Assessing and measuring resilience

Concepts of resilience take two broad forms: (1) hard resilience : the direct strength of structures or institutions when placed under pressure, such as increasing the resilience of a structure through specific strengthening measures to reduce their probability of collapse. (b) soft resilience: the ability of systems to absorb and recover from the impact of disruptive events without fundamental changes in function or structure, which depend on the flexibility and adaptive capacity of the system as a whole, rather than simply strengthening structures or institutions in relation to specific stresses, as in the hard resilience approach. However, there are three possibilities in response to threats of disturbance: (a) Resistance and maintenance, which is characterized by resistance to change. A human system of this type would do its utmost to avoid change and would typically deny that a problem exists. (b) Change at the margins, characterized by acknowledgement of the problem, discussion of the implications, and, hopefully, a clear acknowledgement that the present system is not sustainable and that change is needed. (c) Openness and adaptability, an approach reduces vulnerability by having a high degree of flexibility. Its key characteristic is a preparedness to adopt new basic operating assumptions and institutional structures. Once the resilience options have been identified to meet the vulnerability of a system, it is necessary to compare the degree of resilience that the different alternatives may offer. The different concepts are examined to propose both a qualitative and a possible quantification of the degree of resilience that may be achieved by the different measures proposed for implementation. (C) 2014 The Authors. Published by Elsevier B. V.