Presentation on theme: "Identifying landslide triggers and estimating inundation zones in the Monte Sano Nature Preserve Applications of Spatial Analysis tools and ArcInfo Workstation."— Presentation transcript:
1Identifying landslide triggers and estimating inundation zones in the Monte Sano Nature Preserve Applications of Spatial Analysis tools and ArcInfo Workstation softwareATS 515 – Advanced Topics in GISRobert Griffin, Instructor28 February 2012Eric R. AndersonUniversity of Alabama in HuntsvilleDepartment of Atmospheric Science
2Lesson Outline Overall goals and specific objectives Context and important conceptsPinpoint landslide triggersSimulate rock avalanche inundation zonesVisualize results (time permitting)Discuss the methods and results
3Overall goals and specific objectives Pinpoint locations most prone to slope failureDelineate rock fall inundation hazard zonesPerform basic surface and hydrology analyses of high resolution digital terrain model (DTM)Predict the locations of unstable conditions as a function of slope and upslope contributing areaSimulate rock avalanches to estimate inundation hazard areas(time permitting) Visualize results in ArcScene.
4Context and important concepts Annual losses attributed to landslides are greater than any other natural disaster except hurricanes (Lee 2009)$3 billion + annually in the US (USGS 2006)$10 billion + annually worldwide (Lee 2009)Where they happenTypes of landslides
5Landslide potential in the U.S. Red – very highYellow – highgreen – moderate(Abbott 2012)
6Classification of Mass Movements Speed and water content(Abbott 2012)Insert Table 15.2
7Classification of Mass Movements Downward – falling or subsidingDownward and outward – sliding and flowing(Abbott 2012)
8FallsElevated rock mass separates along joint, bedding or weakness and falls downward through air in free fall until hitting the ground, bouncing and rollingYosemite National Park, California, 1996162,000 ton granite mass slid and launched into air, fell 500 m before hitting valley floorBlast knocked down 1,000 trees50 acres covered with inch-thick layer of dustOne person killed by tree(Abbott 2012)
9Flows La Conchita, CA, Slump, Debris Flows, 1995, 2005 Cliff behind La Conchita is ancient landslide1995: two slow landslides destroyed 14 houses, no deaths2005: 15% of 1995 slide mass remobilized into highly fluid debris flow, at 10 m/sec, went over retaining wall, destroyed 13 houses, damaged 23 others, killed 10 people(Abbott 2012)19952005
10Landslide Susceptibility in Alabama (extract of Madison County)Moderate to Very High susceptibility throughout Monte Sano State Park and the Land TrustBy: Sandy M. Ebersole, Steven Driskell and Anthony M. Tavis. Geologic Mapping and Hazards Section, Geological Survey of Alabama, December 2011.
11Landslide triggers Converging upslope contributing areas Failure slope thresholdRegions of continuous steep slopes(Montgomery and Dietrich 1994; Dietrich et al 1998; in Griswold 2012)
12Inundation hazard zones LAHARZ softwareFor a given volume, V, Objectively delineates hazard zones based on elevationCross-sectional inundation area, APlanimetric inundation area, BIverson et al 1998
19Visualize the results Open the following in ArcScene: Original DEMHillshadeTriggers shapefileLAHARZ outputsFor all layers, set Base Heights to DEMRight click on layer/Properties/Base Heights/ Floating on Custom Surface
21DiscussionWhat were our inputs for a) trigger and b) inundation estimates?What are the assumptions?What are the uncertainties, and how do we deal with these?How can we improve these models?a) DTM and user-defined thresholds for slope, flow accumulation, and upslope contributing areab) DTM, volumes2. Basing inundation zone measurement on an average of observed cases; LAHARZ does not account for snowball effect (increasing volume); assuming that these things begin in stream or channel (rather than a far-off slope) – this can be remedied - to start wherever you want, just include more “stream” cells from the flow accumulation definition3. Vertical and horizontal error in DTM – greater uncertainty in flow path once debris reaches flat terrain (fewer contours / unit area in flat than steep terrain—LiDar greatly improves this). Volumes we use are just estimates.4. Include other factors like geology, precipitation, seismic activity; consider the timing of these events rather than just the “where”
22Acknowledgements Julia Griswold, Steve Schilling, Jon Major, USGS Sundar Christopher, Robert Griffin, Tom Sever, Kevin Knupp, Stephanie Mullins, Africa Flores, UAHuntsvilleDaniel Irwin, Jason Kessler, Gwen Artis, Ashutosh Limaye, Francisco Delgado, Burgess Howell, Karthik Srinivasan, NASA/SERVIRCarrie Stokes, Michelle Jennings, Orlando Altamirano, Ruben Aleman, USAIDEmilio Sempris, Emil Cherrington, Antonio Clemente, Alejandro del Castillo, CATHALACManuel Diaz, Giovanni Tobar, Karla Marroquín, Luis Mixco, SNET/MARN (El Salvador)