Exploring Groundwater Memory in Baltic States: Controls and Complexities of timeseries analysis

This study used groundwater memory timeseries as a proxy for groundwater drought vulnerability to unveil dominant patterns and their correlations with physiographic and climatic controls within hydrogeological systems of Baltic states. Clustering of groundwater memory timeseries was performed to identify regions with similar hydrodynamic systems, while random forest classification identified significant site-descriptive features, giving insights into system similarities and dissimilarities. Catchment characteristics showed the greatest importance followed by climate, topography and land use features. Moreover, spatial analysis of cluster distribution revealed feature combinations which are not covered by groundwater observations, presenting a challenge in understanding groundwater dynamics in these data-scarce locations. The study underscores the importance of considering not only locations with groundwater level data but also regions of typical feature patterns without monitoring infrastructure, thus identifying possible locations for new groundwater monitoring wells.