随机产汇流理论

Random theory of runoff yield and flow concentration

引入随机理论,将流域上一场具有一定时空分布的降雨视作无穷多雨滴之集合。流域上任一位置雨水的下渗、蒸散发,以及向流域出口断面的汇集,用水动力学处理;呈时空分布的无穷多雨滴的集体表现,即流域产流量的形成和流域出口断面流量的形成,则用概率论处理。从而同时考虑了降雨空间分布不均和下垫面条件空间变异对流域产流的影响,也揭示了流域瞬时单位线的物理本质,阐明了倍比性和叠加性是净雨空间分布均匀条件下流域汇流的本质特性。最后提出了一个确定流域汇流速度空间分布的方法。

Rainfall with time and space distribution is regarded as muster of infinitely great“drop of rainfall” from the view of random theory. Infiltration, evapotranspiration and flow concentration for rainfall of a point located in the watershed can be handled by hydrodynamics. The collective expression of infinitely great“drop of rainfall” with space distribution, i. e. , formations of runoff yield and flow concentration of watershed can be handled by probability theory. The above-mentioned idea not only resolves the runoff yield of watershed affected by space variations of rainfall and underlying surface condition, but also reveals physical nature of watershed instantaneous unit hydrograph（ IUH） , i. e. , proportionality and superposition of watershed flow concentration. Finally, a method for determining space distribution of flow concentration velocity is put forward.