3-dimensional drainage network analysis. A key for geomorphologic studies

摘要

In general the drainage network length measurement is done in a 2-dimensional space taking into account the features extracted from topographic maps. By using Digital Elevation Models (DEM), one can obtain more accurate results by replacing the drainage network segments with their 3-dimensional length. The value of each segment is equal to L-s = root D-s(2) + D-a(2) where D-s is the horizontal length of the segment and D-a is the absolute value of the difference between the altitude values of the extremities of this segment. On the other hand, the method developed allows us to quantify the difference between the length calculated either in a 2-dimensional or 3-dimensional space. The amplitude of this difference depends on the DEM resolution and on the topography. Several geomorphometric parameters use the drainage network to provide geomorphologic information about the studied region.