Development And Application Research Of Flood Forcasting Model In Lower Reaches Of WeiHe Basin

Flood forecasting in river basin is the key to flood control and an important non-project measure to control flood and reduce disasters. And hydrologic model is the main method to do hydrologic forecast. Distributed hydrologic model based on DEM can model spatial differentiation of parameters in the model using discrete spatial information. The main advantage of the model is that the irregularity of spatial distribution of climatic factors and underlying factors can be considered in the model. So the real physical process of precipitation-runoff can be modeled.Complex underlying condition, uneven characteristics of runoff producing and concentration, so many branches and water of branches flowing into the mainstream of the Weihe River have disadvantages to flood control in the lower reaches of the river. Because of the serious influence of climatic changes and human activities, water quantity and sand quantity in the lower reaches of the Weihe River has greatly changed since 1990s. Especially, the phenomena of the sharp decrease of runoff and the shrink of river channel bring a great change of the rule of runoff generation and concentration and difficulties to flood control in Weihe River.The development and present situation of hydrologic models are reviewed first in the paper. The sensibility and pertinence of parameters in Xinanjing model are analyzed and studied. Then main formulas in TOPMODEL are deducted in the paper. Finally, the applicability is compared between the two models. Parameters in Qinduzhen catchment in the lower reaches of the Weihe River are used to model the flood process of the local area of the Weihe River. The study results indicate that the simulation results in Zhangjiashan and the area between Xianyang and Lintong are more reasonable. Layered Continuous Muskingum method is used to rout the flood in mainstream, and the runoff process at Huaxian station is composed of the results of Muskingum and the runoff simulated in interzone. The results show that the flood of downstream in the Weihe River is affected complicatedly by many factors. The rainfall-runoffsimulation in inerzone will be carried on if the discharge in this area exceed some rate. The study results indicate that the simulation results in Zhangjiashan and the area between Xianyang and Lintong are more reasonable. While the results of flood simulation in Huaxian station are more accurate only when the local inflow is more than 5% of the discharge at Huaxian station.