DESCRIPTION

r.sim.terrain is a short-term landscape evolution model that simulates topographic change for both steady state and dynamic flow regimes across a range of spatial scales. It uses empirical models (RUSLE3D & USPED) for soil erosion at watershed to regional scales and a physics-based model (SIMWE) for shallow overland water flow and soil erosion at subwatershed scales to compute short-term topographic change. This either steady state or dynamic model simulates how overland sediment mass flows reshape topography for a range of hydrologic soil erosion regimes based on topographic, land cover, soil, and rainfall parameters.

EXAMPLES

Basic instructions

A basic example for the North Carolina sample dataset. Install the add-on module r.sim.terrain. Copy the raster elevation map elev_lid792_1m from the PERMANENT mapset to the current mapset. Set the region to this elevation map at 1 meter resolution. Run r.sim.terrain with the RUSLE model for a 120 min event with a rainfall intensity of 50 mm/hr at a 3 minute interval. Set the empirical coefficients m and n to 0.4 and 1.3 respectively. Use the `-f` flag to fill depressions in order to reduce the effect of positive feedback loops.

g.extension  extension=r.sim.terrain
g.copy raster=elev_lid792_1m@PERMANENT,elevation
g.region raster=elev_lid792_1m res=1
r.sim.terrain -f elevation=elevation runs=event mode=rusle_mode rain_intensity=50.0 rain_duration=120 rain_interval=3 m=0.4 n=1.3

Figure: Net difference (m) for a dynamic RUSLE simulation of a 120 min event with a rainfall intensity of 50 mm/hr with a 3 minute interval.

Spatially variable soil and landcover

Clone or download the landscape evolution sample dataset with a time series of lidar-based digital elevation models and orthoimagery for a highly eroded subwatershed of Patterson Branch Creek, Fort Bragg, NC, USA.

Run r.sim.terrain with the simwe model for a 120 min event with a rainfall intensity of 50 mm/hr. Use a transport value lower than the detachment value to trigger a transport limited erosion regime. Use the -f flag to fill depressions in order to reduce the effect of positive feedback loops.

g.mapset -c mapset=transport location=nc_spm_evolution
g.region region=region res=1
r.mask vector=watershed
g.copy raster=elevation_2016@PERMANENT,elevation_2016
r.sim.terrain -f elevation=elevation_2016 runs=event mode=simwe_mode \
rain_intensity=50.0 rain_interval=120 rain_duration=10 walkers=1000000 \
detachment_value=0.01 transport_value=0.0001 manning=mannings runoff=runoff

Figure: Net difference (m) for a steady state, transport limited SIMWE simulation of a 120 min event with a rainfall intensity of 50 mm/hr.

For more detailed instructions and examples see this in-depth tutorial.

ERROR MESSAGES

If the module fails with

ERROR: nwalk (7000001) > maxw (7000000)!

then a lower nwalkers parameter value has to be selected. If the module fails with

ERROR: Unable to insert dataset of type raster in the temporal database. The mapset of the dataset does not match the current mapset.

check that the input elevation map is in the current mapset. The input elevation map must be in the current mapset so that it can be registered in the temporal datasbase.

REFERENCES

Harmon, B., Mitasova, H., Petrasova, A., Petras, V., 2019. r.sim.terrain: a dynamic landscape evolution model.
Mitasova H., Barton M., Ullah I., Hofierka J., Harmon R.S., 2013. 3.9 GIS-Based Soil Erosion Modeling. In J. F. Shroder, ed. Treatise on Geomorphology. San Diego: Academic Press, pp. 228-258. DOI: http://dx.doi.org/10.1016/B978-0-12-374739-6.00052-X.

AUTHORS

Brendan A. Harmon
Louisiana State University
brendan.harmon@gmail.com

Last changed: $Date: 2014-08-14 11:34:43 -0400 (Thu, 14 Aug 2014) $

DESCRIPTION

EXAMPLES

ERROR MESSAGES

REFERENCES

SEE ALSO

AUTHORS