The Study On Topography And River System Correlation In Jianghan Plain

The shaping of topography is closely related to the function of the hydrologic process,and is also one of the important subjects in the field of geography.Finding the relationship between hydrogeology processes and establishing the quantitative relationship between each of them are always the hot topics for geographers,in order to analyze the hydrological characteristics from the topographic parameters.The fractal theory,which origins from hydrogeology,provides a new method to explain the topography and hydrological correlation in quantitative ways.The landform types of China are complex and diverse,there are many rivers and lakes in the middle and eastern part of the region.Jianghan Plain is a typical area with the mutual influence of the hydrogeology process processes.Finding the coupling relationship between topography and hydrology of Jianghan Plain,not only reduce the dependency on hydrological data,but also create value to the quantitative scientific analysis in the future.In this paper,Jianghan Plain is used as the study area,and five topographic factors(elevation,slope,aspect,relief amplitude and surface roughness)are selected as the main representative indexes in GIS environment.By using the fractal theory,compare the differences of the fractal dimension of different river channel grades and deduce its influence on hydrogeology features through extracting and classifying river networkThe main results are as follows:(1)The fractal dimension of river system in Jianghan Plain is between 0.85 and 1.20,shows the young stage of river system.While with the increase of river system levels,the fractal dimension is decreases.The fractal dimension of the lowest grade river channels is 1.20,and the highest one is 0.89.Box-counting method is a practicable way to calculate the fractal dimension of the raster data,which meet the real situation.Influenced by the overall low terrain of Jianghan Plain,the river mainly under down-cutting and lateral erosion.(2)The results show that the coupling relationship between the fractal dimension of river system and each topographical factors is tight and obviously self-correlation.The fractal dimension of the first grade river channel is very close to the slope of the log-log coordinatealtitude related to relief amplitude and altitude.Under the idealized result,we figure out the slope of the relief amplitude and altitude is 1.2077,and the fractal dimension of the first grade river is 1.2081,which can deduce the definite relationships.