Abstract
Groundwater use affects groundwater storage continuously as the removal of water changes both short-term and long-term groundwater level variation. This has implications for groundwater droughts, i.e. a below-normal groundwater level. The impact of groundwater use on groundwater droughts, however, remains unknown. Hence, the aim of this study is to investigate the impact of groundwater use on groundwater droughts in the absence of actual abstraction data. We present a methodological framework that consists of two approaches. The first approach compared groundwater droughts at monitoring sites that are potentially influenced by abstraction to groundwater droughts at sites that are known to be near natural. Observed groundwater droughts were compared in terms of drought occurrence, duration, and magnitude. The second approach investigated long-term trends in groundwater levels in all monitoring wells. This framework was applied to a case study of the UK, using four regional water management units in which groundwater levels are monitored and abstractions are licensed. Results show two asymmetric responses in groundwater drought characteristics due to groundwater use. The first response is an increase in shorter drought events and is found in three water management units where long-term annual average groundwater abstractions are smaller than recharge. The second response, observed in one water management unit where groundwater abstractions temporarily exceeded recharge, is a lengthening and intensification of groundwater droughts. Analysis of long-term (1984-2014) trends in groundwater levels shows mixed but generally positive trends, while trends in precipitation and potential evapotranspiration are not significant. The overall rising groundwater levels are consistent with changes in water use regulations and with a general reduction in abstractions during the period of investigation. We summarised our results in a conceptual typology that illustrates the asymmetric impact of groundwater use on groundwater drought occurrence, duration, and magnitude. The long-term balance between groundwater abstraction and recharge plays an important role in this asymmetric impact, which highlights the relation between short-term and long-term sustainable groundwater use.
| Original language | English |
|---|---|
| Pages (from-to) | 4853-4868 |
| Number of pages | 16 |
| Journal | Hydrology and Earth System Sciences |
| Volume | 24 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 13 Oct 2020 |
Funding
Acknowledgements. We would like to thank Richard Morgan and Catriona Finch for providing data and offering their valuable feedback in the initial stages of this study, and Michael Kehinde, Vicky Fry, Alex Chambers, and Kevin Voyce for providing the groundwater monitoring data and background material. The study has benefited from valuable discussions during meetings and workshops with the “Drought in the Anthropocene” working group of the International Association of Hydrological Sciences (IAHS) Panta Rhei network, and we would like to thank Henny Van Lanen in particular. We also thank the editor and two anonymous reviewers for their constructive comments. Doctoral training and financial support was provided by CENTA NERC as well as BGS. John P. Bloomfield publishes with the permission of the director of the British Geological Survey (NERC; UKRI). Financial support. This research has been supported by the
