Select Committee on Environment, Food and Rural Affairs Minutes of Evidence

Supplementary memorandum submitted by the Flood Hazard Research Centre, Middlesex University (FL 113a)

Is it easier to justify flood defence protection for well-off households and urban areas than poor or rural areas?

  Decisions about flood risk management measures (including flood defence) are guided by a benefit cost analysis. Such analyses have also dominated the Priority Score system that Defra has had in place to "sieve" out those schemes that are to be funded. There is evidence that, within the "block grant" system of funding to the Environment Agency from Defra, the Agency's funding decisions remain dominated by the benefit costs tests.


  The benefits of flood defence are the flood losses thereby avoided. The higher these potential losses, the more worthwhile will be investment to reduce these losses.

  Thus, for one residential property defended, it will be worthwhile to spend more on flood defence if that property is large and full of valuable contents. In these circumstances it will indeed be "easier to justify flood defence protection for well-off households'.

  But flood defence projects traditionally do not protect just one property; indeed there are substantial economies of scale in flood defence works such as embankments, so that most (if not all) state funded flood defence projects protect land on which a number of properties are built. And the larger the area of land (other things being equal) the more cost-effective will be most flood defence schemes (because cost is related, very approximately, to the length of the perimeter of the area affected).

  Poor households tend to live in small houses packed closely together. Thus for any given area protected (and any given length of perimeter embanked) there will be more poor households protected.

  Taking examples from the Thames catchment, in affluent Maidenhead there might be just five households per hectare of land protected, living in large detached houses, whereas in one hectare on the Osney Island area of Oxford there might be 100 households occupying small terraced dwellings. The potential flood damage to one house in Maidenhead is not 20 times the flood damage in a house in Osney Island, so in that case it is not "easier to justify flood defence protection for well-off households (rather) than poor ... areas". Indeed, other things being equal, the reverse is the case.

  So, it all depends on the density and type of each development, rather than just the affluence or poverty of the households.


  By definition, rural areas are less densely developed than urban areas. Therefore flood defences there are less easy to justify, in that fewer households and businesses are likely to be defended per unit area of land or per unit length of embankment or river works.

  But there may be other factors that influence decisions. Rural flood defences may be cheaper than urban flood defences. This can be because rural areas can accommodate earth embankments whereas urban areas may have to have concrete walls, owing to the lack of space for building the flood defence works. The one may be cheaper than the other. And land purchase costs for these works may be lower in rural areas than in urban locations although, since land purchase involves a transfer between buyer and seller, there is no economic gain/loss to the nation (which is what benefit-cost analysis counts).

  In general, however, it is easier to justify flood defence protection for urban areas than for rural areas.

Edmund Penning-Rowsell

Flood Hazard Research Centre

Middlesex University

December 2007

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