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A systematic assessment of drought termination in the United Kingdom

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posted on 25.11.2016 by Simon Parry, Robert Wilby, Christel Prudhomme, Paul Wood
Drought termination can be associated with dramatic transitions from drought to flooding. Greater attention may be given to these newsworthy and memorable events, but drought terminations that proceed gradually also pose challenges for water resource managers. This paper defines drought termination as a distinctive phase of the event. Using observed river flow records for 52 UK catchments, a more systematic and objective approach for detecting drought terminations is demonstrated. The parameters of the approach are informed by a sensitivity analysis that ensures a focus on terminations of multi-season to multi-year droughts. The resulting inventory of 467 drought terminations provides an unprecedented historical perspective on this phenomenon in the UK. Nationally and regionally coherent drought termination events are identifiable, although their characteristics vary both between and within major episodes. Contrasting drought termination events in 1995-1998 and 2009-2012 are examined in greater depth. The data are also used to assess potential linkages between metrics of drought termination and catchment properties. The duration of drought termination is moderately negatively correlated with elevation (irsg‰Combining double low lineg‰ĝ'0.47) and catchment average rainfall (irsg‰Combining double low lineg‰ĝ'0.42), suggesting that wetter catchments in upland areas of the UK tend to experience shorter drought terminations. More urbanized catchments tend to have gradual drought terminations (contrary to expectations of flashy hydrological response in such areas), although this may also reflect the type of catchments typical of lowland England. Significant correlations are found between the duration of the drought development phase and both the duration (irsg‰Combining double low lineg‰ĝ'0.29) and rate (irsg‰Combining double low lineg‰0.28) of drought termination. This suggests that prolonged drought development phases tend to be followed by shorter and more abrupt drought terminations. The inventory helps to place individual events within a long-term context. The drought termination phase in 2009-2012 was, at the time, regarded as exceptional in terms of magnitude and spatial footprint, but the Thames river flow record identifies several comparable events before 1930. The chronology could, in due course, provide a basis for exploring the complex drivers, long-term variability, and impacts of drought termination events.

Funding

This research was funded through the Learning & Development programme at the Centre for Ecology & Hydrology (CEH), as well as the Natural Environment Research Council’s (NERC) “Analysis of historic drought and water scarcity in the UK” (NERC grant ref.: NE/L01016X/1) and “Improving predictions of drought to inform user decisions (IMPETUS)” (NERC grant ref.: NE/L010267/1) projects.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Hydrology and Earth System Sciences

Volume

20

Issue

10

Pages

4265 - 4281

Citation

PARRY, S. ... et al, 2016. A systematic assessment of drought termination in the United Kingdom. Hydrology and Earth System Sciences, 20, pp. 4265-4281.

Publisher

Published by Copernicus Publications on behalf of the European Geosciences Union. © Author(s)

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 3.0 Unported (CC BY 3.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/by/3.0/

Acceptance date

05/09/2016

Publication date

2016

Notes

This is an Open Access Article. It is published by Copernicus Publications on behalf of the European Geosciences Union under the Creative Commons Attribution 3.0 Licence (CC BY). Full details of this licence are available at http://creativecommons.org/licenses/by/3.0/.

ISSN

1027-5606

eISSN

1607-7938

Language

en

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