Spectral Analysis of groundwater level time series: Hydrogeological parameter estimation for groundwater modelling

The sustainable management of groundwater resources faces significant challenges in light of progressing climate changes with decreasing groundwater recharge, as well as the associated increase in withdrawals. At several observation wells in Germany in particular, declining groundwater levels are being observed, highlighting the need for robust forecasting methods to assess both the long-term availability of water resources and the vulnerability and resilience of aquifers.

Using spectral analysis of groundwater level fluctuations, hydrogeological parameters such as transmissivity, storativity, and the characteristic response time can be derived from time series of groundwater levels and recharge in the frequency domain. The characteristic response time serves as a measure of an aquifer’s resilience to droughts, enabling the classification of groundwater monitoring wells and their respective aquifers, while the derived transmissivity and storativity can be used for transient groundwater modelling.

Thus, the presented methodological workflow allows a rapid assessment of hydrogeological properties as well as the application of these parameters in numerical and analytical models for predicting groundwater levels under changing climatic conditions.