岔巴沟流域汛期径流模拟及地表产流特征分析

气候变化是影响流域水文循环过程的重要驱动因素，近年来，气候变化导致极端降雨—径流事件的频繁发生对人类社会经济发展构成了严重的威胁。因此，迫切需要开展流域水文模拟和产流特征分析。土壤和水评估工具(SWAT)是一种具有物理机制的分布式水文模型，已被广泛用于评价变化环境下的水文过程。以黄土高原岔巴沟流域为研究区，通过利用与黄土高原地区产流模式更为接近的Green-Ampt下渗法驱动SWAT模型模拟了岔巴沟流域日尺度的水文过程，并以水文响应单元为分析对象，结合4个降雨—径流事件的地表产流量和地表径流系数分析了降雨强度和前期土壤含水量对不同土地覆被产流特征的影响。结果表明：(1)基于Green-Ampt下渗法驱动的SWAT模型率定期和验证期E_NS为0.76,0.74,R²为0.78,0.75,模型能够较好地模拟日尺度流域水文过程；(2)流域不同土地覆被下地表径流系数随最大雨强的增加呈显著上升趋势，且最大降雨强度大于16 mm/h后地表径流系数显著增加，当土地覆被为耕地时降雨转化为地表径流的比例最大，其次为草地和林地；(3)前期土壤含水量的大小可以揭示大...

Simulation of Runoff in Flood Season and Analysis of Surface Runoff Characteristics in Chabagou Watershed

Climate change is an important driving factor affecting the hydrological cycling processes of watershed. In recent years, the frequent occurrence of extreme rainfall-runoff events caused by climate change has posed a serious threat to social and economic development. Therefore, it is urgent to carry out hydrological simulation and runoff characteristics analysis. SWAT(Soil and Water Assessment Tool)is a distributed hydrological model with physical mechanisms and has been widely used to evaluate hydrological processes under changing environments. The Chabagou watershed on the Loess Plateau was taken as the study area, and the daily scale hydrological processes of the Chabagou watershed were simulated by the SWAT model driven by the Green-Ampt infiltration method, which is more suitable for the Loess Plateau. Based on the Hydrological Response Units, the effects of rainfall intensity and soil moisture on runoff yield characteristics of different land covers were analyzed based on the surface runoff yield and surface runoff coefficient of four rainfall-runoff events. The results show that:(1)driven by the Green-Ampt infiltration method, E_NS and R² of SWAT model in calibration and validation period are 0.76 and 0.74, 0.78 and 0.75, respectively; the model can successfully simulate the hydrological process of the watershed at daily scale;(2)the surface runoff coefficients under different land covers all show a significant upward trend with the increase of the maximum rainfall intensity, and increase significantly when the maximum rainfall intensity is greater than 16 mm/h; the largest surface runoff coefficient existed in farmland, followed by pasture and forest;(3)the antecedent soil moisture can reveal the change of the part surface runoff coefficient under the high rainfall intensity, and antecedent soil moisture under different land covers has a good linear relationship with surface runoff coefficient; according to the slope of the fitting equation, the surface runoff coefficients of farmland and pasture are more sensitive to the change of antecedent soil moisture. In conclusion, this study can be informative for daily runoff simulation and analysis of runoff yield characteristics under the variable environmental conditions of loess hilly-gully region.