考虑空间变异性的统计产流模型研究

A statistically-based runoff-yield model considering spatial variation

针对控制产流过程的降雨等主要因素在空间分布不均匀的特征,提出了考虑空间变异性的统计产流模型.引入一个新的概率密度函数描述每个时段降雨的空间变化,采用土壤下渗容量曲线描述流域土壤下渗能力的空间变化,利用土壤水蓄水容量曲线表征土壤蓄水容量空间分布不均匀性.采用超渗产流模式根据降雨与下渗能力的联合概率分布计算地表径流的空间统计分布,通过推导得到计算地表产流量的准解析表达式;采用蓄满产流模式根据下渗与土壤蓄水容量曲线计算地下径流.选用黄河支流伊河东湾流域的资料对模型进行了验证,并将其结果与新安江模型产流结果进行对比,表明模型在该半湿润地区具有一定的适用性.

This paper describes a statistically-based runoff-yield model considering the spatial variation of rainfall, soil infiltration capacity and soil water storage capacity that are three main factors controlling the runoff-yield process. It assumes that the spatial variation of rainfall at every time step can be described by introducing a new probability density function （pdf）. Meanwhile, the soil infiltration capacity over a basin is simulated by a parabolic type pdf, and a water storage capacity curve is also used to reflect the spatial variability of soil water storage. Following the infiltration excess mechanism, the probability distribution of the surface runoff is derived based on the joint probability distribution of rainfall and soil infiltration capacity, thus obtaining the quasi-analytical solution of surface runoff. According to the saturation excess mechanism, the underground runoff （flows below ground are collectively referred to as underground runoff in this paper） can be calculated by means of infiltration and the spatial distribution of soil water storage capacity. Therefore, the total runoff is composed of infiltration excess and saturation excess runoff. The model was then applied to Dongwan basin, a sub-basin at the middle reach of Yellow River, and the results were compared with those obtained by the Xinanjiang model. It is shown that the model presented in this study is applicable to such a basin with humid or semi-humid hydrological characteristics.