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Outline

Outline. Risk and HazardBrief review of flood hazard assessment criteriaFLO-2D Hazard delineation methodCase study: 1999 floods in VenezuelaHazard delineation toolDamage assessment tool. Hazard ? Risk. Hazard

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Outline

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    2. Outline Risk and Hazard Brief review of flood hazard assessment criteria FLO-2D Hazard delineation method Case study: 1999 floods in Venezuela Hazard delineation tool Damage assessment tool

    3. Hazard ? Risk Hazard “a potentially damaging physical event, phenomenon or human activity that may cause the loss of life or injury, property damage, social and economic disruption or environmental degradation (UN-USDR, 2004). ”

    4. Hazard ? Risk Risk “is defined as the probability of harmful consequences, or expected losses (deaths, injuries, property, livelihoods, economic activity disrupted or environment damaged) resulting from interactions between natural or human-induced hazards and vulnerable conditions (UN-USDR, 2004.”

    5. Hazard ? Risk Risk Risk = Hazards × Vulnerability Many people say Risk, but they mean Hazard

    7. Hazard Zones for Flooding Hazard Intensity FEMA: f(h) Austria: f(h, v2/2g) Switzerland: f(h, v × h) Flood hazard depends on Depth Velocity Event frequency

    8. Hazard in the U.S.A. The U.S. Bureau of Reclamation (1988) also identifies hazard as a combination of depth and velocity and differentiates these for adults, cars, and houses as shown in the following figures. USBR. 1988. Downstream Hazard Classification Guidelines. ACER Technical Memorandum No. 11.

    12. FLO-2D Hazard delineation criteria Based on Swiss and Austrian standards (see OFEE et al. 1997, Fiebiger 1997). Three zones identify the potential hazard in a location. Flood hazard is defined as a discrete combined function of the event intensity (severity of the event) and return period (frequency). The intensity of the event is a function of the flow depth and velocity. Frequency of the event is based on the simulation of 3 scenarios, e.g. 10, 100 and 500 years return period. Hazard maps simpler to understand by planners, managers, and “end users”.

    13. Event intensities f(h, v)

    14. Spreadsheet

    15. Proposed methodology

    16. Definition of hazard level

    17. Apply hydrological model: Inflow hydrographs Estimate total sediment volume Apply FLO-2D model to obtain maximum velocities and maximum depth maps for mud floods of three return periods (10, 100 and 500 years or other) Determine intensity maps for these three events based on the established criteria Determine hazard potential from intensity maps and event return period Methodology for hazard mapping

    18. Case study Debris Flow and Flooding. Northern Venezuela. December 1999. 20 alluvial fans affected. ~15.000 people died/disappeared . US $5+ billion in losses.

    19. Location

    24. Macuto, Edo. Vargas.

    25. Macuto River in the alluvial fan, Sept. 2001.

    45. Macuto, aguas arriba de toma.

    60. Approximately 15 x 106 m3 sediment.

    65. Picacho Galpán

    71. Ars longa, vita brevis

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