Landslide risk management

According to the project's terminology (see glossary of terms), the risk associated with landslides is understood as the combination of the probability of an event occurring and its negative consequences. In other words, risk results from the combination of threat, vulnerability, and responsiveness to a landslide.

Managing such risk consists on the systematic application of policies, procedures and practices to the tasks of identifying, analysing, assessing, monitoring and mitigating risk (Figure 1).

Figure 1. Framework for landslide risk management (Adapted from Fell et al., 2008)

  • Consequence analysis: Consists in identifying and quantifying the elements at risk (properties, people, environmental assets ...) and their vulnerability (Fell et al., 2005).

  • Hazard analysis: Consists  identifying the mechanisms that trigger landslides and quantifying their corresponding spatial and temporal occurrence (in terms of probability) and their intensity (Fell et al., 2005).

  • Monitoring: Comparison of landslide conditions, such as extension area, movement speed, surface topography, or soil moisture at different time periods to assess landslide activity. Landslide monitoring comprises a series of tasks including; (i) detection: recognition of new landslides from spatial or aerial images, (ii) rapid mapping: rapid semi-automatic image processing for change detection, (iii) rapid characterization: information retrieval on failure mechanism, volume involved and depletion length, (iv) long-term monitoring: data processing to recover deformation patterns and time series (Bazin. S., 2012)

  • Risk analysis: The use of available information to estimate the risk to individuals or populations, property or the environment, from hazards. Risk analyses generally contain the following steps: definition of scope, danger (threat) identification, estimation of probability of occurrence to estimate hazard, evaluation of the vulnerability of the element(s) at risk, consequence analysis, and their integration (Corominas et al., 2015).

  • Risk assessment: The process of making a recommendation on whether existing risks are acceptable and present risk control measures are adequate, and if not, whether alternative risk control measures are justified or will be implemented. Risk assessment incorporates the risk analysis and risk evaluation phases (Corominas et al., 2015).

  • Risk control: The implementation and enforcement of actions to control risk, and the periodic re-evaluation of the effectiveness of these actions (Corominas et al., 2015).

  • Risk evaluation: The stage at which values and judgement enter the decision process, explicitly or implicitly, by including consideration of the importance of the estimated risks and the associated social, environmental, and economic consequences, in order to identify a range of alternatives for managing the risks  (Corominas et al., 2015).

  • Risk mitigation: Measures taken to limit the adverse impact of, for example, natural hazards, environmental degradation and technological hazards. Mitigation measures encompass threat-resistant engineering and construction techniques, as well as better environmental policies and greater public awareness (UNISDR 2009).

  • Tolerable risk: Level of potential losses that a society or community considers acceptable, according to its existing social, economic, political, cultural, technical and environmental conditions (UNISDR 2009).