Spatial Analyst/Digital Soil Mapping Workshop

Terrain Analysis Applications Using Digital Elevation Data

Dwain DanielsCentral National Technology Support Center

Phone: 817 509 3358dwain.daniels@ftw.usda.gov

APPLICATIONS: CUSTOM TOOBOXES AND TOOLSETS

Collection of tools and models for NRCS applications.

User can make a copy and changes as needed.

Specialized Map Algebra Functions: Terrain

Slope GradientSlope CurvatureAspectHillshadeContour

Slope Gradient

• Primary elevation derivative

• D-8 slope calculation

• Maximum rate of change of the z value through the cell.

• Degree is default, Percent is optional.

Reclassification• Most of the Generalization Tools require an INTEGER dataset.• Can be created by the INT function or values can be grouped into

categories for analysis using the RECLASSIFY tool.• In the dialog box the original values are grouped into categories

and the corresponding new values are entered.• If the input raster is symbolized with the classification method,

those categories are automatically used by the tool.• The reclassification values can be saved out to a file and loaded

again.

Exercise 1. Slope Gradient

Model creates slope group shapefile

Supplemental Accuracy Locations• Non-Level Terrain• Woodland vegetation

Slope Range COUNT Acres Percent0 to 2 1136719 1137 7.12 to 5 5822333 5822 36.45 to 8 4333138 4333 27.1

8 to 12 2407156 2407 15.012 to 15 851857 852 5.315 to 30 1244734 1245 7.8

Rep Value 10%

Display Exercise 1 Word Doc.