1. Interpreting Landscape to Predict
Landslide Vulnerability
A brief overview of the techniques
involved to evaluate the conditions
for a landslide
Christopher Bride
GEP635
Spring 2012
Prof. Yuri Gorokhovich Photo courtesy of Riverkeeper.org
5. Parameters to Study
• Slope
• Soil type
• Tree/vegetation cover
• Many others outside the scope of this class
– Hydration
– Impermeable surface
– Other man-made factors
6. GIS
• DEM files: Digital
Elevation Model
• GIS Clearinghouse
• County boundaries
• Hudson River
shoreline shapefile
7. Data acquisition
Grid enables easy
location of the tiles
needed to acquire for
this project
Also can be done by
town name.
Download, unzip, add
to map, symbolize via
“stretched value”,
“discrete colors”, or
“classify”
24. Index/Model
• Landslide susceptible soils categorized into one
class
• Landslide susceptible slopes categorized into one
class (slopes >30 degrees)
• Vegetation coverage was not on hand, but would
have otherwise been given a classification as well
• For now, we will look at where soil type and
landslides overlap/intersect.
• Then use GoogleEarth or orthophotos to evaluate
vegetation coverage.
25. Union of Slope and Soil
Type Layers
Need to convert slope raster into a
polygon so that a Union geoprocess
can be performed with the Soil layer
26. Slope Raster to Polygon
Slope Raster from DEM Slope polygon file >30o
27. Union these two layers for Landslide
susceptibility analysis
Slope polygon Soil polygon
28. Soil and Slope Union
After “Union” geoprocess, the areas
with >30 degree slope that overlay the
landslide susceptible soil types are
indicated in red. All other areas, soil
and slop alike, are indicated in green.
32. Potential Problem Area
Residential, tree removal apparent,
strong slope and soil type correlation
to landslide conditions.
Advice? Don’t remove the trees or
vegetation in these areas.
