DEFINITION FROM WIKI (understand and write it yourself)

In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbanceby resisting damage and recovering quickly. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms, insect population explosions, and human activities such as deforestation and the introduction of exotic plant or animal species. Disturbances of sufficient magnitudeor duration can profoundly affect an ecosystem and may force an ecosystem to reach a threshold beyond which a different regime of processes and structures predominates.Human activities that adversely affect ecosystem resilience such as reduction of biodiversity, exploitation of natural resources,pollution, land-use, and anthropogenic climate change are increasingly causing regime shifts in ecosystems, often to less desirable and degraded conditions. Interdisciplinary discourse on resilience now includes consideration of the interactions of humans and ecosystems via socio-ecological systems, and the need for shift from the maximum sustainable yield paradigm to environmental management which aims to build ecological resilience through "resilience analysis, adaptive resource management, and adaptive governance".

The concept of resilience in ecological systems was first introduced by the Canadian ecologist C.S. Holling in order to describe the persistence of natural systems in the face of changes in ecosystem variables due to natural or anthropogenic causes. Resilience has been defined in two ways in ecological literature: 1. as the time required for an ecosystem to return to an equilibrium or steady-state following a perturbation (which is also defined as stability by some authors). This definition of resilience is used in other fields such as physics and engineering, and hence has been termed ‘engineering resilience’ by Holling. 2. as "the capacity of a system to absorb disturbance and reorganize while undergoing change so as to still retain essentially the same function, structure, identity, and feedbacks".

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Human impacts on resilience
Resilience refers to ecosystem's stability and capability of tolerating disturbance and restoring itself. If the disturbance is of sufficient magnitude or duration, a threshold may be reached where the ecosystem undergoes a regime shift, possibly permanently. Sustainable use of environmental goods and services requires understanding and consideration of the resilience of the ecosystem and its limits. However, the elements which influence ecosystem resilience are complicated. For example various elements such as the water cycle, fertility, biodiversity, plant diversity and climate, interact fiercely and affect different systems.
There are many areas where human activity impacts upon and is also dependent upon the resilience of terrestrial, aquatic and marine ecosystems. These include agriculture, deforestation, pollution, mining, recreation, overfishing, dumping of waste into the sea and climate change
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Resilience and sustainable development
There is increasing awareness that a greater understanding and emphasis of ecosystem resilience is required to reach the goal of sustainable development.A similar conclusion is drawn by Perman et al. who use resilience to describe one of 6 concepts of sustainability; "A sustainable state is one which satisfies minimum conditions for ecosystem resilience through time

ABSTRACT
Human adaptation remains an insufficiently studied part of the subject of climate change. This paper examines the questions of adaptation and change in terms of social-ecological resilience using lessons from a place-specific case study. . Short-term responses to changes in land-based activities, which are identified as coping mechanisms, are one component of this adaptive capacity. The second component is related to cultural and ecological adaptations of the Inuvialuit for life in a highly variable and uncertain environment; these represent long-term adaptive strategies. These two types of strategies are, in fact, on a continuum in space and time. This study suggests new ways in which theory and practice can be combined by showing how societies may adapt to climate change at multiple scales. Switching species and adjusting the "where, when, and how" of hunting are examples of shorter-term responses. On the other hand, adaptations such as flexibility in seasonal hunting patterns, traditional knowledge that allows the community to diversity hunting activities, networks for sharing food and other resources, and intercommunity trade are longer-term, culturally ingrained mechanisms. Individuals, households, and the community as a whole also provide feedback on their responses to change. Newly developing co-management institutions create additional linkages for feedback across different levels, enhancing the capacity for learning and self-organization of the local inhabitants and making it possible for them to transmit community concerns to regional, national, and international levels.

INTRODUCTION
The debate on climate change has only recently begun to take into account issues related to human response or adaptation (Smithers and Smit 1997), and the present agenda for research on climate change is still not devoting much attention to the question of adaptation (Wilbanks and Kates 1999). The word "adaptation" figures prominently in the titles of some of the major publications in this area (e.g., Watson et al. 1996), but not in their contents. "There is thus a grave mismatch between the knowledge that is needed to act locally and what is currently being done globally to generate knowledge about climate change, its impacts, and responses to concerns ... " (Wilbanks and Kates 1999:616). Limits to our current levels of adaptation to existing climatic variation are demonstrated by the impacts and costs to society associated with events such as floods, ice storms, droughts, and hurricanes. All societies have to face extreme events, and societies and economies evolve with the fluctuations of their climatic environment. Probably the largest body of literature on how societies deal with climate change is in the fields of history and archaeology (McIntosh et al. 2000).
Although history is instructive, there is also a need to carry out place-specific analyses of adaptation to climate change in the present-day world. This is because the inevitable surprises of climate change will unfold on a regional and local stage where adaptive response becomes central (Holling 1997). Understanding the dynamic interaction between nature and society requires case studies situated in particular places and cultures. The outcomes of stresses such as climate change may be addressed by " ... integrated place-based models that employ semi-quantitative representations of entire classes of dynamic behavior ... " (Friibergh Workshop on Sustainability Science 2000). Research of this type must be created through a process by which researchers and local stakeholders interact to define important questions, relevant evidence, and convincing forms of argument (Friibergh Workshop on Sustainability Science 2000).
There are three reasons why the Arctic is one of the best places to study human adaptations to climate change. First, it is expected that the effects of climate change will be felt earlier and more keenly in the polar latitudes than elsewhere in the world. Above-average temperature increases are projected for northwest Canada and Alaska, with high regional variability (Maxwell 1997). The western Arctic rim of North America is the "miner's canary" that exhibits the early warning signs of global climate change. Second, the peoples of the Arctic have always lived with a high degree of environmental variability, and the capacity to adapt to extreme variability is part of Inuit culture (Balikci 1968, Langdon 1995). The "flexibility" of social relations in Inuit culture is often explained by scholars in terms of ecological adaptiveness (Freeman 1996). Third, there has been a growing body of participatory research in the Canadian Arctic since the 1980s, in areas ranging from wildlife co-management to the use of traditional knowledge in environmental assessment (Berkes et al. 2001).
In our previous work, we provided some examples of how communities in the Canadian North were responding to large-scale alterations of the environment, and the ways in which the systems that allow them to make their livelihoods on the land might be vulnerable to change. Their experience indicates that increased variability and the greater frequency of extreme events create adaptation problems because they interfere with the ability of people to access resources on the land, making resource availability itself less predictable (Fast and Berkes 1998). We suggested ways in which traditional knowledge in northern communities might complement our western science-based understanding of climate change in the Arctic, and argued that local observations and knowledge were essential for comprehending the effects of climate change on communities such as Sachs Harbour in the Canadian western Arctic (Riedlinger and Berkes 2001).
In this paper, we analyze the adaptive capacity of the community of Sachs Harbour to deal with climate change. One component of this adaptive capacity is the actual response to change; we identify these responses as coping strategies. A second component is related to Inuit adaptations for life in a highly variable and uncertain environment; these we consider long-term adaptive strategies. We deal with the adaptation of the integrated social-ecological system, and we analyze change through the lens of resilience.
To clarify our terminology, we use the term "adaptive" in the usual evolutionary ecological sense to mean any response that increases a population's probability of survival. We distinguish between coping mechanisms and adaptive strategies in accordance with the terminology commonly used in anthropology (e.g., McCay 1978) and the development literature (Davies 1993, Singh and Titi 1994). Coping mechanisms are the bundle of short-term responses to situations that threaten livelihood systems, and they often take the form of emergency responses in abnormal seasons or years. Adaptive strategies, on the other hand, are the ways in which individuals, households, and communities change their productive activities and modify local rules and institutions to secure livelihoods. The two kinds of responses may overlap across the temporal scale, and coping mechanisms may develop into adaptive strategies over time. Coping mechanisms are more likely to emerge at the level of the individual and the household and at smaller spatial scales, whereas adaptive strategies, which are related to variables such as cultural values that change more slowly, are more likely to emerge at larger spatial scales. Explicit attention to these two kinds of responses helps highlight the multiscale nature of the problem of change.
The scope of our study is the response related to the land-based activities of the people of Sachs Harbour, who live in a mixed economy (wage income, transfer payments, and subsistence harvesting) and who have continued to obtain much of their protein from hunting and fishing activities, as do many communities in the Canadian North (Berkes and Fast 1996). This focus on land-based activities makes good analytical use of the integrated concept of humans-in-nature or the social-ecological system as defined by Berkes and Folke (1998). Note that we are not focusing exclusively on environmental change or on social change, but rather on changes in the social-ecological system.
We assess change in terms of the organizing concept of resilience, which has three defining characteristics. It is a measure of (1) the amount of change the system can undergo and still retain the same controls on function and structure, (2) the degree to which the system is capable of self-organization, and (3) the community's ability to build and increase its capacity for learning and adaptation (Resilience Alliance 2001). The terms "self-organization," "learning," and "adaptation," which are important for our arguments, are those defined by the Resilience Alliance (www.resalliance.org). Although the concept of resilience is most commonly used in the study of ecosystem dynamics (Holling 1973), it can also be applied to social systems (Adger 2000, Adger et al. 2001), social-ecological systems (Gunderson et al. 1995, Berkes and Folke 1998, Gunderson and Holling 2001), and the study of global change (Holling 1997).
In this paper, we first illustrate a method of carrying out place- and culture-specific research into climate change by means of participatory methodologies and a way of using resilience thinking to explore the issue of adaptation to climate change. We investigate how human societies deal with change in social-ecological systems, and we also seek to generate insights for the use of coping strategies and available adaptive strategies to build the capacity to adapt to change. To address these questions, we use the place-specific case of climate change in an Arctic community.

A MODEL OF A COMMUNITY RESEARCH PARTNERSHIP
This paper is based on "Inuit Observations of Climate Change," a collaborative project carried out by the Inuvialuit people of Sachs Harbour and the International Institute for Sustainable Development (IISD). The project setting was the community of Sachs Harbour on Banks Island in the Canadian western Arctic. Sachs Harbour is the smallest of the six Inuvialuit (western Arctic Inuit) communities in the region covered by a comprehensive land claims agreement, the Inuvialuit Final Agreement, also known as the Inuvialuit Final Agreement of 1984 (Fast et al. 2000). Sachs Harbour, which has been a permanent settlement since only 1956, is an outgrowth of the white fox trade that began in the 1920s. The current residents are descendants of the Mackenzie Delta people to the south, the Inupiat (Alaska Inuit) to the west, and the Copper Eskimo of Victoria Island to the east (Usher 1970).
The project's objectives were to produce a video on how climate change is affecting Sachs Harbour residents, to educate southern Canadians and decision makers regarding climate change, to document Inuvialuit knowledge of climate change, and to explore the potential contributions of traditional knowledge to climate change research (Ford 1999, Riedlinger 1999).
The results are based on a study of Sachs Harbour that covered all four seasons during a 12-month cycle in 1999–2000, plus a follow-up visit for verification and project evaluation. The larger project team included the organizers from the IISD, a film crew that documented Inuvialuit perspectives on video, technical experts who conducted science interviews on the more specialized areas of change (e.g., sea ice, permafrost geology, and terrestrial wildlife), local experts and liaison people from the Inuvialuit region (including the project's scientific coordinator), and a university team. The university team was responsible for leading the traditional knowledge component of the study, arranging follow-up visits by the project team, conducting longer-term field work in the community, and providing documentation.
The project was initiated by Sachs Harbour, a tiny community of some 30 households, through their representative, who had served as a national leader for the Canadian Inuit. A total of 13 households participated directly throughout the project by taking part in its main components (the planning workshop, the video, and the science interviews) and by guiding project team members on the land; many other local people participated indirectly. The 13 households represent the full population, not just a sample, of elders and hunters whose families are active harvesters who spend significant amounts of time on the land. The Sachs Harbour residents involved in the study were those considered by the rest of the community to be the local experts on climate-related change.
The project design was based on participatory methodologies that were intended to facilitate collaboration and provide the most accurate reflection of Inuvialuit observations and perspectives (Ford 1999). The methods used drew on a series of techniques developed by the project leader based on the ZOPP (Ziel Orientierte Projekt Planung, or Objectives Oriented Planning) approach, in addition to established approaches such as Participatory Rural Appraisal (Ford 1999). The research process was inclusive, i.e., open to participation by all; all the elders were included, and gender representation was balanced.
One of the key features of the project was the initial planning workshop, in which the people of Sachs Harbour were asked to tell the researchers what they considered important. The priority issues, research questions, plans for the video, and the overall process for the project were defined in partnership by the project personnel and the community. The climate change video, a main output of the project, was also used for community feedback and for the verification of findings. Interviews allowed people to explain their more detailed observations and to interact with western scientists with expertise in specific areas (Ford 1999).
Considering the project as a model research partnership, some of its most relevant features were the planning workshop; repeat visits to the community that focused on activities appropriate for that season; the reporting of the results back to the community in the form of videos, trip reports, and newsletters; and the continuity provided by two members of the team who took part in all four trips and stayed for longer periods. Information was collected using a variety of interlinked participatory methodologies: brainstorming workshops, focus groups, video interviews, and individual semidirective interviews. Also used was participant observation, a very important methodology from the point of view of the Sachs Harbour Inuvialuit because "going on the land" is how people are supposed to learn about the environment.

CHANGES AND THE ANNUAL HARVESTING CYCLE
The observations of Sachs Harbour hunters and elders were remarkably consistent in providing tangible evidence of climate change. The changes observed in the 1990s were said to be without precedent and outside the range of variation that the Inuvialuit consider normal. The changes reported involved the extent of sea ice, the timing and intensity of weather events, fish and wildlife distribution, permafrost depth, and soil erosion. A summary of these changes and their impacts on land-based activities may be found in Table 1. More detailed results of the community's observations of climate change have been reported elsewhere (Ford 1999, Riedlinger 1999, Riedlinger and Berkes 2001), and captured on the video "Sila Alangotok: Inuit Observations of Climate Change." The short version of the video is available through the IISD Web site.
Table 2 shows the results of a survey carried out near the end of the project to verify that the observations reported on the video and in the project reports did indeed represent community consensus. The survey was administered verbally by the community fieldworker to 12 of the 13 households that participated directly in the project, plus 5 households that did not; the latter were included to obtain a wider range of views from the community. The results indicate near-unanimous views on the reported changes. For example, the one informant who did not think that the video accurately reflected the changes they were observing commented that the video captured "only some of it."
These observations indicate an increase in variability in the climate that is causing the environment to become increasingly unpredictable. According to the Inuvialuit, these observed changes are having an impact on hunting, fishing, and other subsistence activities as well as on guiding sport hunters and traveling on the land. In fact, Sachs Harbour is not unique in this regard. Several communities in the Canadian Arctic and Alaska have been reporting environmental changes different from normal variability (Fisheries Joint Management Committee 1999, Riedlinger and Berkes 2001).
To provide context, we reviewed the annual cycle of harvesting activity at Sachs Harbour. Some 20 species of terrestrial and marine mammals, fish, and birds are taken throughout the year. Of these, the main species is musk-ox (Ovibos moschatus); others include the lesser snow goose (Anser caerulescens), the ringed seal (Phoca hispida), and various fish species. During the winter, people hunt musk-ox and, to a lesser extent, caribou (Rangifer tarandus), Arctic foxes (Alopex lagopus), wolves (Canis lupus), polar bears (Ursus maritimus), and ringed seals. The island supports a large population of musk-ox that has increased since the 1950s (Gunn et al. 1991, Nagy et al. 2001). Small game includes ptarmigan (Lagopus spp.) and Arctic hare (Lepus arcticus). In the past, winter was the season for Arctic fox trapping, which was a mainstay of the local economy until the European fur ban of the 1980s.
As the weather begins to warm in March and April, people head out to numerous inland lakes to ice fish for lake trout (Salvelinus namaycush) and Arctic char (Salvelinus alpinus). In May, fishing slows down as the snow goose hunting season approaches. Banks Island supports a large breeding colony of snow geese. Goose hunting, along with collecting goose eggs, is one of the most important community activities. Families camp at rivers and inland lakes, and the entire community is busy hunting, plucking, cleaning, and drying geese; some of the resulting products are intended for intercommunity trade.
The goose hunt is over by mid-June, and people return to the lakes to fish if there is still ice. They will also fish for Arctic cod (Boreogadus saida) on sea ice and begin hunting seals. With the advent of summer and the breakup of the ice in June and July, people hunt mainly for ringed seals and some bearded seals (Eringnathus barbatus) off the ice floes and from boats in open water. From July through early September, people set gillnets for char, Arctic cod, and least cisco (Coregonus sardinella). There is some rod-and-reel fishing in lakes as well. In September, people turn to musk-ox and caribou hunting again. The peak of the musk-ox hunt is in November. In some years, the musk-ox hunt is a commercial harvest that employs almost the entire community, plus some outsiders, for much of November.
The actual annual cycle of harvesting activity differs from year to year. Probably no two years are alike in terms of harvesting success. Some data on harvest numbers are available from the Inuvialuit Harvest Study, but these statistics are often incomplete, and the numbers hide the complexity of year-to-year variations. Langdon (1995) refers to the "extraordinary range" of annual harvest levels in the Inupiat communities of northern Alaska, in which anomalies (extremely high or low levels of harvest) occurred for one resource species, on the average, every year. Such variations may characterize the harvests of Inuvialuit communities as well.

PROBLEMS AND OPPORTUNITIES
RELATED TO CLIMATE CHANGE
Problems and opportunities related to climate change need to be considered against a background of a highly variable Arctic ecosystem and an equally variable social-ecological system of harvesting activities. The impacts observed by the people of Sachs Harbour may be divided into these groupings: access to resources, safety, predictability, and species availability (Table 1).
Access to resources is often related to the ability to travel on land or sea ice. For example, changes in the rate of spring melt and the increased variability associated with spring weather conditions can affect community access to hunting and fishing camps. In May, families go out to camps at lakes for ice fishing and the spring goose hunt. They travel by snowmobile, pulling a qamutik (sled), staying on snow-covered areas, and often using the coastal sea ice and frozen rivers to gain access to the camps. However, warmer springs have resulted in earlier, faster snow melt and breakup of the river ice, making access to camps difficult and shortening the length of time people are able to spend out on the land. In some areas, increased snowfall and deeper, softer snow make it more difficult to travel than on hard, packed snow.
The second theme, safety, comes up most frequently in conversations about the sea ice environment. The sea ice in the vicinity of the community is used for travel, ice fishing, and hunting seal and polar bear. The condition of the ice, the distribution of the ice floes, the location of the floe edge, and the timing of freeze-up and breakup events are monitored from both kitchen windows and the ice itself. Weekly flights into the community are used as a source of information about ice conditions on a larger scale. Sound knowledge of the sea ice is critical to hunting success and safety, and daily observations are embedded in an understanding of past events. In recent years, it has been noted that ice conditions are less reliable than they were in the past. In the 1990s, people in Sachs Harbour observed more ice movement in winter and spring, overall thinning, and changes in the distribution of leads, cracks, and pressure ridges in the ice. People say that, in the past, they rarely had to worry about the ice the way they do now, but "now you really have to watch" when you travel on the ice.
The safety theme is often linked to predictability. The Inuvialuit rely on their ability to predict phenomena such as snow and ice conditions, the weather, and the timing of wildlife migrations. All of these phenomena have become more unpredictable. Many of the local residents were of the opinion that weather patterns and events were happening "at the wrong time now." For example, as one elder pointed out, weather changes have become more frequent.
"The weather never changed that much years ago ... it was always cold. Not like today. You can't even tell when the weather is going to change. Years ago we knew when the weather was going to change—mild weather meant a storm was going to come, and so we would get ready for it. But today it changes so much; we can be expecting a big storm—next day it is clear as can be. I can't predict the weather anymore like we used to years ago. I used to predict weather when I could see it—it's coming ..." (P. Esau, personal communication).
The fourth group of impacts on subsistence activity involves species availability. Indirect effects of climate change, such as changes to the availability of forage and water or the intensity of parasitic infections, may have an impact on Arctic wildlife, and thus on the community harvest. For example, although warmer temperatures and higher amounts of rainfall have increased the availability of summer forage for caribou and musk-ox, they have also increased the risk of extreme events such as freezing rain that covers the ground with a layer of ice, which makes forage unavailable in the autumn. The availability of some species may change not only because of environmental impacts on the species itself but also because people are forced to hunt them under changing environmental conditions. For example, less summer ice means that ring seals will be harder to spot and hunt. The distribution, abundance, and movement of the species in the region may change as new species appear or established ones, e.g., caribou, change the timing of their migrations (Babaluk et al. 2000).

RESPONDING TO CHANGE: COPING MECHANISMS
The climate-related changes experienced by the community of Sachs Harbour are relatively recent. Although these changes are affecting subsistence activities, many of the impacts have been absorbed thanks to the flexibility of the seasonal cycle and the Inuvialuit way of life. For the most part, Inuvialuit coping strategies relate to adjusting or modifying subsistence activity patterns, i.e., changing when, where, or how hunting and fishing occur. They also harvest a mix of different species and try to minimize risk and uncertainty.
Increased seasonal variability is causing hunters to adjust the timing of their seasonal calendar. For example, warmer temperatures and unpredictable ice conditions, as described by local experts, have resulted in hunters going out earlier for polar bear. In response to shorter, warmer springs and increased rates of snow and ice melt, people say that they do not go out on the land in the spring for as long as they used to. They return to the community after the goose hunt, rather than proceeding to the lakes to ice fish. Waiting is a coping strategy; people wait for the geese to arrive, for the land to dry, for the weather to improve, or for the rain to end.
Because of erosion and slumping at one nearby fishing lake, the community has begun fishing at other lakes instead. More bare ground and unreliable snow conditions mean that families are traveling along the coastal sea ice rather than along inland routes. Recent changes to the sea ice have meant that hunters now stay close to the community because of safety concerns, while the animals they seek remain farther out. Permafrost thaw in many areas has forced travelers to make new trails and routes to avoid slumps, mudslides, and erosion. Community members describe using all-terrain vehicles instead of snowmobiles to travel to spring camps when there is not enough snow. They also describe hunting seals from boats in the open water, an adjustment necessitated by the lack of ice floes, where the seals normally spend the summer months.
The community reports that it is catching more qaaqtaq (least cisco) in nets at the mouth of the Sachs River. Because of the lack of open water and bare ground in the spring of 2000, the geese arrived late and laid fewer eggs, and the community collected almost none of them. Pintail ducks (Anas acuta) and mallard ducks (A. platyrhynchos), which are considered mainland ducks, have been observed in the area, and there are higher numbers of white-fronted goose or yellow legs (Anser albifrons) and tundra swans (Cygnus columbianus), birds that have not been abundant on Banks Island in the past.
In response to the increased variability and unpredictability associated with the weather and other environmental phenomena, the Inuvialuit feel a need to monitor conditions more closely, e.g., in rivers in the spring. There is a heightened risk of getting caught on the far side of the river because it is more difficult to tell when the ice will break. People indicate that " ... you really need to have experience to travel on the sea ice now ... " and describe being more careful when they travel.
The Inuvialuit of Sachs Harbour draw on their accumulated knowledge base and experience to come up with these coping strategies. They state quite clearly that they have always adjusted and adapted to change: social, political, and economic as well as environmental. People may now use all-terrain vehicles more than dog teams, but as one man said, " ... it is pretty well the same, how we do things ... " (J. Lucas Sr., personal communication). When asked about the impact of changes on hunting, trapping, and fishing, most people were quick to point out that they always found some way of getting something. Some people described how, in one sense, it is easier to cope with environmental change now than in the past, because the community does not rely exclusively on local foods. Also, environmental changes are an expected part of the Arctic environment. In the past, severe weather events such as freezing rain could significantly reduce a caribou herd through starvation, leading to severe food shortages for the local people as well. In the contemporary mixed economy, the Inuvialuit have a wider range of food options.
The effects of some changes are more severe than others and require different types of responses. Although this paper focuses on the impacts and adaptations associated with harvest and subsistence activity, climate change may have other economic and cultural consequences as well. For example, whereas recent changes to the sea ice environment have been making travel dangerous and wildlife less accessible, the lack of sea ice also makes some people "lonely for the ice," because the ice is a central feature of Inuvialuit life. Other environmental changes, such as those related to permafrost (e.g., thaw slumps, soil erosion), may not pose a direct threat to the subsistence lifestyle of the Inuvialuit, but do have direct impacts on other aspects of community life, such as the maintenance of buildings and roads.

LONG-TERM RESPONSE OPTIONS:
ADAPTIVE STRATEGIES
The scope and scale of climate change experienced by the community of Sachs Harbour in the 1990s were substantial, but these changes were not beyond the range of the community's ability to respond by adjusting its subsistence activities to accommodate increased seasonal variability. This ability to cope is not unique to Sachs Harbour. As Krupnik (1993:210) notes, "Dynamic and flexible use of the environment constitutes the chief adaptive strategy of Arctic communities." However, the changes observed in Sachs Harbour are recent, and how the community has responded up to now may not be a reliable indication of their ability to adapt in the future.
The adaptive capacity of the Inuvialuit to absorb perturbations will depend in part on their ability to learn and reorganize and in part on culturally available response options. This section addresses the traditional cultural adaptations made by the Inuit (here we use Inuit as the more inclusive term) to deal with environmental variability and uncertainty. The question of whether these strategies are still viable in the contemporary world will be examined in the next section.
Anthropologists and other social scientists (Balikci 1968, Krupnik 1993, Freeman 1996) have identified several clusters of cultural practices that are considered to be adaptive responses to the arctic environment. These include: (1) mobility and flexibility in terms of group size, (2) flexibility with regard to seasonal cycles of harvest and resource use backed up by oral traditions to provide group memory, (3) detailed local environmental knowledge and related skill sets, (4) sharing mechanisms and social networks to provide mutual support and minimize risks, and (5) intercommunity trade.
The Arctic is an environment in which biological production is relatively low, resources are patchy, and resource availability is unpredictable. These conditions have a profound influence on social organization because adaptive pressures are against large social groupings and permanent settlements in favor of small groups and a high degree of mobility. Thus, traditional Inuit society was generally organized to facilitate the constant grouping and regrouping of economically self-supporting households to maximize the amount of resources obtained and their distribution throughout the group (Freeman 1996). For example, one study of settlement and mobility patterns showed a statistically significant correlation between resource abundance and seasonal preferences for settlement location (Freeman 1967). This is also evident in events such as the hunts for beluga whale on the Mackenzie Delta, where large social groups come together for short periods to increase the number of whales harvested.
In traditional Inuit resource use, there was a great deal of flexibility in seasonal cycles, and mobile groups did not always follow the same sequence of hunting locations or rely on the same complex of resources. They worked with unpredictability, harvesting what was available when it was available. Species could be switched opportunistically; for example, a good spring harvest of ringed seals might compensate for a late snow goose migration. In their seasonal cycle, there was a plan that covered target areas and species, but also a whole repertoire of backup plans in case the primary plan did not work. These plans were based on their accumulated knowledge of factors such as habitat and animal behavior. The most successful (i.e., food-rich) family leaders were those who had the most comprehensive set of backup plans and who could always find an alternative that produced food (Balikci 1968). The Inuit also relied on oral traditions and group memory of past situations to respond to fluctuations in the physical environment and extreme events (Minc 1986).
In conjunction with their seasonal harvest cycles and backup plans, the Inuit had detailed local environmental knowledge and related skill sets. The unpredictable nature of resource availability creates incentives for individuals to master a diversity of hunting and fishing skills and accumulate a detailed knowledge of the various species and the biophysical environment in general. Diversification is well known as a risk-spreading strategy related to uncertainty and surprise (e.g., McCay 1978, Kelly and Adger 2000), and the Inuit tend to be generalists rather than specialists. Although Inuit society normally has a division of labor based on gender, men can sew skins and women can hunt, if necessary. In fact, three Sachs Harbour sisters, who are now community elders, were raised by their mother when she took over their father's role (e.g., hunting seals at the ice hole) after his premature death. Competence on the land (survival skills) is highly valued and allows individuals to exercise a great degree of personal autonomy (Freeman 1996).
Food sharing was very important among the traditional Inuit, as in many aboriginal groups, especially those who were hunter-gatherers. Co-resident social groups among Canadian Inuit bands were small until the 1960s and 1970s, with winter groups numbering 50 to 100 and summer groups generally comprising fewer than 25 people. When groups consisted of only a dozen or so households, it was possible to share a kill such as a seal or a small whale with the entire community (Freeman 1996). Inuit food sharing often went beyond the immediate group as well, because the Inuit tended to have complex networks of social relationships, and exchanges took place based on these extensive networks. A very high value was attached to sharing: the most socially prestigious families were those who always had food to share. Social networks for sharing are adaptive in terms of providing mutual support and minimizing risks (Sabo 1991).
In many parts of the Arctic, intercommunity trade was important as a means of addressing regional differences in resource availability. Some of these trading partnerships were highly formalized, but they should also be understood as mechanisms for providing mutual support when traveling into the territories of neighboring groups. Trading was as much a symbolic act, intended to establish social relationships between groups and recruit loyal partners as it was an economic transaction (Freeman 1996).

EVALUATING TRADITIONAL ADAPTIVE STRATEGIES
Human history in the Arctic has been described as a series of adaptations, or a process of sequentially accumulating cultural mechanisms, designed to deal with the characteristics of the environment (Krupnik 1993). To evaluate the resilience of Inuvialuit society in the face of climate change, we first asked which of these five sets of adaptive mechanisms were still viable. Second, we tried to determine if there were other response options the Inuvialuit could choose to deal with environmental change.
Inuit society has undergone profound changes since the 1960s and the 1970s, when the people first settled into permanent villages. For this reason, the cultural adaptations that involve mobility and flexible group size are no longer available or relevant. However, the other four clusters of adaptations still seem to be viable. Our analysis in this section is based on observations and interviews in Sachs Harbour, but parts of our discussion are necessarily speculative, because the evaluation of traditional cultural adaptations was not part of our initial research objectives.
The Sachs Harbour case indicates that hunters still make " ... dynamic and flexible use of the environment ... " (Krupnik 1993). The flexibility of seasonal cycles of harvest and resource use provides the social-ecological resilience needed to cope with increased variability and unpredictability and adapt to change. We infer resilience from those project results that show a diversity of short-term responses to changing patterns of game availability and access. Cultural values in the community of Sachs Harbour that emphasize the appropriateness of harvesting what is available and acting opportunistically no doubt facilitated the observed coping strategies. Likewise, we observed that oral traditions and group memory were used to establish baselines for expected variability. For example, the people recalled the past to make sense of unusual ice years or late freeze-up. In some cases, however, oral history and the elders' memories did not help much. A case in point is the thunder and lightning observed in the 1990s; only two elders had ever experienced this weather phenomenon in their lifetimes, one of them in the 1930s when she was only five years old. Thus, recent occurrences are seen as indicators of environmental change on a larger scale.
A great deal has been written about the loss of detailed knowledge about the local environment and related skill sets. This is only partly true. Some knowledge and skills have obviously been lost, some are being transmitted incompletely, and yet others are new skills (such as the use of snowmobiles) that the older generations did not possess. In this regard, the situation in Sachs Harbour is probably not very different from those of other northern communities in which the transmission and retention of knowledge and skills have been studied systematically. One general finding is that skills tend to be transmitted later in life and incompletely (Ohmagari and Berkes 1997). In the case of Sachs Harbour, even the younger people know about traditional food preservation techniques such as fermented marine mammal meat, and some of them have assisted with the process. However, only a small number of elders had the experience needed to carry out all the steps of the preservation process by themselves; the others did not have sufficient expertise.
A second general finding is that there has been a change in the skill sets and kinds of land-based knowledge held and transmitted. For example, many teenage boys in Sachs Harbour can use guns, but not too many can build snowhouses and snow shelters, which was once universal knowledge. However, those who are often on the land do learn to build snow shelters, because it is an essential survival skill. Thus, some traditional skills that were once universal in Inuvialuit society have become restricted to the relatively few families who are active on the land. This is because learning traditional knowledge and skills requires on-the-land education (Ohmagari and Berkes 1997) or " ... people's practical engagement with the environment ... " (Ingold and Kurttila 2000). As the nature of this practical engagement changes, so does the reservoir of local knowledge. For example, hunters in Sachs Harbour and elsewhere in the Canadian North use GPS units for navigation and safety—a very recently acquired skill. The use of snowmobiles since the 1970s has required a greater degree of knowledge of safe and unsafe ice, because sled dogs can sense dangerous ice, but snowmobiles cannot.
The sharing of food is still very much in evidence in Sachs Harbour, but it remains for the most part within extended family units, or involves providing for elders. Partly because the community is so small and the families are interrelated, just about everyone gets to share some of the food coming in. However, because a relatively small number of hunters now account for most of the fish and game harvest, fewer and fewer people seem to be providing for more and more nonhunters, a potentially nonsustainable situation. This imbalance is being addressed by new forms of reciprocity in which food-rich members of extended families share with cash-rich members, thus bringing wage income and material goods into the sphere of sharing relationships.
One kind of adaptation that does not seem to have declined at all, and may even have increased, is intercommunity trade. Sachs Harbour has an abundance of snow geese and musk-ox, but a dearth of caribou and beluga whales because it lacks the shallow, rocky bays suitable for hauling and butchering beluga. Therefore, the community exports snow geese and musk-ox to Tuktoyaktuk and Inuvik, and in turn receives beluga products (muktuk, the inner skin of the beluga) and caribou from them. For example, in the fall of 1999, the community of Tuktoyaktuk sent Sachs Harbour one caribou per family. These exchanges are based on norms of generosity (giving without asking), sharing, and generalized reciprocity, not on western rules of economic exchange (Freeman 1996). When the first bowhead whale in decades was landed in Aklavik, Sachs Harbour received a share of that as well.
Because of family connections, Sachs Harbour trades not only with the Inuvialuit communities to the south but also with Holman on Victoria Island to the east. Holman, in turn, trades with or receives food from other communities. For example, during a caribou crisis on Victoria Island in 1992–1993, the Holman Inuit received caribou meat by air freight from relatives in other communities. The Hunters and Trappers Association of neighboring Kugluktuk (Coppermine) held several caribou hunts, the proceeds of which were shipped to Holman and distributed free to elders (Collings 1997). Thus, intercommunity trade is obviously alive and well.
In sum, Inuvialuit adaptive strategies of flexibility of resource use, local environmental knowledge and skills, sharing through social networks, and intercommunity trade are still largely intact. These strategies provide considerable buffering capacity when dealing with perturbations such as climate change. Are there other response options as well for the Inuvialuit that help them cope with environmental change?

NEW INSTITUTIONS
AND ADAPTIVE RESPONSE OPTIONS
Linkages to Inuit regional institutions and government agencies provide potential adaptive response options that were not available to the Inuvialuit in the past. The Inuvialuit Final Agreement of 1984 sets up five joint decision-making bodies dealing with different aspects of the land and the environment. These co-management bodies provide a formal mechanism that allows individual communities to interact with the regional Inuvialuit government, the territorial government, and the federal government when dealing with large-scale problems (Berkes et al. 2001). Such cross-scale linkages, both horizontal (across space) and vertical (across levels of organization), facilitate new kinds of adaptive responses. They also provide communities access to scientific information through co-management bodies such as the Fisheries Joint Management Committee (Fisheries Joint Management Committee 1999).
Figure 1 shows the relationship between space and time scales in the way in which a community such as Sachs Harbour may respond to climate change. It can be seen that responses on the level of the individual and the household operate at scales ranging to a day to a season; these are the coping strategies. Community and regional-level responses, once established at the scale of years and decades, develop over time into adaptive strategies of the kind discussed by Krupnik (1993) and Freeman (1996).
At the lower ends of the space and time scales, the response to environmental feedback is rapid, e.g., hunters mobilize if the snow geese are migrating early. At the higher ends of the scales, responses are mediated by slow variables (Gunderson and Holling 2001), such as cultural values that change slowly. For example, the adaptive strategy of sharing requires the development and reinforcement of cultural values that favor generosity, reciprocity, and communitarianism and discourage hoarding and individualism. A key question for the new adaptive strategy of co-management is whether it can facilitate or speed up responses to climate change. For example, the polar bear hunt, an important source of employment in Sachs Harbour, is often affected by unreliable sea ice in spring. The sport hunting season is a fixed period, set by the territorial government. Can the season be changed to reflect changing ice conditions? More generally, the question is: how quickly can a community concern (e.g., unreliable ice in the spring) be translated into action at the larger institutional scale, if the local institution (e.g., Hunters Trappers Committee of Sachs Harbour) wants to change the polar bear hunting season to respond to changes in the supply of polar bear resources?
According to John Nagy (personal communication) of the Department of Resources, Wildlife and Economic Development (RWED), the community polar bear agreements that RWED and Inuvialuit institutions are presently working on provisions that will allow the communities to adjust their hunting seasons by means of HTC bylaws within the broader Northwest Territories hunting season. These new agreements may be signed off sometime in 2001, giving communities greater flexibility to adjust seasons both for their members and for sport hunters.
Regionally, co-management arrangements have since the 1980s provided greater northern aboriginal participation in environmental management. In the western Arctic, the Inuvialuit have joint decision-making powers in a range of areas, from fish and wildlife management to protected areas, environmental assessment, and policies governing research on contaminants (Berkes et al. 2001). These powers provide greater local flexibility and response capability in dealing with uncertainties such as climate change. They enable local communities to respond to environmental feedback more quickly, without having to wait for the intervention of distant governments. Interaction with scientists in jointly planned meetings such as the Beaufort Sea Conference (Fisheries Joint Management Committee 1999) provide additional means for learning and self-organization that help to build local adaptive capacity to address environmental management issues at the regional, national, and international levels.

CONCLUSION
In carrying out place-specific research in Sachs Harbour, we have tried to develop an approach that involves (1) observing and analyzing the actual response of the community to climate change, (2) evaluating these observations in the light of the adaptive strategies known to exist in that society, and (3) using these two streams of thought to generate insights about the resilience of the social-ecological system (the community and its resources) and further response options. One of the insights from this study is the key importance of participatory research in the production of knowledge that is based on social understanding. The research team could not have made much sense of the observations if it did not have the benefit of a planning workshop in which the people of Sachs Harbour indicated what they considered important at the outset of the project; other helpful components were the use of video to capture local observations, repeat visits, multiple feedback of results, and the verification of those results.
Such an approach is consistent with the sustainability science statement of the Friibergh Workshop, which points out that the complex systems problems facing humanity are not adequately addressed by the familiar scientific approach of developing and testing hypotheses. Because of nonlinearity, complexity and long time lags, sustainability science will need to use new methodologies, build upon lessons provided by case studies, and work with the local people to produce knowledge " ... that is both scientifically sound and rooted in social understanding ... " (Friibergh Workshop on Sustainability Science 2000).
Climate change provides a good example of a complex systems problem for which place-specific case studies and participatory methodologies are particularly apt. The effects of change unfold at the local level, and so do adaptive responses, creating opportunities to investigate the dynamics of the two. The Sachs Harbour case is informative in studying how societies adapt to climate change because the Inuvialuit response occurs on multiple scales. One set of responses is short term; these are the coping mechanisms. Because the Inuvialuit are experts at living in highly variable environments, it is not surprising that switching species and adjusting the "where, when, and how" of hunting have enabled them to cope successfully with climate change in the 1990s.
The question of the ability to adapt to further changes brings into focus longer-term adaptations and responses, including the flexibility of seasonal hunting patterns, detailed traditional knowledge of the environment that enables the Inuvialuit to diversify their activities, and inter- and intracommunity sharing networks. Climate change puts these adaptations under stress by making the environment even more variable and thus less predictable. The range and extent of both the short-term and long-term responses define the resilience of the community in the face of change. To the extent that these responses are impaired, the population becomes vulnerable to change (Kelly and Adger 2000).
Climate change at Sachs Harbour, as elsewhere, has not followed a pattern of smooth or gradual change. It has been marked by disruptions due to uncertainty and extreme events. Our research supports the observation that changes in long-term averages are not so important. Rather, it is extreme events that are important, " ... events of greater magnitude, especially those which exceed a system's 'absorptive capacity' ..." (Smithers and Smit 1997:135). However, not all extreme events (e.g., thunder and lightning) are dangerous, and not all ecological surprises are negative from the local point of view (e.g., the appearance of Pacific salmon in the Beaufort Sea). The two species of Pacific salmon, observed for the first time in the 1990s by the people of Sachs Harbour and recorded by biologists (Babaluk et al. 2000), and mainland ducks that are now extending their range into the High Arctic both provide a welcome supplement to the Sachs Harbour diet.
This multiscale approach to studying the system's "absorptive capacity" or resilience is useful in highlighting the fact that coping and adaptive strategies are continuous along the temporal scale (Fig. 1). There is feedback between the various levels of responses to change (household, community, etc.), especially between those that overlap on the temporal scale. Feedback is weaker and slower between the levels at the extremes of the scale in Fig. 1, that is, between the individual/household levels and the levels above the community), which tends to weaken the relationship between them (Levin 1999). co-management institutions that have been developing since the 1980s have the potential to connect the different levels of the system and speed up feedback among the levels. They can facilitate self-organization and learning; for example, the Inuvialuit and scientists may learn from one another and find ways in which local knowledge may complement science (Fisheries Joint Management Committee 1999, Riedlinger and Berkes 2001). By providing the community with vertical linkages across levels of organization, these co-management arrangements allow community concerns to be transmitted to regional, national, and international levels. New institutional linkages can thus increase the resilience of the social-ecological system by providing for cross-scale communication that did not exist before the 1980s, and by increasing the capability for self-organization and the capacity for learning.

CLD SAMPLE

RESILENCE ON FLOODS

ABSTRACT
River cities require a management approach based on resilience to floods rather than on resistance. Resisting floods by means of levees, dams, and channelization neglects inherent uncertainties arising from human–nature couplings and fails to address the extreme events that are expected to increase with climate change, and is thereby not a reliable approach to long-term flood safety. By applying resilience theory to address system persistence through changes, I develop a theory on “urban resilience to floods” as an alternative framework for urban flood hazard management. Urban resilience to floods is defined as a city’s capacity to tolerate flooding and to reorganize should physical damage and socioeconomic disruption occur, so as to prevent deaths and injuries and maintain current socioeconomic identity. It derives from living with periodic floods as learning opportunities to prepare the city for extreme ones. The theory of urban resilience to floods challenges the conventional wisdom that cities cannot live without flood control, which in effect erodes resilience. To operationalize the theory for planning practice, a surrogate measure—the percent floodable area—is developed for assessing urban resilience to floods. To enable natural floodplain functions to build urban resilience to floods, flood adaptation is advocated in order to replace flood control for mitigating flood hazards.
Key words: flood adaptation; flood control; flood hazard management; resilience-based management; resilience surrogate; resilient cities; urban floodplains; urban resilience
INTRODUCTION
Flood hazards challenge river cities around the world, despite many of them being protected by extensive flood-control infrastructures, such as levees, dams, and channelization. The twenty-first century has already seen large-scale flood disasters in Bangkok, Thailand (2011); Brisbane, Australia (2011); Guangdong, China (2007); New Orleans, USA (2005); Dresden, Germany (2002); and Taipei, Taiwan (2001), among others. The industrialized world has heavily relied on flood control to mitigate flood hazards, yet it is criticized for harming riverine ecosystems and increasing long-term flood risk (Burby et al. 2000, Smits et al. 2006). Alternative management concepts have emerged, emphasizing the integration between land and water management and of structural and nonstructural measures (e.g., Schneidergruber et al. 2004, Associated Programme on Flood Management 2009). Nevertheless, scholars continue to assert the indispensability of flood-control infrastructure for cities (e.g., Birkland et al. 2003, Godschalk 2003), which reflects the entrenched management paradigm of controlling nature.

Designed and operated under an obsolete assumption that the pattern of flow variability remains unchanged over time (Milly et al. 2008), flood-control infrastructure is not a reliable mitigation approach in the face of climate change uncertainties (Zevenbergen and Gersonius 2007). Cities that depend on flood-control infrastructure can resist floods only up to a certain magnitude, thereby these cities are ill-prepared for capacity-exceeding extreme floods, which are expected to increase with more intense storms whose exact natures are unpredictable (Alley et al. 2007). An alternative mitigation approach is needed, which this paper addresses by developing a flood hazard management concept that focuses on resilience.

The idea of resilience has a long history in ecology and engineering, but its application to natural hazard management is relatively recent (Berkes 2007). What defines resilience to floods remains ambiguous, despite the increasing attention given to the concept of resilience in flood hazard management. In this paper I address urban built environment and riverine flooding to develop a theory on “urban resilience to floods”. There are two major resilience interpretations—engineering resilience and ecological resilience (Holling 1996). I explain why the latter is a more appropriate theoretical framework for management and for defining urban resilience to floods. In order to operationalize the theory for planning practices, a resilience surrogate measure is proposed for assessing urban resilience to floods. The theory and the measure together indicate that flood adaptation should replace flood control in order to build urban resilience to floods.

INTERPRETATIONS OF RESILIENCE
Engineering resilience and ecological resilience are two distinct interpretations (Holling 1996). Discerning their fundamental differences is important because they lead to divergent problem definitions, focuses, and approaches when applied to flood hazard management.

Engineering resilience and ecological resilience
In engineering, resilience is concerned with disturbances that threaten the functional stability of engineering systems, which are often linked with low probabilities of failures or, in the case of failure, quick recovery to normal levels of functionality (Wang and Blackmore 2009). Such resilience depends on four properties: robustness, or the physical strength to withstand a disturbance without functional degradation; redundancy, or the extent to which system components are substitutable; resourcefulness, or the capacity to identify problems and mobilize needed resources; and rapidity, or the capacity to restore the system in a timely manner (Bruneau et al. 2003). This engineering resilience concept encompasses both resistance to and recovery from disturbances, although the measurement is focused exclusively on recovery—the faster the full functionality is restored, the greater the resilience (for example, Hashimoto et al. 1982, Hollnagel et al. 2008, Fig. 1). Engineering resilience thus emphasizes the ability to bounce back to the original condition when relaxed from stress (Wang and Blackmore 2009).

In ecology, Holling (1973) introduces the term resilience to describe observed ecosystem dynamics. It challenges the conventional ecological paradigm of equilibrium that assumes a predetermined stable state for every ecosystem, to which it eventually returns after a disturbance. Empirical studies show that some ecosystems never stabilize due to frequent disturbances. Multi-equilibria also exist when the ecosystem stabilizes after a disturbance but in a different state. It means the ecosystem is characterized by a different set of structures and processes, and returning to the previous ecosystem is extremely difficult if not impossible (Holling 1973, Scheffer et al. 2001). Building on the alternative paradigm of multi-equilibria/nonequilibrium, Holling (1973) defines resilience as the system’s ability to absorb disturbances and still persist. This ecological resilience concept focuses on persistence, or remaining within the same regime defined by the same processes, structures, feedbacks, and identity (Walker et al. 2004). Because systems do not operate near equilibrium, resilience is associated with the change the system can tolerate and the ability to reorganize or renew (Carpenter et al. 2001). It is measured by the magnitude of the disturbance the system can undergo before shifting to a different regime (Gunderson and Holling 2002).

In addressing different types of systems, several disparities exist between engineering and ecological resilience (Table 1). They derive mainly from the different assumptions of system dynamics regarding the number of possible regimes (Holling 1996, Fig. 2). The assumption behind engineering resilience, which is about maintaining the optimal state of functionality, is congruent with the ecological paradigm of equilibrium, presuming only one regime with an idealized stable state as the norm. The paradigmatic divergence reflects different perceptions towards normalcy. In the engineering resilience concept any change from the optimal state is deviant, while in the ecological resilience concept any fluctuation within the regime is normal because systems are inherently dynamic (Holling 1973).

Essentially, engineering resilience is the ability to maintain stability—remaining unchanged in system state or having minimum fluctuation; whereas ecological resilience is the ability to survive, regardless of the state. They are two different, even contradictory, system properties. Systems with high engineering resilience may have low ecological resilience; low engineering resilience may introduce high ecological resilience (Holling 1973, 1996).

Community resilience to natural hazards
The two resilience concepts receive increasing attention in hybrid systems, such as social–ecological systems (e.g., Berkes and Folke 1998) and socio-technical systems (e.g., Hollnagel et al. 2008). In natural hazard management, which deals with the interaction between humans and environmental fluctuations (Mileti 1999), engineering resilience prevails in current definitions of community resilience. Few authors define it without implying an optimal reference state, and it is frequently viewed as the capacity to withstand and recover quickly from disasters (Table 2). For example, Birkland and Waterman (2009) propose three features of community resilience—damage prevention, speedy recovery, and preservation of community functionality—arguing that the more stresses the community can bear to preserve functionality, the faster the recovery is.

Discussions on community resilience place an overwhelming emphasis on recovery (e.g., Vale and Campanella 2005, Lamond and Proverbs 2009). In many cases, resilience is taken to mean exclusively the capacity to bounce back to the predisaster state, to differentiate from resistance, which means the ability to withstand a disturbance without disruption (e.g., Etkin 1999). In flood hazard management, for example, resistance means flood prevention by flood-control infrastructure, while resilience is the rate of return from a flood-impacted state to the normal one (De Bruijn 2004).

ECOLOGICAL RESILIENCE AS THE THEORETICAL FRAMEWORK
Applying the engineering resilience concept to communities that are subject to natural hazards is fundamentally problematic because of the outdated equilibrium paradigm. Recovery is often interpreted as returning to predisaster conditions, implicitly assuming an optimal reference state, which nevertheless does not exist in coupled human–natural systems (Berkes 2007). Urbanized floodplains are such systems, where climate, socioeconomic trends, built systems, and riverine processes affect flood hazards and disasters. They operate like evolving ecosystems rather than engineering systems and are characterized by complex behaviors associated with nonlinearity, emergence, uncertainty, and surprise (Liu et al. 2007). Such dynamic systems will not stay at a predetermined state. To be sure, moving quickly from a chaotic state to an organized one after a disaster is paramount, but it is unconstructive to restore the predisaster socioeconomic activities and built environments that are vulnerable in the first place (Klein et al. 2003). What remains unchallenged in this recovery notion is the preoccupation with stability. Stability becomes problematic when forced at temporal and spatial scales, at which the system is inherently dynamic (Cumming et al. 2006).

The ecological resilience concept is a more appropriate framework for flood hazard management, for it builds on a more realistic paradigm of multi-equilibria, focusing pragmatically on persistence in a world of flux (Adger et al. 2005). Thanks to studies on integrated social–ecological systems (e.g., Berkes et al. 2003), the ecological resilience concept has become a sophisticated resilience theory, addressing complex human-nature couplings. It is instrumental for addressing flood hazards that arise from the interaction between riverine and urban dynamics.

From maintaining stability to building resilience
Two key arguments in resilience theory would shift the paradigm of flood hazard management. First, resilience arises from adapting to inherent variability, uncertainty, and surprise (Folke 2003). Coupled human–natural systems lose resilience when the inherent variability is artificially suppressed to promote stability through command-and-control management (Holling and Meffe 1996, Holling et al. 2002). This suggests that forcing floodplains to be inundation-free and building socioeconomic functionality upon forced environmental stability results in resilience erosion. It thus challenges the bias towards maintaining a dry floodplain and steady socioeconomic activities. Flood hazard management based on resilience theory would begin with acknowledging periodic floods as inherent environmental dynamics, by which socioeconomic activities on floodplains are inevitably affected.

Secondly, resilience theory holds that periods of gradual development and sudden changes complement each other (Folke 2006). As demonstrated in frequently disturbed ecosystems, resilience is borne out of experiencing and learning from disturbances (Holling 1973, Gunderson and Holling 2002). Research into communities relying on natural resources also indicates that resilience to large, unpredictable disturbances derives from allowing smaller ones to enter the system (Berkes and Folke 1998, Berkes et al. 2003). It suggests that flooding itself is an agent for resilience because each flood experience creates a chance for cities to adjust internal structures and processes and to build knowledge, leading to diverse coping strategies cumulated over time (Folke 2006, Smit and Wandel 2006). This contrasts with the attitude toward floods as being threatening, idiosyncratic events that legitimize flood control. As flood-control infrastructure prevents most floods, cities only learn painfully from rare, catastrophic ones with high prices. In the resilience-based flood hazard management, periodic floods are learning opportunities for cities to become better fit for extreme floods.

Overall, resilience theory suggests a paradigm shift in flood hazard management that should focus on building resilience as opposed to maintaining stability. Because flooding is inherently a part of the normal urban dynamics, resilience is neither flood resistance nor recovery to predisaster conditions—both are simply means to an end of stability. Here, resilience is the tendency to survive, which is itself an end.

URBAN RESILIENCE TO FLOODS
Two issues must be confronted before building the theory of urban resilience to floods based on resilience theory that originates in ecology. The resilience of ecological systems is concerned with system collapse; yet such a concern for cities is almost irrelevant, as history shows that most cities that have experienced catastrophic destructions have persisted and even flourished (Vale and Campanella 2005). A city remaining as a city means little to those who have lost their lives and to those forced into permanent hardship (Klein et al. 2003). Moreover, individual people matter in hazard management, although individual creatures are irrelevant to ecological systems that build resilience through system-level adaptation where less-fit individuals are continuously replaced (Gunderson 2010). Thus, urban resilience to floods encompasses dual concerns: the flood safety of individual citizens and the maintenance of the city’s current identity.

A definition
Resilience theory has been applied to community resilience, stressing the capacity to absorb recurrent hazard impacts and reorganize while undergoing change so as to maintain fundamental structures, processes, identity, and feedbacks (Table 3). Likewise, urban resilience to floods is defined as the capacity of the city to tolerate flooding and to reorganize should physical damage and socioeconomic disruption occur, so as to prevent deaths and injuries and maintain current socioeconomic identity. It can be conceptualized as the capacity to remain in a desirable regime while experiencing a flood. The desirable regime is defined by a set of variables reflecting aspects such as livelihood security, economic performance, and mobility that collectively represent the city’s socioeconomic identity (Adger 2000, Cumming et al. 2005, Gunderson 2010). Urban resilience to floods is measured by the flood magnitude the city can undergo until it reaches a threshold and shifts to an undesirable regime.

Unlike that for biophysical systems, a regime is socially rather than scientifically defined. The desirable regime reflects the city’s tolerable range of socioeconomic state changes, which matters to urban resilience to floods (Fig. 3). A wider range implies that the city considers a greater degree of socioeconomic fluctuations normal, hence a larger/deeper basin of attraction; whereas a narrow range leads to a smaller/shallow basin of attraction, and a flood could cause a regime shift easier (Carpenter et al. 2001, Walker et al. 2004).

A city is considered to have shifted to an undesirable regime when experiencing a flood disaster involving widespread human, economic, and environmental changes that exceed the city’s own ability to cope (United Nations International Strategy for Disaster Reduction 2004). The undesirable regime is characterized by significantly reduced resources and assets, large-scale population displacement, livelihood disruption, and loss of security (Adger 2000, Berkes et al. 2003). Once in it, moving to a better regime or developing a socioeconomic identity similar to the previous one is costly or impossible.

Essentially, urban resilience to floods is the capacity to avoid flood disaster. To prevent physical damage and socioeconomic disruption from occurring, it would depend on the city's floodability, which is defined here as the physical ability to accommodate—not resist—flooding. If damage and disruption had occurred, remaining in the regime counts on reorganization—reestablishment of socioeconomic order. While the return to preflood conditions is irrelevant, the speed of reorganization matters because prolonged socioeconomic disruption can eventually push the city into an undesirable regime (Walker and Westley 2011). Overall, urban resilience to floods is defined by floodability and reorganization, not flood resistance and recovery that engineering resilience would suggest.

Key properties
Resilience is frequently associated with self-organization, adaptive capacity, and redundancy (Carpenter et al. 2001, Low et al. 2003, Tompkins and Adger 2004). Self-organizing systems are resilient to disturbances because of the distributed character (Heylighen 2001). Adaptive capacity can increase resilience over time, as it is associated with learning—the ability to adjust to changing internal demands and external conditions (Gunderson 2000, Carpenter and Brock 2008). Redundancy provides insurance against total system failure. These concepts can be translated into the following key properties of urban resilience to floods.

Localized flood-response capacity
Self-organizing cities, where each citizen and public manager could act immediately to avoid damage, are more agile in coping with flooding and are thus more resilient than cities that rely on centralized mechanisms such as flood-control infrastructure. If disrupted, they can also quickly reorganize because of the internal ability to clean up and fix damage without waiting for external help from the central government or aid agencies, which do not always act soon enough.

Timely adjustments after every flood
The adaptive capacity contributing to increasing urban resilience to floods is associated with the ability to learn from each flood, i.e., making timely behavioral, physical, and institutional adjustments to be better prepared for the next flood. Every flood entails something new, e.g., debris deposition at unexpected locations. By understanding new phenomena and making necessarily adjustments, the city incrementally increases floodability. It is a learning-by-doing process, where novelty is involved in the adaptation to avoid repeating the previous configuration (Walker et al. 2004, Adger 2006, Berkes 2007).

Redundancy in subsystems
Here, redundancy is more than duplication of the same element in an engineering sense, e.g., the freeboard added on top of the levee height required for confining a certain flow. It entails diversity and functional replication across scales (Peterson et al. 1998, Adger et al. 2005). For example, a water supply network with redundancy would incorporate both regional and localized systems and utilize different water sources. A flood hazard management system with redundancy would comprise a diversity of measures for mitigation, preparedness, response, and reorganization. The flood-response capacity would be distributed across the levels, i.e., individuals, communities, and the municipality, such that when the capacity of one level is overwhelmed, the city can still count on the others.

Underpinning the aforementioned three properties are diversity and flexibility. Short-term adjustments and long-term adaptation are impossible without a diversity of options to choose from (Folke et al. 2002, Davidson-Hunt and Berkes 2003). Diversity is particularly key to resilience because it enables adaptation by providing seeds for new opportunities (Berkes 2007). For example, a diverse economy or livelihood is known to facilitate reorganization after disasters (Berke and Campanella 2006). Flexibility allows the self-organizing city to preserve overall functionality during flooding by making immediate changes at smaller, faster scales in its subsystems (Allen et al. 2005). For example, if the public transportation system could quickly switch its service mode from land-based to waterborne when a flood occurs, it would ensure mobility to keep the city functional. Flexibility also promotes adaptive capacity, for rigidity prevents timely adjustments.

Urban resilience to floods and urban river resilience
Resilience of ecological systems plays an important role in human ability to cope with hazards. This is because it concerns the persistence of ecosystem services, the loss of which limits the options to adapt (Adger 2000, Berkes et al. 2003, Gunderson 2010). Ecosystem goods and services, such as fisheries and clean water, provided by rivers and other freshwater ecosystems are highly valuable (Costanza et al. 1997). While it is clear why ecosystem services are important to communities that are dependent on local resources for livelihoods (Adger et al. 2005), it is not obvious how resilience of local urban rivers relates to urban resilience to floods in modern cities. With significantly altered hydrology, geomorphology, biochemistry, and species composition, many urban rivers today are arguably already in socially–ecologically undesirable regimes, too degraded to offer ecosystem services (Paul and Meyer 2001, Groffman et al. 2003). Although drawing on services generated elsewhere buffers the impact of local declines, the degrading urban river still affects urban resilience to floods. Flooding of a polluted river increases damage and complicates reorganization; moreover, if a flood disrupts the imports of goods and services, the city would have no access to critical resources such as potable water. Resilience of urban rivers matters to urban resilience to floods as the ultimate insurance against the most socioeconomically disruptive floods.

Urban resilience to floods and flood resistance
Conventional wisdom assumes that flood resistance is necessary for cities; however, resilience theory suggests that it erodes urban resilience to floods (Holling and Meffe 1996). In effect, flood-control infrastructure puts the city in one or the other contrasting conditions: dry and stable, or inundated and disastrous. With flood-control infrastructure in place, flooding results exclusively from the infrastructure's failure and is more hazardous than if there were no flood-control infrastructure (Tobin 1995), such that the natural process of flooding becomes a synonym to disaster. Cities that are dependent on flood-control infrastructure are highly resistant—but not resilient—to floods because they have physically adapted to the artificially expanded dry-and-stable conditions to become intolerant of wet conditions (Fig. 4).

In cities that are dependent on flood-control infrastructure, the river’s high flows are mostly confined between levees or held behind the upstream dam. The flood frequency is dramatically reduced and river dynamics are largely unnoticed. Each flood that is prevented is a loss of opportunity for learning (Klein et al. 1998, Colten and Sumpter 2009). Little flood experience leads to low awareness of flood risk among citizens (Correia et al. 1998), who are too accustomed to operating under the dry-and-stable conditions, and know little about how to cope with inundation once the flood-control infrastructure fails. Furthermore, flood-control infrastructure’s structural rigidity and large scope leave little flexibility for making timely adjustments to constantly changing boundary conditions (Pahl-Wostl 2002). The existence of flood-control infrastructure also prevents the development of a diversity of flood-coping measures because the development of such measures is too expensive (Castonguay 2007). Whereas flood-control infrastructure as a system may incorporate a diversity of engineering measures, each with structural redundancy, there is little diversity and cross-scale redundancy with regards to physical measures. Cities that are dependent on flood-control infrastructure tend to address only the river and not the built environment because flood-control infrastructure, as a centralized measure, creates a false sense of security that precludes the need for localized flood-response capacity.

As flood-control infrastructure erodes urban resilience to floods over time, a flood could easily cause high casualties and severe damage, complicate reorganization that relies heavily on external forces, and push the city to an undesirable regime, as was demonstrated in New Orleans after Hurricane Katrina in 2005 (Colten and Sumpter 2009). Flood-control infrastructure also decreases urban resilience to floods through its very function—i.e., prevention of periodic flooding. Periodic flooding is a critical mechanism to maintain the ecological functions and high biodiversity of floodplain rivers (Junk et al. 1989). The altered flood regime, with which native species are unfamiliar, affects the resilience of river ecosystems and contributes to system collapse (Poff et al. 1997, Folke 2003). Therefore, flood-control infrastructure compromises the river's ability to provide ecosystem services (Tockner et al. 2008), which in turn limits the city's options to adapt.

The argument that flood resistance erodes urban resilience to floods echoes the widely supported notion of risk transference, which holds that resistance to natural hazards is simply postponing them, only to build up risks and worsen disasters later (Etkin 1999, Mileti 1999). Because flood resistance compromises urban resilience to floods, persistence resulting from the flood being resisted—in effect no flood occurs—should not be considered resilience.

OPERATIONALIZING THE THEORY
Turning theory into practice requires measuring urban resilience to floods. The growing interest in managing for social–ecological resilience has prompted research into methods for assessing potential resilience to future disturbances (e.g., Bennett et al. 2005, Cumming et al. 2005). Because resilience is not directly observable, it must be inferred from surrogates—forward-looking proxies for future resilience—although it is recognized that it is not possible to represent resilience with one surrogate alone (Carpenter et al. 2005).

Assessing urban resilience to floods requires surrogates for floodability and the capacity for quick reorganization. The former is addressed here. One way to find resilience surrogates for coupled human–natural systems is to look for the internal properties that alter resilience over time (Bennett et al. 2005). Slowly changing properties are often good candidates because they define the system’s underlying structure, thus controlling the shape of the basin of attraction, threshold location, and system’s position within the state space (Carpenter et al. 2001, Scheffer et al. 2001). For river cities, a property defining floodability would be one that reflects the physical and hydrologic changes of the floodplain, over which human interests conflict with flood processes to give rise to flood disasters.

Functions of natural floodplains
Floodplains are essentially a part of the river, which naturally function to convey and store the share of high flows and sediments that spill overbank. During large floods the amount of floodplain conveyance and storage is significantly greater than that of the channel (Leopold 1994). Floodplain storage occurs when the water is disconnected from the main channel flow and is slowly released after the peak has passed (Richards and Hughes 2008). Longer term storage takes place on the surface of floodplain wetlands and through infiltration into the floodplain soils, which can store large amounts of water during wet periods (Keddy 2000). Floodplain vegetation represents hydraulic roughness and exerts significant impacts on the flood process. For example, the overall patchiness increases the heterogeneity of flow patterns; dense vegetation dampens the flood wave and traps sediments during minor floods; the floodplain forest delays the release of floodwater stored on the surface though frictional effect, thus further enhancing floodplain storage (Tabacchi et al. 2000, Richards and Hughes 2008). Because of these hydrologic and hydraulic functions, floodplain rivers have lower flood peaks and velocities, and smaller flood discharges in downstream locations, compared to other types of rivers (Leopold 1994).

As a floodplain becomes urbanized, its functions are often replaced by artificially enhanced channel capacity, drainage efficiency, and upstream impoundment. At the same time, the river sees higher peak flows with increased downstream discharges (Criss and Shock 2001), leading to higher flood risk. The urbanized floodplain becomes less tolerant of flooding for there is less land functioning to convey and store floodwater and sediments.

Floodable lands and percent floodable area
To assess floodability, I propose a new concept—the floodable land—which is defined as a land capable of storing or conveying floodwater and sediments without incurring damage locally and elsewhere. Floodable lands can be of any land use and cover, thus not exclusively referring to undeveloped or green areas such as wetlands. A green area with contaminated soils, for example, would not be floodable; a residential lot with the building raised on poles may be. Floodable lands contribute to the city’s flood tolerance, as a flood is benign where it is floodable. With a large combined area, floodable lands can lower flood peaks to reduce the overall flood impact. Everything else being equal, the more floodable lands the higher the floodability, which can be quantified by the percentage of the total area of floodable lands within the floodplain area, or percent floodable area. The floodplain area here refers to the entire valley floor between valley walls (Anderson et al. 1996). It is not defined by any flood recurrence interval because larger floods are always possible.

It is worth noting that with a percent floodable area of 100% a city could still be damaged by a rare, extreme flood, in which case reorganization plays a major role in urban resilience to floods. I hypothesize a positive but nonlinear relationship between percent floodable area and floodability because at a higher percent floodable area its marginal contribution to floodplain storage and conveyance should decrease significantly (Douglas et al. 2007). I further hypothesize that there may be hysteresis involved in the relationship between percent floodable area and urban resilience to floods (Fig. 5), as seen in other complex systems (Scheffer et al. 2001, Alberti and Marzluff 2004). The city may have to “go back further” in reestablishing floodplain functions in order to shift to a regime where the city is resilient and able to self-organize to remain orderly during most floods, with a healthy urban river to provide ecosystem services. As a surrogate for urban resilience to floods, percent floodable area represents a city’s physical fitness for flooding that matters to flood safety. Improving percent floodable area to build resilience can be a management approach that is an alternative to increasing the protection standard of flood-control infrastructure for enhancing resistance.

RESILIENCE-BASED FLOOD HAZARD MANAGEMENT
Enhancing resistance to one disturbance in complex adaptive systems often creates vulnerabilities to others (Holling and Meffe 1996, Roberge 2002). Flood control ignores complexity and unpredictability, exacerbating flood risk and creating ecological disasters. Today many cities are not flood-safe because they are premised on the artificial environmental stability that is forced by flood-control infrastructure and tolerate little socioeconomic fluctuation (Fig. 4). The management paradigm of control must be abandoned (Folke 2003, Anderies et al. 2006). For long-term flood safety, cities need to switch to resilience-based flood hazard management.

Living with floods
Resilience derives from living with disturbances (Gunderson 2000, Walker et al. 2004). Studies have shown that communities that are adapted, not resistant, to disturbances are long enduring (Berkes et al. 2003). Building urban resilience to floods is essentially a process of adaptation—instead of fighting the river, cities live with periodic floods, allowing them to enter the city to learn from them, so as to become resilient to extreme ones. It is a paradigm shift from resistant to resilient cities with the management agenda redirected from “safety against floods” to “safety at floods” (Schielen and Roovers 2008). Urban resilience to floods lies in a principle that has long been called for—working with the river rather than against it (e.g., White 1945, Leopold 1977). It also echoes the ancient philosophy of “living with floods” that is still practiced today in rural communities in countries such as Bangladesh, Cambodia, and Egypt (Laituri 2000, Berkes 2007). Distinguishing between benign frequent floods and disastrous rare ones, these communities adapt lifestyles and built environments to river dynamics, harnessing the postflood productivity boosts in fisheries and agriculture (Cuny 1991).

Although relatively uncommon in the industrialized world, similar practices can be seen in management schemes that restore floodplain functions in rural areas to prevent downstream flooding, such as the Yolo Bypass for Sacramento River in the United States, the “Room for the River” project in the Netherlands, and the “Making Space for Water” policy in England (Moss and Monstadt 2008, Opperman et al. 2009). While at the watershed scale the notion of living with floods is increasingly accepted, it is dismissed in cities where lands are deemed culturally and economically too valuable to be inundated. That cities and floods are incompatible is an entrenched perception, further enhanced by the argument that retreating from floodplains is the fundamental solution to flood hazards. Although logical, this prohibitionist discourse can close down options and prevent creative solutions (Antrobus 2010). Because retreat is politically difficult in highly populated areas and people intuitively assume there is no room for flooding, cities have no choice but to continue relying on flood-control infrastructure. However, cities are too valuable to reject the paradigm shift to live with floods in order to survive.

Flood adaptation
The assertion that cities and floods cannot coexist shows a lack of imagination, resulting from being too accustomed to the kind of built environment not adapted to floods. With a shift in perception and creative planning and design, cities can eventually phase out flood-control infrastructure and live with floods by retrofitting the built environment and adding redundancy, diversity, and flexibility into every subsystem. Open spaces can become multifunctional to convey and store floodwater during wet seasons (Douglas et al. 2007). Infrastructure can be redesigned into a collection of diverse functional elements that are flexible in operation (Fiering 1982). Buildings can be remodeled to be elevated, floatable, or wet-proofed (Guikema 2009).

It would require a change in city design. An initiative called “Water Sensitive Cities” is unfolding to integrate water management into urban planning and design to promote resilience to climate change (Howe and Michell 2012), with Rotterdam being a notable example of flood adaptation (Jacobs 2012). But a paradigm shift in city design is also necessary—it should be based on dynamism instead of presumed environmental stability. Floodplains are constantly changing, rearranged not only by inundation but also by channel migration in which land could become the site of a flowing river and vice versa. Forgoing stability and perpetuity, building structures that are adaptive, removable, and temporary are the most realistic way to live on floodplains.

Flood adaptation as the mitigation approach would correct several problems induced by flood control. First, it would not transfer the city’s own problem elsewhere, as levees and channelization do by reducing floodplain retention and increasing flow velocity to increase downstream flooding, and as flood-control dams do by submerging upstream areas to displace people. Second, it would not increase long-term flood risk, as there is no threat of flood-control infrastructure failure, through which damages by larger floods would be more catastrophic than if there were no flood-control infrastructure (Tobin 1995). Third, it would not conflict with, but rather could reconcile with ecological preservation and restoration of urban rivers by allowing ecologically critical periodic floods to reconnect the channel and floodplain (Nienhuis and Leuven 2001). Resilience-based management supports the recovery of river health because the ability of the river to provide ecosystem services promotes urban resilience to floods.

The process of incorporating change continuously gives rise to resilience (Holling 1986). Therefore, resilience-based management is itself adaptive and a learning-by-doing process, where specific objectives are open to adjustment after each flood. In resilient cities, the built environment is adaptive in two ways: it is fit for known river dynamics based on historic patterns; it is also easily adjustable to changing boundary conditions, such as climate change and population growth. The resilient city is always a work in progress.

Redefining the norm
Managing resilience is an agenda of multiple scales, because resilience is controlled by dynamics at scales above and below the scale of the system in question (Walker et al. 2004, Anderies et al. 2006). The city’s subsystems affect urban resilience to floods by controlling its position in the basin of attraction. Compare different mitigation approaches for example: flood control places the city very close to the threshold between desirable and undesirable regimes during high flows, because the city tolerates little inundation; whereas flood adaptation places the city further away. Other internal factors that affect urban resilience to floods includes river health, economic status of households, institutional flexibility, design and operation of buildings and critical infrastructure, crisis support network, etc. The subsystems are simultaneously influenced by economic, cultural, biophysical, and climatic dynamics at regional and even global scales, which change the shape of the basin of attraction to affect urban resilience to floods. Managing for urban resilience to floods thus requires attending to these cross-scale interactions.

A large-scale factor critically affecting urban resilience to floods is the norm of socioeconomic dynamics. Cities that are dependent on flood-control infrastructure are nonresilient not only because they are too close to the threshold but also because the current desirable regime is small/shallow (Fig. 3), resulting from little tolerance of socioeconomic fluctuation (Fig. 4). The norm in modern society is the execution of unabated socioeconomic activities, such that when a flood occurs and goods and services are not produced it is called economic loss, and that when mobility is limited by a flood it is considered inconvenient. However, the ideology that the same socioeconomic activities should be carried out continuously is built on the premise of environmental stability, the maintenance of which is likely to be more difficult because extreme storm events are expected to increase with climate change (Alley et al. 2007). As environmental stability becomes uncertain, the best strategy to remain in the desirable regime is to enlarge the regime itself (Carpenter et al. 2001). Because the boundary of desirable regime is socially constructed, expanding it involves redefining the norm—society needs to accept necessary changes in the form and intensity of socioeconomic activities, because the supporting infrastructure, even if adaptive to flooding, may still be limited by it. It does not mean accepting system failure during flooding, rather it implies socioeconomic flexibility and adaptability. This would involve a worldview change away from the obsession of stability (Folke 2003).

CONCLUSION
With growing popularity, the term resilience is increasingly used vaguely such that it is becoming like the word sustainability, i.e., having a diluted and unclear meaning (Brand and Jax 2007). Without a rigorous definition and some form of measurement, resilience would not be a useful concept for practice (Manyena 2006). This paper presents a comprehensive theory of urban resilience that embraces inherent dynamism and uncertainties to provide unconventional perspectives for coping with flood hazards. It addresses the issue of extreme floods, which cannot be neglected any longer. The theory suggests flood adaptation, and it challenges the conventional wisdom that cities cannot live without flood control. The development of the theory of urban resilience to floods is an attempt to enrich the existing body of resilience theory through focusing on a specific type of system with a specific problem. Research on resilience associated with human-nature couplings is still in an explorative stage with few practical methods for real-world applications (Carpenter et al. 2005, Folke 2006). The theory of urban resilience to floods, along with the surrogate measure of percent floodable area for assessing floodability, helps facilitate the application of field-based, interdisciplinary research.

The immediate real-world challenge, however, is not how to increase urban resilience to floods but how to catalyze the transformation from resistant to resilient cities. A daunting problem is that the current management regime of flood control is itself very resilient. While disasters can be catalysts for social transformation (Pelling and Dill 2010), transforming by choice is much less costly. It requires transformability—the capacity to create a fundamentally new system, about which we know much less than what makes a system resilient (Walker et al. 2004, Pelling and Manuel-Navarrete 2011). The move towards creating resilient cities is a research frontier.