Chronic groundwater decline: a multi-decadal analysis of groundwater trends under extreme climate cycles

Le Brocque, Andrew F. and Kath, Jarrod and Reardon-Smith, Kathryn (2018) Chronic groundwater decline: a multi-decadal analysis of groundwater trends under extreme climate cycles. Journal of Hydrology, 561. pp. 976-986. ISSN 0022-1694

Abstract

Chronic groundwater decline is a concern in many of the world’s major agricultural areas. However, a general lack of accurate long-term in situ measurement of groundwater depth and analysis of trends prevents understanding of the dynamics of these systems at landscape scales. This is particularly worrying in the context of future climate uncertainties. This study examines long‐term groundwater responses to climate variability in a major agricultural production landscape in southern Queensland, Australia. Based on records for 381 groundwater bores, we used a modified Mann-Kendall non-parametric test and Sen’s slope estimator to determine groundwater trends across a 26-year period (1989–2015) and in distinct wet and dry climatic phases. Comparison of trends between climatic phases showed groundwater level recovery during wet phases was insufficient to offset the decline in groundwater level from the previous dry phase. Across the entire 26-year sampling period, groundwater bore levels (all bores) showed an overall significant declining trend (p<0.05) of an average 0.06 metres year-1. Fifty-one bores (20%) exhibited significant declining groundwater levels (p<0.05), 25 bores (10%) exhibited significant rising groundwater levels (p<0.05), and 175 bores (70%) exhibited no significant change in groundwater levels (p>0.05). Spatially, both declining and rising bores were highly clustered. We conclude that over 1989–2015 there is a significant net decline in groundwater levels driven by a smaller subset of highly responsive bores in high irrigation areas within the catchment. Despite a number of targeted policy interventions, chronic groundwater decline remains evident in the catchment. We argue that this is likely to continue and to occur more widely under potential climate change and that policy makers, groundwater users and managers need to engage in planning to ensure the sustainability of this vital resource.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: First online 27 April 2018. Accepted Version embargoed until 30 June 2020 (24 Months) in accordance with the copyright policy of the publisher. Restricted access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 21 May 2018 01:49
Last Modified: 29 May 2018 00:54
Uncontrolled Keywords: groundwater decline; groundwater extraction; temporal trend; drought; aquifer recharge/depletion; climate extremes
Fields of Research : 07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070199 Agriculture, Land and Farm Management not elsewhere classified
05 Environmental Sciences > 0502 Environmental Science and Management > 050299 Environmental Science and Management not elsewhere classified
Socio-Economic Objective: D Environment > 96 Environment > 9609 Land and Water Management > 960905 Farmland, Arable Cropland and Permanent Cropland Water Management
Identification Number or DOI: 10.1016/j.jhydrol.2018.04.059
URI: http://eprints.usq.edu.au/id/eprint/34070

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