小流域产流汇流模型试验的应用研究

Study on Application of Runoff Yield and Runoff Concentration Model Test in Small Watershed

在降雨１：１相似的小流域产汇流模型试验中，不仅产流发生畸变，而且汇流畸变作用更大。本文旨在通过对降雨径流形成及土壤入渗动态方程的推导，分析，实际产流方式与模型产流方式的异同，引入模型产流畸变系数，导出模型试验结果的应用转换函数。在此基础上，又从线性汇流理论出发，依据推理公式，求得实际与模型试验最大洪峰流量及汇流时间之间的畸变关系。该研究使模型试验结果与原型趋于吻合，为小流域治理和水土保持工程设计提供了依据。

In small watershed's runoff yield and runoff concentration model test that the rainfall and the soil are under a similitude condition of one to one respectively,the runoff process is unavoidably distorted by model effect. In order to reveal the distortion phenomena,applying rationally the results of model test to prototype,in this paper,firstly,the difference of runoff occurrence pattern between prototype and model is analysed on the basis of soil infiltration equation,then the distortion coefficient of runoff depth is introduced,deriving a transformation function which transforms the runoff depth of the model to that of the prototype,finally,distortion relationships of peak discharge and of concentration time between model and prototype are deduced according to linear runoff concentration theory and rational runoff formula.The study results show that not only runoff yield but also runoff concentration are distorted greatly by model effect,and further,the distortion in the latter is still greater than that in the former,and show that the runoff depth and the factors of the runoff concentration in small watershed model are not converted depending on only the geometric similar proportion but are also on the distortion transformation function to prototype. Taking the data of Liudao Gully small watershed,Shenmu County,Shaanxi Province as an example,if geometric similitude proportion is changed from 100:1 to 400:1,whereas the distortion coefficient of runoff depth is changed from 1.0125 to 1.198;the distortion coefficient of peak discharge is changed from 454.321 to 2350.584;and the distortion coefficient of concentration time is changed from 21.41 to 57.694. This study may take model results coincide well with prototype and will give a help to the regulation of small watershed and the design of soil and water conservation engineering.