UK Management of Flooding

Presented by: Stephen Scott

How has the UK flood management programme changed over the years?

What does the future hold?

ContentsIntroduction

UK flood management

Case Study – Thames Barrier

The Future – likely impact of global warming

Conclusions

IntroductionLocation Estimated Financial Cost Estimated Human Loss

Madeira (Portugal) N/A 42 dead, 100 injured

Pakistan $1 - $2 billion 2000 dead, 2500 injured

China $13 billion 3200+ dead, 1,000+ missing

Queensland (Australia) $10 - $25 billion 30-40 dead

Brazil Unknown 51+ dead

- Recent major flooding events worldwide

-Discharge of River Thames 100 times smaller than Indus river- Estimated that 1.5 million people live on floodplain- £80 billion infrastructure at risk (RGS, 2010)

- Flooding in the UK a major concern for those responsible for the management of rivers and coastal defences

Causes of UK FloodingHeavy rainfall or thunderstorms over short period of

timeTewekesbury – 2007Boscastle -2004

UrbanisationDeforestation Cultivation

Tidal Surges – most likely form of flooding in the UKKent & Yorkshire - 2007

UK Flood managementFlood management evolves as a result of social

and economic conditions

Bear the Loss – Do NothingModify Damage Susceptibility – Land Use PlanningModify the Flood – Flood ProtectionModify the Loss Burden – Disaster Relief

Land Use PlanningFlood alleviation technique

- reducing impact of flooding

Manages flooding risk to development in the flood plain

Flood map of River Avon running through Bristol

‣ Floodplain development managed by use of FRAs

Land Use PlanningFloodplain divided into 3

zones (1-3)

Functional Flood Plain (3b)‘land where water has to flow

or be stored in times of flood’

Limited use – No reduction in Volume, Flood routes Maintained

Structural Flood DefencesHard engineering preventative technique

Developments in mathematical modelling in the 1980s created powerful tools for flood management

Flood Gates, River Walls, Sea Walls, Modification of River Channel etc.

Thames BarrierOpened in 1982, costing £365 million estimated

to protect £80 billion infrastructure

Designed to protect against a storm with return period of 1000 years (up until 2030)

Consists of 10 movable gates spanning 520m

The FutureGlobal warming: increase in coastal waters, tidal

surges and higher intensity rainfall

Structural defences too expensive to maintain

Increase severity and spread of floodwaters

Greater threat to cities as the urban sprawl continues

Humber EstuaryCurrent Flood Defences

Flood Defences 2060

Green RoofsNot a new technology

Utilised heavily in Germany 10% of all roofs are ‘green’

Shown to attenuate runoff- reduces runoff rate and flow volume

Some studies show a 50% reduction in runoff (Rowe, Monterusso, Russell, 2003)

Weather Control?Cloud seeding

Utilised in Olympic Games?

Not designed to prevent rainfall but to control where it falls by causing moisture to condense prematurely

ConclusionsLand use planning and structural flood defences

currently are major parts of the UK flood management strategy

Flood management over the next 50 years looks set to be dominated by global warming

Management strategies may have to move from traditional ‘hard engineering prevention’ to a more ‘risk management strategy’