Assessing the characteristics and drivers of compound flooding events around the UK coast
<p>In low-lying coastal regions, flooding arises from oceanographic (storm surges plus tides and/or waves), fluvial (increased river discharge), and/or pluvial (direct surface run-off) sources. The adverse consequences of a flood can be disproportionately large when these different sources occ...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-07-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/23/3117/2019/hess-23-3117-2019.pdf |
| _version_ | 1811286907418574848 |
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| author | A. Hendry I. D. Haigh R. J. Nicholls H. Winter R. Neal T. Wahl A. Joly-Laugel S. E. Darby |
| author_facet | A. Hendry I. D. Haigh R. J. Nicholls H. Winter R. Neal T. Wahl A. Joly-Laugel S. E. Darby |
| author_sort | A. Hendry |
| collection | DOAJ |
| description | <p>In low-lying coastal regions, flooding arises from oceanographic (storm
surges plus tides and/or waves), fluvial (increased river discharge), and/or
pluvial (direct surface run-off) sources. The adverse consequences of a flood
can be disproportionately large when these different sources occur
concurrently or in close succession, a phenomenon that is known as
“compound flooding”. In this paper, we assess the potential for compound
flooding arising from the joint occurrence of high storm surge and high
river discharge around the coast of the UK. We hypothesise that there will be
spatial variation in compound flood frequency, with some coastal regions
experiencing a greater dependency between the two flooding sources than
others. We map the dependence between high skew surges and high river
discharge, considering 326 river stations linked to 33 tide gauge sites. We
find that the joint occurrence of high skew surges and high river discharge
occurs more frequently during the study period (15–50 years) at sites on the
south-western and western coasts of the UK (between three and six joint events per
decade) compared to sites along the eastern coast (between zero and one joint
events per decade). Second, we investigate the meteorological conditions
that drive compound and non-compound events across the UK. We show, for the
first time, that spatial variability in the dependence and number of joint
occurrences of high skew surges and high river discharge is driven by
meteorological differences in storm characteristics. On the western coast of
the UK, the storms that generate high skew surges and high river discharge
are typically similar in characteristics and track across the UK on
comparable pathways. In contrast, on the eastern coast, the storms that
typically generate high skew surges are mostly distinct from the types of
storms that tend to generate high river discharge. Third, we briefly examine
how the phase and strength of dependence between high skew surge and high
river discharge is influenced by the characteristics (i.e. flashiness, size,
and elevation gradient) of the corresponding river catchments. We find that high
skew surges tend to occur more frequently with high river discharge at
catchments with a lower base flow index, smaller catchment area, and steeper
elevation gradient. In catchments with a high base flow index, large
catchment area, and shallow elevation gradient, the peak river flow tends to
occur several days after the high skew surge. The previous lack of
consideration of compound flooding means that flood risk has likely been
underestimated around UK coasts, particularly along the south-western and western
coasts. It is crucial that this be addressed in future assessments of flood
risk and flood management approaches.</p> |
| first_indexed | 2024-04-13T03:09:18Z |
| format | Article |
| id | doaj.art-f7fcce7d5ccc450dbefebdcf7bd16fd1 |
| institution | Directory Open Access Journal |
| issn | 1027-5606 1607-7938 |
| language | English |
| last_indexed | 2024-04-13T03:09:18Z |
| publishDate | 2019-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Hydrology and Earth System Sciences |
| spelling | doaj.art-f7fcce7d5ccc450dbefebdcf7bd16fd12022-12-22T03:05:09ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382019-07-01233117313910.5194/hess-23-3117-2019Assessing the characteristics and drivers of compound flooding events around the UK coastA. Hendry0I. D. Haigh1R. J. Nicholls2H. Winter3R. Neal4T. Wahl5A. Joly-Laugel6S. E. Darby7Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UKOcean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UKSchool of Engineering, University of Southampton, Highfield, Southampton, SO17 1BJ, UKNatural Hazards and Environmental Group, EDF Energy R&D UK Centre, Croydon, CRO 2AJ, UKDepartment of Weather Science, Met Office, Exeter, EX1 3PB, UKCivil, Environmental, and Construction Engineering & National Center for Integrated Coastal Research, University of Central Florida, 12800 Pegasus Drive, Suite 211, Orlando, FL 32816-2450, USANatural Hazards and Environmental Group, EDF Energy R&D UK Centre, Croydon, CRO 2AJ, UKGeography and Environmental Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, UK<p>In low-lying coastal regions, flooding arises from oceanographic (storm surges plus tides and/or waves), fluvial (increased river discharge), and/or pluvial (direct surface run-off) sources. The adverse consequences of a flood can be disproportionately large when these different sources occur concurrently or in close succession, a phenomenon that is known as “compound flooding”. In this paper, we assess the potential for compound flooding arising from the joint occurrence of high storm surge and high river discharge around the coast of the UK. We hypothesise that there will be spatial variation in compound flood frequency, with some coastal regions experiencing a greater dependency between the two flooding sources than others. We map the dependence between high skew surges and high river discharge, considering 326 river stations linked to 33 tide gauge sites. We find that the joint occurrence of high skew surges and high river discharge occurs more frequently during the study period (15–50 years) at sites on the south-western and western coasts of the UK (between three and six joint events per decade) compared to sites along the eastern coast (between zero and one joint events per decade). Second, we investigate the meteorological conditions that drive compound and non-compound events across the UK. We show, for the first time, that spatial variability in the dependence and number of joint occurrences of high skew surges and high river discharge is driven by meteorological differences in storm characteristics. On the western coast of the UK, the storms that generate high skew surges and high river discharge are typically similar in characteristics and track across the UK on comparable pathways. In contrast, on the eastern coast, the storms that typically generate high skew surges are mostly distinct from the types of storms that tend to generate high river discharge. Third, we briefly examine how the phase and strength of dependence between high skew surge and high river discharge is influenced by the characteristics (i.e. flashiness, size, and elevation gradient) of the corresponding river catchments. We find that high skew surges tend to occur more frequently with high river discharge at catchments with a lower base flow index, smaller catchment area, and steeper elevation gradient. In catchments with a high base flow index, large catchment area, and shallow elevation gradient, the peak river flow tends to occur several days after the high skew surge. The previous lack of consideration of compound flooding means that flood risk has likely been underestimated around UK coasts, particularly along the south-western and western coasts. It is crucial that this be addressed in future assessments of flood risk and flood management approaches.</p>https://www.hydrol-earth-syst-sci.net/23/3117/2019/hess-23-3117-2019.pdf |
| spellingShingle | A. Hendry I. D. Haigh R. J. Nicholls H. Winter R. Neal T. Wahl A. Joly-Laugel S. E. Darby Assessing the characteristics and drivers of compound flooding events around the UK coast Hydrology and Earth System Sciences |
| title | Assessing the characteristics and drivers of compound flooding events around the UK coast |
| title_full | Assessing the characteristics and drivers of compound flooding events around the UK coast |
| title_fullStr | Assessing the characteristics and drivers of compound flooding events around the UK coast |
| title_full_unstemmed | Assessing the characteristics and drivers of compound flooding events around the UK coast |
| title_short | Assessing the characteristics and drivers of compound flooding events around the UK coast |
| title_sort | assessing the characteristics and drivers of compound flooding events around the uk coast |
| url | https://www.hydrol-earth-syst-sci.net/23/3117/2019/hess-23-3117-2019.pdf |
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