A Study On Extraction Of Digital Basin Characteristic And Building Hydro-networks Based On DEM

The digital watershed is proved to be an effective means to optimize the allocation of river basin resources and protect the ecological environment of the river basin at home and abroad,which has also become China's high-tech means to study and solve the problem of river water and water damage.The key to building digital watershed is extraction of basin characteristic and hydrological model.The DEM(Digital Elevation Model)because of containing a wealth of topography,hydrological features and other information becomes a digital basin to extract a reliable data source.The establishment of hydrological model needs to reveal the water movement process in the basin.Therefore,the establishment of the hydro-network of the river basin is not only the answer to the process of water,but also provides services for the research and transfer of River Basin Water and Hydrodynamic Model.In this paper,the data of the study area is established with the SRTM 3 DEM data source in the Qingjian River Basin,and the Arc Hydro tool is used to extract the watershed feature.The main research is shown below:(1)Extraction of digital basin characteristic based on DEM.This paper summarized the principle and method of digital watershed feature extraction.Then,the flow direction analysis,confluence analysis,water system extraction and classification,sub-watershed delineation and delineation of watershed are carried out based on slope runoff theory.At the same time,the watershed characteristics of the Qingjian River were analyzed by parameter of the watershed area,watershed shape and slope and river network density.(2)The method of determining the catchment area threshold is studied.Firstly,the drainage under the different of catchment area threshold is extracted.Secondly,the influence of different threshold values and fractal dimension is found by the method of river network density and water system fractal method,which is to explore the variation rule between the density of river network and the threshold value.The water level is estimated by 1: 250,000 digital water system.The reasonable threshold for water system extraction is deduced in the study area,in order to improve the extraction effect of water system and avoid subjectivity and arbitrariness.(3)Research on the construction of hydrological networks in the basin.this paper uses Arc Hydro to construct the hydro-network of the basin.The hydro-network uses the topological relations of hydrological nodes,hydrological sidelines and hydrological regions to express basin-level convergence relations.Arc Hydro records the topological relations of each element class by attribute association,so as to construct hydro-network,also achieve to determine the river basin direction,flow through the route and flow distance.