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  1. Vulnerability and Adaptation Assessments Hands-On Training WorkshopCoastal Resources: Analytical Approaches

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

  3. 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

  4. 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

  5. Table 5.2. The main biophysical effects of relative sea level rise, including relevant interacting factors. Some factors (e.g., sediment supply) appear twice because they may be influenced by both climate and nonclimate factors (adapted from Nicholls, 2002). Biogeophysical effect Other relevant factors Climate Nonclimate Inundation, flood and storm damage Surge Wave and storm climate, morphological changes, sediment supply Sediment supply, flood management, morphological changes, land claim Backwater effect (river) Runoff Catchment management and land use Wetland loss (and change) CO2 fertilization Sediment supply Sediment supply, migration space, direct destruction Erosion Sediment supply, wave and storm climate Sediment supply Saltwater intrusion Surface waters Runoff Catchment management and land use Groundwater Rainfall Land use, aquifer use Rising water tables/impeded drainage Rainfall Land use, aquifer use The Main Biophysical Effects of Relative Sea Level Rise

  6. Table 5.1. Some climate change and related factors relevant to coasts and their biogeophysical effects (taken from Nicholls, 2002) Climate factor Direction of change Biogeophysical effects Sea water temperature (of surface waters) Increase Increased coral bleaching; migration of coastal species toward higher latitudes; decreased incidence of sea ice at higher latitudes Precipitation intensity/run-off Intensified hydrological cycle, with wide regional variations Changed fluvial sediment supply; changed flood risk in coastal lowlands; but also consider catchment management Wave climate Poorly known, but significant temporal and spatial variability expected Changed patterns of erosion and accretion; changed storm impacts Storm track, frequency, and intensity Poorly known, but significant temporal and spatial variability expected Changed occurrence of storm flooding and storm damage Atmospheric CO2 Increase Increased productivity in coastal ecosystems; decreased CaCO3 saturation impacts on coral reefs Some Climate Change Factors

  7. 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

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

  9. Processes Controlling Sea-LevelChange • Relative sea-level changes

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

  11. 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)

  12. Sea Level Rise at New York City1850 to 2100 IPCC TAR range due to SRES emission scenarios McCarthy et al., 2001

  13. Land Subsidence

  14. Other Climate Change(Hurricane Katrina)

  15. Elevation and Population Density Maps for Southeast Asia

  16. Population and Population Density vs. Distance and Elevationin 1990

  17. Tianjin Dhaka Seoul Osaka Istanbul Tokyo New York Shanghai Los Angeles Manila Bangkok Lagos Mumbai Lima Karachi Madras Jakarta Rio de Janeiro Buenos Aires Calcutta Coastal Megacities (>8 million people)Forecast for 2010

  18. National Vulnerability Profiles

  19. Deltaic Regions

  20. Atolls

  21. 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

  22. 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

  23. Sea level rise Potential impacts Anticipatory adaptation Initial impacts Reactive adaptation Residual impacts Definition of Impacts

  24. Shoreline Management and Adaptation

  25. Responding to Coastal Change(including sea level rise) • Retreat • Accommodation • Protect • Soft • Hard

  26. Shoreline Management and Adaptation (2)

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

  28. Adaptation Methods (continued) • Protect • Hard options • Revetments, breakwaters, groins • Floodgates, tidal barriers • Soft options • Beach/wetland nourishment • Dune restoration

  29. 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

  30. 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

  31. 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

  32. 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

  33. Coastal Vulnerability andRisk Assessment • Three levels of assessment • Screening assessment (3-6 months) • Vulnerability assessment (1-2 years) • Planning assessment (ongoing)

  34. 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

  35. 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)

  36. 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

  37. 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

  38. 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)

  39. Screening Assessment Matrix Biophysical vs. Socioeconomic Impacts

  40. Vulnerability Assessment


  42. 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

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

  44. Beach Erosion

  45. Bruun Rule

  46. 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

  47. 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

  48. 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

  49. Coastal Flood Plain

  50. Global Incidence of Flooding No Sea Level Rise 30 20 People Flooded (Millions/yr) 10 0 1990 2020s 2050s 2080s Time (years)