SCS模型中CN值的优化率定方法——以天山北坡云杉森林为例

The Estimation of CN Parameter for Small Mountain Forest Watershed by SCS Method

利用SCS模型可以计算出已知CN值流域的径流量,但由于地形条件、降水特性存在差异,适用于不同流域的CN值较难获取。以乌鲁木齐河流域板房沟林场为试验区,利用2009-2014年的各类径流观测小区降水-径流量观测数据反算出CN值范围,然后以理论产流曲线与实测降水-产流曲线的拟合度对CN值进行优化筛选,最后以留一交叉验证法对CN值进行率定,从而得到各林分条件下径流观测小区的最优CN值。结果表明:(1)天山林区不同林分条件下的径流观测小区CN值都大于74;(2)CN值与林分郁闭度显著相关(P<0.05)。提出了一种获取干旱区山地林区CN值的改进型方法,此方法将有助于SCS模型及CN值在我国的应用。

CN values are the key to estimating runoff depth from rainfall by using soil conservation service（ SCS） method. But it＇s difficult to obtain the values of CN due to the difference in regional conditions,which are the main causes of less frequent use of the model. This paper calculates the CN values of 11 types of forest by using rainfall and runoff data of 2009-2014. The result shows：（1） The CNs of all plots are above 74 for slop areas.（2） There is a significant correlation of CNs with canopy density. This paper proposes a new method for CN obtainment.