Rainfall Threshold for Flash Flood Early Warning Based on Rational Equation: A Case Study of Zuojiao Watershed in Yunnan Province

1st International Global on Renewable Energy and Development

Li, Q.^1,2 ; Wang, Y.L.^1,2 ; Li, H.C.^1,2 ; Zhang, M.^1,2 ; Li, C.Z.^1,2 ; Chen, X.^1,2

China Institute of Water Resources and Hydropower Research, Beijing

10038, China^1

Research Centre on Flood and Drought Disaster Reduction of the Ministry of Water Resources, Beijing

100038, China^2

关键词: Critical rainfall;    Depression storages;    Flash-flood-warning;    Manning equation;    Rainfall thresholds;    Rational equations;    Soil infiltration;    Technical support;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/100/1/012215/pdf
DOI  :  10.1088/1755-1315/100/1/012215

来源: IOP

【 摘 要 】

Rainfall threshold plays an important role in flash flood warning. A simple and easy method, using Rational Equation to calculate rainfall threshold, was proposed in this study. The critical rainfall equation was deduced from the Rational Equation. On the basis of the Manning equation and the results of Chinese Flash Flood Survey and Evaluation (CFFSE) Project, the critical flow was obtained, and the net rainfall was calculated. Three aspects of the rainfall losses, i.e. depression storage, vegetation interception, and soil infiltration were considered. The critical rainfall was the sum of the net rainfall and the rainfall losses. Rainfall threshold was estimated after considering the watershed soil moisture using the critical rainfall. In order to demonstrate this method, Zuojiao watershed in Yunnan Province was chosen as study area. The results showed the rainfall thresholds calculated by the Rational Equation method were approximated to the rainfall thresholds obtained from CFFSE, and were in accordance with the observed rainfall during flash flood events. Thus the calculated results are reasonable and the method is effective. This study provided a quick and convenient way to calculated rainfall threshold of flash flood warning for the grass root staffs and offered technical support for estimating rainfall threshold.