Reaching harmony between humans, and between man and nature states the Brundtland Report. Sustainable development, governance, negotiation, conservation ; after dissecting these four concepts, our two questions are : (i) how are articulated relations between individuals (social link) and relations between human and non-human (natural link) in a territorial hydrosystem? (ii) how to provide operational assistance for an environmental negotiation in a multi-stakeholders context? Our proposition : the Actor in 4 dimensions. This multidisciplinary conceptual model aims at taking into account weak actors and absent actors on a territory, in order to enhance negotiation with more ecology and conservation with more humanity. The A4D model has been applied on 3 hydrosystems : Forez Plain, France, south slopes of Mount Kilimanjaro, Tanzania, and Barthes of Adour, France. The A4D results can be visualized by the territorial footprint, a graphical representation, and a knowledge and debate vector.
