Groundwater levels in Warsaw, Poland were studied to understand the causes and effects of changes in urban-area aquifers. By analyzing 27 years of daily measurements, researchers found that the water table in the Quaternary aquifers fluctuated over time, indicating variable recharge rates. They also observed a decrease in the water table in these aquifers. In contrast, the Oligocene aquifer showed an opposite trend with an increase in the water table. This information is crucial for sustainable groundwater planning and management in urban areas.