Local highway authorities will be expected to pinpoint the location and condition of their gulleys and the flow rate of their watercourses, in order to reduce the risk of surface water flooding.
The Department for Environment, Food and Rural Affairs has published new guidance on producing surface water management plans, which recognise that the quality of data on drainage infrastructure is often poor.
The document says the ‘best of breed’ data for the plans would include the use of LiDAR surveys on asset locations, and information on the flows of sewers and culverted watercourses.
However, the draft recognises that councils and water companies are likely to have to make ‘heroic assumptions’ when assembling the necessary data. The guidance is non-prescriptive on the solutions which can be implemented, as the Environment Agency (EA) has promised (Surveyor, 14 August 2008).
However, the guidance does clearly state that ‘de-culverting can reduce flood risk’ by adding channel capacity, a move which will be welcomed by the Chartered Institution of Water and Environmental Management. CIWEM has criticised DEFRA and the EA for not providing a clear steer or guidance on the process of restoring ‘lost rivers’.
The guidance says investment plans for improving parks and other ‘green infrastructure’ should be considered by SWMPs as a way of taking de-culverting forward. Six local authorities are piloting the new SWMP approach, including West Berkshire. Its principal engineer, Stuart Clark, told Surveyor that the plan ‘will show the benefits of investment, allowing funding bids to be made’.
The Draft Floods Bill, expected to be published for consultation next month, will include measures to assist implementation of the SWMPs. The EA, which will be expected by ministers to ensure consistency in the quality of the plans, has suggested that there is ‘some kind of stick’ to ensure that they are implemented (Surveyor, 14 August 2008).
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