3 research outputs found
Assessing future flood risk at BGS and NERC observatory sites : summary report
UK Research and Innovation (UKRI) recognises the
problems posed by climate change, its impact on
society, and the need for positive action to address
the environmental sustainability challenges we
now face. By 2040, UKRI aspires to be ‘net-zero’
for its entire research undertaking, which includes
reducing and mitigating all carbon emissions
from UKRI owned operations (UKRI, 2020).
Surface water flooding can cause disruption to
people’s daily activities, businesses, and societal
functioning, consequently increasing the pressure
on natural resources. UKRI aims to understand
the risk of flooding to its properties to act where
possible to enhance climate resilience.
This Summary Report describes work undertaken
by the British Geological Survey (BGS) in
partnership with the Natural Environment Research
Council (NERC) to investigate the risk of flooding
to the BGS Keyworth and BGS Edinburgh sites,
and to four NERC observatory sites (at Capel
Dewi, Eskdalemuir, Hartland, and Herstmonceux).
Flood risk was assessed under both ‘current’
and ‘future’ climate conditions. After reviewing
existing assessments of the risk of flooding at
these locations, additional flood analyses and
modelling were undertaken for the sites that
have been mapped as being at risk of fluvial or
pluvial flooding. These sites are BGS Keyworth,
BGS Edinburgh, and the National Centre for
Atmospheric Science (NCAS) Capel Dewi
Atmospheric Observatory (CDAO). This report
summarises the findings from the analyses and
hydraulic modelling studies of the three sites. It is
accompanied by a second report, which provides
more detailed technical information (Nagheli et al.,
2022).
Flooding due to direct heavy rainfall (pluvial
flooding) or due to overflowing surface water
features (fluvial flooding) could cause water to
inundate areas of the sites investigated, potentially
resulting in business disruption and damage
to infrastructure. The risk of this is assessed by
evaluating whether a feature would be affected by
surface water or not, and if so, how often it would
be expected.
The UKCEH Flood Estimation Handbook (Institute
of Hydrology, 1999) methodology was used
to obtain profiles of rainfall over time for design
storms (see Glossary). The ReFH2 software (the
Revitalised Flood Hydrograph rainfall-runoff
method version 2; Kjeldsen, 2006) was used
to estimate the corresponding surface runoff
hydrographs for catchments above points of
interest.
The HEC-RAS flood modelling software (US Army
Corps of Engineers, 2022) was used to simulate
fluvial flooding. The SWMM modelling software
(Storm Water Management Model; US EPA. 2022)
was used to simulate pluvial flooding and to assess
the capacity of drainage infrastructure (for BGS
Keyworth only).
The assessment of how flood risk will change in
the future makes use of climate change ‘uplift’
factors. These factors have been used to shift
historical design storms. Uplift factors have
been estimated using the latest UK Met Office
Hadley Centre climate projections—the UKCP18
projections—by the UKRI-funded FUTUREDRAINAGE project (Chan et al., 2021). Factors
are only available for a ‘worst case’ atmospheric
greenhouse gas concentration trajectory (referred
to as a Representative Concentration Pathway or
RCP)—the RCP8.5 pathway. Based on these uplift factors, Table 1 summarises
how flood risk at each of the sites is predicted by
the modelling to change between the historical
period (1961–1990) and the two future time
horizons considered: the 2050s (2041–2060) and
the 2070s (2061–2080).
The following findings and recommendations (see
also Appendix 2) are presented for the three sites
considered:
BGS Keyworth
• The site is not at risk of flooding from rainfallrunoff causing the water level within the
channels running along the north-west and north-east of the site to rise and inundate parts
of the site.
• The critical storm duration (see Glossary for
definition) for BGS Keyworth was calculated to
be seven hours.
• There are three culverts in the channel along the
north-west of the site. If we adjust the historical
7-hour duration, 100-year return period summer
storm to account for climate change, then the
modelling indicates that the culverts in the
drainage channel along the north-west of the
site will surcharge but not result in inundation
of any parts of the site. (Summer and winter
storms are treated separately statistically by flood
hydrologists because summer storms are more
intense).
• Considering the same storm as described in
the previous bullet, then if it is assumed that the
bottom half of the culverts become blocked, the
modelling predicts that the Platt Lane entrance
to the site will be inundated by approximately
20 cm of water. No other part of the site would
be affected.
• Again, considering a 7-hour storm with a return
period of 100 years (calculated using data for
the period 1981–2020), analysis of the UKCP18
climate projections for RCP8.5 suggests that the
frequency of this event will change to:
» 1 in 20 years over the period 2021–2040
» 1 in 10 years over the period 2061–2080
• BGS facilities team should inspect the culverts
at least annually and arrange for any debris
to be cleared by the appropriate authority, if
necessary.
• BGS should make Nottinghamshire County
Council, the Lead Local Flood Authority (LLFA)
for Keyworth, aware of this work, given the
potential vulnerability to flooding of the new
homes recently built on the northern side of
Platt Lane, and of Severn Trent Water’s sewage
pumping station at the corner of Platt Lane and
Nicker Hill.
• There has not been sufficient information
about the site’s drainage network to assess
the risk of water appearing on the ground
surface when the drainage network becomes
surcharged. Furthermore, the development of
a model to do this would be a complex task.
Consequently, we have modelled the capacity
of the subsurface drainage pipes and used
this as a proxy to indicate which parts of the
system are more likely to cause water to pond
on the surface. Those pipe sections that have
been simulated to surcharge, or exceed 90% of
their capacity, during a 30-minute storm, need
further investigation. The model simulates that
6% of the network’s pipes exceed 90% of their
capacity during a 30-minute, 10-year return
period storm, which increases to 9% during a
30-minute, 75-year return period storm. First, the
slopes and lengths of the problematic network
sections should be measured accurately, and
the modelling exercise repeated to confirm the
findings of this study. Updating and rerunning
of the model would be relatively quick. After
confirming the fidelity of the model, several
potential solutions could then be reviewed, and
their costs and benefits evaluated against the
level of risk that NERC BGS are willing to accept.
Solutions could include replacing small diameter
pipes with larger pipes, increasing the slopes
of the pipes, optimising the size of catchment
areas generating runoff by altering the direction
of surface flow paths/directions. It is important
to maintain the drainage infrastructure to avoid
surcharging of the network and flooding.
BGS Edinburgh
• The levee and flood gates constructed along
the Murray Burn in 2020 have enhanced the
protection of the Lyell Centre. However, our
modelling predicts that the Lyell Centre would still be affected by flood water under a 20-year
return period storm. We conclude that the
levee is not sufficiently high at its downstream
end and, based on our new drone-based
LIDAR survey of land surface elevations,
flood water overtopping the levee here flows
towards the Lyell Centre. If it is considered
that the degree of flood protection is currently
insufficient, we recommend that NERC and
Heriot Watt University discuss what the options
are for increasing the level of protection to the
Lyell Centre. For example, this could include
extending the levee downstream and increasing
its height, or potentially increasing the crosssectional area of the channel.
• The critical storm duration for BGS Edinburgh
was calculated to be seven hours. Considering
a 7-hour storm with a return period of 100 years
(calculated using data for the period 1981-2020),
analysis of the UKCP18 climate projections for
RCP8.5 suggests that the frequency of this event
will change to:
» 1 in 20 years over the period 2021–2040
» 1 in 7.1 years over the period 2061–2080
• Our modelling has shown the potential for
flooding of other buildings on the Heriot Watt
campus, e.g. the Energy Academy and the
buildings north-east of the Lyell Centre on the
opposite side of the Murray Burn and Research
Avenue South. This report should be shared
with the Heriot-Watt estate management
department to make them aware of the risks to
the occupiers of these buildings, and to allow
them to consider any necessary actions.
NCAS Capel Dewi Atmospheric
Observatory (CDAO)
• The south-east corner of the site was flooded
on 21 January 2018. Measurements of rainfall
every 10 minutes during this day have been
made available by the CDAO’s Project Scientist.
Comparison against long-term historical
observations of rainfall has indicated that the
design storm that most closely matches the
peak rainfall intensity and total rainfall of the
observed storm has a 7-hour duration and 30-
year return period.
• Land surface elevation data for the site are
only available on a relatively coarse, 5 m grid.
Because of this, there is significant uncertainty
about the cross-sectional shape, and slope, of
the Afon Peithyll, which flows east to west along
the south of the site. The results of the modelling
must, therefore, be considered as ‘indicative’.
• For a 7-hour, 30-year return period design storm
the current model simulates flooding that was
more extensive than that observed in January
2018. However, it does indicate the area of the
facility that is at higher risk—the south-east
and east of the site, which is consistent with the
observations.
• Simulation of the influence of the culvert
(approximately 300 m downstream of the
site) and whether it is partially blocked or not,
suggests that it has little impact on the flood risk
of the site.
• The critical storm duration for the site was
calculated to be four hours. The modelling
suggests that a 4-hour storm with a return period
of seven years will initiate out of bank flooding at
the south-east corner of the site.
• Considering a 4-hour storm with a return period
of 100 years (calculated using data for the
period 1981–2020), analysis of the UKCP18
climate projections for RCP8.5 suggests that the
frequency of this event will change to:
» 1 in 20 years over the period 2021–2040
» 1 in 10 years over the period 2061–2080
• A survey of the Afon Peithyll and its floodplain is
needed to define the dimensions and slope of
the channel accurately and improve confidence
in the model.
• A number of engineering options are listed that
could be considered to protect the site from
flooding; their viability would depend on the
characteristics of the site, cost, and possible
environmental impacts.
• Consideration could be given to the feasibility,
and costs and benefits of moving infrastructure
located in the south-east of the site, where flood
risk is higher, to another part of the site
Equipping for risk: Lessons learnt from the UK shale-gas experience on assessing environmental risks for the future geoenergy use of the deep subsurface
\ua9 2024 The Authors. Summary findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 \ub1 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane. The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term
Equipping for risk: Lessons learnt from the UK shale-gas experience on assessing environmental risks for the future geoenergy use of the deep subsurface
Summary findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 ± 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane.The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term