Blue Corridors Make Space For Water

Alternative approaches, such as up-stream storage, flow diversion, dredging, underground tanks and river widening, were evaluated on their technical, environmental and economic performance. All were rejected on the grounds of being too expensive without providing sufficient protection. The EA believes that the only realistic option is to manage water flow through the present river corridor, leading them to propose realigning the defences over time to form a blue corridor of least 120 metres width.

In addition to the blue corridor, the EA proposes to modify a major transport crossing to provide increased conveyance through the centre of the city. This will involve opening up two of the five closed arches in the Derby Junction Railway Bridge to improve water flow through it. The long term management regime for the catchment will also include changes in land management to increase retention time. This could include changes to farming practices, reduced upland grazing, increased woodland coverage, restoring peat moorlands and creating wetlands.

As part of Defra's Making Space for Water policy, which puts greater emphasis on managed realignment, the proposal will increase protection to 3,600 residential properties and a large number of commercial properties. And environmental improvements could include enhanced habitats, improved access to and recreational use of the river, and improvements to its ecosystem. However, the scheme has disadvantages, affecting existing land uses and property and having significant impact on development and regeneration aspirations within the blue corridor.

This idea fits well with CIWEM's call for ‘blue belt' land to be designated in flood risk areas to avoid any development in unsustainable locations, recognising that with climate change and rising sea levels, building homes on floodplains is not sustainable.

John Gosden, Senior Consultant at Jacobs will present the paper Putting ‘Making Space for Water' into practice: a case history on Tuesday 29th April, describing the analysis, approach to option selection and the consultation with key stakeholders and the public.