The economic value of NBS restoration measures and their benefits in a river basin context: A meta-analysis regression

Abstract

Across the NAIAD case studies a consistent pattern emerged: the cost of implementing Nature Based Solutions is typically lower than the cost of grey alternatives delivering the same reduction in water risk, but the avoided damage alone is usually not enough to cover investment and maintenance. What closes the gap is the co-benefit stream — improved air quality, reduced urban heat, landscape and amenity gains, climate change mitigation, biodiversity.

This work assembles the valuation evidence behind that claim into a meta-analysis regression for river basin restoration measures, so that the value of restoration benefits can be expressed as a function of the characteristics of the site and the measure rather than as a single transferred number. The explanatory variables cover the type of measure, the ecosystem affected, the scale of the intervention and the socio-economic context of the study site.

The result is both a synthesis of what is known about the economic value of restoration and a practical instrument: it allows a project developer to produce a first estimate of co-benefit value for a basin where no local study exists, and to see how sensitive that estimate is to the assumptions being made.