Interpreting Landscape to Predict          Landslide Vulnerability               A brief overview of the techniques       ...
Study Site: Milton, NY
Milton Landslide into the Hudson River
SlopeProfile via Google  Earth
Parameters to Study•   Slope•   Soil type•   Tree/vegetation cover•   Many others outside the scope of this class    – Hyd...
GIS• DEM files: Digital  Elevation Model• GIS Clearinghouse• County boundaries• Hudson River  shoreline shapefile
Data acquisitionGrid enables easylocation of the tilesneeded to acquire forthis projectAlso can be done bytown name.Downlo...
Digital Elevation ModelColored to indicate elevation in feetThis is actually 4 grid tiles
Analyze slope: Geoprocess/Slope
Soil Analysis
Simplified: Dangerous types vs.        everything else
Slope & Soil Type
Slope & Soil Type
Orthophotos: Tree/Vegetation cover
Data Acquisition
Download Ortho-index grid
Input Ortho-grid into GIS
What tile do I need?Choose “ID” tool in ArcGISSelect the grid position you needRecord or memorize the grid number
Find tile coordinate in list,download/unzip, and add to map
Start combining layers• Ulster County Orthophotos underneath Slope  Analysis
Milton Landslide & Slope           Landslide                  Area
Landslide Site & Soil Type     Glacial Deposits        Bedrock (type “r”)                                “other”          ...
Slope & Soil Type        Landslide               Area
Index/Model• Landslide susceptible soils categorized into one  class• Landslide susceptible slopes categorized into one  c...
Union of Slope and SoilType LayersNeed to convert slope raster into apolygon so that a Union geoprocesscan be performed wi...
Slope Raster to PolygonSlope Raster from DEM    Slope polygon file >30o
Union these two layers for Landslide         susceptibility analysisSlope polygon       Soil polygon
Soil and Slope UnionAfter “Union” geoprocess, the areaswith >30 degree slope that overlay thelandslide susceptible soil ty...
Ulster Landslide Area Analysis
Landslide site, 2011
Final map
Potential Problem AreaResidential, tree removal apparent,strong slope and soil type correlationto landslide conditions.Adv...
GoogleEarth Photo of Potential       Landslide Area
References• Orthophotos and Soil Data: http://gis.ny.gov/  (NYState GIS Clearinghouse)• Digital Elevation Models:  http://...
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Landslide Susceptibility Evaluation Techniques

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A GIS analysis of landslide characteristics that contribute to the chance of a landslide occurring.

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Landslide Susceptibility Evaluation Techniques

  1. 1. Interpreting Landscape to Predict Landslide Vulnerability A brief overview of the techniques involved to evaluate the conditions for a landslideChristopher BrideGEP635Spring 2012Prof. Yuri Gorokhovich Photo courtesy of Riverkeeper.org
  2. 2. Study Site: Milton, NY
  3. 3. Milton Landslide into the Hudson River
  4. 4. SlopeProfile via Google Earth
  5. 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. 6. GIS• DEM files: Digital Elevation Model• GIS Clearinghouse• County boundaries• Hudson River shoreline shapefile
  7. 7. Data acquisitionGrid enables easylocation of the tilesneeded to acquire forthis projectAlso can be done bytown name.Download, unzip, addto map, symbolize via“stretched value”,“discrete colors”, or“classify”
  8. 8. Digital Elevation ModelColored to indicate elevation in feetThis is actually 4 grid tiles
  9. 9. Analyze slope: Geoprocess/Slope
  10. 10. Soil Analysis
  11. 11. Simplified: Dangerous types vs. everything else
  12. 12. Slope & Soil Type
  13. 13. Slope & Soil Type
  14. 14. Orthophotos: Tree/Vegetation cover
  15. 15. Data Acquisition
  16. 16. Download Ortho-index grid
  17. 17. Input Ortho-grid into GIS
  18. 18. What tile do I need?Choose “ID” tool in ArcGISSelect the grid position you needRecord or memorize the grid number
  19. 19. Find tile coordinate in list,download/unzip, and add to map
  20. 20. Start combining layers• Ulster County Orthophotos underneath Slope Analysis
  21. 21. Milton Landslide & Slope Landslide Area
  22. 22. Landslide Site & Soil Type Glacial Deposits Bedrock (type “r”) “other” Landslide Area
  23. 23. Slope & Soil Type Landslide Area
  24. 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. 25. Union of Slope and SoilType LayersNeed to convert slope raster into apolygon so that a Union geoprocesscan be performed with the Soil layer
  26. 26. Slope Raster to PolygonSlope Raster from DEM Slope polygon file >30o
  27. 27. Union these two layers for Landslide susceptibility analysisSlope polygon Soil polygon
  28. 28. Soil and Slope UnionAfter “Union” geoprocess, the areaswith >30 degree slope that overlay thelandslide susceptible soil types areindicated in red. All other areas, soiland slop alike, are indicated in green.
  29. 29. Ulster Landslide Area Analysis
  30. 30. Landslide site, 2011
  31. 31. Final map
  32. 32. Potential Problem AreaResidential, tree removal apparent,strong slope and soil type correlationto landslide conditions.Advice? Don’t remove the trees orvegetation in these areas.
  33. 33. GoogleEarth Photo of Potential Landslide Area
  34. 34. References• Orthophotos and Soil Data: http://gis.ny.gov/ (NYState GIS Clearinghouse)• Digital Elevation Models: http://cugir.mannlib.cornell.edu/datatheme.js p?id=23 (CUGIR: Cornell University Geospatial Information Repository)• Opening photo: http://hudsonriverkeeper.blogspot.com/2012/ 04/landslide-into-wetland-at-residential.html
  35. 35. Thank You!

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