In hydrological applications of Digital Elevation Models (DEMs), the errors in heights give rises to different drawbacks. These drawbacks comprise the generation of drainage anomalies, as well as errors associated with the modelling of (i) drainage patterns and (ii) boundaries of catchment basins and sub-basins. Otherwise, it is known that errors present in DEMs are preferentially located in areas of low ground and valley bottoms. The DEM correction techniques proposed here involve the use of drainage pattern constraints based on one layer of a digitized geographical information system. This data layer is firstly made available by means of a vector mode, and is then imported into the DEM as a raster mode. The aim of this correction is to obtain DEMs having grid cell elevations fully consistent with the drainage pattern that they are projected onto.
The results of applying this correction lead to, firstly, a reduction in the number and amplitude of drainage anomalies and, secondly, a perfect fit between the drainage pattern derived from the DEM and the drainage pattern used for defining the constraints. Finally, a certain number of improvements are obtained which make it possible to perform local corrections and supplement the digital database of the drainage pattern.
Key words : digital elevation model, drainage pattern, drainage anomalies, spatial modelling, catchment basin boundaries.
Short title : DEMs constrainted
by drainage pattern data
