1A.1

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Vulnerability and Adaptation Assessments Hands-On
Training Workshop Coastal Resources
Analytical Approaches
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Outline

• Introduction
• Sea level rise
• Predictions and uncertainties
• Scenarios
• Global processes
• Local uncertainties
• Impacts
• Adaptation and shoreline management

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Outline (continued)

• Methods to assess impacts of sea level rise
• Levels of assessment
• Screening
• Vulnerability
• Planning
• Review of African region situation
• Models
• Data sources
• DIVA

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Climate Change and Coastal Resources

• Coastal resources will be affected by a number of
  consequences of climate change, including
• Higher sea levels
• Higher sea temperatures
• Changes in precipitation patterns and coastal
  runoff
• Changes in storm tracks, frequencies, and
  intensities

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The Main Biophysical Effects of Relative Sea
Level Rise
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Some Climate Change Factors
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Current Global Predictions of Sea Level Rise

• IPCC Third Assessment Report (TAR) range for
  global-mean rise in sea level is between 9 cm
  and 88 cm by 2100
• Change outside this range is possible, especially
  if Antarctica becomes a significant source
• There is a commitment to sea level rise even if
  atmospheric GHG concentrations are stabilized

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Global-Mean Sea Level Rise 1990 to 2100 (SRES
scenarios)
Houghton et al., 2001
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Processes Controlling Sea-LevelChange

• Relative sea-level changes

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Ocean Water Volume

• Controlled by
• Ocean temperature thermal expansion
• Melting of land-based ice
• Small glaciers
• Greenland
• Antarctica
• The hydrological cycle (including human influence)

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Uncertainty in Local Predictions

• Relative sea level rise global and regional
  components plus land movement
• Land uplift will counter any global sea level
  rise
• Land subsidence will exacerbate any global sea
  level rise
• Other dynamic oceanic and climatic effects cause
  regional differences (oceanic circulation, wind
  and pressure, and ocean-water density differences
  add additional component)

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Sea Level Rise at New York City1850 to 2100
IPCC TAR range due to SRES emission scenarios
McCarthy et al., 2001
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Land Subsidence
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Other Climate Change(Hurricane Katrina)
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Elevation and Population Density Maps for
Southeast Asia
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Population and Population Density vs. Distance
and Elevationin 1990
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Coastal Megacities (gt8 million people)Forecast
for 2010
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National Vulnerability Profiles
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Deltaic Regions
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Atolls
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Biogeophysical Effects of Sea Level Rise

• Displacement of coastal lowlands and wetlands
• Increased coastal erosion
• Increased flooding (frequency and depth)
• Salinization of surface and groundwaters
• Plus others

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Socioeconomic Impacts

• Loss of property and land
• Increased flood risk/loss of life
• Damage to coastal protection works and other
  infrastructure
• Loss of renewable and subsistence resources
• Loss of tourism, recreation, and coastal habitats
• Impacts on agriculture and aquaculture through
  decline in soil and water quality

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Definition of Impacts
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Shoreline Management and Adaptation
Proactive Adaptation Coastal Adaptation (IPCC) Shoreline Management (Defra)
Increasing robustness Protect Hold the line
Increasing flexibility Accommodate Advance the line
Enhancing adaptability Retreat Managed realignment
Enhancing adaptability Retreat No active intervention
Reversing maladaptive trends (Project appraisal methods)
Improving awareness and preparedness (Flood plain mapping and flood warnings)
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Responding to Coastal Change(including sea level
rise)

• Retreat
• Accommodation
• Protect
• Soft
• Hard

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Shoreline Management and Adaptation (2)
Proactive Adaptation Coastal Adaptation (IPCC) Shoreline Management
Increasing robustness Protect Hold the line
Increasing flexibility Accommodate Advance the line
Enhancing adaptability Retreat Managed realignment
Enhancing adaptability Retreat No active intervention
Reversing maladaptive trends (Project appraisal methods)
Improving awareness and preparedness (Flood plain mapping and flood warnings)
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Adaptation Methods

• Retreat
• Managed retreat
• Relocation from high risk zones
• Accommodation
• Public awareness
• Natural disaster management planning

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Adaptation Methods (continued)

• Protect
• Hard options
• Revetments, breakwaters, groins
• Floodgates, tidal barriers
• Soft options
• Beach/wetland nourishment
• Dune restoration

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Example Approach to Adaptation Measures

• Caribbean small island developing country
• Climate change predictions
• Rise in sea level
• Increase in number and intensity of tropical
  weather systems
• Increase in severity of storm surges
• Changes in rainfall

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Example Approach to Adaptation Measures
(continued)

• Coastal impacts
• Damage to property/infrastructure
• Damage/loss of coastal/marine ecosystems
• Destruction of hotels and tourism facilities
• Increased risk of disease
• Damage/loss of fisheries infrastructure
• General loss of biodiversity
• Submergence/inundation of coastal areas

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Example Approach to Adaptation Measures
(continued)

• Adaptation (retreat, protect, accommodate)
• Improved physical planning and development
  control
• Strengthening/implementation of EIA regulations
• Formulation of Coastal Zone Management Plan
• Monitoring of coastal habitats, including beaches
  
• Formulation of national climate change policy
• Public awareness and education

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Methods to Assess Impacts of Sea Level Rise

• Sea level rise scenarios
• Levels of assessment
• Screening assessment
• Vulnerability assessment
• Erosion
• Flooding
• Coastal wetland loss
• Planning assessment

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Coastal Vulnerability andRisk Assessment

• Three levels of assessment
• Screening assessment (3-6 months)
• Vulnerability assessment (1-2 years)
• Planning assessment (ongoing)

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Screening Assessment

• Rapid assessment to highlight possible impacts of
  a sea level rise scenario and identify
  information/data gaps
• Qualitative or semiquantitative
• Steps
• Collation of existing coastal data
• Assessment of the possible impacts of a 1-m sea
  level rise
• Implications of future development
• Possible responses to the problems caused by sea
  level rise

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Step 1 Collation of Existing Data

• Topographic surveys
• Aerial/remote sensing images topography/ land
  cover
• Coastal geomorphology classification
• Evidence of subsidence
• Long-term relative sea level rise
• Magnitude and damage caused by flooding
• Coastal erosion
• Population density
• Activities located on the coast (cities, ports,
  resort areas and tourist beaches, industrial and
  agricultural areas)

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Step 2 Assessment of Possible Impacts of 1-m Sea
Level Rise

• Four impacts are considered
• Increased storm flooding
• Beach/bluff erosion
• Wetland and mangrove inundation and loss
• Salt water intrusion

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Step 3 Implications of Future Developments

• New and existing river dams and impacts on
  downstream deltas
• New coastal settlements
• Expansion of coastal tourism
• Possibility of transmigration

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Step 4 Responses to the Sea Level Rise Impacts

• Planned retreat (i.e., setback of defenses)
• Accommodate (i.e., raise buildings above flood
  levels)
• Protect (i.e., hard and soft defenses, seawalls,
  beach nourishment)

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Screening Assessment Matrix Biophysical vs.
Socioeconomic Impacts
Biophysic-al Impact of Sea Level Rise Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts Socioeconomic impacts
Biophysic-al Impact of Sea Level Rise Tourism Human Settlements Agriculture Water Supply Fisheries Financial Services Human Health Others?
Inundation
Erosion
Flooding
Salinization
Others?
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Vulnerability Assessment
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The Coevolving Coastal System
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Barriers to Conducting Vulnerability Assessments

• Incomplete knowledge of the relevant processes
  affected by sea level rise and their interactions
• Insufficient data on existing physical conditions
• Difficulty in developing the local and regional
  scenarios of future changes
• Lack of appropriate analytical methodologies
• Variety of questions raised by different
  socio-political conditions

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Controls on Coastal Position
littoral sediment
sea-level
antecedent
change
supply (ve)
physiography
boundary conditions (external)
fluvial-delta inlet bypassing
C
D
resuspension inlet bypassing
mid-shelf mud
lagoon basin mud
lower shoreface
backbarrier
inner-shelf sand
marine sand wedge
B
A
cross-shelf
bypassing
upper
shoreface
transport
inlet
coastal tract
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Beach Erosion
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Bruun Rule
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Bruun Rule (continued)

• R G(L/H)S
• where H B h
• R shoreline recession due to a sea-level
  rise S
• h depth at the offshore boundary
• B appropriate land elevation
• L active profile width between boundaries
• G inverse of the overfill ratio

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Limitations of the Bruun Rule

• Only describes one of the processes affecting
  sandy beaches
• Indirect effect of mean sea level rise
• Estuaries and inlets maintain equilibrium
• Act as major sinks
• Sand eroded from adjacent coast
• Increased erosion rates
• Response time best applied over long timescales

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Flooding

• Increase in flood levels due to rise in sea level
• Increase in flood risk
• Increase in populations in coastal floodplain
• Adaptation
• Increase in flood protection
• Management and planning in floodplain

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Coastal Flood Plain
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Global Incidence of Flooding No Sea Level Rise
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20
People Flooded (Millions/yr)
10
0
1990
2020s
2050s
2080s
Time (years)
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Vulnerable RegionsMid-estimate (45 cm) by the
2080s
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Impacts of Flooding on Arable Agriculture in 2050
No Adaptation
Land unavailable for arable Agriculture ( cell)
Reference (1990)
Low climate change
High climate change
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Global Impacts of Coastal Flooding in 2050
Effects of Mitigation
People flooded (Millions/yr)
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The Thames Barrier
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Flood Methodology
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Ecosystem Loss

• Inundation and displacement of wetlands
• e.g., mangroves, saltmarsh, intertidal areas
• Areas provide
• Flood protection
• Nursery areas for fisheries
• Important for nature conservation
• Loss of valuable resources, tourism

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Coastal Ecosystems at Risk

• KEY
• mangroves, o saltmarsh, x coral reefs

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Coastal Squeeze (of coastal wetlands)
Sea Level Rise
(a) no hard defenses
(b) hard defenses
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Mangrove Swamp
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Areas Most Vulnerable to Coastal Wetland Loss
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Saltmarsh Losses to 2050
Present day loss rate
High Climate Change
Low Climate Change
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Wetland Loss Model Structure
Relative Rate of Sea Level Rise Scenarios
Tidal Range
Rate of Sea Level Rise Scenarios
Horizontal Migration Assessment
Vertical Wetland Response
No Loss
Coastal Geomorph-ology
Coastal Population Density
Migration Potential
Wetland Loss
Corrected wetland loss
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Wetland Vertical Response Model

• RSLR RSLR/TR
• where
• RSLR the rate of relative sea level rise
  (meters/century)
• TR the mean tidal range on spring tides
  in meters
• RSLR gt RSLRcrit loss
• RSLR RSLRcrit no loss

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Planning Assessment

• Ongoing investigation and formulation of policy
• Requires information on
• Role of major processes in sediment budget
• Including human influences
• Other climate change impacts
• Example of assessment from the UK
• Combined flood hazard and erosion assessment

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The ProblemCliff Protection Has Local and Wider
Effects
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ErosionOften Exported Alongshore
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Coastal Flood Risk Exacerbated by Declining
Sediment Input

• Beach evolution
• Defense degradation/upgrades
• Socioeconomic changes
• Sea level rise
• Increased storminess

Changing loads
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Goals for Planning Assessment

• For future climate and protection scenarios,
  explore interactions between cliff management and
  flood risk within sediment sub-cell (in Northeast
  Norfolk)
• In particular, quantify
• Cliff retreat and associated impacts
• Longshore sediment supply/beach size
• Flood risk
• Integrated flood and erosion assessment

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Method for Planning Assessment
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Bathymetry and Wave Modelling
Offshore sandbank
Nearshore sandbank
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SCAPE Model of Cliff Retreat
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Future PolicyMaintain Defenses, 6 mm/yr Sea
Level Rise
Sheringham Cromer Overstrand Trimmingham Mundes
ley Bacton Happisburgh
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Future PolicyAbandon All Defenses, 6 mm/yr Sea
Level Rise
Sheringham Cromer Overstrand Trimmingham Mundes
ley Bacton Happisburgh
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Policy ComparisonMaximum Retreat at Abandoned
Defenses
Hold existing defenses
Abandon all defenses
Sheringham Cromer Overstrand Trimmingham Mundes
ley Bacton Happisburgh
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Erosion Visualization Protection Abandoned (10
year time steps)
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Conclusions

• 45 sea-level/wave/protection scenario
  combinations assessed
• Used to assess implications for flood risk
• Data management, visualisation, and stakeholder
  involvement used
• Further improvements to the overall method are
  being developed

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Models

• DIVA Dynamic and Interaction Vulnerability
  Assessment
• Project DINAS-Coast
• RegIS2 Development of a metamodel tool for
  regional integrated climate change management
• COSMO
• RamCo

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Data Sources

• IPCC Data Distribution Centre
• Sea level data
• Permanent service for mean sea level
• GLOSS Global Sea-Level Observing System
• Remotely sensed data
• Land Processes Distributed Active Archive Centre
  (NASA)
• Shuttle radar topography mission

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GLOSS Tide Gauges
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GTOPO30Global Digital Elevation Model
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SRTM Data Morocco and Gibraltar (vertically
exaggerated)
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Data Sources

• Local observational data
• Sea level measurements
• Elevation/topography
• Wave recording
• Aerial photography
• Habitat mapping

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Concluding Remarks

• Sea level rise could be a serious problem, but
  the uncertainties are large
• Impacts are strongly influenced by human choice
• Reducing GHG emissions reduces but does not avoid
  sea level rise impacts
• Preparing to adapt would seem prudent, in the
  context of multiple stresses and managing
  existing problems

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