Assessment of groundwater drought risk in arid regions using standardized indices and reliability analysis

Groundwater drought poses a significant threat to water and food security. In arid regions, groundwater can be the primary resource for irrigation and related agri-food sectors. Hence, herein, we investigated meteorological drought using the standardized precipitation index (SPI) to assess its impact on groundwater drought occurrence in the region of Souss-Massa in Morocco. Groundwater risk modeling was performed by combining reliability analysis with the Standardized Water Level Index (SWI). This methodology generates values for Groundwater Drought Risk (GDR) and the Environmental Hazard Index (EHI), which are spatially distributed to evaluate groundwater risk under various drought bands. Results showed fluctuating dry and wet periods, with a weak correlation between SPI and SWI ( r = 0.07), suggesting that factors other than meteorological drought predominantly drive groundwater drought occurrence. GDR values range from 19.2% to 57.94% under mild conditions and 15% to 36.62% under extreme conditions, showing increased vulnerability, particularly in the middle Souss and Massa areas. These lower values at higher severity levels reflect the reduced frequency but greater potential impact of severe drought events. EHI results further suggest that the Massa basin and the middle Souss are particularly susceptible to groundwater drought, with values exceeding 80% in some areas, indicating severe environmental impacts, necessitating immediate intervention to properly manage the groundwater resources. Thus, this work could provide valuable insights for policymakers and could be implemented by water resources managers to better anticipate groundwater occurrence and its spatial distribution.