Résumé
In many catchments of Southern France, the objective of good ecological status for all water bodies in 2015 has led to defining water volumes that can be withdrawn by all uses, including irrigation, without arming aquatic ecosystems and revising corresponding water abstraction authorizations. These revisions are based on standardized approaches to assess environmental flows, which often ignore the reality of water uses in the watersheds and how local communities value them, leading to conflicts among users and with water management authorities. An ecosystem services-based approach is proposed here to holistically assess current and potential benefits of aquatic ecosystems at catchment level and identify trade-offs and synergies between them. Volume 1 of the report the report presents the state of the art about the concept of values in economics and social and human sciences. It then describes various methods to assess the value of ecosystem services: standard monetary valuation, non-monetary valuation, psychometric tests, and deliberative valuation. The present volume first describes the case study chosen to apply the non-monetary deliberative valuation approach: the upstream part of the Gardons river basin (the Cévennes), confronted with quantitative and qualitative water management problems (section 2). The following sections describe the approach implemented to identify the ecosystem services of hydrosystems in the catchment (section 3) and the ecosystem services thus identified (section 4). The processes followed to design the individual non-monetary valuation instrument, on one hand, and the protocol of the deliberative workshops, on the other hand, are detailed in sections 5 and 6 respectively. The individual questionnaire addresses domestic uses of water and recreative uses of rivers of local residents. It then combines questions about how important ecosystem services are for the local people with an exercise to allocate a limited quantity of water between various uses and the aquatic ecosystem. Linkages between these contextual values of ecosystem services and more fundamental values are assessed through a psychometric test based on the Values-Beliefs-Norms theory and the New Environmental Paradigm (NEP) theory. The protocol proposed for the deliberative workshops comprises (i) a first phase of role-playing game, adapted from the Wat-A-Game kit developed by the joint research unit G-eau, to initiate a first discussion on water management stakes in the catchment and ecosystem services provided by aquatic ecosystems, (ii) a second phase of discussion on the principles that should guide the allocation of water between uses and the environment in the catchment and (iii) a collective exercise to allocate a limited quantity of water, similar to the exercise realized individually in the questionnaire.