- Hydrological conditioning, sink removal
r.hydrodem [-afc] input=name [depression=name] [memory=integer] output=name mod=integer size=integer [--overwrite] [--help] [--verbose] [--quiet] [--ui]
- Remove all sinks.
- By default only minor corrections are done to the DEM and the result will not be 100% hydrologically correct.Use this flag to override default.
- Fill sinks.
- By default a least impact approach is used to modify the DEM.Use this flag to force filling of sinks.
- Carve out of sinks.
- By default a least impact approach is used to modify the DEM.Use this flag to force carving out of sinks.
- Allow output files to overwrite existing files
- Print usage summary
- Verbose module output
- Quiet module output
- Force launching GUI dialog
- input=name [required]
- Elevation map
- Elevation map to be hydrologically corrected
- Depression map
- Map indicating real depressions that must not be modified
- Maximum memory to be used in MB
- Default: 300
- output=name [required]
- Name of hydrologically conditioned raster map
- mod=integer [required]
- Only remove sinks requiring not more than <mod> cell modifications.
- Default: 4
- size=integer [required]
- Only remove sinks not larger than <size> cells.
- Default: 4
applies hydrological conditioning (sink removal) to
a required input elevation
map. If the conditioned elevation
map is going to be used as input elevation for r.watershed
only small sinks should be removed and the amount of modifications
restricted with the mod
option. For other modules such as
or third-party software, full sink removal is
- Input map, required: Digital elevation model to be corrected. Gaps
in the elevation map that are located within the area of interest should
be filled beforehand, e.g. with r.fillnulls or
r.resamp.bspline, to avoid distortions.
- Output map, required: Hydrologically conditioned digital elevation
model. By default, only minor modifications are done and not all sinks
- All sinks of up to size cells will be removed.
Default is 4, if in doubt, decrease and not increase.
- All sinks will be removed that require not more than mod
cells to be modifed. Often, rather large sinks can be removed by
carving through only few cells. Default is 4, if in doubt, increase
and not decrease.
- Not recommended if input for r.watershed is generated.
With the -a flag set, all sinks will be removed using an impact
reduction approach based on Lindsay & Creed (2005). The output will be a
depression-less digital elevation model, suitable for e.g.
r.terraflow or other hydrological analyses that require a
depression-less DEM as input.
This module is designed for r.watershed
with the purpose to
slightly denoise a DEM prior to analysis. First, all one-cell peaks and
pits are removed, then the actual hydrological corrections are applied.
In most cases, the removal of one-cell extrema could already be
sufficient to improve r.watershed
results in difficult terrain,
particularly nearly flat areas.
The impact reduction algorithm used by r.hydrodem is based on
Lindsay & Creed (2005), with some additional checks for
hydrological consistency. With complete sink removal, results of
r.terraflow are very similar to results of r.watershed.
r.hydrodem uses the same method to determine drainage directions
Lindsay, J. B., and Creed, I. F. 2005. Removal of artifact depressions
from digital elevation models: towards a minimum impact approach.
Hydrological Processes 19, 3113-3126.
Available at: r.hydrodem source code (history)
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GRASS Development Team,
GRASS GIS 7.8.4dev Reference Manual