Estimating karst groundwater recharge from soil moisture observations-a new method tested at the Swabian Alb, southwest Germany

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Romane Berthelin - , University of Freiburg (Author)
  • Tunde Olarinoye - , University of Freiburg (Author)
  • Michael Rinderer - , University of Freiburg (Author)
  • Matías Mudarra - , University of Málaga (Author)
  • Dominic Demand - , University of Freiburg (Author)
  • Mirjam Scheller - , University of Freiburg (Author)
  • Andreas Hartmann - , Institute of Groundwater Management, Chair of Groundwater Systems, University of Freiburg, TUD Dresden University of Technology (Author)

Abstract

Understanding groundwater recharge processes is important for sustainable water resource management. Experimental approaches to study recharge in karst areas often focus on analysing the aquifer response using a disintegration of its outlet signals, but only a few approaches directly investigate the recharge processes that occur at the surface of the system. Soil moisture measurements have a high potential to investigate water infiltration to deeper soil depth or epikarst with an easy and not too intrusive installation. They can yield long-Term measurements with high temporal resolution. Using these advantages, we developed and tested a method to estimate recharge based on soil moisture measurements. The method consists of the extraction of linked events in rainfall, soil moisture, and discharge time series, as well as a subsequent fitting of the parameters of a simple drainage model to calculate karst recharge from soil moisture metrics of individual events. The fitted parameters could be interpreted in physically meaningful terms and were related to the properties of the karstic system. The model was tested and validated in a karst catchment located in southwest Germany with hourly precipitation, soil moisture, and discharge data of 8 years duration. The soil moisture measurements were distributed among grassland (ngCombining double low lineg8) and woodland areas (ngCombining double low lineg7) at 20gcm depth. A threshold of about 35g% (±g%) of volumetric water content was necessary to initiate effective infiltration. Soil moisture averaged during the wetting period of each event was the best metric for the prediction of recharge. The model performed reasonably well, estimating recharge during single rainfall events. It was also capable of simulating 88g% of the average annual recharge volume despite considerable differences in the performance between years. The event-based approach is potentially applicable to other karstic systems where soil moisture and precipitation measurements are available to predict karst groundwater recharge.

Details

Original languageEnglish
Pages (from-to)385-400
Number of pages16
JournalHydrology and earth system sciences
Volume27 (2023)
Issue number2
Publication statusPublished - 19 Jan 2023
Peer-reviewedYes

External IDs

ORCID /0000-0003-0407-742X/work/159171590