Unravelling Regional Water Balance Dynamics in Anthropogenically Shaped Lowlands: A Data-Driven Approach

Effective management of water resources in anthropogenically shaped lowlands requires a comprehensive understanding of hydrological processes and balancing various effects in complex settings, especially like lowland hydrology. Unlike mountainous headwater catchments with shallow soils, lowland hydrology is typically dominated by groundwater dynamics, often exhibiting pronounced spatial correlation lengths, though other factors may also contribute. This necessitates consideration of distant anthropogenic impacts in water resources management. This study focuses on the Lusatia region in the northern German, a lowland area heavily altered by mining activities, including extensive groundwater lowering and rebound, impacting the overall water regime. We applied an efficient, data-based approach to unravel various impacts on the landscape water balance over a 30-year period (1993–2022). We integrated over 1800 ground-based time series data on groundwater levels, surface water dynamics and runoff, supplemented by evapotranspiration estimates from multi-temporal Landsat satellite data to account for land use effects. Through principal component analysis, we identified key patterns driving water balance dynamics. The first four components explained 84% of the variance in groundwater and surface water levels, as well as of runoff dynamics. The dominant processes attributed to these components include anthropogenic influences from mining activities, as well as natural hydrogeological effects such as seasonal variability and the damping of the groundwater recharge signal in the unsaturated zone. A separate principal component analysis that included evapotranspiration data explained 87% of the variance, with the first component predominantly reflecting seasonal variations and subsequent components elucidating land use impacts and long-term vegetation changes. By linking both analyses, we generated comprehensive maps detailing the spatial distribution of effects on regional water balance. Our approach provides a quantitative tool to assess the size and influence of natural and anthropogenic effects on water resources, offering a comprehensive tool for assessing spatial and temporal effects on hydrological dynamics in a lowland region affected by human activities.