| Mountain torrential flood disaster is means the natural disasters caused by rainfall in hilly areas,which cause the national economy and people's life loss,including floods,mudslides and landslides.Rainfall is an important factor in mountain torrential flood disaster.Therefore,the research of critical rainfall have great significance to the prevention and control of mountain torrential flood disaster.Critical rainfall is an important basis for the preparation of rainfall divisions,is an important indicator in the planning of prevention and control of mountain torrential flood disaster,is also a key indicator to judge mountain torrential flood disaster occurrence and take preventive measures timely.The critical rainfall,means the minimum rainfall of a certain period of time that resulting the mountain torrential flood disaster,that is the initial rainfall.That is to say,in a watershed,the rainfall reaches or exceed a certain magnitude is likely to occur the mountain torrential flood disaster.In this paper,taking Longdong Loess Plateau as an example for the study,based on the collection of the hydro-meteorological,river system,historical flood disasters and other informations,combined with the present situation of prevention and control of mountain torrential flood disaster in the region,selecting 3 methods from the current 14 methods of calculating the critical rainfall(the measured rainfall statistics,disasters and rainfall frequency analysis,and the stage/discharge inversion)to analyse and compare the critical rainfall of mountain torrential flood disaster in the study area,and selecting the applicable calculation method of critical rainfall for the study area.(1)Based on the data collected from the 2~3 flood datas of 5 hydrological stations and the corresponding rainfall data in the small watershed of hilly area of the study area,using the measured rainfall statistics method to calculate the critical rainfall of mountain torrential flood disaster,calculated 1 hour of critical rainfall of 5 small watershed of hilly area hydrological station respectively:20~30mm(Yaofengtou),20~40mm(Huating),20~25mm(Baili),25~40mm(Caijaimiao),25~30 mm(Wangjiachuan);(2)By collecting the data of the historical mountain torrential flood disaster in the study area,using the method of disaster and rainfall frequency analysis to calculate the critical rainfall,calculated 1 hour of critical rainfall of 5 small watershed of hilly area hydrological station respectively:35.6mm(Yaofengtou),19.7mm(Huating),25.5mm(Baili),35.1mm(Caijaimiao),19.9mm(Wangjiachuan);(3)By collecting the investigation data of historical mountain torrential flood disaster of study area,based on the disaster discharge backstepping the flood level and thinking the same frequency of rainfall and flow,using the stage/discharge inversion method to calculate the critical rainfall,calculated 1 hour of critical rainfall of 4 small watershed of hilly area hydrological station(Because the field investigation of Wang Jia Chuan hydrological station region without investigated,the results are not listed)respectively: 23.2mm(Yaofengtou),41.9mm(Huating),19.2mm(Baili),?20.0mm(Caijaimiao);(4)compared and analyzed the critical rainfall calculated results of 3 methods.It is found that the measured rainfall statistics method is comprehensive and complete,having the long date series and high-precision,that method provides a powerful data support for the calculation of critical rainfall.Therefore,it is recommended to adopt the method of the measured rainfall statistics. |
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