Rheinblick2027: a multi-model approach to generate large-scale hydrological scenarios for the Rhine River and assess climate change impacts on key hydrological signatures

The Rheinblick2027 project investigates the impacts of climate change on the discharge of the Rhine River and its major tributaries as assessed by different working groups in the riparian countries of the Rhine. Initiated by the International Commission for the Hydrology of the Rhine Basin (CHR), the project builds on its predecessor Rheinblick2010 (formerly denoted as Rheinblick2050). The project’s main objectives are to compare model differences, develop hydrological scenarios through 2150, and assess the effects of climate change on key hydrological signatures over the Rhine catchment, such as annual water balance and high- and low flow situations.

The project started with a model intercomparison involving four hydrological models: wflow_sbm (Deltares, NL), LARSIM-ME (BfG, DE), PREVAH (WSL, CH), GRSD (INRAE, FR). A first round of simulations was conducted using the KNMI’23 scenarios, one of the few CMIP6 based downscaled climate scenarios available, providing a valuable opportunity to test and establish common workflows towards a well-defined hydrological simulation protocol.

Initial projections reconfirm increasing winter discharge and decreasing summer discharge, when water demand is highest. This first round of simulations represents a crucial step in preparing for the second round using a set of EURO-CORDEX CMIP6 scenarios as processed in the "DWD-Reference Ensemble" provided by the German weather service, scheduled for early 2026. In parallel, the Rheinblich2027 team has begun investigating the impacts of climate change on six selected key topics, among which groundwater recharge and extreme value statistics.

Beyond its core goals, Rheinblick2027 aims to strengthen stakeholder engagement and foster collaboration among modelling groups by regularly organising outreach activities and interactive platforms that bring together stakeholders from the Rhine catchment and scientists from various institutions. These interactions are essential to ensure that the final products align with stakeholder needs and provide actionable climate services for water resources management.