Impact of groundwater extraction on saltwater movement in the lower Spree catchment under climate change and water scarcity

This study investigates the effects of groundwater extraction on saltwater movement in Berlin/Brandenburg's lower Spree catchment, a critical freshwater resource increasingly impacted by climate change and water scarcity. A high-resolution groundwater flow model was developed to simulate transient flow and saltwater dynamics. The model incorporates recharge data (1979–2019), pumping records (1994–2021), and a detailed geological framework derived from borehole data and cross-sections. Artificial neural networks (ANNs) were used to capture spatial heterogeneity, with the model discretized into ≈ 3.5 million active flow cells using a finite-difference approach with 100 m horizontal, 5 m vertical, and monthly temporal resolutions. The initial conditions determined through a spin-up period. Model calibration, supported by PEST, ensured robust performance in both steady-state and transient conditions.

 

Results reveal significant interactions between freshwater and saline zones, with prolonged extraction driving saltwater upconing. Scenario analyses highlight the sensitivity of saltwater movement to climate change, projecting accelerated saltwater intrusion under intensified pumping and reduced recharge conditions.

 

These findings underscore the need for adaptive groundwater management strategies, such as optimized pumping schedules and integrated management practices, and Managed Aquifer Recharge (MAR)to mitigate saltwater intrusion and ensure sustainable freshwater availability under changing climatic and resource pressures.