Coastal Processes, Hazards, and Society

Selecting Strategies


Selecting Strategies

Communities can use two broad types of strategies for preparing for sea level rise and related hazards: structural and non-structural. Structural strategies involve direct manipulation of the coastal environment through the construction, removal, alteration, or restoration of coastal structures, including both human structures (such as homes, businesses, and sea walls) and natural structures (such as dunes, beaches, mangroves, and oyster beds). Non-structural strategies are changes to coastal policy that encourage citizens, businesses, and governments to take steps to protect themselves from sea level rise and related hazards, but do not require specific structural responses.

Structural Strategies

In Module 8, we explored various types of structural options for coastal protection, including hard and soft engineering. In Module 9, we explored several non-structural options that can be classified as managed retreat. In Module 10 we looked at smart building options, and in Module 12 we considered structural and non-structural mitigation policy. So, by now, you should have a good idea of the adaptation options available to a sea level rise planning group as they make their selections during the planning process.

Below, we have listed strategies and their potential costs and benefits.

Structural strategies for preparing for sea level rise and related hazards.
Hard Structures
Structure Type Potential costs Potential benefits
Dikes Vulnerable to wave action and erosion Excellent protection against storm surge and moderate sea level rise
Seawalls Expensive to build; enhances erosion on the seaward side of the wall; limits access to and views of the water Strong protection against storm surge, waves, and sea level rise
Breakwaters Provide only limited protection against storm surge and do not protect against sea level rise Protect against waves and erosion
Groins Encourage down-drift erosion Provide limited protection against waves; can encourage up-drift accretion of sand and sediment
Jetties Encourage down-drift erosion Stabilize and protect navigation channels at river mouths and tidal inlets
Structural strategies for preparing for sea level rise and related hazards.
Soft Structures
Structure Type Potential costs Potential benefits
Living shoreline Can be over-topped by high storm surge Strong protection against erosion, moderate protection against low storm surge and wave action; if not blocked by roads, buildings or other impermeable cover, can retreat shoreward with sea level rise
Dune restoration Subject to erosion, may periodically require expensive re-nourishment with sand Provides strong protection against waves, most storm surge, and moderate sea level rise
Structural strategies for preparing for sea level rise and related hazards.
Managed retreat / multi-layered protection
Structure Type Potential costs Potential benefits
Managed retreat Moving or demolishing the most vulnerable structures can be very financially expensive and can damage the local community and economy if not done with care and sensitivity Can significantly reduce potential loss of life and property by moving homes and business out of the most exposed locations
Multi-layered protection Generally more expensive and complicated to implement than single-layer strategies Can significantly reduce exposure compared to single-layer strategies
Structural strategies for preparing for sea level rise and related hazards.
Smart Building
Structure Type Potential costs Potential benefits
Elevated construction May not protect against waves; can add significantly to cost of construction Protects against storm surge, applicable to many different building types
Floating construction Does not protect against wave damage; difficult to implement for many building types; difficult to connect utilities Strong protection against storm surge and gradual sea level rise

Non-Structural Strategies

Non-structural Strategies
Non-structural strategy Potential Costs Potential Benefits
Insurance Can encourage those who can afford premiums to remain in high-risk areas Supports disaster recovery; can incentivize structural protections or retreat
Zoning Rezoning or establishing special sea level rise overlay zones can be politically contentious, depending on the prohibitions and restrictions proposed for the new zones; zoning allowing or encouraging hard armoring can cause erosion and other negative environmental effects Flexible tool that can prohibit new construction, rebuilding, or renovation in high risk areas; protect environmentally sensitive areas; or specify the types of structural protections that may be used in an area
Flood plain regulation Often used to enforce building codes but not for more protective prohibitions/restrictions on construction; National Flood Insurance Program (NFIP) flood plain zones are based on historical flooding and do not account for sea level rise Can be used to restrict what can be built in flood plains and/or how such structures can be built (e.g., elevation and anchoring requirements); required for community participation in NFIP
Building codes Can be costly when retrofitting existing development; may provide inadequate protection for extreme sea level rise-enhanced storm surge events Easy to implement for new development; can reduce insurance premiums
Tax breaks Can reduce tax revenue Can provide politically popular incentive to steer development away from high-risk areas
Direct payments Direct payments for acquiring high-risk properties can be expensive; some property holders may not be willing to sell Purchased land can be used for environmental restoration and can provide buffer against surge and erosion for adjacent properties
Real estate disclosures Requires expensive sea level rise modeling to determine geographic extent of notification requirement; may reduce property values Can discourage development in high-risk areas; can encourage buyers/developers to adopt flood protection measures

Source: Non-structural strategies for preparing for sea level rise and related hazards. Costs and benefits based on Georgetown Climate Center’s Adaptation Tool Kit

Other Policy Options

Coastal communities also have several other non-structural policy options. They can use land-use management – including zoning and flood plain regulations – to limit or prohibit construction of new buildings (or post-disaster reconstruction of old ones) in areas where the risk of flooding due to sea level rise and related hazards is particularly high. Building codes can be used to require all new construction in high-risk areas to adopt specific structural improvements, such as elevating to a specific height on stilts or pilings. Communities can offer residents tax breaks or direct payments to restore natural shoreline protections, elevate or harden their homes or businesses, or move their homes and businesses to safer areas further inland. Communities can also require local real estate agents to disclose a property’s potential exposure to sea level rise and related hazards to any potential buyers. Such disclosure requirements can dissuade less risk-tolerant buyers from choosing property near the coast, but it may also reduce the value of property for current coastal landowners.

The next section describes how communities and their stakeholders can use cost-benefit analysis to rule out strategies that are not viable and arrive at a short list of strategies that are both suitable and desirable.