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Calculation of Design Flood for Small Watershed of Miaoyuanxi Stream

The flood in the mountainous area is characterized by remarkable outburst, low foreseeability, sudden rise and sudden fall and large destruction and is one of the natural disasters in rural area. In order to reduce the loss from mountain flood, this Thesis, taking the section of Siwu Village on the upstream of Miaoyuanxi Stream as the study object, conducts the calculation of the design flood for the small watershed of Miaoyuanxi Stream. The small watershed is short of the data of actually measured rainfall, especially runoff; therefore, based on the geographic information system (GIS), with irregular triangle net and spatial analysis function, we have realized the interpolation of the hydrologic characteristic value isoline of the research area; with frequency analysis, we have calculated the design rainfall of different time at different frequency and further calculated the design peak with the rational formula; in addition, with the hydraulic method, we have calculated the corresponding water depth of the three control sections of Siwu Village. The result shows that, the combination of small watershed design flood calculation and the GIS can make the hydrologic calculation more accurate and convenient. The research result may be the reference for the establishment of the flood prevention and avoidance guarantee system for the rural area.