Actors involved in water resource management and development policies from the large water cycle (at the river basin level) to the small water cycle (drinking water, sanitation and distribution) are numerous and diversified, in their institutional and economic positioning, as well as in the logic of the approaches they develop. In view of the expectations of a comprehensive policy in this field and of the obviously limited results obtained so far, the phasing of these approaches and the coordination of these actors is a major axis of the actions to be carried out in order to better manage the water resources. We argue the need for an explicit and assumed strengthening of the coordination of water stakeholders at all levels of governance. We question the reasons for these partial successes and failures and the way to overcome these difficulties, questions renewed on the basis of recent experiences. In particular, interdisciplinary and intersectoral collaboration using new hybrid modeling approaches (coupling multi-agent system, geographic information system, equation models, cellular automata, etc.), allows to precisely simulate the scenarios of evolution of water resource management and development, to assess ex ante their social, economic and environmental impacts and to anticipate the contribution of an increased coordination of water stakeholders in a logic of development-friendly actions.