Distributed Hydrological Simulation Based On High Resolution DEM Of Small Catchments

Digital Basin concept and Distributed Hydrological Model theory provide a reliable theoretical basis for the Comprehensive harness of soil and water loss in Loess Plateau of China, Research on the Small Watershed Distributed Hydrologic Model is not only the Precondition of Small watershed Comprehensive Harnessing but also the key to profound comprehending and simulating of large scale Process of Runoff and Sediment Yield. This paper builds a Small watershed distributed Hydrological model based on the basic theory and methods of sediment motion Dynamics, Hydrology and Demography ,in support of Geographic Information System (GIS),by studying progress and mechanism of water and sediment production and transportation in Gully Watershed of the Loess Plateau Hilly Region. High-resolution Digital Elevation Model (DEM, with resolution as 1m) ,which is built by small watershed terrain data acquiring from 3D laser scanner and Global poisoning system (GPS) receiver and other equipment, applied to the distributed hydrological model simulation system to stimulate water and sediment motion of study area, and a Series of inspiring results and progress are made.1. The application of base station-3D laser scanner and GPS receiver to obtain terrain and location information and build High-resolution DEM is realized, and presenting Buffer Superposition Method based on contour regression to evaluate DEM Precision, which achieved good effect.2. This paper builds physical foundation distributed Hydrological model based on Horton infiltration formula and improves runoff yield model.For the characteristics of study area,which is a QiaoGou Basin small catchment, this paper presents a mode of runoff formation of Stored-full Runoff and super-infiltrating runoff dynamic transition based on previous research,and adjusts runoff formation according to Water Content of the vadose to conform to reality more.Small catchments distributed Hydrological model with the basis of the physical is built using Horton infiltration formula, saint Venant movement wave theory and principle of energy balance.3. The distributed hydrological stimulation system is developed based on VB(Microsoft Visual Basic) plus AE(Esri ArcEngine).The system includes data manager module, data pre-process module, model calculate module, result query module, dynamic demonstration module, and other modules,which can stimulate and analyze by using the collected data.4. The model uncertainty analysis adopts study area rain data form 1986 to 2004. Ten rainfall and runoff sediment data are select form the rain data, five of them are used to Parameter Solving, others are to verify. The simulation results show that the average NASH Efficiency respectively is 0.78 and 0.69 by adopting Height-resolution DEM and its ordinary counterpart. It indicated that Physically Distributed Hydrological Model has a certain practicability, its efficiency can be improved further by adopting High-resolution DEM, and it can provide more reliable basis for studying small watershed water and sand motion characteristics.