Study On Flood Forecasting Scheme And Graduation Of Design Flood Hydrograph Of Biliuhe Reservoir

The flood disaster is one of the top ten natural disasters that threaten to human survival. It threatens people’s lives and property, while bringing significant losses to agriculture, industry, etc. As an important non-structural measures for flood control, flood forecasting can help the human defense flood; reduce flood losses, better control and use of water resources. Existing flood forecasting scheme in Biliuhe watershed not only have low-precision analog, but also no longer meet the current situation of the basin. Since the scheme formulated, the basin has accumulated12years of hydrological data. Extension of the hydrological data series also provided the conditions, while put forward the new demands to the scheme re-formulating. During this period, the construction of water conservancy projects in the basin, the impact of human activities, as well as hydrological surface conditions change, also asked to make adjustments to flood forecasting scheme. Considering the above factors, it is necessary to formulate a new flood forecasting scheme by using1984-2012flood data, to improve the forecast accuracy and reasonableness of the program. In this paper, the main contents and conclusions are as follows:(1) Analyzing the status and hydrological characteristics of the Biliuhe basin, the paper improved flood forecasting scheme of the existing scheme. The Dahuofang flood forecasting model (DHF model) and the experience unit hydrograph model both were introduced. Considering that the watershed evapotranspiration and soil storage capacity parameters of the DHF model were oversimplified, the paper simplified them again and gave the fuzzy description to them. Last, the paper introduced an improved particle swarm optimization to optimize model parameters.(2) According to the existing hydrological data, the paper formulated the watershed runoff and convergence forecasting scheme. When formulating convergence scheme, the paper calculated the watershed convergence by using the DHF mode and the experience unit hydrograph model, and compared the two schemes. The results showed that the simulated flood fitted the actual flood better when applied the flood forecasting scheme combining DHF runoff model and watershed experience unit hydrograph model. The level of simulated runoff and convergence results were Class A and the new scheme more fitted the status of the basin. (3) According to the watershed status quo, during formulating the scheme, the impact that the Yushi reservoir brought to the flood process of Biliuhe should be considered. This paper analyzed the impact of Yushi reservoir on the total runoff and convergence process, on this basis, and formulated the flood forecasting scheme considering the Yushi reservoir. The paper simulated the series of floods after the construction of the Yushi reservoir by the new scheme. The level of simulated results was Class A.(4) Appling the natural law characteristics that the reservoir convergence model can reflect the rainfalls lead to floods, the paper put forward a method for smoothing the unsmooth or discontinuous design flood hydrograph by amplifying the typical flood at the same frequency, and determined Biliuhe design flood hydrograph by using the methods. The example of application showed that the method was reasonable and practicable, and made the design flood hydrograph without smoothing.