1 / 16

Dam break risk in Colombia

Dam break risk in Colombia. A Geospatial Assessment of Population Vulnerability from Flood Inundation. Eugene Derner, GEOG 594a Spring 2014. Analytic Question. Colombia. Two large dams with towns located very close, downstream.

dee
Download Presentation

Dam break risk in Colombia

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dam break risk in Colombia A Geospatial Assessment of Population Vulnerability from Flood Inundation Eugene Derner, GEOG 594a Spring 2014

  2. Analytic Question Colombia Two large dams with towns located very close, downstream. What would be the flood impacts if either of these dams failed?

  3. Assessment of two dams • La Esmeralda and Salvajina Dams • Characteristics • Large reservoirs: >500k acre-ft storage • Tall Dams: >=500 ft • Embankment style construction: not likely to fail unless over filled • Why these two dams? • Nearby population! • Small town < 2 miles downstream La Esmeralda Salvajina

  4. La esmeralda • Characteristics • 778 ft (237 m) tall • Reservoir capacity over 550k acre-ft • Population at risk • Santa Maria 3 miles downstream • Mountainous canyon terrain • Elevation drop from dam to town 1500 feet (500 ft/mile)

  5. Salvina Dam • Characteristics • 486 ft (148 m) tall • Reservoir capacity over 560k acre-ft • Population at risk • Suarez 1 mile downstream • Foothills – small mountain terrain • Elevation drop from dam to town 165 feet

  6. Assumptions • Reservoirs are full. Dams in danger of being overtopped. • Worst case scenario • Condition consistent with the failure of embankment construction dam. • Reservoir capacity is at maximum • Dam failure due to overtopping and erosion of dam from top to bottom.

  7. Data – inputs to dambreak model Hydrologic • Type of dam • Water elevation behind dam • Volume of water OR surface area of reservoir • Channel bottom elevation at foot of dam Geospatial • DEM • Hydrosheds– 3 arc second (90 meter) best source • Derive inputs for dambreak model • Cross-section elevation slices • River channel slope • Distance to points of interest • Terrain – Mountainous, foothill or plains

  8. Methodology – Model #1 • Dambreak Rules of Thumb • Only 2 parameters needed • Spreadsheet computes answer – flow and stage every mile

  9. Methodology – Model #1 • Dambreak Rules of Thumb • “Delineate” flood depth elevations as polygon

  10. Methodology – Model #2 • Derive elevation cross section data from DEM • One at midpoint between dam and town • Two at upstream and downstream sides of town Cross sections

  11. Methodology – Model #2 • Run Simplified Dambreak • Input dam/reservoir data • Elevation cross section data

  12. Methodology – Model #2 • Run Simplified Dambreak • “Delineate” flood depth elevations as polygons

  13. ResultsLa Esmeralda • Certain inundation of ENTIRE town of Santa Maria and highway leading from Dam to town • Rules of Thumb shows higher flood (typical) • Max water depth 248 ft! • Time to flood less than 10 minutes! • Population 4,498 (2005)

  14. ResultsSalvajina • Certain inundation for MOST of Suarez • Rules of Thumb shows higher flood (typical) • Max water depth 188 ft! • Time to flood less than 15 minutes! • Population 4519 (2005)

  15. Conclusions • Dam failure, although highly unlikely, would be catastrophic • Very little time for warning • 15 minutes or less • HydroSHEDS DEM resolution ~90 meters • Too coarse? • Does it matter for a flood of this magnitude?

  16. Thank YouQuestions?

More Related