室内小流域降雨产流过程试验

该研究采用新型的小水流流量自动观测系统,在室内小流域模型上进行了不变雨强和变雨强模拟降雨试验,实时观测了模型流域各沟道的产流过程。试验进行了不同降雨强度(25、50、75、120mm/h)和不同降雨历时(5、10、15min)组合的12次降雨试验,同时进行了30-70mm/h和70-30-70mm/h的变雨强降雨试验。在不变雨强的条件下,仪器与人工测量所得稳定流量的最大平均相对误差仅为2.02%。测量得到的流量过程线呈现出起流、稳定和退水3个明显的阶段。其中,起流和退水过程涨落的剧烈程度、稳定阶段的流量大小随雨强增大而增大,稳定阶段的持续时间与降雨历时成正比。空间上,主沟出口的产流过程明显滞后于支沟出口的产流过程,且其两者之间具有一致的流量过程。在变雨强的情况下,流量过程线没有稳定的阶段,流量随雨强变化而变化。该研究对于深入理解流域产流过程具有重要意义,可为相关的模型研究提供可靠的试验支持。

Laboratory experiments of runoff processes in small watershed under simulated rainfall

A new automatic measurement system of flow was applied.Simulated rainfall experiments were conducted under constant and variable rainfall intensity in small watershed in the laboratory.Runoff processes of the watershed branches were monitored realtimely.Under the constant rainfall intensity,12 rainfall experiments were conducted involving a complete combination of four kinds of rainfall intensity(25,50,75,120 mm/h)and three kinds of rainfall duration(5,10,15 min).The experiments of variable rainfall intensity were conducted at 30-70 mm/h and 70-30-70 mm/h rainfall events.Under the constant rainfall intensity,the maximum averaged relative error of the measured values of stable flow between the automatic system measurement and the manual measurement is only 2.02%.The runoff diagrams had three obvious stages of initial runoff,stable flow and recession flow.The severe degrees of fluctuation in the processes of initial runoff and recession flow and the flow of stable flow were increased with the increasing of rainfall intensity while the duration of the stable crest segment was directly proportion to rainfall duration.The runoff processes at the watershed outlets delayed to those at the branches,but the processes no matter at the outlets or branches of the watershed were identical in shape.Under the variable rainfall intensity,the runoff processes had no stable segment and the flow changed with the rainfall intensity.The results are significantly meaningful for understanding the runoff process.The results also can provide reliable experimental support for related model research.