Amenity valuation of urban and peri‑urban nature in high resolution on continental scale

Space is a highly valued asset in cities. This is a key reason why nature-based solutions (NBS) for water management are often perceived to be more expensive than traditional grey solutions. However, the allocation of space also provides benefits relative to grey solutions. In a planning paradigm driven by cost-effectiveness, NBS implementation requires methods for quantifying these benefits in a standardized and easily applicable manner. Based on 114 stated-preference valuation studies of nature in urban areas and openly available geographic data from the developed world, we develop a predictive metamodel for the aggregate benefit value of urban nature, covering the entire range of NBS types with sizes from 0.5 to 900,000 ha. Using a cross-validation procedure, we compare the predictive performance of 8.4 million model permutations that consider different combinations of site properties and topographic and socio-economic characteristics of the surroundings as input. We find that the aggregate benefit value is determined by the size of the nature areas and population densities in their surroundings. There is clear evidence for substitution effects where available nature areas reduce the willingness to pay for new nature. Beyond the dependency on area, there is little evidence for making distinctions between nature types. Economic values do depend on the average income at a site, but these variations are entirely captured by purchase power corrections. Our value estimates are aligned with related literature and range between 150 and 400,000 USD/ha/year. A Python implementation of our metamodel is provided alongside this paper, which generates maps of the predicted values for any place in Europe in a spatial resolution of 100m.