拉林河流域水系分维研究

Calculation of the fractal dimension in Lalin River based on GIS

针对传统方法在水系分维估算中对集水面积阈值的确定主观性和不确定性较强,同时传统的数盒子等分维估算方法存在计算强度大、工作效率低、数据结果不客观等问题,该文基于SRTM DEM数据,运用ArcGIS软件对拉林河流域自动提取河网水系图;对水系进行不同集水面积阈值下的分维值计算,利用趋势线、相关系数检验等方法对拉林河流域集水面积阈值进行估算;并将提取出的集水面积阈值与实际测绘地形图进行对比,发现利用该方法确定阈值得到的水系与实际水系较为一致。同时,基于GIS的分维研究与传统的数盒子等方法计算水系维数相比,具有客观、经济、高效的优势。最后根据集水面积阈值与水系分维的相互关系,得出该流域水系分维值为1.28,说明拉林河流域尚处于侵蚀发育阶段的幼年期,发育受地质条件影响较大。

Fractal theory is a new branch of modern mathematics,which is important in hydrology applications.The fractal dimension has great significance to reveal the hydrological function.Fractal dimension values can quantitatively describe the geomorphology of the watershed within the study area,it can also provide a reference for the drainage area threshold to determine.River network is a kind of natural fractal.It has become more and more popular in deriving basin characteristics based on GIS.This paper briefly described the application of fractal theory in the study of hydrology and development based on the SRTM DEM data,and set a different catchment area threshold combined with the use of hydrological analysis module ArcGIS9.3.The Lalin River drainage nretwork was extracted depending on the catchment area threshold and through calculating the water system under the threshold of the corresponding catchment area fractal dimension estimation methods based on the fractal dimension of the covering law.The drainage network fractal dimension value was calculated to be 1.28 based on the relationship between fractal dimension and the threshold of the catchment area and the water system.Thus,the Lalin River basin is still in the erosion of the developmental stages of childhood development by the geological conditions of the river basin district and the terrain is more rugged.