**4. Conclusions**

The developed operational modelling platform allows the simulation of an unlimited number of scenarios. Several scenarios were implemented in order to evaluate its performance after a judicious effort for model calibration and validation.

Main obtained results for the rivers within the basin reveal an almost uniform longitudinal profile for BOD concentration with a good agreement between observed and simulated results. The installed wastewater treatment capacity in the watershed (domestic and industrial wastewater) is reflected in the observed values leading to low concentrations of BOD. However, a quite different situation is observed for bacteriological indicators. In the lower part of the basin, concentrations results for all simulated scenarios are always lower than the observed ones even in the dry season. The reason for this fact can be the existence of untreated discharges or the lack of disinfection in WWTP.

The presented decision support tool for the river Cávado basin constitutes a robust and efficient technological platform to support water management at a river basin scale. Obtained results allow predicting that this new tool will be extremely effective and important to achieve the objectives of water management at river basin scale. In the next years, the use of all the potentialities of this kind of platforms in practical situations under different water management problems constitutes a major challenge for its evaluation. Moreover, water authorities once decide to use this kind of management tools will certainly see improved their analysis capabilities, strengthening their technological skills for the adoption of more sustainable water management policies. Especially it is adequate for developing big projects since it facilitates collaborative studies in one common platform and the modelling results became much more transparent for all project partners.
