Nick Reynard
Science Area Leader: Natural Hazards
CEH Wallingford
Contributions from: Bob Moore, Steve Cole,
Joint COST - WssTP Strategic Conference, 17 April 2013
CEH RESEARCH ON HYDROLOGICAL EXTREMES
One of the world’s leading centres for flood research
– Flood Estimation
– Flood Studies Report (1975)
– Flood Estimation Handbook (1999)
– Flood forecasting – Seasonal prediction – Climate Change
• Nationwide modelling
• Research to underpin policy
• BIS Foresight Flooding (2004, 2008, US and China) • Pitt Review (Science and Engineering Panel)
In scope for UK NHP
•
Resilience
•
Natural Hazards
•
Fast tracking world class science into services
•
Timescales of 0-5 years
•
UK and in those countries affecting UK citizens
•
Governments and responder community
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Public good
• Improved cross-working: more joined-up scientific advice and
analysis.
• Provision of single source of daily hazard assessment. • New level of scientific expert challenge to the UK NRA. • The provision of prepared scientific advice packs for all
emergency responders.
• Development of the Hazard Impact Model (HIM)
Underpinning framework enabling cross-agency working to develop impact models for specific hazards.
Deliver more targeted risk assessments to government and resilience community
Work Packages and leads:
● Surface Water Flooding Centre for Ecology and Hydrology ● Land Instability British Geological Survey
● Wind UK Met Office
● Impact and Vulnerability UK Health and Safety Lab
Science Advisor: Ken Mylne (Met Office)
● How many homes, businesses, critical infrastructure could be affected by surface water flooding?
Hazard Impact Model will:
• provide longer lead times and better intelligence for
Emergency Services, Local Authorities, Health Protection and Environment Agencies, Utilities and Transport
• help improve resilience and reduce impact of hazards,
including loss of life
● Surface Water Flooding (SWF)
Major hazard with ~4 million properties at risk
in England alone (EA, 2009)
● Summer 2007 floods
£3 billion insurance payouts
55,000 properties flooded, ~36,000 due to SWF
National infrastructure impacts
140,000 homes without clean water for 17 days
42,000 homes without power for 24 hours
10,000 people trapped on M5
Pitt Review recommendations on improving SWF alert capability
Flood Forecasting Centre & Scottish Flood Forecasting Service formed
● Rainfall based alerts (current practice)
Extreme Rainfall Alert. Uses national rainfall-thresholds
Feeds in to Flood Forecasting Centre daily Flood Guidance Statement
● Localised runoff thresholds (ongoing HIM developments)
G2G distributed hydrological model converts rainfall to runoff G2G soil moisture conditions influence surface runoff production
Scientific advances to improve national SWF hazard footprint
G2G already used by Flood Forecasting Centre
● New impact information (ongoing HIM developments)
Use national datasets on property, infrastructure & population Potential for real-time hazard and impact forecasts
● Extreme Rainfall Alerts (ERA)
● National rainfall-threshold based method
● Based on FEH 30 year return period
rainfalls “averaged” across 8 UK cities
● G2G runoff production affected by:
● Rainfall amount plus
● Urban/suburban coverage
● Soil and geology properties
● Antecedent soil moisture conditions
● Prototype runoff threshold
exceedances seem more targeted
1h radar rainfall totals >30mm >25mm 1h runoff totals >8.5mm >7mm
1h rainfall totals >30mm >25mm 1h runoff totals >8.5mm >7mm 17:00 Thorne Thorne Rainfall (15 min, mm) G2G runoff (15 min, mm) G2G SMD (15 min, mm) ERA Threshold Crossed G2G Threshold Not Crossed Thorne Thorne 18:00 ERA Threshold Not Crossed G2G Threshold Crossed Moderate rain High runoff % Saturated Heavy rain Low runoff % Pixel becomes saturated
SMD recovers
17:00 18:00
How to map from G2G “Hazard Footprint” to “Impact”?
G2G surface flooding impact alerts
Thorne Goole Goole York 15:00 1h runoff totals >8.5mm >7mm 16:00 17:00 18:00
Thorne Goole Goole York 15:00 1h runoff totals >8.5mm >7mm 16:00 17:00 18:00 IMPACT? Number of houses?
• EA National Receptors Database
G2G surface flooding impact alerts
Thorne Goole Goole York 15:00 1h runoff totals >8.5mm >7mm 16:00 17:00 18:00 IMPACT?
Number of vulnerable people?
• HSL National Population Database
G2G surface flooding impact alerts
Next steps
● Targeted improvements to G2G formulation Runoff-production, urban hydrology, ...
● Use of latest Met Office rainfall forecast products High-resolution deterministic and probabilistic products ● Mapping of surface water flooding impacts (with HSL)
Aim to move from static to dynamic maps of hazard and impact Potential areas are people, property, transport, infrastructure, ... ● Further case studies and validation (where possible!)
Historical surface water flooding data scarce and sporadic Link to other initiatives, e.g. Hazard Impact Database
Nick Reynard
Science Area Leader: Natural Hazards
CEH Wallingford
Contributions from: Bob Moore, Steve Cole,
Joint COST - WssTP Strategic Conference, 17 April 2013