Coastal areas are particularly vulnerable to the effects of climbing temperatures and climate change, including rising sea levels, amplified storm surges, and a greater frequency and intensity of storms. These can result in damaging erosion and flooding as well as a loss of natural habitat, damage to property and infrastructure, and population displacement. The ability of a community to successfully recover rather than simply react to such impacts, its “coastal resiliency”, is linked to the strengths and capacities of individuals, families, businesses, and other parts of a community. It is a societal, economic, and ecological issue. Being well informed, understanding the risks, adopting new planning and development practices to compensate for vulnerabilities, and preparing for the future consequences of climate change and other natural and human-induced perturbations will help a coastal municipality rebound more quickly, while supporting a healthy ocean, sustainable fisheries, and thriving economies.1
Common Strategies for Coastal Resiliency
Faced with sea level rise and the intensification of extreme events, human populations living on the coasts are developing various responses and adaptations to address local sea level rise, erosion, and coastal flooding situations. Four primary strategies are generally employed: protection (including advance), accommodation, managed retreat, and ecosystem-based adaptation.
- Hard protection, or “gray infrastructure” responses, include dikes and static seawalls that are effective in stabilizing the shoreline, but they can cause scour and destabilize the beach; groins and artificial headlands that intercept long-shore sand transport and are effective in building the beach updrift but induce scour and erosion downdrift; and detached breakwaters and artificial reefs that reduce wave activity and energy along the shoreline, and are effective in building beaches, but can produce downdrift erosion.2
- Responses known as soft protection include more adaptive strategies such as dune rehabilitation and sand nourishment, allowing the coast to respond dynamically to change, and representing an environmentally friendly protection response. However, accessibility to enough sand and the high costs of yearly beach nourishment efforts are problematic.
- Advance response refers to the creation of artificial land above sea level as a way to create new buildable areas. Its main advantage is the high accessibility of new sites, both by sea and by land, which is an asset for ports as well as residential and recreational development.3 Coastal cities can develop their waterfront or benefit from infrastructure with direct access to the ocean by building offshore, protecting themselves from the sea behind seawalls and dikes.4
- Another category of response is accommodation, which takes projected sea level rise into account when adapting existing infrastructure to changing climatic conditions. These coastal planning strategies are not homogeneous but rather encompass diverse methods with a common goal: mitigating coastal hazards. Rather than building infrastructure, accommodation responses comprise a variety of technological, architectural, and urban planning responses including technologies and innovations that physically modify exposed buildings or infrastructure by raising buildings, protecting them individually, adapting urban drainage systems,5 and/or developing floating housing.6 Also included are the development and dissemination of information systems, flood hazard mapping, contingency plans, and insurance systemization that improve understanding and awareness of coastal risks and enable the development of appropriate responses.
- While sea level rise will reshape coastal ecosystems and population distribution, managed retreat involves rethinking living on the coast by accepting that certain coastal infrastructure, neighborhoods, or even cities will need to relocate entirely. This response can take place at different scales and levels of complexity – resettling a few particularly exposed houses, relocating whole neighborhoods, moving large cities, or moving entire island populations to new host countries. The larger the geographic scale at which managed retreat is implemented, the more anticipatory planning and cooperation is needed.7, 8 This is complex and often highly controversial, both politically and socially, raising a range of social, cultural, psychological, and economic considerations.9
- Ecosystem-based adaptation (EbA) includes the restoration of salt marshes, mangroves, oyster beds, and coral reefs, allowing coastal ecosystems to mitigate marine flooding and coastal erosion and reduce risks for people living in coastal areas.10 These ecosystems provide multiple ecological functions, such as nursing grounds for fish and shellfish, resting places for migratory birds, and groundwater and surface water runoff filtration. However, implementing EbA requires a deep understanding of the ecology of the species involved and raises the risk of introducing new invasive species, especially under changing climatic conditions.11
Taken a step further, a “green” infrastructure approach to coastal improvement – a so-called “living shoreline” – can be created using plants, reefs, sand, and natural barriers to reduce erosion and flooding while maintaining natural shoreline processes. It also can lessen the associated impacts on human health and property. For example, restoring affected wetlands can reduce wave heights and property damage by buffering the velocity and intensity of waves. In contrast to hard structures such as bulkheads and sea walls, vegetative shorelines provide multiple ecosystem benefits, including improved water quality, aquatic habitat, and carbon sequestration.12
Given these various strategies to employ, coastal municipalities choose resiliency preferences based on their individual circumstances, including long-range socio-economic and ecological factors, not to mention funding availability, stakeholder engagement and political realities. There is no one-size-fits-all solution for climate change adaptation and sea level rise.
Hybrid approaches – a combination of natural and built infrastructure to protect coastlines from erosion and flooding – may be both useful and more cost-effective in the long-term. As an example, hybrid approaches developed in the U.S. after Hurricane Sandy combined many natural options (salt marsh restoration, rock groins, and oyster restoration) with infrastructure-based approaches, such as removable floodwalls and mobile floodgates that are only used when a storm is approaching.13
More generally, a combination of decision analysis, coastal land use planning, civic participation, economic incentives, scenario development, and conflict resolution can help address the complexity of implementing responses.
Finally, and importantly, coastal adaptation raises equity concerns, and requires ensuring that responses do not further marginalize the most vulnerable populations, especially in fast-growing cities in developing countries14 and in areas with large, existing wealth and resource gaps, which could trigger or aggravate social conflicts.15 Efforts to promote climate resilience should be undertaken alongside sustainable, just, and equitable development.
Other coastal resilient efforts outside of individual coastal community policies also exist in the U.S. such as:
1. State Programs
The Virginia Coastal Resilience Master Plan under the Virginia Department of Environmental Quality’s Coastal Zone Management Program.
2. Federal Legislation
H.R.3228 – National Coastal Resilience Data and Services Act 117th Congress (2021-2022) “To direct the Secretary of Commerce, acting through the Administrator of the National Oceanic and Atmospheric Administration, to improve science, data, and services that enable sound decision making in response to coastal flood risk, including impacts of sea level rise, storm events, changing Great Lakes water levels, and land subsidence.” (Introduced 05/13/2021)
3. Regional Planning
4. Non-Governmental Organizations
Coastal Resilience is a program led by The Nature Conservancy to examine nature’s role in reducing coastal flood risk. The program consists of a four-pronged approach (assessment of risk, identification of nature-based solutions, conservation and restoration actions, and measurement of effectiveness), a web-mapping tool, and a network of practitioners around the world supporting hazard mitigation and climate adaptation planning.
How Scout Can Help
A coastal resiliency plan at any level of governance will require the development of several reports, policy documents, surveys, studies, permits, and environmental site and impact assessments. Scout Environmental is experienced and well positioned to prepare the requisite environmental planning documents including Environmental Assessments (EA) and Environmental Impact Statements (EIS). Scout is equipped to oversee environmental surveys and studies, and to perform environmental compliance audits necessary for a coastal community to plan for sea-level rise and climate change impacts. Contact us at firstname.lastname@example.org.
1 https://oceanservice.noaa.gov/facts/resilience.html Accessed April 27, 2022.
2 Gracia, A., Rangel-Buitrago, N., Oakley, J. A., and Williams, A. T. (2018). Use of ecosystems in coastal erosion management. Ocean Coast. Manage. 156, 277–289.
3 Alves, B., Angnuureng, D. B., Morand, P., and Almar, R. (2020). A review on coastal erosion and flooding risks and best management practices in West Africa: What has been done and should be done. J. Coastal Conserv. 24:38.
4 Donchyts, G., Baart, F., Winsemius, H., Gorelick, N., Kwadijk, J., and van de Giesen, N. (2016). Earth’s surface water change over the past 30 years. Nat. Climate Change 6, 810–813.
5 Linham, M. M., and Nicholls, R. J. (2010). Technologies for climate change adaptation: Coastal erosion and flooding. Roskilde, Denmark: UNEP Riso Centre on Energy, Climate and Sustainable Development.
6 Thi Thu Trang, N. (2016). Architectural Approaches to a Sustainable Community with Floating Housing Units Adapted to Climate Change and Sea Level Rise in Vietnam. Int. J. Archit. Environ. Engin. 10, 168–179.
7 Haasnoot, M., Brown, S., Scussolini, P., Jimenez, J. A., Vafeidis, A. T., and Nicholls, R. J. (2019). Generic adaptation pathways for coastal archetypes under uncertain sea-level rise. Environ. Res. Commun. 1:071006.
8 Barnett, J., and O’Neill, S. (2012). Islands, resettlement, and adaptation. Nat. Climate Change 2, 8–10.
9 Abel, N., Gorddard, R., Harman, B., Leitch, A., Langridge, J., Ryan, A., et al. (2011). Sea level rise, coastal development, and planned retreat: Analytical framework, governance principles and an Australian case study. Environ. Sci. Policy 14, 279–288.
10 Barbier, E. B., Hacker, S. D., Kennedy, C., Koch, E. W., Stier, A. C., and Silliman, B. R. (2011). The value of estuarine and coastal ecosystem services. Ecol. Monogr. 81, 169–193.
11 David, A. A. (2020). Oyster reef restoration and biological invasions: An Overlooked or a Non-issue? Front. Mar. Sci. 7:544691.
12 https://www.epa.gov/wetlands/coastal-wetlands Accessed May 9, 2022.
13 Sutton-Grier, A. E., Wowk, K., and Bamford, H. (2015). Future of our coasts: The potential for natural and hybrid infrastructure to enhance the resilience of our coastal communities, economies and ecosystems. Environ. Sci. Policy 51, 137–148.
14 See, J., and Wilmsen, B. (2020). Just adaptation? Generating new vulnerabilities and shaping adaptive capacities through the politics of climate-related resettlement in a Philippine coastal city. Glob. Environ. Change 65:102188.
15 McGinlay, J., Jones, N., Clark, J., and Maguire-Rajpaul, V. A. (2021). Retreating coastline, retreating government? Managing sea level rise in an age of austerity. Ocean Coast. Manage. 204:105458.