Prediction Of Flash Flood Based On Arcgis Technology

Flash flood triggered by rainstorm is a natural disaster in mountainous areas of poor geology structure. It is extremely harmful to traffic and economic construction. Because the causes and the influencing factors of flash flood are complicated, it is hardly managed completely currently and the occurrence of flash flood can't be restrained. Flash flood early warnings system is put forward which consists time on the basis of physical fundamentals, climate and human activities and its comprehensive action according to the induced factors. Thus we can adopt defend measure to ease the loss of the disaster. For this purpose, Geographic Information System is used to predict flash flood in small catchments in Urumqi.In the first part, it is briefly summarized the theory and background about prediction o f flash flood. Then the b asic theory of such research is analyzed using Geographic Information System.In the second part, regional status is the base of prediction of flash flood. So the geology, hydrology, climate, economy and the origin of flash flood is introduced in Urumqi.In the third part, after analyzing the cause of flash flood, the task is divided into time prediction and spacial prediction. Then methods are introduced for these two predictions separately.In the forth part, critical rainfall is used to predict flash flood. Critical rainfall is set up according to statistic analysis about the rainfall process before the flash flood happened in a region. In gaged base, critical rainfall is confirmed by analyzing rainfall records. In ungaged basin, it is supposed that the frequency of disaster and rainfall is the same, critical rainfall is assured by surveying the frequency of disaster. Because rainfall stations in Urumqi have not enough data to draw isoline, Inverse Distance to a Power Method is adopted to map critical rainfall of Urumqi and make certain the critical rainfall of all small drainage basins.In the last part, the research area is classified to gaged basin and ungaged basin prediction for the spacial prediction. In gaged basin, the rational formula method is adopted to calculate rain parameters and empirical parameter of runoff-producing and flow concentration combining s tochastic simulation and evolutionary program. The trend line formula of empirical parameter is gotten by the relationship between empirical parameters and basin characteristics parameter. Then the chart of the spacial interpolation of hard rain parameter in Urumqi is ensured by spatial analyst andgeostatistical analyst of Geographic Information System. According to the trend line formula of empirical and the chart of the spacial interpolation of hard rain parameter, maximum discharge of ungaged basins are confirm. Supposed that the flood contain the same water depth, the water surface curve is simplified as one bevel. Then the risk fig of Urumqi is confirmed according to water level of export section.