Several methods for filling closed depressions in digital elevation models that would affect hydrological modeling.
rsaga.fill.sinks(in.dem, out.dem, method = "planchon.darboux.2001", out.flowdir, out.wshed, minslope, ...)
Input: digital elevation model (DEM) as SAGA grid file (default extension:
Output: filled, depression-free DEM (SAGA grid file). Existing files will be overwritten!
The depression filling algorithm to be used (character). One of
"wang.liu.2001"): Optional output grid file for computed flow directions (see Notes).
"wang.liu.2001"): Optional output grid file for watershed basins.
Minimum slope angle (in degree) preserved between adjacent grid cells (default value of
method="planchon.darboux.2001", otherwise no default).
Optional arguments to be passed to
rsaga.geoprocessor(), including the
envRSAGA geoprocessing environment.
This function bundles three SAGA modules for filling sinks using three different algorithms (
"planchon.darboux.2001": The algorithm of Planchon and Darboux (2001) consists of increasing the elevation of pixels in closed depressions until the sink disappears and a minimum slope angle of
0.01 degree) is established.
"wang.liu.2006": This module uses an algorithm proposed by Wang and Liu (2006) to identify and fill surface depressions in DEMs. The method was enhanced to allow the creation of hydrologically sound elevation models, i.e. not only to fill the depressions but also to preserve a downward slope along the flow path. If desired, this is accomplished by preserving a minimum slope gradient (and thus elevation difference) between cells. This is the fully featured version of the module creating a depression-free DEM, a flow path grid and a grid with watershed basins. If you encounter problems processing large data sets (e.g. LIDAR data) with this module try the basic version (
"xxl.wang.liu.2006": This modified algorithm after Wang and Liu (2006) is designed to work on large data sets.
The type of object returned depends on the
intern argument passed to the
intern=FALSE it is a numerical error code (0: success), or otherwise (default) a character vector with the module's console output.
The function writes SAGA grid files containing of the depression-free preprocessed DEM, and optionally the flow directions and watershed basins.
The flow directions are coded as 0 = north, 1 = northeast, 2 = east, ..., 7 = northwest.
minslope=0, depressions will only be filled until a horizontal surface is established, which may not be helpful for hydrological modeling.
Planchon, O., and F. Darboux (2001): A fast, simple and versatile algorithm to fill the depressions of digital elevation models. Catena 46: 159-176.
Wang, L. & H. Liu (2006): An efficient method for identifying and filling surface depressions in digital elevation models for hydrologic analysis and modelling. International Journal of Geographical Information Science, Vol. 20, No. 2: 193-213.