# rsaga.fill.sinks

0th

Percentile

##### Fill Sinks

Several methods for filling closed depressions in digital elevation models that would affect hydrological modeling.

Keywords
spatial, interface
##### Usage
rsaga.fill.sinks(in.dem, out.dem, method = "planchon.darboux.2001",
out.flowdir, out.wshed, minslope, ...)
##### Arguments
in.dem

Input: digital elevation model (DEM) as SAGA grid file (default extension: .sgrd).

out.dem

Output: filled, depression-free DEM (SAGA grid file). Existing files will be overwritten!

method

The depression filling algorithm to be used (character). One of "planchon.darboux.2001" (default), "wang.liu.2006", or "xxl.wang.liu.2006".

out.flowdir

(only for "wang.liu.2001"): Optional output grid file for computed flow directions (see Notes).

out.wshed

(only for "wang.liu.2001"): Optional output grid file for watershed basins.

minslope

Minimum slope angle (in degree) preserved between adjacent grid cells (default value of 0.01 only for method="planchon.darboux.2001", otherwise no default).

...

Optional arguments to be passed to rsaga.geoprocessor(), including the env RSAGA geoprocessing environment.

##### Details

This function bundles three SAGA modules for filling sinks using three different algorithms (method argument).

"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 minslope (default: 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.lui.2006).

"xxl.wang.liu.2006": This modified algorithm after Wang and Liu (2006) is designed to work on large data sets.

##### Value

The type of object returned depends on the intern argument passed to the rsaga.geoprocessor(). For 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.

##### Note

The flow directions are coded as 0 = north, 1 = northeast, 2 = east, ..., 7 = northwest.

If minslope=0, depressions will only be filled until a horizontal surface is established, which may not be helpful for hydrological modeling.

##### References

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.

rsaga.sink.removal(), rsaga.sink.route().