Relating wellfield drawdown and water quality to aquifer sustainability – A method for assessing safe groundwater abstraction

Ryle Nørskov Gejl*, Poul Løgstrup Bjerg, H. J. Henriksen, K. Bitsch, L. Troldborg, J. Schullehner, J. Rasmussen, Martin Rygaard

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Planning for sustainable groundwater abstraction requires realistic and reliable assessments of groundwater drawdown in aquifers as well as impacted groundwater-dependent terrestrial and aquatic ecosystems. Present-day impact assessments allocate water for the environment and ecosystems in the form of environmental groundwater requirements (EGWRs). However, securing sustainable groundwater abstraction also requires stable groundwater quality for consumers and receptors (e.g. streams and groundwater-dependent ecosystems). We suggest dividing EGWR into two parts, namely EGWRflow, related to impacts on surface water, and EGWRwq, related to impacts on groundwater quality. We then propose a method for modelling maximum safe groundwater abstraction rates based on a relationship between water quality and piezometric heads. The method provides estimations of sustainable abstraction rates that secure stable water quality and maintain water security. Using hydrological modelling, we estimated spatially differentiated EGWRwq, for Zealand, Denmark, based on three different conditioned drawdowns of 3, 6 and 9 m. We found that depending on the boundaries and the different conditioned drawdowns EGWRwq poses a 2.5–83% share of the groundwater recharge. We found that a redistribution of water abstraction would make 27 million m3 available compared with actual abstraction, dependent on scale, while keeping within a conditioned drawdown of 3 m. Our results demonstrate how conditioned drawdown can be implemented with the objectives of evaluating actual abstraction and securing stable water quality, hence comprising a step towards more reliable and relevant groundwater impact assessments.

Original languageEnglish
Article number105782
JournalEcological Indicators
Volume110
Number of pages11
ISSN1470-160X
DOIs
Publication statusPublished - 2020

Keywords

  • Environmental water requirements and flow requirements (EWR and EFR)
  • EU Water Framework Directive
  • Groundwater impact assessment
  • Sustainable groundwater abstraction
  • Water utility management

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