An essential component in the appraisal of flood risk management schemes is to take into account of their impact on the environment (both positive/ benefits or negative/costs).
This appraisal should be:
- Approached positively to explore the case for flood risk management schemes contributing to environmental improvement.
- Part of mainstream appraisal, both from the outset and throughout.
An appraisal should aim to assess all the costs and benefits, including those environmental costs and benefits which are not straightforward to value in monetary terms. The costs and benefits of goods and services that are not traded in markets must not be ignored just because they are more difficult to assess (e.g. nutrient capture or a breeding site for birds).
In principle, all environmental costs and benefits that can be valued in monetary terms should be included in the benefit-cost analysis to make that analysis more multi-criteria in character. The only exceptions are:
- When environmental valuation is likely to be very difficult (or disproportionately expensive), and when a sensitivity test has clearly shown that it would make no difference to the decision about what scheme/option to develop;
- Where no meaningful monetary valuation is possible. In this case the environmental costs and benefits should still be fully described and taken account of outside the benefit-cost analysis, so as still to have a bearing on the overall appraisal. Even if it is not feasible or practical to value all costs and benefits of a proposal, it is important to consider:
- How the scheme options differ in environmental terms; and
- How only these differences might be best described and possibly valued in money terms.