2026-08-07 パシフィック・ノースウェスト国立研究所（PNNL）
＜関連情報＞
- https://www.pnnl.gov/publications/changing-snow-dynamics-alter-water-travel-times-headwater-streams
- https://www.nature.com/articles/s41598-026-46539-1
雨と雪の分配の変化により、米国太平洋岸北西部では水の移動時間が短縮される Shifts in rain-snow partitioning drive faster water transit times in the US Pacific Northwest
Zachariah Butler,Stephen P. Good,Huancui Hu,Xingyuan Chen,Mark S. Raleigh,Catalina Segura & Aubrey Dugger
Scientific Reports Published:01 April 2026
DOI:https://doi.org/10.1038/s41598-026-46539-1
Abstract
Water transit times strongly influence water quality, temperature, and seasonal hydrologic response of river systems. How water transit times may shift under future climates remains unconstrained, especially in mountainous regions experiencing rapid snowpack declines. Here, we estimated historical (2006–2013) and future (2086–2093) water transit times in five headwater catchments within the U.S. Pacific Northwest using sequential precipitation input tagging within the Water Tracer enabled version of the Weather Research and Forecasting Hydrologic model. Our results indicate water transit times are 18% (35–64 days) faster on average under the Representative Carbon Pathways (RCP) 8.5 climate scenario due to shifts in rain-snow partitioning, with higher fractions of younger water in the wet season and older water in the dry season. These results suggest shifts in rain-snow partitioning in snowmelt dominated catchments of the Pacific Northwest will shorten water transit times leading to likely impacts on regional water quality, temperature, and hydrologic seasonality.
