This course proposes a multidisciplinary scientific approach to better understand the functioning of the aquatic ecosystem, in particular in its interaction with the anthropological activities, aiming at a better water resource quality management. It allies diverse scientific disciplines: physics, chemistry, digital modelling, maps, and allows – thanks to the use of dedicated tools (model, software, sig …) - to model the pressure/impact relationships on the receiving environment. Finally, the student will get acquainted with an operational software suite (used by numerous european administrations: water agencies, ministries, administrations…) the pegopera community edition model, by the execution of a water quality management plan. The course covers, the themes connected to the modelling of the river ecosystems, the integrated modelling of the water cycle and decision-making tools dedicated to planning. To give to the students a global vision of the modelling and a critical mind for the selection of tools / software, the course presents a general introduction to the modelling, presents various methodologies (integrated modelling, planning, decision-making support, risk analysis) which come in support to the gire. To widen the knowledge of what can be realized with this type of tool, various models mono-and multi – compartments are presented as well as the notions of system, typology, implementation (identification, conceptualization, mathematical representation, calibration and validation, analysis) and operational exploitation. Case studies are presented and allow to approach the question of technical / legal / socioeconomic constraints. The student will then be placed in situation of "management" (as if he was a project leader (supervisor) of planning within an administration (in charge of sate of the art, management plan, discharge permit, license to operate, environmental study…). Concretely, the tp (practical classes) will allow to make a management plan by using a dedicated software and to learn to use or to create indicators to define the state of the water bodies. The course allows to understand how to represent the ecosystem watershed/river by means of a mathematical / numeric model with the aim of modelling it and studying projections (scenarios) as well as management plans (such as demand it the dce). The dce (wfd, water framework directives, 2000/60/ce) is a major element of the european regulations concerning the protection of water resources (superficial, subsurface, transition, coastal …). This directive aims at preventing and at reducing the pollution, at promoting its sustainable use, at protecting the environment, at improving the state of the aquatic ecosystems and at limiting the effects of floods and droughts.