institute of Water Resources and Hydropower Research,to establish a distributed hydrologi-cal model considering reservoir regulation in the upper catchment of the Guilin City in the Lijiang River Basin.The model demonstrates good applicability,with absolute peak flow errors of 3.7%and 5.4%during the calibration and validation periods,respectively,and Nash-Sutcliffe efficiency(NSE)values of 0.87 and 0.83.Taking the"6·19"extreme flash flood event in 2024 as a case study,with the accurate modelling results(peak flow error 10.5%,NSE 0.94),the research investigated the flood dynamics under reservoir influence.The analysis reveals that this event was triggered by a bimodal heavy rainfall pattern,with a three-day average rainfall of 442 mm across the watershed above Guilin and a maximum cumulative rainfall of 777 mm at Maolingjiao Station.Simulation results indicate the formation of combined infiltration-excess and saturation-excess runoff mechanisms,along with subsurface stormflow in major runoff-producing areas,leading to rapid runoff generation and posing severe challenges to midstream reservoirs and downstream flood safety.The joint operation of 4 upstream reservoirs upstream of Guilin played a crucial role in flood control and disaster mitigation.Without reservoir regulation,the peak flow at Guilin Station would have exceeded the 100-year return period level.After regulation by the upstream reservoirs,the peak flow at Guilin Stationwas reduced to 6380 m³/s(approximately equivalent to a 30-year return period flood),significantly mitigating downstream disas-ter losses.This study validates the applicability of the distributed hydrological model in the Guilin region,demonstrat-ing its capability to accurately characterize watershed runoff mechanisms and quantify the benefits of regulation by hydraulic projects.The proposed approach holds potential for extension to other mountainous watersheds in China and can provide scientific support for regional flood management decision-making.