黄土土壤结皮对产流临界雨强的影响分析

Effects of Soil Crust on Critical Rainfall Intensity of Runoff Production

依据野外资料,从影响产流的各项因子出发,分析黄土高原典型区土壤结皮对产流临界雨强条件的影响,得出:在该区特殊的超渗产流方式下,土壤结皮降低入渗,使得产流时的临界雨强条件降低,因而大大提高了产流的可能性。但是,在实际情况下,雨强变异很大,应考虑不同雨强情况下土壤结皮对产流量的影响。而在室内条件下,各项因子均是可控的,一般情况下,雨强恒定,产流时的临界雨强条件降低,意味着产流提早,必然带来产流量的增加。

Soil crust is formed on many soils of the Loess Plateau during rainfall, and a number of researchers paid attention to its effects on infiltration, runoff production and sediment yield. Based on field data, this paper analyzed the factors influencing runoff production （ such as infiltration and rainfall intensity） and the effects of soil crust on runoff production in critical condition. It is found that in the condition of the special runoff mode, that is, runoff begins when rainfall intensity exceeds soil infiltration rate of the study area, soil crust reduce infiltration, and so reduce the critical rainfall intensity condition of runoff production and improve the probability of runoff beginning. Under the field condition, rainfall intensity is changeful, high probability of runoff beginning does not induce the increasing of runoff volume, for that the runoff volume is affected by other factors, such as rainfall lasting time and rainfall intensity. However during the indoor experiments, the factors are controllable,for example, rainfall intensity and rainfall lasting time is constant, so the reduction of critical rainfall intensity means the predating of runoff beginning and the increasing of runoff volume.