摘要：
美国农业部开发的SCS-CN模型是较为常用的一种径流计算方法.模型中的CN值是模型中反映土地利用、土壤类型和土壤前期含水量的一个综合参数,其值的选择对于准确计算地表径流具有重要意义.利用黄土高原地区杨青川流域、燕沟流域和西川流域不同土地利用类型42场模拟降雨的径流资料,应用平均值法、中值法、算术平均值法、S对数频率分布法和渐近线法5种方法计算CN值,并利用CN值反推径流深.采用均值比较、模型评价指标的方法比较了5种方法计算的径流深与实测值的差异,根据相对隶属度最大最优原则确定最优计算方法.结果表明:在杨青川流域,最优的计算方法是平均值法,燕沟流域和西川流域的最优计算方法则是中值法,不同流域同一计算方法确定的同一土地利用类型CN值差异较大;单独进行草地和裸地的评价分析时,草地的最优计算方法是平均值法,裸地的最优计算方法是算术平均值法,不同土地利用类型CN值的最优计算方法不同.%Soil Conservation Service Curve Number(SCS-CN)model developed by the US Department of Agriculture is a more commonly method of calculating runoff. The CN value in the model is a comprehensive parameter reflecting the land use, soil type and soil moisture, and the choice of its value is important for accurately calculating surface runoff. The purpose of this study was to compare the differences in determining CN by using mean method, median method, arithmetic mean method, S logarithmic frequency distribution method and asymptotic method by the rainfall and runoff data from 42 simulated rainfalls in Yangqingchuan,Yangou and Xichuan watersheds,and used the CN value to calculate the simulated runoff depth. Using the methods of mean comparison and the model evaluation were compared the measured runoff depth with the simulated runoff depth by the above five methods,and the optimal calculation method was determined by the maximum optimal principle of relative membership. The results show that the optimal calculation method is the mean value method in Yan-gqingchuan basin,the optimal calculation method of Yangou watershed and Xichuan watershed is the median method, and the CN value of the same land use type determined by the same calculation method is different;Evaluation of grassland and bare land alone,the optimal cal-culation methods of grassland and bare land are the average method and arithmetic mean method,and the optimal calculation method of CN value of different land use types is also different.
