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基于数字高程模型(Digital Elevation Models)进行河网提取是数字地形分析的重要研究内容和水文分析的关键步骤,而流向算法是其中最重要的部分。然而,传统的流向算法在平坦地形区域容易形成平行河网。为解决平行河网问题,该文提出了一种结合Priority-Flood算法漫水思想和改进D8算法的流向算法。借助Priority-Flood算法的漫水思想,可以保证流向符合宏观地形特征;同时将地形划分为上坡、平地和下坡3种类型,辅以PriorityFlood算法可以实现在不填洼的基础上计算流向,而且针对不同地形,采用相应的改进D8流向算法,从而保证流向符合微观地形特征。通过这两种算法的结合,可以直接使用原始DEM提取河网,消除了填洼过程,提高了流向计算效率,同时消除了填洼造成的大量平地,有效地解决了平地区域平行河网问题。最后,选取全球不同区域SRTM数据对J&D算法与新算法进行对比实验,结果表明,新算法能够有效地改善平行河网问题。
River network extraction based on Digital Elevation Models is an important research content of digital terrain analysis and a key step of hydrological analysis. And the flow direction algorithm is the most important part. However, the traditional flow-direction algorithm is easy to form a parallel river network in the flat topography. In order to solve the problem of parallel river networks, this paper presents a flow algorithm which combines Priority-Flood algorithm and D8 algorithm. Priority-Flood algorithm with the idea of diffuse water can ensure the flow to meet the macro-topographical features; at the same time the terrain is divided into three types: uphill, flat and downhill, combined with PriorityFlood algorithm can be calculated on the basis of not filling the flow direction, And for different terrain, the corresponding improved D8 flow algorithm, so as to ensure that the flow in line with the microscopic topographic features. Through the combination of these two algorithms, the original DEM can be directly used to extract the river network, eliminating the process of filling depression and improving the calculation efficiency of the flow direction, and eliminating a large amount of flat land caused by filling depression and effectively solving the problem of parallel river networks in the area of flat land. Finally, the comparison between J & D algorithm and the new algorithm by SRTM data from different regions around the world shows that the new algorithm can effectively improve the parallel river network problem.