北京地区径流曲线数模型中的径流曲线数

The runoff curve number of SCS-CN method in Beijing

径流曲线数模型(SCS-CN模型)是国内外最受欢迎的地表径流评价方法,该模型只需综合参数——径流曲线数(CN),该参数反映降雨前流域的地表和土壤特征。本文的目的是确定北京地区径流曲线数模型中的径流曲线数。研究采用了北京密云、延庆、门头沟64个坡面径流小区的降雨径流资料,用算术平均值法计算出小区径流曲线数值,用定水头法测定了北京主要土壤类型和土地利用类型的饱和导水率,用经验公式确定出64个坡面径流小区的饱和导水率值,并根据饱和导水率确定了北京地区和坡面径流小区的水文土壤组类型,得到了北京不同水文土壤组、土地利用下的径流曲线数数据库。结果表明:北京地区主要水文土壤组为B类;土地利用、水土保持措施、植被盖度和前期土壤湿度等对径流曲线数有显著影响;根据北京径流小区径流资料得到的径流曲线数值比美国土壤保持局查算表提供的数值要大。本研究结果可为该区域的地表水资源量评价以及土地利用管理提供服务。

Soil Conservation Service curve number （SCS-CN） is widely used to calculate runoff because it only needs one parameter - runoff curve number （CN） which reflects the soil and landuse characteristics. The purpose of this study is to identify the curve number in the SCS-CN method in Beijing. The rainfall and runoff data of 64 runoff plots in three counties of Miyun, Yanqing and Mentougou, were used to calculate runoff curve number. The constant water head method was used to measure the saturated hydraulic conductivity of main soil types and landuse types in Beijing. The empirical equation was used to calculate the saturated hydraulic conductivity of the 64 runoff plots. The saturated hydraulic conductivity was used to determine the hydrologic soil groups of runoff plots in Beijing. The runoff curve numbers under different hydrologic soil groups and landuse types in Beijing were provided. The results show that the hydrologic soil groups could be identified into and B. The B hydrologic soil group covers most parts of Beijing. The curve number was greatly affected by land use, soil conservation measures, land use cover and antecedent moisture condition. When the other conditions remained unchanged, the curve number obtained from Beijing＇s runoff plots was greater than that provided by Soil Conservation Service. These results can be served as runoff prediction and landuse management.