This experiment comprises data that have been used in Hagemann et al. (submitted). It comprises daily data of surface runoff and subsurface runoff from HydroPy and simulated daily discharges (river runoff) of the HD model. The discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. a) HD5-ERA5 ERA5 is the fifth generation of atmospheric reanalysis (Hersbach et al., 2020) produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). It provides hourly data on many atmospheric, land-surface, and sea-state parameters at about 31 km resolution. The global hydrology model HydroPy (Stacke and Hagemann, 2021) was driven by daily ERA5 forcing data from 1979-2018 to generate daily input fields of surface and subsurface runoff at the ERA5 resolution. It uses precipitation and 2m temperature directly from the ERA5 dataset. Furthermore, potential evapotranspiration (PET) was calculated from ERA5 data in a pre-processing step and used as an additional forcing for HydroPy. Here, we applied the Penman-Monteith equation to calculate a reference evapotranspiration following (Allen et al., 1998) that was improved by replacing the constant value for albedo with a distributed field from the LSP2 dataset (Hagemann, 2002). In order to initialize the storages in the HydroPy model and to avoid any drift during the actual simulation period, we conducted a 50-years spin-up simulation by repeatedly using year 1979 of the ERA5 dataset as forcing. To generate river runoff, the Hydrological discharge (HD) model (Hagemann et al., 2020; Hagemann and Ho-Hagemann, 2021) was used that was operated at 5 arc minutes horizontal resolution. The HD model was set up over the European domain covering the land areas between -11°W to 69°E and 27°N to 72°N. First, the forcing data of surface and sub-surface runoff simulated by HydroPy were interpolated to the HD model grid. Then, daily discharges were simulated with the HD model. b) HD5-EOBS The E-OBS dataset (Cornes et al., 2018) comprises several daily gridded surface variables at 0.1° and 0.25° resolution over Europe covering the area 25°N-71.5°N x 25°W-45°E. The dataset has been derived from station data collated by the ECA&D (European Climate Assessment & Dataset) initiative (Klein Tank et al., 2002; Klok and Klein Tank, 2009). In the present study, we use the best-guess fields of precipitation and 2m temperature of vs. 22 (EOBS22) at 0.1° resolution for the years 1950-2018. HydroPy was driven by daily EOBS22 data of temperature and precipitation at 0.1° resolution from 1950-2019. The potential evapotranspiration (PET) was calculated following the approach proposed by (Thornthwaite, 1948) including an average day length at a given location. As for HD5-ERA5, the forcing data of surface and sub-surface runoff simulated by HydroPy were first interpolated to the HD model grid. Then, daily discharges were simulated with the HD model. Main reference: Hagemann, S., Stacke, T. Complementing ERA5 and E-OBS with high-resolution river discharge over Europe. Oceanologia. Submitted.

The data of this experiment have been used in (Hagemann et al., 2020). It comprise daily data of surface runoff and subsurface runoff (drainage) from JSBACH and MPI-HM and simulated daily discharges (river runoff). To generate river runoff, the Hydrological discharge (HD) model (Hagemann et al., 2020; Hagemann and Ho-Hagemann, 2021) was used that was operated at 5 arc minutes horizontal resolution. Different to the published version of HD model parameters (5.0) on Zenodo, an earlier version (4.0) of flow directions and model parameters has been used that is provided as an auxiliary data file. The HD model was set up over the European domain covering the land areas between -11°W to 69°E and 27°N to 72°N. First, the respective forcing data of surface and sub-surface runoff were interpolated to the HD model domain using conservative remapping. Then, daily discharges were simulated with the HD model for the period 1979-2009 (1999-2009 for HD5-MESCAN). In addition, daily discharges were analogously simulated using only JSBACH forcing with the global 0.5° version 1.10 of the HD model. The associated flow directions and model parameters of vs. 1.10 are provided as an auxiliary data file. The HD forcing data are: a) HD5-JSBACH In order to generate daily input fields of surface runoff and drainage, the land surface scheme JSBACH (vs. 3 + frozen soil physics; (Ekici et al., 2014)) was forced globally at 0.5° with daily atmospheric forcing data based on the Interim Re-Analysis of the European Centre for Medium-Range Weather Forecast (ERA-Interim; (Dee et al., 2011)). These forcing data are bias-corrected (see (Beer et al., 2014)) towards the so-called WATCH forcing data (WFD; (Weedon et al., 2011)) that have been generated in the EU project WATCH. b) HD5-MPIHM The MPI-M hydrology model MPI-HM (Stacke and Hagemann, 2012) was driven by daily WATCH forcing data based on ERA-Interim (WFDEI; (Weedon et al., 2014)) from 1979-2009 to generate daily input fields of surface runoff and drainage at global 0.5° resolution. c) HD5-MESCAN Six hourly data of surface runoff and drainage (variable name: percolation) were retrieved from the MESCAN-SURFEX regional surface reanalysis (Bazile et al., 2017) created in the EU project UERRA (Uncertainties in Ensembles of Regional ReAnalysis; www.uerra.eu). SURFEX (Masson et al., 2013) is a land surface platform that was driven by atmospheric forcing at 5.5 km. The forcing comprises 24h-precipitation, near-surface temperature and relative humidity analyzed by the MESCAN surface analysis system as well as radiative fluxes and wind downscaled at 5.5 km from the 3DVar re-analysis conducted with the HARMONIE system at 11 km (Ridal et al., 2017). The latter has been generated using six-hourly fields of the ERA-Interim reanalysis as boundary conditions and covers a domain comprising Europe and parts of the Atlantic, which is similar to the European domain of the Coordinated Downscaling Experiment (CORDEX) at 11 km.

The data of this experiment have been used in (Hagemann et al., 2020). It comprise daily data of surface runoff and subsurface runoff (drainage) from JSBACH and MPI-HM and simulated daily discharges (river runoff). To generate river runoff, the Hydrological discharge (HD) model (Hagemann et al., 2020; Hagemann and Ho-Hagemann, 2021) was used that was operated at 5 arc minutes horizontal resolution. Different to the published version of HD model parameters (5.0) on Zenodo, an earlier version (4.0) of flow directions and model parameters has been used that is provided as an auxiliary data file. The HD model was set up over the European domain covering the land areas between -11°W to 69°E and 27°N to 72°N. First, the respective forcing data of surface and sub-surface runoff were interpolated to the HD model domain using conservative remapping. Then, daily discharges were simulated with the HD model for the period 1979-2009 (1999-2009 for HD5-MESCAN). In addition, daily discharges were analogously simulated using only JSBACH forcing with the global 0.5° version 1.10 of the HD model. The associated flow directions and model parameters of vs. 1.10 are provided as an auxiliary data file. The HD forcing data are: a) HD5-JSBACH In order to generate daily input fields of surface runoff and drainage, the land surface scheme JSBACH (vs. 3 + frozen soil physics; (Ekici et al., 2014)) was forced globally at 0.5° with daily atmospheric forcing data based on the Interim Re-Analysis of the European Centre for Medium-Range Weather Forecast (ERA-Interim; (Dee et al., 2011)). These forcing data are bias-corrected (see (Beer et al., 2014)) towards the so-called WATCH forcing data (WFD; (Weedon et al., 2011)) that have been generated in the EU project WATCH. b) HD5-MPIHM The MPI-M hydrology model MPI-HM (Stacke and Hagemann, 2012) was driven by daily WATCH forcing data based on ERA-Interim (WFDEI; (Weedon et al., 2014)) from 1979-2009 to generate daily input fields of surface runoff and drainage at global 0.5° resolution. c) HD5-MESCAN Six hourly data of surface runoff and drainage (variable name: percolation) were retrieved from the MESCAN-SURFEX regional surface reanalysis (Bazile et al., 2017) created in the EU project UERRA (Uncertainties in Ensembles of Regional ReAnalysis; www.uerra.eu). SURFEX (Masson et al., 2013) is a land surface platform that was driven by atmospheric forcing at 5.5 km. The forcing comprises 24h-precipitation, near-surface temperature and relative humidity analyzed by the MESCAN surface analysis system as well as radiative fluxes and wind downscaled at 5.5 km from the 3DVar re-analysis conducted with the HARMONIE system at 11 km (Ridal et al., 2017). The latter has been generated using six-hourly fields of the ERA-Interim reanalysis as boundary conditions and covers a domain comprising Europe and parts of the Atlantic, which is similar to the European domain of the Coordinated Downscaling Experiment (CORDEX) at 11 km.

This experiment comprises data that have been used in Hagemann et al. (submitted). It comprises daily data of surface runoff and subsurface runoff from HydroPy and simulated daily discharges (river runoff) of the HD model. The discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. a) HD5-ERA5 ERA5 is the fifth generation of atmospheric reanalysis (Hersbach et al., 2020) produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). It provides hourly data on many atmospheric, land-surface, and sea-state parameters at about 31 km resolution. The global hydrology model HydroPy (Stacke and Hagemann, 2021) was driven by daily ERA5 forcing data from 1979-2018 to generate daily input fields of surface and subsurface runoff at the ERA5 resolution. It uses precipitation and 2m temperature directly from the ERA5 dataset. Furthermore, potential evapotranspiration (PET) was calculated from ERA5 data in a pre-processing step and used as an additional forcing for HydroPy. Here, we applied the Penman-Monteith equation to calculate a reference evapotranspiration following (Allen et al., 1998) that was improved by replacing the constant value for albedo with a distributed field from the LSP2 dataset (Hagemann, 2002). In order to initialize the storages in the HydroPy model and to avoid any drift during the actual simulation period, we conducted a 50-years spin-up simulation by repeatedly using year 1979 of the ERA5 dataset as forcing. To generate river runoff, the Hydrological discharge (HD) model (Hagemann et al., 2020; Hagemann and Ho-Hagemann, 2021) was used that was operated at 5 arc minutes horizontal resolution. The HD model was set up over the European domain covering the land areas between -11°W to 69°E and 27°N to 72°N. First, the forcing data of surface and sub-surface runoff simulated by HydroPy were interpolated to the HD model grid. Then, daily discharges were simulated with the HD model. b) HD5-EOBS The E-OBS dataset (Cornes et al., 2018) comprises several daily gridded surface variables at 0.1° and 0.25° resolution over Europe covering the area 25°N-71.5°N x 25°W-45°E. The dataset has been derived from station data collated by the ECA&D (European Climate Assessment & Dataset) initiative (Klein Tank et al., 2002; Klok and Klein Tank, 2009). In the present study, we use the best-guess fields of precipitation and 2m temperature of vs. 22 (EOBS22) at 0.1° resolution for the years 1950-2018. HydroPy was driven by daily EOBS22 data of temperature and precipitation at 0.1° resolution from 1950-2019. The potential evapotranspiration (PET) was calculated following the approach proposed by (Thornthwaite, 1948) including an average day length at a given location. As for HD5-ERA5, the forcing data of surface and sub-surface runoff simulated by HydroPy were first interpolated to the HD model grid. Then, daily discharges were simulated with the HD model. Main reference: Hagemann, S., Stacke, T. (2022) Complementing ERA5 and E-OBS with high-resolution river discharge over Europe. Oceanologia 65: 230-248, doi:10.1016/j.oceano.2022.07.003

1 Dataset description In ocean model or Earth System model applications, the riverine freshwater inflow is an important flux affecting salinity and marine stratification in coastal areas. However, in climate change studies, the river runoff based on climate model output often has large biases on local, regional or even basin wide scales. If these biases are too large, the ocean model forced by the runoff will drift into a different climate state compared to the observed state, which is especially relevant for semi-enclosed seas like the Baltic Sea. In order to fulfil the demands for low biases in river runoff, a three-part bias correction was developed by Hagemann et al. (in prep.) that comprises different correction factors for low, medium and high percentile ranges of river runoff over Europe. First, we utilized the global hydrology model HydroPy (Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model (Hagemann et al. 2020) to simulate daily discharge time series over the European domain at 1/12° horizontal resolution Sect. 1.1) from 1901-2019. Then, we bias-corrected these time series as described in Sect. 1.2 to generate bias-corrected discharges at coastal ocean boxes of the European HD model domain from 1901-2019. 1.1 Century-long high-resolution discharge simulation over Europe Analogous to Hagemann and Stacke (2022), the global hydrology model HydroPy (Vs. 1.0.2 Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model (Vs. 5.2.0, Hagemann et al. 2023) were used to simulate daily discharge time series over the European domain at 1/12° horizontal resolution. Daily data of two atmospheric datasets were utilized to force HydroPy that provided the input to the HD model. The Global Soil Wetness Project Phase 3 (GWSP3; Dirmeyer et al. 2006; Kim 2017) dataset is available at 0.5° resolution from 1901-2014. Here, we used the data from 1901-1978, and then the simulated time series were continued by using the WFDE5 dataset (Cucchi et al. 2020; 0.5° resolution) from 1979-2019. 1.2 Generation of bias corrected HD discharge data In order to apply the bias correction of Hagemann et al. (in prep.) to the simulated time series of daily discharge from 1901-2019, two sets of bias correction factors were derived. The first set uses the WFDE5-based discharges and discharge station observations for the period 1979-2014. This set was used to bias-correct the simulated discharge at HD river mouths from 1979-2019. The second set uses a further discharge simulation where we continued the GSWP3-based simulation with GSWP3 forcing until 2014. Again, the set of bias-correction factors was derived for the period 1979-2014 using discharge station observations. Then, this set was applied to bias-correct the simulated discharge at HD river mouths from 1901-1978. Detailed information you can find in the specified sections of the attached PDF https://www.wdc-climate.de/ui/entry?acronym=Biasc_hr_riverro_Eu_AdI_v1_0 Recently, a bug has been discovered in the part of the bias correction procedure, which transfers the bias correction factors from the station locations to the river mouths. Here, accidentally the bias correction factors from a previous simulation, which had utilized GSWP3 data, HydroPy and the HD model, were transferred to the river mouths for the whole considered period from 1901-2019. It can be noted that these factors still have improved the simulated inflows for most of the basins compared to the uncorrected HD model discharges. However, fixing this bug (see Version 1.1: https://www.wdc-climate.de/ui/entry?acronym=Biasc_hr_riverro_Eu_v1_1) has led to general improvement for most of the basins. Note that the other datasets of this Version 1.0 did not change. Acknowledgments This dataset was generated within the CoastalFutures project that was funded by the German Federal Ministry of Education and Research under grant number 03F0911A-K.

1 Dataset description In ocean model or Earth System model applications, the riverine freshwater inflow is an important flux affecting salinity and marine stratification in coastal areas. However, in climate change studies, the river runoff based on climate model output often has large biases on local, regional or even basin wide scales. If these biases are too large, the ocean model forced by the runoff will drift into a different climate state compared to the observed state, which is especially relevant for semi-enclosed seas like the Baltic Sea. In order to fulfil the demands for low biases in river runoff, a three-part bias correction was developed by Hagemann et al. (in prep.) that comprises different correction factors for low, medium and high percentile ranges of river runoff over Europe. First, we utilized the global hydrology model HydroPy (Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model (Hagemann et al. 2020) to simulate daily discharge time series over the European domain at 1/12° horizontal resolution Sect. 1.1) from 1901-2019. Then, we bias-corrected these time series as described in Sect. 1.2 to generate bias-corrected discharges at coastal ocean boxes of the European HD model domain from 1901-2019. 1.1 Century-long high-resolution discharge simulation over Europe Analogous to Hagemann and Stacke (2022), the global hydrology model HydroPy (Vs. 1.0.2 Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model (Vs. 5.2.0, Hagemann et al. 2023) were used to simulate daily discharge time series over the European domain at 1/12° horizontal resolution. Daily data of two atmospheric datasets were utilized to force HydroPy that provided the input to the HD model. The Global Soil Wetness Project Phase 3 (GWSP3; Dirmeyer et al. 2006; Kim 2017) dataset is available at 0.5° resolution from 1901-2014. Here, we used the data from 1901-1978, and then the simulated time series were continued by using the WFDE5 dataset (Cucchi et al. 2020; 0.5° resolution) from 1979-2019. 1.2 Generation of bias corrected HD discharge data In order to apply the bias correction of Hagemann et al. (in prep.) to the simulated time series of daily discharge from 1901-2019, two sets of bias correction factors were derived. The first set uses the WFDE5-based discharges and discharge station observations for the period 1979-2014. This set was used to bias-correct the simulated discharge at HD river mouths from 1979-2019. The second set uses a further discharge simulation where we continued the GSWP3-based simulation with GSWP3 forcing until 2014. Again, the set of bias-correction factors was derived for the period 1979-2014 using discharge station observations. Then, this set was applied to bias-correct the simulated discharge at HD river mouths from 1901-1978. Detailed information you can find in the specified sections of the attached PDF (https://www.wdc-climate.de/ui/entry?acronym=Biasc_hr_riverro_Eu_AdI_v1_1). Recently, a bug has been discovered in the part of the bias correction procedure, which transfers the bias correction factors from the station locations to the river mouths. Here, accidentally the bias correction factors from a previous simulation, which had utilized GSWP3 data, HydroPy and the HD model, were transferred to the river mouths for the whole considered period from 1901-2019. It can be noted that these factors still have improved the simulated inflows for most of the basins compared to the uncorrected HD model discharges. However, fixing this bug has led to general improvement for most of the basins. Fig. 1 in the attached PDF (https://www.wdc-climate.de/ui/entry?acronym=Biasc_hr_riverro_Eu_AdI_v1_1) provides an example for the major Baltic Sea sub-basins and shows the inflow biases compared to HELCOM observational estimates. Note that the other datasets of Version 1.0 (https://doi.org/10.26050/WDCC/Biasc_hr_riverro_Eu) did not change.

1 Dataset description This experiment comprises data that have been used in Hagemann et al. (in preparation). It comprises monthly evapotranspiration time series as well as daily data of surface runoff and subsurface runoff from the global hydrology model HydroPy and simulated daily discharges (river runoff) of the HD model, which are based on EOBS31 data (see below). On the one hand, the discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. On the other hand, they can be used to investigate climate induced trends in discharge without considering direct human impact on the river runoff, e.g. by regulation or water abstractions. Please note that a predecessor version of this dataset based on EOBS22 data was published as Hagemann and Stacke (2021) and discussed by Hagemann and Stacke (2023). 1.1 EOBS data The E-OBS dataset (Cornes et al., 2018) comprises several daily gridded surface variables at 0.1° and 0.25° resolution over Europe covering the area 25°N-71.5°N x 25°W-45°E. The dataset has been derived from station data collated by the ECA&D (European Climate Assessment & Dataset) initiative (Klein Tank et al., 2002; Klok and Klein Tank, 2009). To simulate river runoff of the current dataset version 1, we use the best-guess fields of precipitation and 2m temperature of E-OBS vs. 31 (EOBS31) at 0.1° resolution for the years 1950-2024. 1.2 The HD model The HD model (Hagemann et al., 2020) is a river-routing model that is well-established and implemented in a range of global and regional model systems. The HD model can be forced by daily or sub-daily time series of surface and subsurface runoff from the driving climate, land surface or hydrology model. In the present study, we applied the HD model v5.2.4 (Hagemann et al., 2025) over its European domain (land areas between 11°W to 69°E and 27°N to 72°N) at 1/12° spatial resolution. 1.3 European EOBS-based high-resolution river runoff Analogous to Hagemann and Stacke (2022), the global hydrology model HydroPy (Stacke and Hagemann, 2021) and the HD model were used to simulate daily discharge time series over the European domain at 1/12° horizontal resolution. HydroPy was driven by daily EOBS31 data of temperature and precipitation at 0.1° resolution from 1950-2024. The potential evapotranspiration (PET) was calculated following the approach proposed by Thornthwaite (1948) including an average day length at a given location. We conducted a 50-years spin-up simulation by repeatedly using forcing of the year 1950 before the actual simulation was started. Noticeable differences to the EOBS22-based simulation considered by Hagemann and Stacke (2022) occur over Spain and Turkey. Over Turkey, this can be considered as an improvement as the data gaps of EOBS v. 22 over Turkey, which were identified by Hagemann and Stacke (2022), are not present in EOBS31. The daily time series of surface and sub-surface runoff generated by HydroPy were interpolated to the European HD model domain and then used to simulate daily discharges with the HD model. The resulting daily time series of river runoff (HD5-EOBS31) covers the full EOBS31 period 1950-2024. Acknowledgments This dataset was generated while receiving basic funding in the POF IV program “Changing Earth – Sustaining our Future” of the Helmholtz Association (HGF), Germany.

ERA5 is the fifth generation of atmospheric reanalysis (Hersbach et al., 2020) produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). It provides hourly data on many atmospheric, land-surface, and sea-state parameters at about 31 km resolution. It is frequently used to force regional climate models (RCMs) or ocean models. However, it lacks crucial information on riverine freshwater inflows at the land-ocean boundary. The latter is an important flux in ocean model or Earth System model applications, as it is affecting salinity and marine stratification in coastal areas. Therefore, we extended ERA5 with high-resolution river discharge from 1940-2024. Analogous to Hagemann and Stacke (2022), the global hydrology model HydroPy (Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model (Vs. 5.2, Hagemann et al. 2023; Hagemann et al. 2020) were used to simulate daily discharge time series over the whole globe at 1/12° horizontal resolution. HydroPy was driven by daily ERA5 forcing data from 1940-2024 to generate daily input fields of surface and subsurface runoff at the ERA5 resolution. In order to initialize the storages in the HydroPy model and to avoid any drift during the actual simulation period, we conducted a 30-years spin-up simulation by repeatedly using year 1940 of the ERA5 dataset as forcing. To generate river runoff, the HD model was operated globally at 5 arc minutes horizontal resolution. First, the forcing data of surface and sub-surface runoff simulated by HydroPy were interpolated to the HD model grid. Then, daily discharges were simulated with the HD model. This work used resources of the Deutsches Klimarechenzentrum (DKRZ) granted via the Hereon part of the Helmholtz shareholder resources budget. Moreover, ERA5 datasets provided by DKRZ DM via the DKRZ data pool were used.

1 Dataset description Currently, there is a joint effort between the Climate Limited-area Modelling Community (CLM-Community, www.clm-community.eu) and the German Federal Ministry of Research, Technology and Space (BMFTR) project “Updating the data basis for adaptation to climate change in Germany“(UDAG; Früh, 2023) to downscale an ensemble of selected climate change simulations of the Coupled Model Intercomparison Project Phase 6 (CMIP6; Eyring et al., 2016). Different to previous studies, this regional climate modelling ensemble is conducted with the same model version and setup of the Icosahedral Non-hydrostatic (ICON) model used in climate limited-area mode (ICON-CLM; Pham et al., 2021). ICON-CLM belongs to the common class of regional climate models that represent atmosphere and land processes without considering lateral water flows at the land surface, i.e. usually designated as river runoff or discharge. However, discharge is an important component of the global water cycle. Changes in discharge can have a significant impact on the water resources of the respective catchment area (Haddeland et al., 2013; Hagemann et al., 2013). In order to fill the gap that discharge is not provided by ICON-CLM, we used a state-of-the-art river runoff model, the Hydrological Discharge (HD) model (Hagemann et al., 2020), to generate discharges that are consistent with the ICON-CLM output. 1.1 ICON-CLM hindcast In the present study, ICON-CLM was used to conduct regional climate simulations over the European domain of the Coordinated Regional Downscaling experiment (EURO-CORDEX; Jacob et al., 2013). The selected EURO-CORDEX domain has a spatial resolution of 0.11° (approx. 12 km) and the ICON-CLM model setup was determined from optimisation exercises through model extensions and a novel parameter tuning strategy (Geyer et al., 2026). To evaluate the model performance, ICON-CLM was used to generate a hindcast simulation (ICON CLM EVAL) from 1950-2024 by downscaling the ERA5 reanalysis data (Hersbach et al., 2020). 1.2 European hindcast of river runoff based on ICON-CLM surface and subsurface runoff The HD model (Hagemann et al., 2020) is a river-routing model that is well-established and implemented in a range of global and regional model systems. The HD model was forced by 6-hourly time series of surface and subsurface runoff from the ICON-CLM hindcast. In the present study, we applied the HD model v5.2.4 (Hagemann et al., 2025) over its European domain (land areas between 11°W to 69°E and 27°N to 72°N) at 1/12° spatial resolution. The resulting daily series of river runoff (HD5-EVAL) covers the full hindcast period 1950-2024. 1.3 European hindcast of river runoff based on ICON-CLM atmospheric data Analogous to Hagemann and Stacke (2022), the global hydrology model HydroPy (Stacke and Hagemann 2021) and the Hydrological Discharge (HD) model v5.2.4 (Hagemann et al., 2025) were used to simulate daily discharge time series over the European domain at 1/12° horizontal resolution. First, daily atmospheric data of the ICON-CLM hindcast (precipitation and 2 m temperature, downwelling shortwave and longwave radiation, 2m specific humidity, surface pressure, 10m wind) were interpolated to the HD European domain and used to force HydroPy. Here, a restart state of 1950 was taken from a century-long simulation (Hagemann et al., 2024) and used at the start of the simulation in 1950. Then, daily time series of surface and sub-surface runoff from HydroPy (Hpy-EVAL) were used to simulate daily discharges with the HD model. The resulting daily series of river runoff (HD5-Hpy-EVAL) covers the full hindcast period 1950-2024. Acknowledgments This dataset was generated within the project “Updating the data basis for adaptation to climate change in Germany (UDAG)” that was funded by the German Federal Ministry of Research, Technology and Space under grant number 01LP2326D.