Hydrological response to bias-corrected global climate projections data

Global climate models (GCMs) provide potential climate scenarios and are used to understand effects of future climate change. A large number of GCMs is included in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), and these models simulated both the historical and future climate. For the future climate, multiple scenarios are simulated based on different shared socioeconomic pathways and representative concentration pathways. The daily output from these models can be used to force hydrological models, to understand how the hydrological system responds to a changing climate. For this study we focus on the use of the available state-of-the-art ensemble of GCMs to obtain a first climate change signal for the changes in mean and extreme flows of the river Rhine.

However, as the CMIP6 models are all global models, they are known to contain biases at regional scales. Yet, by directly using the GCMs we can obtain the full projection space of the CMIP6 models. Output from the CMIP6 models is often bias-corrected to ensure accurate values for regional applications. For an application in the Netherlands, we investigated the role of bias correction on the hydrological response of the Rhine and Meuse river basins, as these basins play a vital role for the Dutch water safety and security. The hydrological model wflow_sbm is used to simulate both basins and is forced with the CMIP6 data for both the historical and future climate (following the SSP5-8.5 pathway). The results from these simulations highlight the role of bias-corrected forcing data on the simulated discharge characteristics for both the Rhine and Meuse river basins. In the near future the work will be extended with RCM simulations.