结合新安江模型和TOPMODEL模型对流域土壤水分空间分布模式的描述

改进型新安江模型利用双抛物线型曲线来描述流域土壤蓄水容量的空间分布及进行产流计算,双抛物线型曲线有一种内在结构,能够利用同一组参数对流域空间上同时存在的多种土壤水分模式进行描述,然而,这一曲线为统计积分表达式,需要利用流域降雨径流观测资料通过最优率定来确定.传统的TOPMODEL模型利用湿润指数或土壤一地形指数,对流域内每一点的土壤水分进行预测.然而,TOPMODEL模犁假定整个流域处于稳定状态,且地下水位与地面平行.这种简化处理使得TOPMODEL模型并不适用于流域每一点,本文结合新安江模型双抛物线型曲线和TOPMODEL型湿度指数,充分利用流域降雨径流观测资料和分布式地形数据.对不同的土壤水分模式在广东省珠江三角洲双桥流域空间上的分布进行了确定,研究得出了该流域划分TOPMODEL模犁适用范围的湿度指数临界值.

MATCHING XINANJIANG MODEL AND TOPMODEL FOR DESCRIBING SPATIAL SOIL MOISTURE PATTERNS OVER THE CATCHMENT

The modified Xinanjiang model uses a double parabolic curve to represent spatial distribution of soil moisture storage capacity over a catchment for runoff generation. The double parabolic curve has a built-in structure,which is able to simultaneously describe multiple soil moisture patterns co-existing over the catchment. However, it is ina statistically integral form and is usually obtained by optimal calibration using observed rainfall runoff data. The wetness index or the soil--topographic index, proposed in the classical TOPMODEL, predicts the individual point soil moisture.The simplified assumptions of steady state for the whole catchment and the water table parallel to the surface, however,prevent the TOPMODEL applicable to every point in the catchment By matching the double parabolic curve and the wetness index, both rainfall runoff data and the distributed topographic data are fully used. The spatial distribution of different behaviour zones of soil moisture is identified over a specific catchment. The threshold of wetness index for the definition of applicable region of TOPMODEL is identified in the catchment.