The questions diagnosed most of the existing concepts for moving strategies, but we found some inconsistencies. We aimed to create constructed types (related to Max Weber’s ideal types), where a tentative typology is proposed and then compared to empirical instances (Bailey, 1994). The constructed types are then revised to better capture “if and when” factors occur together within each type (Becker, 1950, p. 120). Our aim is not to create a set of moving typologies that are superior in all ways but to see whether concepts can be revised to distinguish who decides about moving and how they manage time and space. The next sections describe general findings from the diagnostic questions and then describe typologies of moving strategies.
6.1 Data analysis: Diagnostic questions
This section gives brief observations about each diagnostic question’s results. In asking whether the retreat and relocation were sponsored, we found that institutions usually sponsored only part of the moving process. Most sponsors organized retreats but not relocations. Sponsored retreat-only projects were not structured to monitor effects of the retreat beyond that site, to support people after they retreated, or to avoid harms at sites where they relocated. People affected by retreat-only projects usually handled their own (unsponsored) relocations. These findings led us to propose the typology of unsponsored retreats or relocations, described below.
Two other diagnostic questions showed how the spatial reach of sponsored retreat and relocation projects differed from the reach of sponsored retreat-only projects. Asking whether decisions about relocation were integrated with decisions about retreat showed that preventive resettlements and en group relocations could prepare relocation sites over time to be ready when people retreat. People who made planned unsponsored moves could also integrate their decisions to manage their access to spaces over time. In some cases, one set of institutions sponsored a retreat and other institutions joined later to assist relocations, especially after disasters. This suggests that one difficulty in managing space and time can be the handoff to other institutions. Asking whether the project aimed to keep neighbors together helped explain why it took years for en group relocations to find suitable relocation sites.
The question asking whether the project removed existing structures found few projects designed to do this. This question helped separate managed realignments, which remove structures, from managed retreats, preventive resettlements, and en group relocations. Cases that combined managed realignment with other strategies are discussed later. In a handful of cases, authorities had setback rules on the books and attempted to enforce those rules to trigger the retreat (Were trigger conditions preset? If yes, was trigger enforced to start the retreat?). To capture cases that created setback rules after a sudden disaster, we added the diagnostic question asking whether the project created or continued a prohibition on new development.
Asking whether the move was planned or sudden found several aspects of timing that could affect adaptation. The cases affirmed research findings that planned projects could phase actions over time and coordinate moving across space. But sudden retreats, with or without sponsors, affected much large sites than most planned retreats did. And in all cases, people retreated only after a site had been degraded, after sudden devastation, or after special funding became available for ecological restoration of a site. Waiting for conditions like these to spark action is not ideal for avoiding harms. Ongoing degradation that reduces soil productivity or the lot’s market value are slow retreats of social value are beyond the scope of this analysis but should be recognized.
6.2 Data analysis: typologies of moving strategies
The diagnostic questions showed how each strategy delimited its aims for managing time and space. As a group, the strategies were structured for three purposes for managing time and space: avoiding harms to the site after a retreat, avoiding harms to people who retreat, and avoiding harms to people and the environment at relocation sites (see Table 2). The next sections describe for each typology the questions that help diagnose it, its strategic purposes for managing time and space, difficulties in assigning cases to it, any findings that led us to revise it, and who typically used it. We then discuss how some projects combined two or more adaptation strategies, expanding their aims for managing space and time.
6.2.1 Avoidance, with setback rules
Several diagnostic questions neatly captured the formal avoidance strategy (see Table 1). Avoidance with setbacks is a sponsored retreat, in that it is required under law or custom, and it is planned, not sudden. It affects future uses by prohibiting new development and its preset triggers require existing structures be removed when water levels come too close. Avoidance with setback rules is structured for one of the three strategic purposes of moving strategies, avoiding harms to the site after a retreat (see Table 2). Avoidance with setback rules can indirectly advance another strategic purpose of reducing harms to people who retreat because it requires them to retreat before they face devastating damage, but its main purpose is to regulate land use at the site. Formal avoidance differs from other moving strategies because it is a policy regulating how land is used in across a region, not a project to retreat or relocate activities from a specific site. Our data fit coastal scientists’ definitions of this strategy (see Table 3). The diagnostic questions identified two ways people used setbacks.
Several sites presented textbook cases of avoidance with setbacks, where laws preventing structures in hazard zones were a condition of ownership. Most governments did not compensate owners when they ordered them to remove structures. In two exceptional cases in Australia (Byron Shire and Mokau Spit), courts found governments had permitted construction on highly erodible sites years ago, and they ordered the governments to compensate owners.
A second set of cases combined avoidance of future hazards with a strategy we present below, emergency sponsored retreat. In several cities or regions ruined by a cyclone, earthquake, or tsunami, governments mapped some damaged areas as no-build zones. In a few of these cases, governments attempted to enforce pre-existing setback rules they had failed to enforce before the disaster. In other cases, governments imposed new post-retreat avoidance zones. We discuss this set of cases further in the section on the emergency retreat strategy.
6.2.2 Managed realignment
The managed realignment strategy is also easily defined by several diagnostic questions (see Table 1). Managed realignment is a planned and sponsored retreat strategy design for same strategic purpose as setback rules, to avoid harms to the site after retreat (see Table 2). Our cases match definitions of the managed realignment strategy given in coastal science (see Table 3).
All realignments we collected removed government-installed protective barriers along government lands or along lands governments acquired from private owners. Managed realignments were costly projects involving coastal agencies and other sponsors such as parks agencies and nongovernmental environmental organizations. For instance, a German project in Sundische Meadow removed barrier protections, allowed the water to revitalize the ecology of the intertidal zone, and relocated hiking trails further inland within the park.
6.2.3 Managed retreat
While diagnosing strategies for managing the coastline was straightforward, it took several iterations to refine diagnostic questions separating the managed retreat of social uses of land from other strategies (see Table 1). Scholars agree that managed retreats are sponsored but debate other features. We included diagnostic questions that echo two lines of critique. The separate questions asking whether the retreat was sponsored and whether the relocation was sponsored reflect one critique that managed retreat is fundamentally different from en group relocation or communal relocation (Siders et al., 2019). A few managed retreat projects relocated structures within the same site, including the U.S. National Park Service’s building a custom track to move a lighthouse inland at Cape Hatteras. But in a managed retreat, institutions sponsored only the retreat from the shoreline; they did not sponsor relocating structures, people, or activities to nonadjacent sites. Asking whether a strategy was planned or done in response to an emergency reflects the second critique that managed retreats are planned, not sudden (O'Donnell, 2022). The managed retreat strategy is therefore built for the strategic purpose of avoiding harms to people who retreat, but it only covers the time period for the retreat (see Table 2). Rather than treating managed retreat as a catch-all term for sponsored projects, the diagnostic questions shift some approaches to the strategies of emergency sponsored retreat, preventive resettlement, or en group relocation (see Table 3).
The mix of sponsors for managed retreats depended on who owned, used, or had authority over the site. Managed retreats were done on clan lands, private lands, and government lands. Cases affecting clan lands were accessible to our sampling plan when external sponsors, scholars, or journalists had documented those projects. Other sponsors included highway departments, parks departments, and polder districts. Government sponsors that initiated a managed retreat claimed they were protecting a public function. For instance, national coastal agencies in Vietnam, the United Kingdom, and Germany organized retreats of farming and other activities along rural shores to create more sustainable coastlines.
Governments also ordered a stop to industrial groundwater extraction in Jakarta, moved a water treatment plant in Fiji, and rerouted a highway in California. In some locations where governments initiated a retreat, people at these locations reacted against the effort, asking for changes in project design or demanding compensation. In cases we collected, managed retreats started by governments were not triggered by setback rules. Instead, governments began these managed retreats when they decided hazards had become too great or when funding became available. The other managed retreats were initiated by groups directly affected by a hazardous site. Most of these groups attempted to attract external sponsors, although some later clashed with these sponsors. The diagnostic questions keep the managed retreat strategy true to its name, as a planned strategy for retreat.
6.2.4 Emergency sponsored retreat
The diagnostic questions led us to affirm emergency sponsored retreat as its own strategy (see Table 1). This strategy organizes the retreat only and is done suddenly, after an extreme geological or weather event. Governments use this ad hoc strategy to encourage permanent retreat from devastated sites after people have initially evacuated (see Table 3). Agencies that set up emergency sponsored retreats may provide temporary services and rules to keep people away. Other agencies and organizations handled longer-term recovery policies for housing, land use, or economic redevelopment. Because emergency sponsored retreats are reactive, they lacked mission statements and formal endpoints and could drag on, adding or dropping aims as they went. Even so, the strategy of emergency sponsored retreat is primarily structured for the strategic purpose of avoiding harms to people who retreat, not managing the retreat site or permanently relocating people who retreat (see Table 2).
Governments were the main sponsors of emergency retreats, using some combination of humanitarian disaster aid, regulating displaced people, keeping people away from the damaged site, building temporary housing, and compensating for property losses. Sponsorship under emergencies differed from managed retreats in several ways. Managed retreats handled ongoing and comparatively predictable risks that were salient to site users and to a range of potential sponsors. Emergency sponsored retreats happened after extreme and sudden events devastated sites in unpredictable ways, activating a small set of potential governmental and nongovernmental sponsors capable of responding quickly with social control tactics and logistical support.
In Tohoku, Japan, households, businesses, schools, and some emergency services attempted to get groups of people to higher ground just before the 2011 tsunami reached shore areas. Damage in some places was so complete that all landmarks were gone. Impromptu groups of civilians and emergency responders searched for survivors and provided immediate aid. Efforts we categorize under the emergency sponsored retreat strategy began with police marking off some damaged sites. Local, regional, and national governments provided compensation or temporary housing to encourage people not to return to the retreat sites, with local citizen groups adding to this transition aid. Long-term policies for permanent housing, land use, coastal planning, nuclear plant safety, schooling, and municipal re-population were created after these initial emergency retreat efforts.
Even well-assisted emergency sponsored retreats left little time to avoid placing people into new hazards, avoid harming people already at the relocation sites, or to create inclusive deliberations about rights and values that would integrate cultural values. A variety of governmental agencies and aid groups provided some temporary housing, as in Banda, Aceh, but housing was often inadequate. Temporary resettlement could intensify existing political or ethnic conflicts, as in Sri Lanka, where people the government had resettled one or more times during the long civil war were shifted again in an emergency sponsored retreat. Asking about sponsorship and about the timing of retreats shows that institutions make critical decisions about the future of sites, regions, and people when responding to emergencies.
6.2.5 Preventive resettlement and en group relocation
Preventive resettlement and en group relocation are diagnosed by the questions asking whether the retreat was sponsored, whether relocation was sponsored, whether decisions about relocation were integrated with decisions about retreat, whether the project was organized to keep neighbors together, and whether the move was planned (see Table 1). The cases fit research definitions of these strategies. Preventive resettlements are planned and sponsored retreats and relocations that integrate decisions about retreat and relocation; they do not aim to keep neighbors or other groups together in the relocation process (see Table 3). En group relocations are planned and sponsored projects that integrate decisions about retreat and relocation and are created specifically to keep groups together when they relocate (see Table 3).
Preventive resettlement and en group relocations are structured for two of the three strategic purposes, to avoid harms to people who retreat and to avoid harms to people and the environment at relocation sites (see Table 2). These two strategies are not structured to avoid harms to the site after the retreat, although some people making en group relocations kept attachments to the retreat sites. For example, in Isle de Jean Charles in Louisiana, members of the Biloxi-Chitimacha Confederation of Muskogees aim to retain claims to their community site because they fear the Louisiana state government might transfer the land to developers or oil companies.
Preventive resettlements are organized by institutions for economic development and aid, and the coastal resettlements in our dataset reflect the power imbalances found in other development projects. Preventive resettlements to nonadjacent sites were driven by the timing and aims of governments or other sponsors. Vietnam’s government stood out for its regular policy of removing deteriorating coastal barriers in rural areas and compelling peasants to build new dikes farther inland and to relocate (see Online Resource 2 for cases from Cho Moi, Hai Thrieu, and the general listing for several sites in Vietnam for rural cases; a proposed project for urban Da Nang would use different methods).
En group relocations were started by small rural communities of Indigenous peoples or other self-distinguished groups, and nearly all of these groups recruited outside sponsors to help them to move. En group relocation projects therefore emerged from existing institutions and practices devoted to social and cultural integrity. Some groups used formal tribal laws. Clans in Pacific Island nations including Kiribati and the Solomon Islands used well-established informal processes for reapportioning clan lands to select relocation sites. A project by the Guna people of Panama allows households on Gardi Sugdub Island to decide whether and when to move to a mainland site their tribe purchased for group relocation. Groups also try to secure livelihoods and safer living conditions by integrating decisions about retreat with decisions about relocation. For instance, several Alaska native villages set a policy to delay their retreats until they find physically and culturally suitable relocation sites, including sites within their customary ranges for fishing and hunting.
6.2.6 Unsponsored retreat or relocation, emergency or planned
Unsponsored retreats or relocations were simple to diagnose with the two questions about sponsorship (see Table 1). We included planned and sudden unsponsored retreats in one large typology because migration researchers find that the timing of permanent, temporary, or cyclic mobility by individuals or households is difficult to pin down. Unsponsored moves include efforts by individuals, households, firms, or other groups to use the moving strategy without formal sponsors. Many aspects of moving are unsponsored, as when an institution sponsors a retreat but does not coordinate how people relocate their activities (see Table 3). People who had a sponsored retreat but who were left to relocate on their own generally used the real estate market or social connections to relocate. Because sponsors and governments did not track these mechanisms, these relocations were socially less visible than the retreats. Unsponsored retreats or relocations are structured for the strategic purpose of avoiding harms to people who retreat (see Table 2).
People who made unsponsored retreats or relocations were, at one extreme, the rare owners who could plan and pay to move their own buildings intact and, at the other extreme, poor people who fled their residences or livelihoods after a sudden damaging event. One wealthy owner of a former lighthouse in the United Kingdom moved this residential building away from the cliff, on the same plot of land. In contrast, workers at the shrimping settlement of Manila Village in Louisiana who survived a hurricane lost their livelihoods, abandoned the site, and relocated on their own. The complexity of the timing and responsibility for decisions is apparent in Bangladesh and India along the Bay of Bengal (see Online Resource 2 for Khulna, Sagar Island; Satabhaya was a case of failed en group relocation in that region). Governments had long allowed or encouraged millions of people to settle on erodible chars (sandbank islands) that are constantly reshaped by rivers and typhoons. Changes in hydrology, illegal land seizures, mangrove destruction, on-land shrimp farming, and erosion from climate change have recently made it necessary for people to relocate their residences and livelihoods more often.
6.3 Combining strategies
People at many sites used more than one adaptation strategy at a time, expanding their project’s capability to manage time and space. We placed combination cases into one of the major typologies it used and described its other strategies in its listing in the Online Resource 2. Some projects combined a moving strategy with a protection or accommodation strategy, and some combined two moving strategies. Analyzing in detail how the protection and accommodation strategies affect management of time and space is beyond the aims of this study, but we comment here about one use of this combination that can complicate a move. We also describe combinations of moving strategies that were most common.
Unsponsored retreat or relocation happened alongside all other moving strategies, even the most lavishly sponsored projects. No one would expect or want a sponsor to manage all the losses people experience from a retreat or to buffer all problems of relocating. But the effects of these unsponsored elements of a move on the retreat site, the relocation sites, and in nearby regions were often unanticipated and unmonitored. Problems could occur at an intended retreat site because a sponsored moving project failed entirely, because some people refused to leave, or because some were unable to join or excluded from a sponsored retreat. People who stayed at an intended retreat site usually tried to use barrier or accommodation strategies, but authorities often treated them as complicating the management of the supposed retreat site. The effects of unsponsored moves, alone in or combination with sponsored moves, appeared difficult to track.
Some projects combined strategies that improved adaptation. Projects combining a managed retreat of social uses with managed realignment included sites at de Noordward in the Netherlands, Gleason Beach in California, and Hesketh Out Marsh West in the United Kingdom. In sites in Vietnam, the government required people to make managed retreats from some shore areas, but some of residents cultivated sections of protective mangroves, by themselves or with sponsorship nongovernmental organizations.
Other governments combined setback rules with an emergency sponsored retreat. After most emergency retreats, governments attempted to use setback rules or they designated the damaged areas as no-build zones. By using setbacks in these cases governments aimed to avoid having to provide services in the damaged zones. Christchurch made ambitious use of new avoidance zones, after severe damage from an earthquake and tsunami. It mapped zones at different risk levels, required full retreat from red zones and accommodation strategies in green zones, and it compensated residents and firms for some losses. But even in the well-resourced efforts of Christchurch and Tohoku, some residents refused to leave the red zones. In Banda Aceh and Tacloban, despite temporary housing, setback zones, and policing of the damaged sites, many people rebuilt at retreat sites, and governments gave up enforcing the setbacks.