General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Correspondence to: andrea.ficchi@irstea.fr 2 AbstractWe investigate the improvement of the operation of a four-reservoir system in the Seine River basin, France, by use of deterministic and ensemble weather forecasts and real-time control. In the current management, each reservoir is operated independently from the others and following prescribed rule-curves, designed to reduce floods and sustain low-flows under the historical hydrological conditions. However, this management system is inefficient when inflows are significantly different from their seasonal average and may become even more inadequate to cope with the predicted increase in extreme events induced by climate change.In this work, we develop and test a centralized real-time control system to improve reservoirs operation by exploiting numerical weather forecasts that are becoming increasingly available.The proposed management system implements a well-established optimization technique, Model Predictive Control (MPC) and its recently modified version that can incorporate uncertainties, Tree-Based Model Predictive Control (TB-MPC), to account for deterministic and ensemble forecasts respectively. The management system is assessed by simulation over historical events and compared to the "no-forecasts" strategy based on rule-curves.Simulation results show that the proposed real-time control system largely outperforms the "no-forecasts" management strategy, and that explicitly considering forecasts uncertainty through ensembles can compensate for the loss in performance due to forecasts inaccuracy.

Adaptation strategies will be needed to cope with the hydrological consequences of projected climate change. In this perspective, the management of many artificial reservoirs will have to be adapted to continue to fulfil downstream objectives (e.g. flow regulation). This study evaluates the sustainability of the management rules of the artificial reservoirs on the Seine River basin, 5 France, under climate change scenarios. The Seine River basin at Paris (43,800 km 2) has major socioeconomic stakes for France, and the consequences of droughts and floods may be dramatic. In this context, four large multipurpose reservoirs were built on the basin during the XX th century for low-flow augmentation and flood alleviation. A hydrological modelling chain was designed to explicitly account for reservoir management 10 rules. It was calibrated in current conditions and then fed by the outputs of seven climate models in present and future conditions, forced by the A1B IPCC scenario, downscaled using a weather-type method and statistically bias-corrected. The results show that the hydrological model performs quite well in current conditions. The simulations made in present and future conditions indicate a decrease in water availability and 15 summer low flows, but no significant trends in high flows. Simulations also indicate that there is room for progress in the current multipurpose management of reservoirs and that it would be useful to define proper adaptation strategies.

No abstract

No abstract

No abstract

Water control structures, used to regulate water levels and flow exchange in coastal marshes, act as barriers during fish migration between the ocean and brackish or freshwater ecosystems. Usual fish pass solutions may be unsuitable for obstacles subject to significant water level variations such as tidal range. This study proposes new solutions that were developed, implemented and evaluated on a marsh controlled by a series of hydraulic structures. These solutions were based on soft physical modifications (passive management) of the control gates, and on adaptations of their operation rules (active management). To evaluate the impacts of these adaptations, a hydraulic model of the marsh was built. It solves the one-dimensional Saint-Venant equations and appropriate gate equations. The model was used to identify management rules of control structures in a way to improve fish migration without significantly affecting the initial hydraulic management of the marsh (i.e. targeted seasonal water levels). It was also showed that fish passability of upstream structures could be improved by managing downstream ones. It was concluded that the combination of active and passive management of water control structures could largely increase the passability of these obstacles during glass eel migration, while limiting seawater intrusion in the marsh and maintaining water levels into a range compatible with marsh management needs.

The Seine River Basin has to face major issues on water resources due to a variety of uses and increasing pressure. Satisfying these water needs is a huge challenge on this basin that hosts the most urbanized and densely populated area in France: more than 6.5 millions inhabitants in the Paris region are supplied with drinkable water coming from rivers while one nuclear power plant and two coal-fired plants ensure power generation in the region. Furthermore, several large wastewater treatment plants (incl. the largest one in Europe) release their waters into the Seine, with possible consequences on the quality of water during low flows. The Seine Grands Lacs basin authority owns and manages four large artificial reservoirs on the river Seine and its tributaries (totaling a capacity of 800 hm 3) with two main goals: flood alleviation and low-flow augmentation. The CLIMAWARE research project (2010-2014) characterized the impacts of climate change on flows of the Seine River Basin and on reservoir management by mid-21 st century. Performance indicators representative of the tension on water resources were calculated to assess the impact of climate change. Various adaptation measures were tested including the modification of the objective seasonal filling curves, as well as modifications of the real-time management techniques. Adaptation measures can bring some improvements, but even with this adaptive management, the indicators show that the impacts of climate change on low flows will be major on the basin.

Engineers always need convenient calculation tools on the field or at the office for evaluating hydraulic characteristics and designing solutions while researchers develop scientific software in most cases nonreusable, invisible, and in the worst case, faulty and unreliable. Funded by the French Biodiversity Office, "Cassiopée" software has first been developed for the design and the verification of upstream and downstream fish passage facilities aggregating multiple tools required for dimensioning: pool-type fishways, pre-barrages, baffle fishways, nature-like fishways, and fish-friendly intakes. "Cassiopée" also includes numerous tools for open flow and pipe flow hydraulics for agriculture and environment. Based on calculation modules, which can be independent or linked in order to carry out complex operations, "Cassiopée" allows an iterative design approach ranging from the definition of the geometric characteristics of the devices to hydraulic simulations of their operating conditions. In a simple and user-friendly interface, it presents the calculation results as clear tables and graphs. Contextual documentation provides detailed information on the different tools and hydraulic formulas used for the calculations. Available in French and English, "Cassiopée" is an open source and free software accessible online (https://cassiopee.g-eau.fr) or as an offline application for Windows, Linux, macOS and Android. An R package is currently under development for advanced users who need to perform intensive calculations without a graphical user interface. Designed as a practical tool resulting from the transfer of research products, it is intended to be widely used by the hydraulic engineering community as a working and educational tool.