密云水库上游流域径流曲线模型的参数修订

Revision of CN Value and Initial Abstraction Ratio in the SCS-CN Model in Upper Reaches of Minyun Reservoir

为探讨同时率定CN值和初损率2个参数得到的模拟结果是否比单独率定一个参数更为理想,且在不同土地利用类型下SCS-CN模型是否均适用,选取了密云水库上游石匣小流域为研究区域,根据石匣小流域坡面试验小区2006—2010年实测降雨-径流数据和SCS-CN模型的计算公式,在0.05-0.40范围内,等间隔选取8个不同的初损率值,并利用算术平均值法反推各初损率值条件下对应的CN值,以纳什效率系数为SCS-CN模型的适用性评价参数,确定裸地、耕地、草地和林地4种不同土地利用类型下模拟效果最佳的CN值与初损率,最后对4种不同土地利用类型下的SCS-CN模型进行了适用性评价。结果表明：（1）4种不同土地利用类型条件下,当初损率为0.05时纳什效率系数值最高,分别为裸地（0.75）、耕地（0.48）、草地（-1.11）、林地（-0.24）;（2）在石匣小流域内利用SCS-CN模型对该研究区域的径流值进行预测时,裸地条件下的CN1值为86,耕地条件下的CN1值为74,草地条件下的CN1值为58,林地条件下的CN1值为63,4种不同土地利用类型的初损率取值均为0.05;（3）通过同时率定2个参数可以使得SCS-CN模型的模拟效果得到一定的提高;（4）在石匣小流域内,SCS-CN模型在裸地和耕地条件下可以较好地模拟地表径流,但草地和林地条件下其模拟结果不理想。

The studies on revision of parameters of SCS-CN model have been done by lots of scholars in China,but most of them focused on using different methods to revise 1of the 2parameters.In order to investigate whether the simulated result obtained from revising the 2parameters at the same time is better than only revising 1parameter,and also to identify the applicability of SCS-CN model under 4different kinds of land use,this paper chose Shixia small watershed,which is the upper area of Miyun Reservoir watershed,as the study area,and the monitoring data during 2006 to 2010of Shixia small watershed was collected.8equal interval of initial abstraction ratio value from 0.05 to 0.40 was selected,and by using the arithmetic mean method,the curve number values of 8different initial abstraction ratios were calculated respectively.This paper also evaluated the applicability of SCS-CN model in study area under 4different kinds of land use by taking Nash efficiency coefficient as criterion.The results showed that：（1）In the study area,when the initial abstraction ratio values were 0.05 under 4different types of land use conditions,the Nash efficiency coefficient were the highest,which were 0.75,0.48,-1.11and-0.24 under bare land,cropland,grassland and woodland,respectively.（2）When we adopted SCS-CN model to predict runoff in upper area of Miyun reservoir,the recommend values of curve number under bare land,cropland,grass land and woodland were 86,74,58,and 63,respectively.And the recommend values of initial abstraction ratio under 4land use patterns were all 0.05.（3）The simulation results of the SCS-CN model could be improved to a certain extent by revising the 2parameters at the same time.（4）SCS-CN model could be adopted in bare land and cropland in Shixia small watershed,but was not recommended to be adopted in grassland and woodland.