Study On The Distributed Rainfall-runoff Modelling Of Luanhe Watershed

Lumped hydrologic model is compared with distributed hydrologic model in thisthesis. Differences are presented between these two kinds of models in modellingmethods and in runoff generation mechanism. The watershed is usually considered asa whole in lumped hydrologic model, while in distributed hydrologic model thewatershed is divided into many grids or subcatchments. The priority of distributedhydrologic model is emphersized. The following outcomes and conclusions areobtained.(1) Based on grid DEM data of Luanhe river basin, the stream networks are extractedby GIS which can be used in hydrologic model directly. Thus , the modellingeffeciecy is developed obviously and RS data can be offered in the modelling.Through the procedure of pre-treatment of DEM, deciding the flow direction andcalculating the contributing area, the stream networks is extracted, which is in goodagreement to the reality.(2) After optimizing some variables of the model, evaporation and infiltration in thewatershed can be calculated. Topmodel is applied to Luanhe watershed, and theresults can be controled in a certain error. So we can say the model structure isreasonable and the principle is consistent with the reality. The main factor whichinfluences the modelling precision is rainfall, because of the distributed rainfallartificially, especially in such a large watershed. The purpose of building distributedhydrologic model is to search the mechanism and the process of water cycle byconsidering the spacial asymmetry. With the development of computer science, geographical information system andremote sensing, distributed hydrologic model, especially the one based on DEM, mustbe developed quickly. We believe that distributed hydrologic models based on DEMwill be the main direction in the future.