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Explore resilience and vulnerability from a dynamic systems perspective. Understand stochastic viability frameworks and recovery trajectories in controlled dynamical systems. Analyze harm values, exit probabilities, and cost distributions to assess vulnerability. The proposed framework emphasizes the interplay between resilience and vulnerability to define low-vulnerability zones.
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Resilience and vulnerability from a stochastic controlled dynamical system perspective Charles Rougé, Jean-Denis Mathias and Guillaume Deffuant
Example: The case of lake eutrophication (Carpenter et al., 1999) Phosphorus input L Bounded!!! (by U>0) Lake (Phosphorus concentration P) Outflow Inflow Algae
Deterministicviability: single trajectories Event Events
Part I Resilience of a stochastic controlled dynamical system
Resilience in a stochasticdynamical system Recoveryisdefined by getting back to the stochasticviabilitykernel Centrality of the probability of recoveryafter a given date: the Probability of resilience No longer a unique measure of recovery but possibility to derivestatistics.
Part II Vulnerability as a measure of future harm
Harm: a value judgement on a state Threshold of harm Properties Ecologicalharm Quadraticincreasewith P Economicharm Increaseslinearly as L decreases
Definingvulnerability One associatesharm values to a trajectory: • Sum of staticharm values (costcriterion) • Crossing of a threshold (viabilitycriterion) Vulnerabilityis a statistic on the distribution of harm values: • Expected value of the cost • Exit probability (crossing of a threshold) • Value-at-risk (e.g. worst 1%) of the cost Interest in low-vulnerabilitykernels.
Vulnerability as exit probability Stochasticviabilitykernel!!!
Part III Towards a resilience-vulnerability framework
Conceptualdefinitions Resilience:capacity to keep or recoverpropertiesafter a hazard, disturbance or change. • Probability of recoveryat date t • Statistic on a recovery time distribution Vulnerability: a measure of future harm(Hinkel, 2011). • Statistic on an exit probability • Statistic on a cost distribution
Combiningresilience and vulnerability Resilience: capacity to recover Vulnerability: harmexperienced (equivalent to a restorationcost) ? Dynamicsafetycriterion (or property of interest) Low-vulnerability zone
Take home messages Complimentarityof resilience and vulnerability The notion of low-vulnerabilitykernelgeneralizesthat of viabilitykernel. Resilienceis the ability to get back to thissafety set after a disturbance or a change. Vulnerabilityis a statisticbased on the harm values associated to the possible trajectories. Choice of the strategydependent on the indicator.