Abstract
In the Pacific Northwest, ensemble projected streamflow datasets are valuable for assessing vulnerabilities and the resilience of reservoir systems across the region. These datasets are typically generated using a climate-hydrologic modeling chain that begins with coarse-resolution outputs from selected Earth System Model (ESMs) and socioeconomic scenarios, which are spatially downscaled, followed by hydrologic simulations driven by the downscaled meteorological forcing. In this work, a calibrated catchment-based hydrology and river model is forced by ESM outputs for several socioeconomic scenarios from the archives of the Coupled Model Intercomparison Project phases 5 and 6, which are downscaled using a computationally efficient weather model. The dataset comprises twenty-nine daily hydrologic traces from 1950 to 2099 for 18,000 river reaches. The dataset also includes a retrospective hydrologic simulation forced by an observation-based meteorological dataset used for hydrologic model calibration. Naturalized flows for 221sites are used to assess historical simulation fidelity. This dataset supports a variety of applications including reservoir modeling, ecological impact assessments, and hydrologic analyses under historical to projected climate conditions.
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Data availability
SUMMA and mizuRoute output data are available from the NSF NCAR Research Archive (https://doi.org/10.5065/8SAK-HM25)68. This archive includes an ancillary geospatial dataset including SUMMA HUC12 catchments, MERIT-basin river reaches and catchments, naturalized gauge points.
Code availability
All the model codes are available from the following GitHub repositories.
1. SUMMA v3.1.2: https://github.com/CH-Earth/summa/tree/v3.1.2
2. mizuRoute v1.2.3: https://github.com/ESCOMP/mizuRoute/tree/v1.2.3
3. MetSim v2.4.1: https://github.com/UW-Hydro/MetSim/tree/2.4.1
4. Bmorph v1.0.0: https://github.com/UW-Hydro/bmorph/tree/1.0.0
5. GMET v2.0: https://github.com/NCAR/GMET.
6. ICAR v2.1: https://github.com/NCAR/ICAR/tree/2.1
Examples of python notebooks are available at https://github.com/nmizukami/pnw_hydrology_analysis for majority of the technical validations used in this paper. These notebooks are compatible with the dataset downloaded from https://doi.org/10.5065/8SAK-HM25, and users are free to use and customize the codes as desired.
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Acknowledgements
This work was primarily funded by U.S. Army Corps of Engineers Grants (W26HM432051759, W26HM432051757, W26HM411547729 and HQUSACE17IIS/003) and was performed at the NSF National Center for Atmospheric Research (NCAR), which is a research and development center of the U.S. National Science Foundation (under Cooperative Agreement No. 1852977). It leveraged modeling and development work underway with sponsorship from the US Bureau of Reclamation Science and Technology Program, and high-performance computing support from the Derecho system (doi:10.5065/qx9a-pg09) provided by the NSF National Center for Atmospheric Research (NCAR), sponsored by the National Science Foundation and CISL for providing computing support.
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N.M. wrote the original draft; B.N., A.W., J.H., E.G. contributed text for sections of the manuscript; All the authors reviewed and edited the manuscript. E.G. contributed the generation of ICAR downscaled forcing. B.N. contributed the bmorph streamflow bias correction. A.W. contributed the baseline SUMMA-mizuRoute model implementation, the model calibration routines, and the GMET-based forcings and forcing preparation routines. N.M. further adapted the calibration routines, ran all model calibrations, adjusted the forcings, and performed all analyses, with input and review from the project team. J.H., M.W., C.F. and C.M. contributed the acquisition of the naturalized flow data. E.G., J.H., M.W., C.F. and C.M. also managed the projects. The views expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the United States Army, the Department of War, or the U.S. Government.
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Mizukami, N., Gutmann, E.D., Wood, A.W. et al. A century long ensemble streamflow dataset in the Pacific Northwest to support water security assessments. Sci Data (2026). https://doi.org/10.1038/s41597-026-06865-5
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DOI: https://doi.org/10.1038/s41597-026-06865-5


