GIS在分布式水文模型中的应用——以北京雁栖河流域为例

Application of GIS in Distributed Hydrol Ogical Model——A Case Study of Yanqi Catchment in Beijing

在GIS支持下,由北京雁栖河流域数字高程模型DEM自动生成子流域单元,每个子流域单元的降雨径流过程利用一个水箱模型来模拟,该水箱模型用一个两参数的非线性分布函数来模拟上土壤层的蓄水容量空间分布特征,计算每个子流域单元TOPMODEL模型地形指数ln(a/tanβ)的空间累积分布曲线,并对其作无量纲化处理,通过地形指数ln(a/tanβ)的空间累积分布曲线的无量纲化曲线的最佳曲线拟合确定每个子流域单元土壤蓄水容量空间变异性参数,这使得模型中的土壤蓄水容量空间变异性参数成为一个有确定物理意义的参数,也使得所建立的模型更加具有物理基础。结果表明:无论从模型的率定期还是从模型的验证期来看,模型计算的径流与实测的日径流过程线都呈现出很好的一致性和吻合性,这说明本文建立的模型对雁栖河流域的日径流量的分布式模拟是有效的。

Subcatchments are automatically extracted and defined from DEM with the aid of GIS. The rainfall -runoff process every subcatchment is represented by a Bucket model for the upper soil layer with two -parametric non-linear distribution function. Spatial cumulative distribution probability of topographical index ln（a/tanB） in the TOPMODEL is calculated automatically by computer. The parameter describing the spatial variability of soil moisture storage capacity distribution within each subcatchment in the model is estimated from dimensionless processing with respect to cumulative distribution curve of In （a/tanB） by curve fitting of least square approximation. That makes the spatial variability parameter for soil moisture storage capacity in the model be more physically-based. Both the calibration and validation hydrographs in the case modeling study show good similarity between observed and simulated runoff. Proposed model gives satisfactory results for the catchment.