ArcMAP Commands for Computing RUSLE


Using Soil Erosion Modeling for Improved Conservation Planning: A GIS-based Tutorial

Computing RUSLE using GIS

ArcGIS 8.1, ArcMap

Soil Loss Prediction

Display Notes:

In ArcMap, color ramps provide for histogram equalization (select layer, right-click to display properties, select Symbology) and allow the creation of custom color ramps. Widely varying values and floating point maps are accurately displayed.
For better visualization purposes, hillshading was used on maps illustrated here. To add hill shading to thematic raster maps in ArcMap:

Select Spatial Analyst > Surface Analysis > Hillshade...
Enter the DEM as input surface.
Place the new hillshaded layer at the bottom of the display list and turn it on.
Right-click on the layer to be shaded to bring up the properties box, go to the Display tab.
Change the Transparent percentage to about 40% (may need to experiment depending on the terrain and color ramp used).

Also note that transparency may be used to help view several layers at a time, such as in this image of erosion/deposition combined with c-factor, both transparent over hillshading.

Given data 

grid:

	elevation
	K factor
	C factor
	(P)


constant: R=220, resolution=10m


Computation

1. Enable Spatial Analyst Under View... Toolbars select Spatial Analyst
2. Calculate Slope From the Spatial Analyst toolbar, select Surface Analysis... Slope.
Enter the elevation layer, select Degree, and enter output information. Give the new theme name slope.
3. Raster Calculator From the Spatial Analyst toolbar, select Raster Calculator. Build an expression: FlowAccumulation(FlowDirection([elevation])) Evaluate Make the new theme permanent and change the name to flowacc
Build an expression in the Raster Calculator (in ArcGIS 9.2 skip radian conversion - multiplication by 0.01745): Pow([flowacc] * resolution / 22.1, 0.4) * Pow(Sin([slope] * 0.01745) / 0.09, 1.4) * 1.4 Evaluate Make the new theme permanent and change the name to lsfac
Build an expression in the Raster Calculator: R * [K] * [C] * [P] * [lsfac] Evaluate Make the new theme permanent and change the name to soilloss

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ArcMAP Slope for RUSLE
ArcMAP Flow Accumulation for RUSLE
ArcMAP Slope Length for RUSLE
ArcMAP Soil Loss for RUSLE

HOME H. Mitasova, et al., Geographic Modeling Systems Lab, UIUC