Study of karst basin SCS runoff model based on GIS and RS
ZHENG Chang-tong1,2,LIANG Hong1,SHU Dong-cai3,JIAO Shu-ling1,XIE Xiao-yun1,WANG Mao-qiang1(1.School of Geography and Environment Science,Guizhou Normal University,Guiyang 550001,China;2.Bureau of Land and Resources of Shouguang in Shandong,Shouguang 262700,Shandong,China;3.Guizhou Bureau of Hydrology and Water Resource,Guiyang 550002,China)
Parameter λ is an important index of the SCS runoff model.Model researchers take the standard value λ= 0.2 as the model parameter.However,the model has not considered the impact of landform types on runoff.There are a lot of differences between soil thickness,surface slope,lithology and the degree of development of rock fracture of different landform types in karst basin.All these factors have a direct impact on runoff mechanism of watershed. The landform types have a great influence on the runoff of karst basin.The SCS model is modified by calibrating the values of λ of different landform types.GIS and RS are important means to obtain the spatial information of a watershed.By using GIS and RS,we extract the information data of landform types,soil classification,land use,and obtain the CN values of different landform types.There are no karst basins with a single landform type.So it is difficult for measured data alone to calibrate the value of the various landform types of λ.This paper attempts to calibrate the parameter λ of different landform types by analyzing the relationship between landscape structure and the parameter λ.The parameter λ values of the karst basin are calculated in combination with measured data and landform characteristics,and the karst basin SCS runoff model is established at last.The model is applied to the Pinghu basin,compared with the SCS runoff model.The results demonstrate that the precision of the karst basin SCS runoff model is much higher than that of the SCS runoff model.It has been shown that the karst basin SCS runoff model can be used to simulate the runoff of a typical basin of karst. The result of this study showed that this method can be used to complete the model parameterization,calibration and verification,which is feasible under the conditions of lack of information.It can refer to other factors which affect runoff also.At the same time,hydrological models are supported by GIS and RS technology,which not only enriches the means of access to spatial information,but also improves the efficiency of the model calculation.
【CateGory Index】： P931.5
【CateGory Index】： P931.5