An overview of the methods for evaluating the resilience of groundwater systems.

Currently, groundwater resources are under anthropogenic and natural pressures. Depending on various factors, aquifers have diverse responses toward stresses. Resilience is among the performance criteria determining the ability of an aquifer to withstand unfavorable circumstances and to recover to a steady state after a failure. Hence, making use of this concept in groundwater systems is of cruciality in sustainable groundwater resources management. The main objective of the current research is to provide an overview on the employed procedures and existing difficulties appertaining to the appraisal of groundwater resilience. To this end, 36 studies which have evaluated groundwater resilience were regarded. Results highlighted that not only a very limited literature has employed groundwater resilience, but there also exist multiple knowledge gaps and complications, including resilience dimension, data scarcity and inaccuracies. In terms of groundwater quality and saltwater intrusion much little research exist, i.e. 7 studies among 36 ones. Evaluating groundwater resilience quantitatively, 11 methods were distinguished, each of which with its own advantages and disadvantages which may be engaged depending on factors such as available data and type of aquifer. Finally, more groundwater resilience analyses must be conducted at different spatiotemporal scales in order to preserve aquifers for the future generations. In summary, followings may be regarded to evaluate groundwater resilience:•To begin with, it must be specified which aspect of the aquifer's resilience and toward which unsatisfactory condition is planned to be considered.•Provided that no groundwater modeling is intended to be conducted, the observation data may be analyzed, considering the current state, governing violations, and new steady state.•On condition that groundwater simulation is planned to be conducted, subsequent to model's calibration and verification, the response of the aquifer, as a resilience criterion, is determined.