Time-Lapse Tomography of a Groundwater Pumping Experiment

Climate change significantly impacts groundwater resources by altering recharge rates and thus availability, making it crucial to manage these vital reserves sustainably to ensure long-term water security. In this study we seismically monitor a series of groundwater pumping tests in the municipality of Nickelsdorf (Burgenland, Austria).  Due to expected increasing demand for water due to population development, wells were installed to ensure a sustainable drinking water supply in the long term. Traditionally monitored through point-wise hydrological wells, our approach combines nodal seismic sensors and ambient noise to broaden insights into subsurface processes affected by pumping activity. Seismic ambient noise was continuously recorded over three months in early 2023, including periods before, during, and after pumping. Our study evaluates various ambient noise sources and seismic signals, especially those generated by passing trains. To gain broader understanding of the subsurface processes we perform a time-lapse tomography to identify the location and strength of the velocity variations. Based on our analysis, we resolve increases/decreases in seismic velocity of around 10 % in the uppermost meters of the subsurface during pumping operations related to local reduction in the water table. This holistic approach aims at unveiling the behavior of the subsurface during and post-pumping, potentially offering a comprehensive understanding beyond individual hydrological wells.