Greater vulnerability of snowmelt-fed river thermal regimes to a warming climate

Journal Article · Fri Apr 16 00:00:00 EDT 2021 · Environmental Research Letters

DOI:https://doi.org/10.1088/1748-9326/abf393· OSTI ID:1807965

Yan, Hongxiang ^[1]; Sun, Ning ^[1]; Fullerton, Aimee ^[2]; Baerwalde, Matthew ^[3]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
2. National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
3. Snoqualmie Indian Tribe, Snoqualmie, WA (United States of America). Environmental and Natural Resources Department

While the advective flux from cool melt runoff can be a significant source of thermal energy to mountainous rivers, it has been a much less addressed process in river temperature modeling and thus our understanding is limited with respect to the spatiotemporal effect of melt on river temperatures at the watershed scale. In particular, the extent and magnitude of the melt cooling effect in the context of a warming climate are not yet well understood. To address this knowledge gap, we improved a coupled hydrology and stream temperature modeling system, Distributed Hydrology Soil Vegetation Model and River Basin Model (DHSVM-RBM), to account for the thermal effect of cool snowmelt runoff on river temperatures. The model was applied to a snow-fed river basin in the Pacific Northwest to evaluate the responses of snow, hydrology, stream temperatures, and potential fish growth to future climates. Historical simulations suggest that snowmelt can notably reduce the basin-wide peak summer temperatures particularly at high-elevation tributaries, while the thermal impacts of melt water can persist through the summer along the mainstem. Ensemble climate projections suggested that a warming climate will decrease basin mean peak snow and summer streamflow by 92% and 60% by the end of the century. Due to the compounded influences of warmer temperatures, lower flows and diminished cooling from melt, rivers reaches in high elevation snow-dominated areas were projected to be most vulnerable to future climate change, showing the largest increases in summer peak temperatures. As a result, thermal habitat used by anadromous Pacific salmon was projected to exhibit substantially lower growth potential during summer in future. These results have demonstrated the necessity of accounting for snowmelt influence on stream temperature modeling in mountainous watersheds.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1807965
• Report Number(s): PNNL-SA--156043
• Journal Information: Environmental Research Letters, Journal Name: Environmental Research Letters Journal Issue: 5 Vol. 16; ISSN 1748-9326
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
DHSVM
climate change
fish growth
snowmelt
water temperature