Integrating propagation and recovery dynamics into groundwater drought vulnerability assessment through exposure, pressure, and aquifer system response

Abstract. Groundwater drought is influenced more by system-specific response dynamics than by meteorological forcing alone. We introduce a multi-scale framework that combines exposure, pressure, and sensitivity with process-based metrics of drought propagation and recovery to assess groundwater drought vulnerability. The Drought Impact Potential Index (DIPI) is developed and tested across a regional aquifer system. Propagation probability, median recovery time, and resilience metrics are examined across temporal scales and in groundwater systems at different depths. The findings reveal that spatial vulnerability patterns are driven by variations in system memory and response time. Deeper aquifer systems tend to have higher propagation probability, longer recovery periods, and increased vulnerability, indicating delayed responses and persistent drought signals. Conversely, shallower systems respond more quickly and recover faster, leading to lower drought persistence. The spatial distribution of DIPI remains consistent whether using weighted or unweighted versions, confirming that the identified patterns are robust and reflect fundamental hydrogeological controls. These results demonstrate that groundwater drought vulnerability arises from interactions between external forcing and internal system dynamics and cannot be understood solely through static indicators. An area-based analysis of exposure–pressure contrast shows that 60.4 % of the study area is dominated by the intrinsic system response, compared to 21.8 % driven primarily by human pressure. The proposed framework offers a process-based approach for groundwater drought assessment and can be applied to other diverse aquifer systems.