Multicriteria decision-making approach as a strategy to deal with land subsidence in affected areas

Unsustainable groundwater extraction may cause groundwater levels drawdown leading to compaction of the aquifer systems and causing the lowering of ground surface, i.e., land subsidence. Thus, to prevent from land subsidence caused by the overexploitation of aquifer systems it is essential avoiding the unsustainable decline of groundwater levels. An effective policy to mitigate land-subsidence should include systematic monitoring and modelling of groundwater bodies in exposed areas, evaluation of potential damages, and cost-benefit analyses permitting the implementation of adequate mitigation or adaptation measures. Among others, these measures should consider groundwater regulation and strategic long-term measures, such as the development of alternative water supplies, the introduction of changes and reallocation of water demands in the different sectors, or the implementation of severe legal control related to water uses.

The RESERVOIR project (PRIMA Foundation) aims to provide new products and services for a sustainable groundwater management model. Within this global aim, one specific task of the project focuses on the establishment of good management practices related to groundwater uses in areas affected by land subsidence.

In this study, a multicriteria decision-making approach is suggested to evaluate the potential possibilities and different scenarios for subsidence mitigation in the affected areas. This methodology is based on the analytical hierarchical process (AHP), an easy-to-use procedure which allows individual and group decisions. The procedure, which has been applied to multiple real-life scenarios, requires the evaluation of various criteria and sub-criteria by assigning them relative weightings to finally choice between a set of alternatives.

The methodology is proposed as a tool to evaluate the different possibilities to deal with subsidence in the affected areas and might be particularized by selecting the criterions to be considered (for instance, environmental, economic, social, technical, or legal, among others) in order to group the different sub-criteria to be evaluated and weighted. This tool can be particularly applied to different areas. In addition, based on the final purpose, different agents (technicians, stakeholders, farmers, businessman, general population, etc.) can contribute to obtain the results and final conclusions of the analysis.

This study has been carried out in the framework of the RESERVOIR project (sustainable groundwater RESources managEment by integrating eaRth observation deriVed monitoring and flOw modelIng Results), funded by the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) programme supported by the European Union (G. A. Nº 1924).