Thames Estuary 2100 Managing tidal flood risk through the 21 st - - PowerPoint PPT Presentation

Thames Estuary 2100 Managing tidal flood risk through the 21st century

Presentation by: Jean Venables CBE FREng

Chief Executive, Association of Drainage Authorities

THAMES ESTUARY 2100 is ...

… developing a Flood Risk Management Plan for London and the Thames Estuary for the next 100 years taking account of increasing flood risk due to:

• a changing climate
• a changing society
• ageing flood management infrastructure

1879 Flood Act Late C19 update to Flood Act 1928 Flood & subsequent 1930 Flood Act Interim Defences during the construction of the Thames Barrier

Managing the tidal risk today (Likelihood - Low) (Consequence - High)

Reduce

The Facts behind the Fiction

The 100th Thames Barrier Closure

What is at tidal risk now ?

1.25m people, £80bn+ of property value 1,116km of railway and 1,330 km of roads 8 power stations 16 hospitals 400 schools 69 Underground and DLR stations

Why is flood risk increasing?

• More intense storm

surges and sea level rise

• Increased rainfall
• More people in the

floodplain

• Sinking of south-east

TE2100 Final Plan Phase 1 Planning Phase 2-4 Planning Jan 2002 2002 2003 2004 2005 2006 2007 2008 2009 2010

Phase 0 Project Establishment (Exploring the problem) Phase 1 Project Scoping Phase 2 Understanding the Estuary and management of water levels Phase 3 Policy Appraisal and Options Investigation and Appraisal Phase 4 Plan Finalisation and Submission to Government Project Closure

Jun 2003 Nov 2004 Dec 2008 Jan 2010 Mar 2010 ECOs May 2007 HLOs 3 i Plan 3 ii Plan

Project phasing

Mar 2008

Evidence based decision making

Involving others

What we have looked at ….

Existing Thames Barrier

• Habitat Replacement
• Floodplain

Restoration Strategic Development Existing Defences Existing Barriers & major gates

Potential Long Reach Barrier Potential Tilbury Barrier

Tidal Flood Storage Potential New Barriers

Time 2007 2050 2100

• more people/property
• climate change
• ageing FD

Unacceptable Tolerable As low as reasonably possible

Managing Flood Risk through the Century

1m 0m 4m 3m 2m

New barrier, retain Thames Barrier, raise defences Raise Defences New barrier, raise defences New barrier with locks

HLO 1 HLO 3a HLO 3b HLO 4 HLO 2

Existing system Improve Thames Barrier and raise d/s defences Over-rotate Thames Barrier and restore interim defences Flood storage, improve Thames Barrier, raise u/s & d/s defences Flood storage, over rotate Thames Barrier, raise u/s & d/s defences Flood storage, restore interim defences

Note: Each box represents one or more portfolios of responses The arrows indicate paths for adapting options for different sea level ranges

Maximum sea level rise:

Defra 2100 Old High ++ 2100 All four options suitable in 2100

Improve defences Maximise storage New Barrier New Barrier with locks

New High ++ 2100

Estuary- wide

• ptions

Barrier with locks Flood Storage Improve existing defences New barrier

Change ahead? Our estuary-wide options

• Continue to maintain the current flood defence

system including planned improvements

• Ensuring that floodplain management is in

place across the estuary

• Safeguard areas that may be required for

future changes to flood defences

TE2100 the first 25 Years

• Commencing work to create new habitats

TE2100 the next 15 years 2035 - 2050

• Commence replacing and upgrading defences

upstream and downstream of the barrier

• Working with regional and local planning

authorities

• Take informed decision on building a new barrier

at Long Reach or other end of the century option

From 2050, moving into the 22nd century

• Plan and construct new barrier, if

necessary, by 2070

The first 25 years

“Continuing investment and planning together”

The middle 15 years

from 2035 to 2050 “Renewal and reshaping the riverside”

To the end of the century

from 2050 “ moving towards the 22nd century”

~ £1.5 bn.

Investment over the century

~ £1.8 bn. ~ £6 - 7 bn.

Current property value protected ~ £200 billion

In summary ….

We have ways of managing the risks up to 2100 under even the worst climate change scenarios. The more we do to reduce emissions the less the cost to us and the environment to adapt. The challenges that face today are …

• reducing the likelihood of surface water flooding
• reducing the likelihood and consequences of freshwater
• river flooding
• reducing the consequences of an unlikely tidal flood

Thames Estuary 2100 Managing tidal flood risk through the 21st century