Currier et al. (2026) Scale and seasonal dependent sensitivity of hydrologic projections in the Colorado River Basin to different downscaling methods

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Hydrometeorology
• Year: 2026
• Date: 2026-04-03
• Authors: William Ryan Currier, Mimi Rose Abel, Rebecca Smith, Jim Prairie, Sarah Baker, Alan Butler, E. D. Gutmann
• DOI: 10.1175/jhm-d-25-0155.1

Research Groups

Not explicitly mentioned in the abstract.

Short Summary

This study compared future streamflow projections derived from dynamic (ICAR) and statistical (LOCA) downscaling methods to assess how downscaling choices impact water supply estimates. It found that while annual regional streamflow changes were not significantly different between methods, local-scale streamflow projections were more sensitive to downscaling choices due to differing seasonal and spatial precipitation and temperature patterns.

Objective

• To evaluate how different downscaling methods (dynamic vs. statistical) for precipitation and temperature projections influence future streamflow estimates and water supply.

Study Configuration

• Spatial Scale: Regional (Lees Ferry, AZ; Upper Basin) and local (smaller catchments within the Upper Basin, high elevations >3000 m).
• Temporal Scale: Future projections, annual, and seasonal (cool-season, summer).

Methodology and Data

• Models used: Intermediate Complexity Atmospheric Research (ICAR) model for dynamic downscaling, Variable Infiltration Capacity (VIC) hydrological model, LOcalized Constructed Analog (LOCA) statistical downscaling method.
• Data sources: Dynamically downscaled precipitation and temperature projections (from ICAR), statistically downscaled precipitation and temperature projections (from LOCA), projections from Earth System Models (ESMs).

Main Results

• ICAR projected a higher ensemble mean annual streamflow change at Lees Ferry compared to LOCA, influenced equally by precipitation and temperature.
• Despite significant differences in precipitation and temperature projections, annual streamflow changes at Lees Ferry were not significantly different between the downscaling methods due to substantial spread and lack of systematic differences across Earth System Models.
• Similar regional streamflow projections resulted from different seasonal and spatial patterns; for example, ICAR projected less cool-season precipitation at high elevations (>3000 m) but increased summer precipitation relative to LOCA.
• Downscaling decisions had a greater impact on streamflow projections at the local scale, with 25–32% of smaller catchments within the Upper Basin showing significant differences in annual streamflow changes between methods.

Contributions

• Provides a direct comparison of streamflow projections derived from physically realistic dynamic downscaling (ICAR) versus widely used statistical downscaling (LOCA).
• Highlights that regional streamflow projections can be similar between different downscaling methods despite significant differences in underlying precipitation and temperature, due to compensating seasonal and spatial patterns.
• Emphasizes that the influence of downscaling choices on streamflow projections is more pronounced at local scales than at regional scales.
• Underscores the importance of process representation in precipitation and temperature and how their spatial and seasonal differences directly affect streamflow projections.

Funding

Not explicitly mentioned in the abstract.

Citation

@article{Currier2026Scale,
  author = {Currier, William Ryan and Abel, Mimi Rose and Smith, Rebecca and Prairie, Jim and Baker, Sarah and Butler, Alan and Gutmann, E. D.},
  title = {Scale and seasonal dependent sensitivity of hydrologic projections in the Colorado River Basin to different downscaling methods},
  journal = {Journal of Hydrometeorology},
  year = {2026},
  doi = {10.1175/jhm-d-25-0155.1},
  url = {https://doi.org/10.1175/jhm-d-25-0155.1}
}