Groundwater drought assessment in a Mediterranean coastal catchment through a multi-index approach

Study region: The Bruna River catchment in Tuscany, Central Italy, is analyzed to assess groundwater drought dynamics. The region exhibits clear seasonal and spatial variability in groundwater levels, influenced by both climatic and local anthropogenic factors. Study focus: This study examines the spatio-temporal dynamics of groundwater drought in the Bruna River catchment in Tuscany (Central Italy) using standardized, threshold-based, and combined indices, and links the analysis to a regional model. New hydrological insights for the region: The groundwater indices detect droughts even for short records (<30 years) and correlate strongly with longer-term meteorological drought indices, indicating that the aquifer is sensitive to prolonged meteorological deficits. The relationship between climate and groundwater is site-specific. Hotspots were identified in the central-southern part of the catchment, while anomalies at specific wells reflected local anthropogenic impacts. This framework enables effective groundwater drought monitoring and supports informed resource management under climate change, even when data availability is limited or monitoring wells are few.