The Environment Agency has set out details of its £256 million River Thames scheme - a proposal to reduce flood risk to over 20,000 properties along the Thames.
The River Thames between Datchet and Teddington has the largest area of developed floodplain in England without flood defences, with over 15,000 homes and businesses within the area at risk from flooding from a 1 in 100 flood (ie a flood with a 1% chance of occurring in any one year). In early 2014, many communities experienced prolonged and widespread flooding from the River Thames.
Major flooding would cause severe disruption to the road network, suspension of several major drinking water abstractions supplying the south-east and threaten up to 20 electricity sub-stations.
The Environment Agency has calculated that damages from a major flood in the area could exceed £850 million. It is predicted that the effects of climate change will double flood damages in a 1 in 200 year (0.5% chance of occurring in any year) flood from the current level of £850million to some £2 billion by 2055, with the number of properties at flood risk reaching 35,000.
Flood channel could extend for 17 kilometres
The River Thames scheme will meet the recommendations set out in the Lower Thames flood risk management strategy. The scheme consists of a new flood channel, improvements to 3 of the existing Thames weirs, installation of property level products for up to 1,200 homes (to make them more resistant to floods) and improved flood incident response plans. The flood channel will be between 30 and 60 metres wide and 17 kilometres long, built in 3 sections.
The Environment Agency is currently working with seven local authorities on the scheme, which will protect 9,500 properties to a 1 in 75 flood (1.33% chance of occurring in any year). In total around 15,000 properties, local infrastructure (eg roads, sewerage network) and many businesses will be better protected from flooding.
Subject to funding, the scheme will be carried out in 2 phases.Phase 1 includes:
•developing a funding strategy for the scheme
•a hydrology and modelling study
•ecological surveys of the River Thames and specific sites
•installation of property level products in some homes
•major incident planning to improve preparedness and response to flooding
•increasing the flow capacity of Sunbury, Molesey and Teddington weirs
•obtaining planning consents for the enabling works on the weirs
•securing government assurance and approvalsPhase 2 includes:
•detailed design of the scheme
•securing full, detailed planning permission and other consents for the work
•building all 3 sections of the flood channel and associated structures, and increasing the capacity of Desborough Cut
The Environment Agency is looking to will appoint consultants in summer 2014 to work with the partnership on the outline design of the flood channel and capacity improvements, and produce environmental assessments. This stage will take approximately 3 years and enable the flood channel to be submitted for planning consents and authorisations.
Subject to funding, construction work could begin as early as summer 2016 on the modifications to the first Thames weir. Construction of the flood channel is expected to start in 2020 and take approximately 5 years to complete.
The estimated cost of the proposed scheme is £256 million and is expected to qualify for a central government grant of £136 million, with the remaining funding of approximately £120 million secured from other sources.
The Thames Regional Flood and Coastal Committee is currently funding the development stages of the scheme. The Environment Agency is working with the Department for Environment Food and Rural Affairson the scheme/ Local authority partners are:
•Elmbridge Borough Council
•Royal Borough of Kingston upon Thames
•London Borough of Richmond upon Thames
•Runnymede Borough Council
•Spelthorne Borough Council
•Surrey County Council
•Royal Borough of Windsor and Maidenhead
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