Resilience

The concept of resilience emerged from ecology in the 1960s and early 1970s (Holling, 1973, Folke, 2006). It has since been adopted by various disciplines and in interdisciplinary work, using diverging definitions ranging from a narrow technical term to an umbrella concept and metaphor [Folke, 2006; Adger, 2000; Carpenter et al., 2001; Klein et al., 2004). Folke (2006) identifies a sequence of resilience concepts, from narrow to broad: (1) engineering resilience, (2) ecosystem resilience and social resilience, and (3) social–ecological resilience. The first two focus on recovery rate and withstanding shock respectively. The last focuses on the interplay between disturbance and reorganization.

In the literature on resilience, the concept is currently defined as “the capacity of a system to absorb disturbance and reorganise while undergoing change so as to still retain essentially the same function, structure, identity, and feedbacks” (Walker et al., 2004). Three characteristics of (social–ecological) resilience are identified (Carpenter et al, 2001; Resiliance Aliance, 2008):
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-(re)organization to accommodate external changes.
3. The ability to build and increase the capacity for learning and adaptation.

This relatively broad definition seems suitable for systems that face not only disturbing events (shocks; e.g. floods), but also disturbing trends (e.g. sea level rise). On longer timescales, withstanding and recovering from singular disturbing events is insufficient. A resilient system should also encompass the dynamics to accommodate trends and co-evolve; to ‘bounce back in better shape’ (Barnett, 2001; Wildavsky, 1988). While umbrella concepts and metaphors are useful inspirational tools, and while using an overly narrow definition could restrict policymakers involved, resilience needs to be made operational to develop policies that increase it. Several studies propose resilience indicators for specific subsystems, aiming to provide a basis for quantitative evaluation of possible policy strategies (e.g. (Adger, 2000; Carrpenter et al., 2001; Villa and McLeod, 2002; De Bruijn, 2004a, 2004b). Other studies (Wardekker et al, 2010), qualitatively explore policy options and strategies that could enhance a system's resilience (e.g. (Sheltair Group, 2003) on urban adaptation strategies in the
Greater Vancouver region, Canada).

The operational definition of a resilient system proposed by Wardekker et al. (2010) is: “a system that can tolerate disturbances (events and trends) through characteristics or measures that limit their impacts, by reducing or counteracting the damage and disruption, and allow the system to respond, recover, and adapt quickly to such disturbances”. In this definition, tolerating disturbances is taken in contrast to resisting these (e.g. by building dikes). A ‘resilience approach’ is a ‘bottom–up’ way of thinking about adaptation to environmental change that aims to promote a system's capability of coping with disturbances and surprises, based on the concept of ‘resilience’. This is very different from the predictand-prevent approaches that are traditional in Dutch water management. Resilience analysis assesses characteristics that make a system resilient and uses these to explore options and to specify and categorise how they can contribute to the system's resilience. Such characteristics are intended to support ‘resilience-thinking’.

The following ‘resilience principles’ are used in ecological and system dynamics literature (first six: Watt and Craig, 1986; Barnett, 2001; Dessai and van der Sluijs, 2007; Remaining: Wardekker et al, 2010)
• Homeostasis: multiple feedback loops counteract disturbances and stabilise the system.
• Omnivory: vulnerability is reduced by diversification of resources and means.
• High flux: a fast rate of movement of resources through the system ensures fast mobilization of these resources to cope with perturbations.
• Flatness: the hierarchical levels relative to the base should not be top-heavy. Overly hierarchical systems with no local formal competence to act are too inflexible and too slow to cope with surprise and to rapidly implement non-standard highly local responses.
• Buffering: essential capacities are over-dimensioned such that critical thresholds in capacities are less likely to be crossed.
• Redundancy: overlapping functions; if one fails, others can take over.
• Foresight, preparedness, and planning (including monitoring, management and contingency plans, evacuation exercises, and specific attention for communication and emerging/unexpected issues).
• Compartmentalisation.
• Flexible planning/design.

Using these resilience principles, Wardekker et al generated policy options to adapt the Urban Delta of Rotterdam city by increasing resilience to climate change. Homeostasis can be enhanced by creating
greater clarity on responsibilities, early-warning, response, and feedback mechanisms, spatial planning strategies that reduce impacts or enhance recovery, and flexible structures, infrastructure and flood defences. Omnivory can be created by diversifying and distributing electricity generation, diversifying transportation options, and creating multi-functional spaces and buildings. High flux can be implemented by reducing planning horizons, possibly combined with cradle-to-cradle approaches, and planning easy-to-modify land-uses in areas that may need quick modification. Flatness involves enabling local populations to self-respond to disturbances (self-sufficiency, self-regulation, and self-organization), and increasing public participation in climate adaptation. Buffering can be enhanced by creating disturbance-proofed, low-elevation spaces (e.g. squares and parks) and ground-floors, with non-essential functions. These absorb the first impacts of disturbances; essential functions are moved to higher elevations. Leaving plenty of open space would enhance buffer-capacity against future trends. Redundancy could be implemented by creating multiple routes for electricity supply and transportation and multiple access levels for buildings, and by duplicating vital functions.

Resilience Alliance workbook
An other method for resilience assessment is provided by the work books of the resilienace alliance. The Resilience Alliance (RA) workbook consists of five chapters wherein stepwise is worked towards a better understanding of a particular social-ecological system, see figure 1.1. In this study, this workbook is used as a guideline where some modifications are undertaken.
The first step is to address the question ‘Resilience of what?’ by describing the social, ecological and economic domain of the system of interest. Also, the influences from the scales below and above the Wadden ecosystem are examined: the smaller building blocks from which the Wadden ecosystem is comprised, and the Wadden ecosystem as part of a larger system. In this study, focus lies on the ecological domain of the system. Therefore, the abiotic and biotic components of the Wadden ecosystem are thoroughly described whereas the social and economic domain receive little less attention. However, the stakeholders of the Wadden ecosystem are extensively described, as well as the way in which the Wadden ecosystem is managed. Then the linkage between past and present is made by examining past ecosystem states, management developments and regime shifts.
Step two addresses the question ‘Resilience to what?’ and explores the (future) shocks or disturbances to which the system of interest (i.e. the Wadden ecosystem in this study) should be resilient. The several internal and external disturbances that influence the system form a disturbance regime consisting of continuous (or press) disturbances and irregular (or stochastic) disturbance events. This disturbance regime ensures renewal within the system and may cause the system to shift to another state. In this study, focus lies on climate change as the disturbance to which the Wadden ecosystem should be resilient. In this step also future visions on the desirable state of the system are explored.
Step three analyses the different alternate states of the system of interest, the thresholds for a regime shift to occur, and the creation of two to three alternate states that will possibly be important in the future. Further, in the RA workbook this step includes an identification of the four phases of the (present and past) adaptive cycle of the system. Also the disturbances that trigger movement through these four phases are investigated as well as the cross-scale interactions. In this study, some adjustments are undertaken to this step. Here, an overview is created of all possible past and future regime shifts whereupon two regime shifts that possibly are important in the future have been further deepened (Pacific oyster dominated state and Crustacea dominated state). These regime shifts do not concern the entire Wadden ecosystem, but an aspect of it. Further, this study does not discuss the phases of the adaptive cycle. Disturbances are discussed in step two whereas cross-scale interactions are explored in the first step (multiple scales).
Finally, step four is about interventions (i.e. measures) which will enhance the resilience of the system of interest. In addition, adaptive management is discussed.

An example application of the resiliance aliance workbooks can be found in Westerlaan (2010) Resilience in the Wadden ecosystem. A case study of the resilience approach as a way to deal with uncertainties around climate adaptation

Resources
Resilience Alliance Workbooks: http://www.resalliance.org/3871.php

References
W.N. Adger, Social and ecological resilience: are they related? Prog. Hum. Geogr. 24 (3) (2000) 347–364.

J. Barnett, Adapting to climate change in Pacific Island countries: the problem of uncertainty, World Dev. 29 (2001) 977–993.

K.M. de Bruijn, Resilience and flood risk management, Water Policy 6 (2004) 53–66.

K.M. de Bruijn, Resilience indicators for flood risk management systems of lowland rivers, Int. J. River Basin Manag. 2 (3) (2004) 199–210.

S. Carpenter, B. Walker, J.M. Anderies, N. Abel, From metaphor to measurement: resilience of what to what? Ecosystems 4 (2001) 765–781.

S. Dessai, J.P. van der Sluijs, Uncertainty and Climate Change Adaptation — A Scoping Study, Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Utrecht, 2007.

C. Folke, Resilience: The emergence of a perspective for social–ecological systems analyses, Glob. Environ. Change 16 (2006) 253–267.

C.S. Holling, Resilience and stability of ecological systems, Annu. Rev. Ecol. Systemat. 4 (1973) 1–23.

R.J.T. Klein, R.J. Nicholls, F. Thomalla, Resilience to natural hazards: how useful is this concept? Global Environ. Change B Environ. Hazards 5 (1–2) (2003–2004) 35–45.

Resilience Alliance, Resilience, The Resilience Alliance, 2008. URL (consulted September 2008): http://www.resalliance.org/576.php.

Sheltair Group, Climate Change Impacts and Adaptation Strategies for Urban Systems in Greater Vancouver, Volume 1, The Sheltair Group, Vancouver, 2003. Available via: http://web.archive.org/web/20060626205505/http://www.sheltair.com/librar....

F. Villa, H. McLeod, Environmental vulnerability indicators for environmental planning and decision-making: guidelines and applications, Environ. Manag. 29 (2002) 335–348.

B. Walker, C.S. Holling, S.R. Carpenter, A. Kinzig, Resilience, adaptability and transformability in social–ecological systems, Ecol. Soc. 9 (2) (2004) 5–13.

J.A. Wardekker, A. de Jong, J.M. Knoop and J.P. van der Sluijs (2010), Operationalising a resilience approach to adapting an urban delta to uncertain climate changes, Technological Forecasting and Social Change 77 (6), 987-998.

K.E.F. Watt, P.P. Craig, System stability principles, Syst. Res. 3 (1986) 191–201.

A.B. Wildavsky, Searching for Safety, Transaction Publishers, New Brunswick, 1988.

P. Westerlaan (2010), Resilience in the Wadden ecosystem. A case study of the resilience approach as a way to deal with uncertainties around climate adaptation. MSc Thesis, Utrecht University.