Coastal Resilience through Hazard Mitigation
The focus of the research and planning methods presented here is on promoting coastal community resilience, with an emphasis on mitigating natural hazards. In coastal settings, that means reducing the risks along coastal shore fronts and within the riverine settings of nearshore coastal areas posed by the action of high-energy waves, wave-runup, and inundation especially during storm events.
In general, hazard mitigation efforts that communities can adopt to enhance coastal resilience range across a spectrum of approaches now commonly characterized as “preparation” (or resistance), “accommodation,” and “managed retreat.” In many instances, coastal resilience strategies employ a combination of approaches ranging across these categories:
- Preparation mitigates coastal risks using physical infrastructure or through habitat restoration. Examples of preparation commonly employed in Michigan include shoreline armoring, beach nourishment, and wetland restoration.
- Accommodation involves modifying the built environment or regulating infrastructure in a way that mitigates risk by keeping structures out of harm’s way, such as by elevating or floodproofing structures.
- Managed retreat coordinates the movement of private and public built assets away from impacts. Some examples of policy instruments typically used to facilitate managed retreat, but not necessarily used extensively or in a coordinated fashion in Michigan, include:
- The public funding and administration of voluntary shoreland property buyouts, in fee;
- Acquiring conservation easements (i.e., acquiring and retiring development rights over portions of shorefront properties);
- Adopting property setbacks through regulation; and
- Recognition of rolling easements through regulation (typically via state law, as opposed to local ordinance).
What is Scenario Planning?
In order to decide which of these approaches – or which combination of approaches – to adopt, a community needs to account for several things simultaneously, including:
- Uncertainties inherent in Great Lakes coastal settings, especially fluctuations in standing lake water levels and the frequency and severity of storms over time;
- Unique characteristics of its shoreland areas, including especially the presence of natural features like sandy beaches, sand dunes, wetlands, and so on;
- Current levels of buildout within the community, and current opportunities for additional buildout given existing zoning code requirements and other related regulations;
- The community’s collective vision on how best to balance its economic vitality, the property rights of shoreland property owners, and the natural features that sustain and define the community given natural coastal dynamics.
Doing all of these things requires innovative planning methods and the use of spatial mapping techniques that identify high risk areas according to the types and potential severity of the risks of concern.
The methods described in this report employ scenario planning, which offers a framework that allows a community to engage in creative visioning and a simplified yet robust analysis process to plan for the future given different uncertainties. Scenario planning provides a way to establish and compare plausible narratives for the future, accounting especially for uncertainties inherent in dynamic natural systems. Uncertainty in a planning setting is common, particularly when the planning issues are rooted in natural environmental processes like water level fluctuations on the Great Lakes. Unlike other techniques like forecasting, however, scenario planning does not try to predict the future. Rather, it seeks to simulate uncertain aspects about the future, and then articulate an array of reasonable potential futures from which decisions regarding those uncertainties can be framed and planned for by the community.(1)
Scenario planning helps navigate short- and long-term uncertainties because it plots different but reasonable future narratives against each other, and then allows for adaptive planning as the future unfolds. Narratives within any given scenario are based on valid economic, social, and environmental data about the present and projected future conditions, and consider multiple variables and perspectives. These narratives can help communities test policies, prioritize strategies, and demonstrate potential future conditions for the public.(2) This gives communities a way to process the uncertain future in the present.(3)
Scenario planning helps navigate short- and long-term uncertainties because it plots different but reasonable future narratives against each other, and then allows for adaptive planning as the future unfolds.
While the future may be uncertain and the dynamics involved complicated, there is some benefit to approaching decision-making in as simple and straightforward a way as possible. The planning methods presented here are based on a combination of three distinct high-hazard areas given potential ‘climate futures’ set against three sets of potential shoreland management approaches, yielding nine discrete scenarios that can be analyzed along a variety of dimensions for comparison, as detailed next.
Analyzing Potential Impacts: Methods
Land Use Mapping
Building upon the assessment of high risk coastal areas, the land use mapping component can be used to determine how a community’s building inventory might be affected given wave-action and flooding risks, both current and future.
Mapping a community’s land use variability requires at least three key maps:
- Current land use. The “current land use” map shows the present position of community assets, providing a baseline for comparison against future development patterns. This map also represents something like a control variable, demonstrating what would happen if the community experiences no changes in its built environment.
- Future land use under current zoning. The “full buildout – current zoning” model (also referred to as “full buildout” throughout the manual) projects a community’s future development based on its existing zoning code. This analysis allows residents to visualize what their future built environment might look like should the municipality allow development as provided by its current zoning scheme, without any modification to that scheme.
- Future land use under current zoning, with best management practices (BMPs). The “full buildout – BMP zoning” analysis is based on a community’s existing code, but it also incorporates “best management practices” (BMPs) that limit future development to certain areas to enable the conservation of natural areas or aid in flood mitigation, primarily through the use of setbacks.
It is important to emphasize that the build-out projections used for this analysis are not forecasts, but rather reasonable possibilities given a community’s existing zoning scheme. That is, the buildout projected using the current zoning scheme, and that projected with the incorporation of BMPs, would be allowed, and could potentially occur, under the terms of the code as it currently exists (or as potentially modified with BMPs). Nonetheless, even though the community’s zoning code may allow for a certain level of build-out, that full level of build-out may not necessarily occur. It is ultimately up to the community to determine its future land use, either by keeping current regulations as they are or by amending them over time in response to new knowledge and changed conditions. Knowing what a full build-out looks like using the current zoning code can help inform those future land use decisions.
Additionally, it is important to note that the full buildout and the BMP buildout projections are built on assumptions made by the analyst, based on some necessary interpretation of the community’s zoning code. Given this, it is vital that analysts consult with local officials, planning and zoning commissions, residents, planners, local community groups and other relevant stakeholders to ground-truth the buildout models early and often throughout the process. This will help ensure that the buildout models are reasonably accurate, as well as enabling more collaboration between different stakeholder groups during their preparation.
It is vital that analysts consult with local officials, planning and zoning commissions, residents, planners, local community groups, and other relevant stakeholders to ground-truth the buildout models early and often throughout the process.
Having created nine distinct scenarios based on combinations of climate futures (mapped spatially to show high-risk zones) and land management approaches, each of those scenarios can then be analyzed across a number of dimensions for comparison. The most straightforward comparisons are the numbers of structures at risk for each scenario (i.e., either structures currently existing or that might be built in the future), along with the estimated dollar values of those structures. In addition, more sophisticated or comprehensive assessments can be conducted for comparison as well, including assessments of environmental futures, community vulnerability, and so on.
Environmental Assessment
Analyzing the different environmental vulnerabilities that a community might encounter under the different climate futures and management options advances future resilient community planning goals. The environmental vulnerability assessment evaluates a community’s current development permissions and/or restrictions (which may or may not be detrimental to natural features) to guide suggested BMPs. These vulnerabilities can be further explored by assessing the different environmental impacts that could occur under each climate future and under each management option. By exploring where the environment is most vulnerable, or where environmental features like wetlands can best be used to absorb and mitigate potential flooding impacts, a community can create more informed and resilience-based long-term planning documents.
Community Vulnerability Assessment
A community vulnerability assessment is a context-sensitive analysis that can provide a community with valuable information about areas or populations that are most vulnerable to coastal hazards, climate change, and related impacts. Vulnerability includes the exposure of the natural and built landscape to different hazards, as well as an accounting of how sensitive a community or segments of a community are to the hazards identified. This assessment can help a community plan for these potential hazards and prioritize climate variability adaptation strategies.
Fiscal Impact Assessment
The purpose of a fiscal impact analysis (FIA) is to quantify the fiscal impacts of different development options under each climate future. For this scenario analysis, an FIA can examine the costs and benefits associated with each of the nine scenarios, allowing communities to make informed choices on how to guide their future growth. The FIA not only looks at issues of potentially lost revenue from property taxes, but also examines direct hazard impacts, such as potential structural damage. The FIA allows communities to compare the costs associated with each climate future and management option with pre-storm positive fiscal considerations, such as increased property taxes of waterfront houses. This analysis gives communities the ability to determine whether the benefits of certain development options outweigh the potential costs associated with the different climate futures.
Visualization
Visualizing the impact of climate change can be one of the most effective ways of communicating risks to citizens and public officials. Maps, graphics, aerial imagery, photographs, and other visualization tools let community members physically see how each climate future, when coupled with each management option, can affect a community. The power of this method comes in its ability to connect public officials and community members with data in a clear and concise way, empowering them to make informed, collaborative decisions about their community’s future.
Works Cited
(1) Scenario Planning. (n.d.). Retrieved November 18, 2020, from https://planning.org/knowledgebase/scenarioplanning/
(2) Holway, J., Gabbe, C. J., Hebbert, F., Lally, S., Mathews, R., Quay, R., & Policy, L. I. of L. (2012). Opening access to scenario planning tools. Policy Focus Report (p. 56). Retrieved from https://www. lincolninst.edu/pubs/2027_ Opening-Access-to-ScenarioPlanning-Tools
(3) Harwood, S. A. (2007). Using Scenarios to Build Planning Capacity. In L. D. Hopkins & M. Zapata (Authors), Engaging the future: Forecasts, scenarios, plans, and projects (pp. 135-154). Cambridge, MA: Lincoln Institute of Land Policy