Improving the understanding of the risk from groundwater flooding in the UK

Macdonald, David; Bloomfield, John P.; Hughes, Andrew; MacDonald, Alan; Adams, B.; McKenzie, Andrew

doi:10.1201/9780203883020.ch125

Cited by 31 publications

(25 citation statements)

References 3 publications

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“…Examples in the United Kingdom of the second type of flooding include the flood events in south Oxford in 1997 (Macdonald et al ., 2007, 2008a); and Pilmuir in Scotland in 1997 (MacDonald et al ., 2008a, b). However, while all of the above mechanisms can result in significant flooding, it is the intense or long duration rainfall that is currently believed to be the most important source of UK groundwater flood risk (Jacobs, 2004), and is the main focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

Flood risk from groundwater: examples from a Chalk catchment in southern England

Hughes

Vounaki

Peach

et al. 2011

Journal of Flood Risk Management

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Groundwater flooding has moved up the policy‐makers' agenda as a result of the United Kingdom experiencing extensive groundwater flooding in winter 2000/2001. However, there is a lack of appropriate methods and data to support groundwater flood risk assessment. The implications for flood risk assessment of groundwater flooding are outlined using a study of the Chalk aquifer underlying the Pang and Lambourn catchments in Berkshire, UK. Groundwater flooding in the Chalk results from the water table reaching the land surface and producing long‐duration surface flows (weeks to months), causing significant disruption to transport infrastructure and households. By analyzing existing data with a farmers' survey, it was found that groundwater flooding consists of a combination of intermittent stream discharge and anomalous springflow. This work shows that there is a significant challenge involved in drawing together data and understanding of groundwater flooding, which includes vital local knowledge, reasonable risk assessment procedures and deterministic modelling.

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Section: Introductionmentioning

confidence: 99%

Flood risk from groundwater: examples from a Chalk catchment in southern England

Hughes

Vounaki

Peach

et al. 2011

Journal of Flood Risk Management

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“…Groundwater flooding is the emergence of groundwater at the ground surface away from perennial river channels and can also include the rising of groundwater into man-made ground, including basements and other subsurface infrastructure (Macdonald et al 2008). The impact of groundwater flooding can be severe under conditions where the 'normal' ranges of groundwater level and groundwater flow are exceeded.…”

Section: Introductionmentioning

confidence: 99%

Groundwater flooding within an urbanised flood plain

Macdonald

Dixon²,

Newell

et al. 2011

J Flood Risk Management

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In Europe in recent years there has been a recognition of the need to better understand the risk from groundwater flooding. This recognition has been due both to the occurrence of major flooding events clearly attributable to groundwater, and the inclusion of groundwater flooding in European and national legislation. The case study of the city of Oxford on the River Thames floodplain in the United Kingdom is used to examine the mechanisms for groundwater flooding in urbanized floodplain settings. Reference is made to an extensive dataset gathered during a major flood event in 2007. Groundwater flooding of a significant number of properties is shown to occur in areas isolated from fluvial flooding due to high ground created historically to protect property and the transport network from flood inundation. The options for mitigating this form of flooding are discussed; measures to increase the rate of conveyance of flood waters through Oxford, designed to reduce fluvial flood risk, have also been recognized as a means for reducing groundwater flood risk within the city.

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“…Groundwater flooding, i.e. when groundwater levels emerge at the ground surface due to intense rainfall (Macdonald et al, 2008), tend to be more severe in areas of permeable outcrop like the English Chalk (Macdonald et al, 2012) as also experienced repeatedly in other karst areas in Europe (Parise, 2003(Parise, , 2010Bonacci et al, 2006;Jourde et al, 2007;Gutiérrez, 2010;Naughton et al, 2012;Parise et al, 2015). Groundwater drought indices tend to be more related to recharge conditions in Cretaceous Chalk aquifers than in granular aquifers (Bloomfield and Marchant, 2013).…”

Section: S Brenner Et Al: Process-based Chalk Groundwater Modellingmentioning

confidence: 99%

Process-based modelling to evaluate simulated groundwater levels and frequencies in a Chalk catchment in south-western England

Brenner

Coxon

Howden

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. Chalk aquifers are an important source of drinking water in the UK. Due to their properties, they are particularly vulnerable to groundwater-related hazards like floods and droughts. Understanding and predicting groundwater levels is therefore important for effective and safe water management. Chalk is known for its high porosity and, due to its dissolvability, exposed to karstification and strong subsurface heterogeneity. To cope with the karstic heterogeneity and limited data availability, specialised modelling approaches are required that balance model complexity and data availability. In this study, we present a novel approach to evaluate simulated groundwater level frequencies derived from a semi-distributed karst model that represents subsurface heterogeneity by distribution functions. Simulated groundwater storages are transferred into groundwater levels using evidence from different observations wells. Using a percentile approach we can assess the number of days exceeding or falling below selected groundwater level percentiles. Firstly, we evaluate the performance of the model when simulating groundwater level time series using a spilt sample test and parameter identifiability analysis. Secondly, we apply a split sample test to the simulated groundwater level percentiles to explore the performance in predicting groundwater level exceedances. We show that the model provides robust simulations of discharge and groundwater levels at three observation wells at a test site in a chalk-dominated catchment in south-western England. The second split sample test also indicates that the percentile approach is able to reliably predict groundwater level exceedances across all considered timescales up to their 75th percentile. However, when looking at the 90th percentile, it only provides acceptable predictions for long time periods and it fails when the 95th percentile of groundwater exceedance levels is considered. By modifying the historic forcings of our model according to expected future climate changes, we create simple climate scenarios and we show that the projected climate changes may lead to generally lower groundwater levels and a reduction of exceedances of high groundwater level percentiles.

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Improving the understanding of the risk from groundwater flooding in the UK

Cited by 31 publications

References 3 publications

Flood risk from groundwater: examples from a Chalk catchment in southern England

Flood risk from groundwater: examples from a Chalk catchment in southern England

Groundwater flooding within an urbanised flood plain

Process-based modelling to evaluate simulated groundwater levels and frequencies in a Chalk catchment in south-western England

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