| Our country occurs flash flood frequently. Flash flood poses a great threat topeople’s life and property safety, has become the prominent question of disasterprevention and mitigation. According to the statistics, each year the loss of the state andthe people’s life and property caused by flash flood disasters accounts for about40%ofthe total losses by natural disasters in China.Flash flood disaster is characteristic of the fast velocity, strength flushing, rise upand down sharply, last short and strength destructive. The formation and developmentof flash flood by hydrology, geology, topography, human, and many other factors, it isstill hard to management, so research on flash flood disaster predict work, study thespatial distribution of the flash flood disaster, let the residents in the disaster dangerzone get the warning information in time, ahead of time to take measures to lower theloss of property and personnel, this work is especially important.The main prediction methods of the spatial distribution of flash flood are directindex forecast method and the indirect index forecast method. At present, theinformation of flash flood is not very complete in many areas, use direct index forecastmethod is restricted, but adopting indirect index method has its greater advantage.Indirect index method, not required to have the complete materials which reflect theflash flood itself characteristic, the indirect index forecast method required topographyand geology, rainfall and temperature, etc materials are belong to base materials, theyare easy to obtain, according to actual condition, selecting proper prediction indexesand build a reasonable forecasting model, and can get the prediction result which isfully reflect the objective reality. The geographic information system (GIS) with a strong advantage in the spatial data analysis and management, therefore the GISbecomes more easily in processing the space data of disasters such as flash flood.This research area is JinChuan in Aba prefecture in China, the area flash flooddisaster is frequently, the loss caused by flash flood disaster is very great. This studywith terrain data as spatial analysis and other material statistics data as special data usedindirect index method and GIS technique to achieve the effective forecast of flash flooddisaster distribution in JinChuan, so as to achieve the effective prevention of flash flooddisaster effect, reduce the staff’s property loss, providing a scientific reference forprevention decision-making work of flash flood in JinChuan.Because the influence factors of the flash flood are complicated and closeassociation each other, how to create effective prediction model, how to select theappropriate forecast indexes, how to divide levels for the selected indexes and how tocalculate the weight, thy are the core and difficult points of this research, this researchcontent mainly includes:（1）Select the forecast indexes of flash flood space distribution. Because of theformation and development of flash flood by hydrological, geological and geomorphic,human, and many other factors. In view of the complexity between the geologicalfactors and efficiency and accurate of research and collected in material, this study saveconsider land use types, lithology, etc. But select the indexes which are most closelywith and the most directly related to flash flood, including weather (average annualprecipitation, etc.), slope, aspect, confluence cumulant, river network density and othernatural factors and population density, cultivated land area and other social economicfactors as the prediction indexes.（2）Build the prediction model. Building the model of this research firstaccording to the characteristics of flash flood and other reference materials usinganalytical hierarchy process to get every index’s weight value of the influence of flashflood, and then use ArcGIS software to extract the forecast indexes in the study area foranalysis, and to divide level of each index, with small watershed as prediction unit,using synthetic index method to calculate each index’s level and comprehensiveweights of each small watershed.（3）Identify the risk level of flash flood. On the basis of comprehensive analysis,classified the flash flood disaster of JinChuan into four grades, safe, dangerous, moredangerous, extremely dangerous.（4）Make the space distribution forecasting map of flash flood.According to theabove analysis, use ArcGIS software to make the space distribution forecasting map of flash flood disaster of JinChuan. Comparing the result with the flash flood disasterhappened in the history of Jinchuan, and drawing the comprehensive conclusion. |
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