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Climate Change_ Hazard Assessmen

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					  Climate Change, Hazard
Assessment and Adaptation in
   Southern Monterey Bay




               Photo by Brad Damitz, MBNMS
Littoral Cell
Summary of RSM Approaches



                      Stable


Reduce or eliminate
mining of sand from
beach
 Continued dune erosion

Beach nourishment
A Scenario Based Approach to assessing
  the Impacts of Sea Level Rise to the
            California Coast




    Photo by D. Revell – 2/23/08              California Coastal Records Project



                 Dr. David Revell and Bob Battalio, P.E.
Matt Heberger, P.E., Dr. Peter Gleick, Heather Cooley, Justin Vandever
                             and Brian Spear
        Uncertainty and Decision making

                         Scientific
                         Confidence
Space




           Societal
           Relevance

                  Time
Time Scales of Climate Change Impacts
     Download


• Climate Action Team
• CA Energy
  Commission
• PWA (www.pwa-ltd.com)

        Questions
              d.revell@p
              wa-ltd.com
     General Approach - Vulnerability



•   Adopt CA climate scenarios (1.4 and 1.0 m by 2100).
•   Expand 1990 Pacific Institute Study of SF Bay to outer coast
•   Develop maps of flood and erosion hazards for CA coast.
•   Identify populations and infrastructure at risk.
•   Offer policy guidance and recommendations.
   Hazard Maps




“Not for planning purposes”
     Risk - Mapping Flood Hazards

      New 100-yr Flood Elevation with Sea Level Rise


             100-yr Flood Elevation

  Wave height

   100-yr Still-Water Elevation




•Review all existing FEMA Flood Insurance Studies
•Extract Coastal Base Flood Elevations into GIS
•Add Sea level rise scenarios to BFE elevations
•Map inundation using terrain datasets
Risk - Mapping Erosion Hazards



        Cliff




                Dune
Analyses Scale
           Dune Erosion Model




• 3 components –
  – Changes in TWL from SLR combined with shoreface slope
  – Historic shoreline trends (USGS)
  – Impact of a “100 year storm event”
            Dune Hazard Zones




Air Photo from 2005
            Cliff Erosion Model




• Acceleration of historic erosion rates (Rh)
• Prorated based on % increase in TWL exceeding
  the elevation of the toe of the beach/cliff junction
• Include geologic unit standard deviation x planning
  horizon to account for alongshore variability
             Cliff Hazard Zones




Air Photo from 2005
                       Results - Dunes
Revell et al in prep




                       •Majority of Norcal “accreting”
                       •Accreting to Erosion reversal in sign
                       seen between 2050 and 2100

                       •300 km or 185 miles
                        Results - Cliffs
                       •Geology exerts strong influence
Revell et al in prep
                       • Wave exposure and toe elevation
                       important

                       •1,140 km or 710 miles




                              California Coastal Records Project
Property at Flood Risk by Sector
          Pacific Coast
               Agriculture
                  <1%



                                        Commercial
                                           32%




 Residential
    51%




                                            Education
                                               1%
                                            Government
                                                1%
                               Industrial
                                 14%
                    Religion
                      1%
Population at Risk - Flooding
         Infrastructure at Risk
At Risk by 1.4m SLR
• Roads: 3,500 miles
• Highways: 400 miles
• Railroads: 300 miles*
• Schools: 139
• Hospitals: 55
• Police/Fire Stations: 34
• Power Plants: 30
• Wastewater Plants: 28
                               Study Products
                                         • Methodology for evaluating
                                           coastal erosion and SLR for
                                           different backshore types
                                         • Down-scalable model for
                                           evaluating local impacts of
                                           climate change
          Photo by D. Revell – 2/23/08   • GIS erosion hazard zones of two
                                           scenarios at 3 planning horizons
                                         • Flood elevations for the CA coast
                                         • Estimates of future erosion rates
                                         • Erosion rates by geologic unit


Photo by P. Barnard
 Potential Impacts to Monterey County
• 4.4 square miles of eroded lands
  – Dunes – Average ~600ft ; Maximum ~1250ft
  – Cliffs – Average ~120ft Maximum – 720ft
• Vulnerable Population
  – Flood – 14,000 people
  – Erosion – 820 people
• Infrastructure
  – Highway – 42 miles
  – Roads – 125 miles
  – Railways – 25 miles



                            Photo by B. Damitz
        Uncertainty and Decision making

                         Scientific
                         Confidence
Space




           Societal
           Relevance

                  Time
                         Is climate change happening?
                                   No                    Yes
Should we take action?
                                                    Food and water
                                                    shortages, global
                               No new problems
                         No

                                                    conflicts. Huge
                                                    $$$ to respond to
                                                    emergency

                               Spend $$$ to         Improve
                         Yes




                               upgrade              sustainability, self
                               infrastructure and   sufficiency, avert
                               improve resiliency   disaster
               Adaptation
       Choices
                                       More people and property
       • Hold the line                 threatened
       • Retreat
       • Change use
Risk




                                             Acceptable Risk




              Time or Sea Level Elevation
       Categories of Alternatives

•   Land Use Planning
•   Non-structural
•   Structural
•   Time Horizons –
    – Immediate 0-5 years
    – Short 5-25 years
    – Medium 25-50 years
    – Long 50-100+
             Evaluation Criteria
•   Effectiveness – reduce threat to structures
•   Effectiveness – maintain beach width
•   Costs – project cost vs no action*
•   Environmental – impacts +/- to ecosystem
•   Recreation – impacts +/- to rec. opportunities.
•   Safety/Access – impacts +/- lateral access
•   Aesthetics – judgment*
•   Regulatory viability – fed, state, local regs.
•   Resiliency – adaptability to future conditions
•   Cumulative –if all oceanfront parcels treated
•   Certainty of success –scientific certainty
           Land Use Planning Tools
•    Rolling Easements
•    Managed Retreat
•    Transfer of development credit
•    Conservation Easements
•    Present use tax
•    Fee Simple Acquisition
•    Structural or Habitat Adaptation
•    Setbacks for Bluff top Development
•    Setbacks + Elevation for Beach Level Development
     Generally issues are: high upfront costs, long
    implementation timelines, limited application,
       or put off the problem until a later date
                 Non Structural
• Sand Mining cessation
• SCOUP/ Opportunistic Sand
• Beach Dewatering
  – Active Pumping
  – Passive – PEMs
  – Desalination wells
• Beach Nourishment

   General approach is: increase natural sand
 supply, accelerate natural accretion processes,
           or augment sand volumes
               Structural Tools
•   Revetments
•   Seawalls
•   Perched Beaches
•   Groins
•   Breakwaters
•   Artificial Reefs/
    Submergent                  Photo courtesy G.Griggs
    Breakwaters/ Low
                       $5.3 million sand mitigation
    Crested Structures
                           fee for lost recreational beach
                           over the life of the seawall

				
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