London Flood Risk Management Strategy Adam Hosking

Thames Estuary 2100 London’s Flood Risk Management StrategyPresented by

Adam Hosking Practice Director Water Resources & Ecosystem Management, CH2M

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Overview

• The UK Strategic Approach• TE2100 – The Strategy• TEAM2100 -‐ Implementation

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• Watershed & Coastal Cell Plans

• Large scale– Physical systems & driving forces

– Integrated response and planning

• Long term view– Climate change

– Sustainable approaches

– Whole life costs

UK Strategic Flood Risk Management Framework

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North Sea

The Thames Estuary 2100 Strategy

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Thames Estuary 2100

Why?Provide continued protection for 1.25 million people and £200 billion worth of property from tidal flood risk on the River Thames, over the next Century.

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• Over 4000 Assets• 9 Major Barriers• 350km linear defences• 300+ active structures

TE2100 – Protection System

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The Thames Barrier

Thames Barrier, UK

• Operational since 1982• 520 meters long• 10 gates : 4 navigable 61 meters

rising sector gates, weighing 3,300 tonnes; 2 No. 31.5m wide RSG plus 4No. 31.5m falling radial gates

• Gates are filled with water when submerged and empty as they emerge from the river

• Cost: £534 million (£1.3 billion at 2001 prices)

• Level of protection: 1 in 1,000 year

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Major Barriers

Largest Programme Since Original Construction

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Other Asset Types

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Climate change scenarios Increases in peak 1000-year surge tide level and sea level rise component

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5.5

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2000 2020 2040 2060 2080 2100 2120Date

Sea level (m AOD) at Southend

Medium High SL rise Medium High total High ++ SL rise High ++ totalDefra SL rise Defra total (= SL rise) High + SL rise High + total

Latest DEFRA SL rise

Increases in peak 1000-year levels at Southend under 5 different climate change scenarios

TE2100 Climate Change Scenarios

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Freeboard: Standards of Protection

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• Four approaches (High Level Options) to manage water levels through the century:– Traditional Engineering (HLO 1)

– Floodplain Storage (HLO 2)

– New Barrier (with/without Thames Barrier) (HLO 3)

– New Barrage (HLO 4)

• The limits to adaptation study identified the thresholds at which each option would no longer provide an adequate standard of protection to London

Estuary-‐Wide Planning for an Uncertain Future

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Feasibility of Raising the Existing Defenses

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Feasibility of New Defenses

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Geomorphology – Impacts on Flood Protection

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Assessment of Managed Re-‐Alignment Sites

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1m0m 4m3m2mMax water level rise:

New barrier, retain Thames Barrier, raise defences

Raise Defences

New barrier, raise defences

New barrage

HLO 1

HLO 3a

HLO 3b

HLO 4

HLO 2

The plan considered a combination of approaches

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

TE2100 H++Defra UKCIP MH TE2100 H+

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Strategy Findings

• With an adaptable plan rising water levels can be managed through this century and into the next

• Continue to maintain/improve existing FRM structures –barriers, gates, levees

• Spatial and emergency planning essential part of future FRM

• New inter-tidal habitats before 2030 to offset SLR impacts

• The Thames Barrier should continue to provide protectiontowards the end of the 21st century

• Barriers and/or barrage are essential under all future scenarios to manage surges and SLR

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Thames Estuary Asset Management 2100 (TEAM2100)

• CH2M appointed as Delivery Partner

• Top 40 UK Government Major Project

• At £300 million -‐ the Environment Agency’s largest single flood risk programme

• Efficiency target of £100 million over 10 years

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TEAM2100

Work Scope – 10 year programme:• Asset Management• Asset Investigations• Appraisal• Detailed Design• Construction• Programme Management and

Scheme Optimisation• Programme Controls• Partnership Funding

To Deliver:• Improved Asset Management –

ISO55000• Reduced Flood Risk• Integrated Solutions• Great Efficiencies• Lessons/Best Practice for Future

FCRM Delivery

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Estuary Wide Asset Management Approaches

TEAM2100

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TEAM2100

AM Approaches – Asset Investigations3D Scene from UAV Imagery

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• Whole Life Cost and Deterioration Modelling• Sensors creating a smart estuary

TEAM2100

AM Approaches – Whole Life Approach

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Cost-‐effectiveness: Investment Scenarios

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Foreshore erosion forming cavity under wall

AM Approaches – Monitoring Duke Shore Wharf-‐ Mass concrete wall undermined by foreshore erosion

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Asset Monitoring

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… and repair!

Operatives removing silt from gate Alpha leaf cell A.Operatives require ear defenders & protective clothing.

Heavy silt material on floor of gate leaf removed using jet wash.

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Thames BarrierPrincipal Inspections – 3D Scanning

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TEAM2100

Status

• Achieved ISO55000 AM Accreditation• Whole life cost modelling to change estuary asset

management approach -‐ £1000m WLC saving?• £50m savings identified on large realignment schemes,

accelerate schemes• £33m programme in 2017• £15m efficiency savings in 2017

Thank You

Any Questions?

[email protected]

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Thames Barrier Closures

https://www.gov.uk/guidance/the-‐thames-‐barrier

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Risk Management

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~ £1.4 bn

~ £1.5 bn

~ £6 -‐ 7 bn

First 25 years 2010 – 2035

Continuing investment and planning together

Middle 15 yearsFrom 2035 to 2050

Renewal and reshaping the riverside

To the end of the centuryFrom 2050

Moving towards the 22nd century

The Strategy

London Flood Risk Management Strategy Adam Hosking

Environment

Transcript of London Flood Risk Management Strategy Adam Hosking