两种不同DEM处理方法提取的水系比较

Comparisons of water systems extracted from DEM with two different processing methods

水系不但是重要的自然地理要素,而且对防洪减灾、资源开发等有着重要意义。基于DEM的坡面径流法是最为常用的水系提取方法,其提取精度直接取决于DEM中洼地的处理方法。为了比较不同DEM处理方法对水系提取精度的影响,本文以江西省潦河流域为例,利用基于DEM数据的J&D算法及基于辅助数据的AGREE方法来处理实验区DEM,然后利用坡面径流法提取水系。结果表明,经两种方法后均可以提取出连续的水系,且提取水系的等级、数量及长度相差不大;在提取精度上,在受人类活动影响较小的山地丘陵地区两种方法提取的水系比较吻合,而在平坦地区或受人类活动影响较大的地区提取的水系差异较大,且AGREE方法处理后提取的水系精度较高。

Water systems are not only important natural details, but also critical data sources for flood preven- tion, disaster reduction and exploitation of natural resources. Water systems are usually extracted from DEM （digital elevation data） with slope-runoff method, the accuracy of which is determined by the pro- cessing method of depressions in DEM. In order to study the effect of different DEM processing methods on the accuracy of extracted water system, we compared water systems extracted from DEM with two pro- cessing methods. In this study, DEM data based on J^d） algorithm and auxiliary data based on AGREE method were tested against 30 meter DEM for Liaohe River valley, Jiangxi Province. The results show that both of the methods are capable of extracting continuous drainage lines of similar orders, quantities and lengths. It revealed that the extracted water systems of two methods agree well in the steep mountain- ous region, but show large differences as for the well-populated flat area. Comparisons also demonstrated that the AGREE method enjoys high extraction accuracy than J＆D methods as for the flat area.