Theory and practice of water ecosystem services valuation: Where are we going?

Water resources have been widely cited as a prime example of ecosystem services (ES), especially when the issue is valuation. Because of the importance of water ecosystem services (ESw), they are being effectively evaluated in at least three aspects: clarity about the type of valuation employed; adoption of a strong theoretical basis guided by ecological knowledge; and the inclusion of analytical elements that ensure social control and direction in decision making. Our study sought to determine whether these prerogatives are actually relevant, by assessing the emphasis in the valuation of ESw among ES publications. From the literature, we define five types of valuation and five major theoretical principles that can be broken down into 14 indicators that we used in our analysis of ESw studies. Our results indicated that the current knowledge about ESw carry the false impression that the ecosystem services valuation is sufficiently consolidated to support decisions about payments for ESw.