Automatic extraction of valley boundary from dems in the hilly Loess Plateau

• Published in: Chinese geographical science 2000, Vol.10 (3), p.238-244
• Main Authors: Qian, Ya-dong, Lu, Guo-nian, Chen, Zhong-ming
• Format: Article
• Language: English
• Subjects: Aerial photography; Algorithms; Drainage patterns; Morphology; Soil erosion; Topography; Valleys; Watershed management
• ISSN: 1002-0063; 1993-064X
• DOI: 10.1007/s11769-000-0007-8

As an important geomorphological divide in the hilly Loess Plateau, valley boundary plays a pivotal role in the construction of distributed models for studying the processes and mechanism of soil erosion, sediment transfer and runoffs within a watershed. In the past, this boundary manually interpreted from large scale maps and aerial photographs. In this paper, the authors first present a simple and practical definition for topographic structures unique to the highly dissected topography in the hilly Loess Plateau in DEMs; then define the valley boundary cells in a DEM with the following features: 1) they are most likely located on a concave slope, 2) these cells have the sharpest transition in slope, 3) those cells on the downward side of the valley boundary should have a slope gradient larger than 20°, 4) as the boundary of the entire valley in a basin valley boundary must be continuous; then devise an algorithm to automatically delineate valley boundary from DEMs and implement it in a computer. This algorithm was applied to detect drainage networks and the valley boundary in the Wangjiagou basin in the hilly loess area of Lishi County, Shanxi Province, China from a 10-m DEM. The extracted results are highly comparable to those manually interpreted from aerial photographs.[PUBLICATION ABSTRACT]