考虑双因子的改进时变分布式单位线汇流方法研究OA

Runoff concentration simulation is a key component of hydrological forecasting.The distributed unit hydrograph method has been widely applied in runoff concentration calculations for small-and medium-sized basins due to its ability to reflect the spatial heterogeneity of basin underlying surface conditions.However,the traditional time-varying distributed unit hydrograph only considers the effect of rainfall intensity and ignores the dynamic influence of soil moisture on flow velocity,which limits the accuracy of runoff concentration simulation.Based on the time-varying distributed unit hydrograph,this study introduces the soil moisture factor and proposes an improved time-varying distributed unit hydrograph method for runoff concentration.The proposed method takes into account the effects of both rainfall intensity and soil moisture on flow velocity,and optimizes the flow velocity calculation and unit hydrograph derivation process.Taking the Meijiang Basin as the study area,10 typical flood events are selected,including floods from 2021 to 2025 and the largest flood since the station establishment.The SCE-UA algorithm is used for parameter calibration.Three indicators,namely relative error of flood peak,error of flood peak time,and determination coefficient,are adopted as evaluation criteria.Comparative verification is carried out against four methods:triangular synthetic unit hydrograph,R-V geomorphologic instantaneous unit hydrograph,distributed unit hydrograph,and traditional time-varying distributed unit hydrograph.The results show that the improved time-varying distributed unit hydrograph method achieves a mean absolute relative error of flood peak of 4.4%,a mean error of flood peak time of 1.2 h,and a mean determination coefficient of 0.80,which are significantly better than those of traditional runoff concentration methods.This method can effectively capture the time-varying characteristics of the runoff concentration process and adapt to various conditions of different rainfall intensities and soil moisture contents,with simulation accuracy meeting practical engineering requirements.The research results enrich the simulation methods for runoff concentration in small-and medium-sized basins and provide a new technical approach for improving the accuracy of hydrological forecasting.