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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.

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


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  • 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. Study Site: Milton, NY
  • 3. Milton Landslide into the Hudson River
  • 4. SlopeProfile via Google Earth
  • 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 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. Digital Elevation ModelColored to indicate elevation in feetThis is actually 4 grid tiles
  • 9. Analyze slope: Geoprocess/Slope
  • 10. Soil Analysis
  • 11. Simplified: Dangerous types vs. everything else
  • 12. Slope & Soil Type
  • 13. Slope & Soil Type
  • 14. Orthophotos: Tree/Vegetation cover
  • 15. Data Acquisition
  • 16. Download Ortho-index grid
  • 17. Input Ortho-grid into GIS
  • 18. What tile do I need?Choose “ID” tool in ArcGISSelect the grid position you needRecord or memorize the grid number
  • 19. Find tile coordinate in list,download/unzip, and add to map
  • 20. Start combining layers• Ulster County Orthophotos underneath Slope Analysis
  • 21. Milton Landslide & Slope Landslide Area
  • 22. Landslide Site & Soil Type Glacial Deposits Bedrock (type “r”) “other” Landslide Area
  • 23. Slope & Soil Type Landslide Area
  • 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 SoilType LayersNeed to convert slope raster into apolygon so that a Union geoprocesscan be performed with the Soil layer
  • 26. Slope Raster to PolygonSlope Raster from DEM Slope polygon file >30o
  • 27. Union these two layers for Landslide susceptibility analysisSlope polygon Soil polygon
  • 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. Ulster Landslide Area Analysis
  • 30. Landslide site, 2011
  • 31. Final map
  • 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. GoogleEarth Photo of Potential Landslide Area
  • 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. Thank You!