High intensity!
Future flood risk in urban and rapid response catchments
Elliot Gill BSc FCIWEM C.WEM Global Practice Leader, Wet Weather & Wastewater Collection
Co-authors:
Murray Dale CH2MElizabeth Kendon Met OfficeHayley Fowler University of NewcastleSteven Chan University of NewcastleBarry Luck UKWIRAndrew Eden Environment Agency
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Agenda
• Our challenge
• The solution
• Preliminary climate change uplifts
• FCRM takeaways
• Related data outputs
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Our challenge
• Climate change predicted to increase storminess and local convective rainfall activity = more frequent flooding
• Cities responsive to short duration ( < 24hr ), intense and localised rain events
• Climate change guidance (Defra / EA) based on UKCP09 regional climate models (RCM)
• UKCP09 RCM @ 25km grid & not intended for sub-daily use
“water companies do not have a way of assessing the growing risk in sewer system management based on climate science”
“major gap in current industry knowledge”
United Kingdom Water Industry Research 2014
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The solution
• Use new Met Office high resolution climate models (1.5km grid)
• Single emission scenario 13 year simulation for 2100
• Derived spatial pattern of percentage uplift to current rain-event depths
– 2030, 2050 & 2080 epochs
– 3, 6, 12, 24 hr durations
– 10 and 30 year return period
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M30-601.5km grid 2100
100%
25%
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North West UK
North East UK
South UK
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Impact of storm duration & frequency
Uplifts are consistent across durations tested and between 10 year and 30 year return period
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UKWIR ‘central estimate’ uplifts to 30 year return period rainfall (<24 hr)
0
20
40
60
80
100
North West North East South Defra EA
%ag
e u
plif
t o
n c
urr
ent
clim
ate
2030s 2050s 2080s
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UKWIR ‘high estimate’ uplifts to 30 year return period rainfall (<24 hr)
0
20
40
60
80
100
North West North East South Defra EA
%ag
e u
plif
t o
n c
urr
ent
clim
ate
2030s 2050s 2080s
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Recommended uplifts
2030s 2050s 2080s
North West UK
Central estimate 20% 35% 55%
High estimate 35% 65% 110%
North East UK
Central estimate 10% 20% 35%
High estimate 30% 50% 85%
South UK
Central estimate 10% 15% 25%
High estimate 20% 35% 65%
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FCRM takeaways
1. Developed for use in urban drainage system & (pluvial) surface water appraisal & design.
2. Also applicable in rapid response fluvial catchments ?
3. Different to current EA guidance (esp. in North and all high estimates)
4. UKCP18 outputs will also use high resolution simulations but with added information on uncertainty
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30 % rainfall uplift = 40% to 130% flooding increase
60 % rainfall uplift =120 % to 280% flooding increase
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Timeseries (wet weather planning for combined sewer overflows)
Tool to convert historical timeseries into 2030s, 2050s, 2080s timeseries
Used in continuous simulation of sewer & river flows
Less drizzle, more larger storms, annual average similar
Thank You – Any Questions?
Visit stand B49…- Speak to me about my presentation- Find out more about CH2M- Play our interactive flood manager game and win…- Enjoy complimentary fresh fruit
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