The HEC-HMS And TOPMODEL Model Application Of Flood Forecast In Dongzhuang Watershed

Guxian is located on Shanxi province,it has the characteristic of the mountains overlap?geological and hydrological conditions are complex.So,these characteristics were leaded to frequent flood disasters of Shanxi province.In this paper,take semiarid and semi humid Dongzhuang watershed as research object.Based on Arcgis platform?the software of HEC-DSS and TOPMODEL model,and wrote calculation program of TOPMODEL.We can establish the flood forecasting scheme that it suitable for the Dongzhuang watershed.The scheme is order to reduce flood monitoring and prevention work.Not only provide theoretical help for project planning,but also provide support of method for mountain flood warning system.In this paper,the achievements are as follows:(1)Collecting rainfall data of seven precipitation station,discharge data and evaporation data of Dongzhuang hydrologic stations,and soil and land use types data.Based on digital elevation model(DEM)data,and with the help of GIS platform,preprocessing DEM,the extraction of digital watershed information for river network and sub-watershed etc.Calculated the slope?the longest flow path and CN value on terrain data for sub watershed.Using the method of SCS curve number to calculate runoff,the method of Snyder unit line to calculate overland flow and the linear Muskingum method to calculate channel flow,so we can set up the prediction scheme of HEC-HMS hydrological model and the parameters were optimized by the optimization method,the simulation results show that the calibration periods of flood: the pass percent was 85.7%,has reached the first-class precision and the average deterministic coefficient was about 0.72,reached second grade.The validation period of flood result show that: the pass percent was 66.7%,which it reaches the third grade and the average deterministic coefficient was about 0.64,the same as reaches third grade.(2)Based on DEM and GIS platform,preprocessing with the DEM,such as fill sinks,the direction of water flow,flow accumulation,and basin slop,then,the topographic index and the flow length of the basin are obtained.The model is used to calculate the evaporation of vegetation area,the runoff calculation includes two parts: overland flow and subsurface flow,and the isochrones method to calculate confluence.Constructing the TOPMODEL and HEC-HMS model on Dongzhuang watershed and selecting the same flood to simulate rainfall-runoff.The simulation result showed that the calibration periods of flood: the pass percent was 85.7%,has reached the first-class precision and the average deterministic coefficient was about 0.70,reached second grade.The validation period of flood result show that: the pass percent was 66.7%,which it reaches the third grade and the average deterministic coefficient was about 0.60,the same as reaches third grade.Based on the HEC-HMS and TOPMODEL model analysis results show that: the two model of prediction scheme can be applied to the Dongzhuang watershed.As far as the average deterministic coefficient,the HEC-HMS model is better than TOPMODEL model.