Bloomfield, John

Brauns, Bentje

Cuba, Daniela

Hannah, David

Heudorfer, Benedikt

Marchant, Ben

Van Loon, Anne

NERC Open Research Archive

© UKRI All rights reservedCharacterising major episodes of groundwater drought at national to continental scaleJohn BloomfieldBentje Brauns1, Daniela Cuba1, David Hannah2, Benedikt Heudorfer2, Ben Marchant1 & Anne Van Loon21British Geological Survey, 2University of BirminghamDrought & Water Scarcity: addressing current & future challengesUniversity of Oxford, 20th & 21st March, 2019© UKRI All rights reservedResearch challenges – expectations & aspirationsBBC, precipitation mapping, February 2019JRC Drought News, August 2015BGS / CEH Hydrological Summary, February 2019© UKRI All rights reservedResearch challenges - dataMarchant & Bloomfield, J. Hydrology, 564, 397-413• The Chalk is the major aquifer in the UK• ~4,000 sites on the Chalk aquifer with groundwater level data• Very little data pre-1960• Data is temporally irregular• Significant gaps in records• e.g. 2001 foot & mouth disease• Currently EA monitor ~3,000 sites• telemetry at ~10% © UKRI All rights reservedResearch challenges – intrinsic heterogeneityHydrogeological Map of Europe 1:1,500,000 map sheets, BGR, 2008Bloomfield et al., 2009. J. Hydrology, 373, 164-176Pembroke College, Oxford© UKRI All rights reservedOutlineQ. How can we better characterise groundwater droughts at the national to continental scale?• Context for groundwater drought• Standardise groundwater levels to compare groundwater drought between sites• Reconstruct groundwater droughts to provide a longer-view• Spatio-temporal analysis of groundwater droughts to understand the spatial distribution of droughts through time• Chalk in the UK• European Groundwater Drought Initiative (GDI)Note:• Focus on UK & Europe (temperate droughts)• Planning & management, anthropogenic impacts and modelling of future change are out of scope,• but will be the focus of a workshop, Birmingham, 1st July 2019 © UKRI All rights reservedGroundwater drought: Context• Lowered groundwater levels• Reduced flows to rivers & GW-dependent ecosystems• Reduced yields from public & private supply boreholes• Less water available for agricultural irrigation & industry• Changes in water quality• Adverse impact on livelihoods & health in vulnerable communities© UKRI All rights reservedSGI and groundwater droughtsBloomfield & Marchant, HESS, 2013, 17, 4769-4787• Standardisation rather than threshold approach enables drought histories between different sites to be compared • Standardised Groundwater drought Index (SGI) is a non-parametric drought index• Standardise level hydrographs using (non-parametric) Normal Scores Transform to remove seasonality and re-scale to deviations from mean Level (m)© UKRI All rights reservedMonthly SGIat each of 54 sitesReconstructing GW droughts© UKRI All rights reserved2010-12 groundwater drought in contextof groundwater droughts since 1891Profile of the 2010-12 drought• Duration 20 months• 5th (out of 17) ranked by av. intensity• 6th (out of 17) ranked by maximum intensity• Joint 2nd (out of 17) ranked in terms of percentage of sites in drought• ~91% sites in drought© UKRI All rights reserved• Four spatially coherent clusters of SGI hydrographs consistent with hydrogeological variations in the Chalk • Two anthropogenically impacted clusters• Declining levels• Groundwater reboundSpatio-temporal analysis - Chalk© UKRI All rights reserved Marchant & Bloomfield et al., J. Hydrology, 2018, 564, 397-413• Kriging of monthly data shows spatio-temporal development of groundwater drought in the Chalk• Example from 1975-76 drought© UKRI All rights reservedEuropean GW Drought Initiative (GDI)All data received Sites with >240 monthly observationsData obtainedWaiting for data,Agreement in principlen = 4014 n = 1017© UKRI All rights reservedEuropean GW Drought Initiative (GDI)• Example of cluster analysis of SGI time series from France and the Low Countries• Four SGI cluster centroids identified• Cluster 1 (yellow) long autocorrelation compared with other clusters• Cluster 2 (brown) consistent with previously published European climatology (Lloyd-Hughes & Saunders, 2002)DateSGI1980 1990 2000 2010© UKRI All rights reservedConclusions• Aspiration for & expectations of hydrological services still lag behind meteorological services• significant opportunities to improve understanding of groundwater drought if we bring all current available data together• Groundwater level reconstructions yield insights into pre-observational groundwater droughts• How can reconstructions be used effectively in water resource/drought management planning? (Thursday pm)• For drought characterisation at national to continental scale• clustering & kriging standardised level hydrographs can identify spatially-coherent responses of groundwater to drought• How do observed groundwater droughts translate into societal impacts? (Wednesday pm)• How can information be effectively used in risk perception & communication? (Thursday pm)

Characterising major episodes of groundwater drought at national to continental scale

http://nora.nerc.ac.uk/id/eprint/524836/1/J%20Bloomfield%20-%20Oxford%20Mar%2020%202019%20-%20NORA.pdf

Characterising major episodes of groundwater drought at national to continental scale

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