A new approach to quantification of groundwater resource stress

Study region: Mond basin, comprising 61 aquifers in southern Iran. Study focus: New indicators and a framework are presented for quantifying the intensity of groundwater stress by considering hydrogeological and anthropogenic factors, including renewable water availability, non-renewable water storage, withdrawal, and return flow. In contrast to existing methods, our proposed indicators consider accumulated historical water stress tolerated by an aquifer during an exploitation period and incorporate groundwater over-extraction from both renewable and non-renewable storages of aquifers. New hydrological insights: We assessed the applicability of existing and newly defined groundwater stress indicators on the Mond aquifers. Our results indicate that the proposed approach is able to inform the degree of groundwater stress and identify vulnerable aquifers with high intensity of groundwater stress. Statistical analysis of long-term mean annual groundwater drawdown and groundwater storage confirmed the results of aquifer classification in terms of intensity of groundwater stress. Finally, the response of aquifers in different stages of water stress was evaluated by scenarios of i) reduced human-induced withdrawal and irrigation return flow and ii) increasing recharge. These scenario analyses indicate that even up to a 50% reduction in human water use or a 50% increase in recharge does not recover the more severely stressed aquifers to sustainable hydrologic conditions.