Vulnerability and Adaptation Assessments Hands-On Training Workshop Coastal

Vulnerability and Adaptation Assessments Hands-On Training Workshop Coastal Resources: Analytical Approaches 1 A. 1

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

Outline n Methods to assess impacts of sea level rise n n n (continued) Levels of assessment n Screening n Vulnerability n Planning Review of African region situation Models Data sources DIVA

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

The Main Biophysical Effects of Relative Sea Level Rise 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). Other relevant factors Biogeophysical effect Climate Inundation, flood and storm damage Nonclimate 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) CO 2 fertilization Sediment supply, migration space, direct destruction Erosion Sediment supply, wave and storm climate Sediment supply Surface waters Runoff Catchment management and land use Groundwater Rainfall Land use, aquifer use Saltwater intrusion Rising water tables/impeded drainage

Some Climate Change Factors 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) 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 CO 2 Increased productivity in coastal ecosystems; decreased Ca. CO 3 saturation impacts on coral reefs

Current Global Predictions of Sea Level Rise n n n 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

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

Processes Controlling Sea-Level Change n Relative sea-level changes

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

Uncertainty in Local Predictions n Relative sea level rise: global and regional components plus land movement n n n 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 additional component)

Sea Level Rise at New York City 1850 to 2100 IPCC TAR range due to SRES emission scenarios Mc. Carthy et al. , 2001

Land Subsidence

Other Climate Change (Hurricane Katrina)

Elevation and Population Density Maps for Southeast Asia

Population and Population Density vs. Distance and Elevation in 1990

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

National Vulnerability Profiles

Deltaic Regions

Atolls

Biogeophysical Effects of Sea Level Rise n n n Displacement of coastal lowlands and wetlands Increased coastal erosion Increased flooding (frequency and depth) Salinization of surface and groundwaters Plus others

Socioeconomic Impacts n n n 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

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

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 No active intervention Reversing maladaptive trends (Project appraisal methods) Improving awareness and preparedness (Flood plain mapping and flood warnings)

Responding to Coastal Change (including sea level rise) n Retreat n Accommodation n Protect n n Soft Hard

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 No active intervention Reversing maladaptive trends (Project appraisal methods) Improving awareness and preparedness (Flood plain mapping and flood warnings)

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

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

Example Approach to Adaptation Measures n n Caribbean small island developing country Climate change predictions n n Rise in sea level Increase in number and intensity of tropical weather systems Increase in severity of storm surges Changes in rainfall

Example Approach to Adaptation Measures (continued) n Coastal impacts n n n n 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

Example Approach to Adaptation Measures (continued) n Adaptation (retreat, protect, accommodate) n n n 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

Methods to Assess Impacts of Sea Level Rise n n Sea level rise scenarios Levels of assessment n n n Screening assessment Vulnerability assessment Erosion Flooding Coastal wetland loss Planning assessment

Coastal Vulnerability and Risk Assessment n Three levels of assessment n n n Screening assessment (3 -6 months) Vulnerability assessment (1 -2 years) Planning assessment (ongoing)

Screening Assessment n n n n 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

Step 1: Collation of Existing Data n n n n n 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)

Step 2: Assessment of Possible Impacts of 1 -m Sea Level Rise n Four impacts are considered n Increased storm flooding n Beach/bluff erosion n Wetland mangrove inundation and loss n Salt water intrusion

Step 3: Implications of Future Developments n n New and existing river dams and impacts on downstream deltas New coastal settlements Expansion of coastal tourism Possibility of transmigration

Step 4: Responses to the Sea Level Rise Impacts n n n 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)

Screening Assessment Matrix Biophysical vs. Socioeconomic Impacts Biophysical Impact of Sea Level Rise Tourism Human Settlements Inundation Erosion Flooding Salinization Others? Socioeconomic impacts Agriculture Water Supply Fisheries Financial Services Human Health Others?

Vulnerability Assessment

The Coevolving Coastal System Historic SENSITIVITY ADAPTIVE CAPACITY EXPOSURE NATURAL SYSTEM BOUNDARY CONDITIONS SENSITIVITY EXPOSURE ADAPTIVE CAPACITY SOCIOECONOMIC SYSTEM Future

Barriers to Conducting Vulnerability Assessments n n n 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 sociopolitical conditions

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

Beach Erosion

Bruun Rule

Bruun Rule n where: n n n (continued) R = G(L/H)S 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

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

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

Coastal Flood Plain

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

Vulnerable Regions Mid-estimate (45 cm) by the 2080 s

Impacts of Flooding on Arable Agriculture in 2050 – No Adaptation Reference (1990) Low climate change Land unavailable for arable Agriculture (% cell) High climate change

Global Impacts of Coastal Flooding in 2050 – Effects of Mitigation People flooded (Millions/yr)

The Thames Barrier

Flood Methodology

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

Coastal Ecosystems at Risk n n KEY: mangroves, o saltmarsh, x coral reefs

Coastal Squeeze (of coastal wetlands) Sea Level Rise (a) no hard defenses (b) hard defenses

Mangrove Swamp

Areas Most Vulnerable to Coastal Wetland Loss

Saltmarsh Losses to 2050 Present day loss rate Low Climate Change High Climate Change

Wetland Loss Model Structure Tidal Range Horizontal Migration Assessment Coastal Geomorph -ology Coastal Population Density Migration Potential Relative Rate of Sea Level Rise Scenarios Vertical Wetland Response Wetland Loss Corrected wetland loss No Loss

Wetland Vertical Response Model RSLR* = RSLR/TR where: RSLR = TR = the rate of relative sea level rise (meters/century) the mean tidal range on spring tides in meters RSLR* > RSLR*crit RSLR* ≤ RSLR*crit loss no loss

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

The Problem Cliff Protection Has Local and Wider Effects

Erosion Often Exported Alongshore

Coastal Flood Risk Exacerbated by Declining Sediment Input n Sediments Changing impacts Beach evolution Defense degradation/upgrades Changing n loads n Socioeconomic changes n Sea level rise n Increased storminess

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

Method for Planning Assessment

Bathymetry and Wave Modelling Offshore sandbank Nearshore sandbank

SCAPE Model of Cliff Retreat

Future Policy Maintain Defenses, 6 mm/yr Sea Level Rise Sheringham Cromer Overstrand Trimmingham Mundesley Bacton Happisburgh

Future Policy Abandon All Defenses, 6 mm/yr Sea Level Rise Sheringham Cromer Overstrand Trimmingham Mundesley Bacton Happisburgh

Policy Comparison Maximum Retreat at Abandoned Defenses Hold existing defenses Abandon all defenses Sheringham Cromer Overstrand Trimmingham Mundesley Bacton Happisburgh

Erosion Visualization Protection Abandoned (10 year time steps)

Conclusions n n 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

Models n DIVA: Dynamic and Interaction Vulnerability Assessment n n Project: DINAS-Coast Reg. IS 2 : Development of a metamodel tool for regional integrated climate change management COSMO Ram. Co

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

GLOSS Tide Gauges

GTOPO 30 Global Digital Elevation Model

SRTM Data – Morocco and Gibraltar (vertically exaggerated)

Data Sources n Local observational data n n n Sea level measurements Elevation/topography Wave recording Aerial photography Habitat mapping

Concluding Remarks n n 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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