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

Abstract

Groundwater drought reflects the combined influence of meteorological forcing, aquifer memory, hydraulic connectivity, and anthropogenic modification. This study develops a hydrogeologically informed statistical framework that integrates temporal groundwater-drought characteristics with spatial indicators of Exposure, Pressure, and environmental Sensitivity. Standardized Precipitation and Groundwater Level Indices were analysed at 3-, 6-, and 12-month aggregation scales for 16 piezometers grouped into shallow unconfined, intermediate confined, and deep confined aquifer systems. The shallow unconfined aquifer showed the strongest SPI–SGI association, whereas the deep confined aquifer exhibited weaker correlations, longer drought persistence, and no observed recovery within the available record. These contrasts are consistent with differences in aquifer memory and hydraulic conditions, but conclusions concerning the deep system remain exploratory because it is represented by only two monitoring wells and may also be affected by sustained anthropogenic pressure. The Drought Impact Potential Index (DIPI) combines piezometer-level SGI-12 drought-response metrics with proxy indicators of groundwater abstraction, mining influence, groundwater-dependent ecosystems, and groundwater quality. Weighted and equally weighted formulations produced broadly similar regional patterns, although leave-one-out cross-validation indicated substantial interpolation uncertainty. The resulting maps should therefore be interpreted as exploratory screening products rather than predictive vulnerability maps. The E − P contrast describes only the relative mapped magnitudes of Exposure and Pressure and does not provide causal attribution of climatic and anthropogenic controls.