How can I identify potential trade-offs among NBS and other management strategies?
The question behind the question
A trade-off is said to exist when an intervention benefits one objective or one group at the expense of another. In the context of Nature Based Solutions they are the rule rather than the exception: retaining water upstream reduces flood peaks downstream and may reduce the land available for production; restoring a floodplain creates amenity and habitat and can constrain what can be built there; a measure that is cheap for the public budget may be expensive for the landowners who have to maintain it.
Trade-offs are often invisible in an assessment because a single aggregate figure conceals them. A net benefit can be composed of large gains for one group and larger losses for another, and a proposal presented that way will be resisted by the group bearing the loss regardless of the size of the total. Identifying trade-offs is therefore part of establishing whether an intervention can be implemented, not an additional refinement of the analysis.
How to identify them
The first step is disaggregation: instead of reporting one result, report the effect of each option on each objective and for each group affected. Spatial disaggregation is often enough to reveal the pattern, because a change in water availability or in flood depth is rarely uniform across an area.
The second step is to establish the trade-offs that the people involved actually perceive, which is not always the same set. Causal mapping and fuzzy cognitive maps, built with the stakeholders concerned, record which effects they expect to trade against which, and where two groups expect opposite consequences from the same measure. Where the maps are given strengths they can be analysed to show how a change propagates through the system as the participants understand it, and this frequently identifies a conflict that no technical assessment would have predicted.
The third step is to make the exchange explicit and negotiable. A trade-off that is stated can be addressed — by compensation, by redesign, by phasing, or by a financing arrangement that pays the party bearing the cost. A trade-off that is concealed in an aggregate figure becomes an objection at the point where the proposal is contested.
Where the methods are described
The multi-criteria decision-making toolkit provides the formal apparatus for comparing options against conflicting criteria and for showing how far a recommendation depends on the weights assigned. The participatory modelling methods provide the route to establishing what the trade-offs are as the people affected experience them, and the co-benefits valuation material provides the methods for expressing the effects that are being traded in a common form where that is possible.
