The research and application on calculation method of design flood in small basin

The flood in small basin specializes in quick confluence, high peak value, hard to forecast and serious destruction effect, and once the flood disaster happens. It will put a great threat to the safety of the lives and properties of the resident alongside the river. Rational determination of design flood peak is crucial to the determination of scale, safety and benefit of the projects such as regulation of small basin, river renovation, danger eliminating and reinforcement of dangerous reservoirs and so on. Most of the small basins in China either lack gauged flood data or the catchment area of the project is quite different from the catchment area of the hydro-station, while the rainfall (metrological) data within this basin is relatively abundant. So, rational utilizing available gauged flood data to calculate the design flood of the project place whose catchment area is quite different from the hydro-station's and utilizing available rainfall data to figure out the design flood are becoming particularly important. The rational method, (comprehensive) instantaneous unit hydrograph, hydrologic analogy, regional comprehensive method, experience formula and some other often-used methods which are often used in the flood calculation of small basin are systematically introduced in this paper. Taking Tingxi Basin in Fujian Province as an example, the above mentioned methods are applied and verified in the four places of Zaoshui hydro-station (10.5km²), Lower dam basin of Xiamen pumping storage power station (12.1km²), Wufeng hydro-station (50.1km²), and Tingxi Water Reservoir (100.8km²), the rationality of the results are analyzed, and the difference of those methods are compared in this paper. On the basis of these things, the application scope and condition of these methods are concluded, and a set of design flood calculation methods of small basin are relatively systematically summarized.