The Extraction Of Drainage System Based On DEM And The Decomposition Of Multilevel Drainage Networks

The extraction of drainage system from DEM or image is one of the foundations of automatic and intelligentive recognition drainage network. This paper detailedly studied the technique of the extraction of drainage system based on the grid DEM, and discussed the theory and method of automatic extracting drainage system from the grid DEM, selected the arithmetic which is fit to extract river in a small-scale area by comparing all kinds of the arithmetics, so and extracted drainage form DEM. Expermentation proved that this arithmetic is more accurate and more detailed, and is fit to extract drainage network in the small-scale area.This paper defined the least unit to describe drainage system from the point of river structure, and design drainage system unit coding project based on the freeman chain coding. The paper selected strahler river classification project to grade drainage system. This paper studied the theory of Multilevel drainage system decomposition based on the theory of drainage system classification and drainage system unit coding, and made out a suit of multilevel drainage system Decomposition project, and achieved the function of multilevel drainage system decomposition from many examples.A module was developed based on D8 processing method and ground water overflow model, which included identifying and processing sunk areas in DEM, automatically generating drainage network. This paper made out a suit of multilevel drainage system decomposition project based on the drainage network, which achieved drainage network decomposition by the progression of the least drainage system cell, and exported drainage system unit codings of each drainage system cells by the coding form, preparing for the following which distilling character and automatous identifing. Taking the puwaigou region near by puxiong station along the chen-kun railway as the research area, this paper automatically extracted drainage network anddecomposited multilevel drainage network. The test result of extracting drainage network showed that the experiment on the depression and plat area was effective, the derived features were similar to the actual case on the whole, the multilevel river decomposition project based on the coding is feasible, and achieved drainage network decomposition by the progression of the least drainage system cell.