## Hillslope Position by Soil Series

Submitted by dylan on Wed, 2013-06-05 18:34.

Soil survey data are typically built upon a foundation of soil-landscape relationships that have been verified in the field.

( categories: )

## Terrain shape indices depicted by scaled arrows

Submitted by dylan on Sat, 2011-04-30 14:57.
( categories: )

## Using R and r.mapcalc (GRASS) to Estimate Mean Topographic Curvature

Submitted by dylan on Tue, 2010-08-03 20:51.

Recently I was re-reading a paper on predictive soil mapping (Park et al, 2001), and considered testing one of their proposed terrain attributes in GRASS. The attribute, originally described by Blaszczynski (1997), is the distance-weighted mean difference in elevation applied to an n-by-n window of cells:

Equation 4 from (Park et al, 2001)

where n is the number of cells within an (odd-number dimension) square window excluding the central cell, z is the elevation at the central cell, z_{i} is the elevation at one of the surrounding cells i, d_{i} is the horizontal distance between the central cell and surrounding cell i. I wasn't able to get a quick answer using r.neighbors or r.mfilter, so I cooked up a simple R function to produce a solution using r.mapcalc. The results are compared with the source DEM below; concave regions are blue-ish, convex regions are red-ish. The magnitude and range are almost identical to mean curvature derived from v.surf.rst, with a Pearson's correlation coefficient of 0.99. I think that it would be of general interest to add functionality to r.neighbors so that it could perform distance-weighted versions of commonly used focal functions.

Elevation surface (left) and resulting mean curvature estimate (right)

## Elevation surface (left) and resulting mean curvature estimate (right)

Submitted by dylan on Sun, 2010-08-01 23:23.
( categories: )

## Soil Depth Mapping at KREW 2

Submitted by dylan on Tue, 2010-03-02 19:58.

linear regression with RCS

( categories: )

## Soil Depth Mapping at KREW

Submitted by dylan on Tue, 2010-03-02 19:55.

regression tree

( categories: )

## Other Information

Submitted by vbullard on Fri, 2009-06-12 17:04.

## Rangeland Soil Management and Hydrology

Submitted by vbullard on Thu, 2009-06-11 18:30.
( categories: )

## SFREC-terrain_classification_004

Submitted by dylan on Sat, 2009-05-23 17:24.

4-class terrain grouping.

( categories: )

## SFREC-terrain_classification_003

Submitted by dylan on Sat, 2009-05-23 17:21.

3-class terrain groupings

( categories: )