Implications of observed changes in high mountain snow water storage, snowmelt timing and melt window

Authors: Elias, Emile; James, Darren; HEIMEL, SIERRA - Fort Lewis College; STEELE, CAITI - New Mexico State University; STELTZER, HEIDI - Fort Lewis College; DOTT, CYNTHIA - Fort Lewis College

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2021
Publication Date: 3/26/2023
Citation: Elias, E.H., James, D.K., Heimel, S., Steele, C., Steltzer, H., Dott, C. 2023. Implications of observed changes in high mountain snow water storage, snowmelt timing and melt window. Journal of Hydrology. 35. Article 100799. https://doi.org/10.1016/j.ejrh.2021.100799.
DOI: https://doi.org/10.1016/j.ejrh.2021.100799

Interpretive Summary: We used measured snowpack data over more than 30 years at 16 SNOTEL sites in the upper Rio Grande basin (NM and CO) to evaluate trends in total snow amount, snow melt timing and length of snowmelt. We found that the modeled impacts of climate change are already being observed in the measured record. We report what these shifts mean for water management, water compacts, upstream communities, mountain ecosystems and riparian vegetation.

Technical Abstract: Study Region: Upper Rio Grande Basin, United States Study Focus: Both measured and modeled hydrologic studies report warming-related changes in the hydrologic cycle. However, studies using measured data often rely on April 1 snow water equivalent (SWE) instead of peak SWE. To understand climate-related hydrograph shifts we investigate trends in maximum SWE, timing of maximum SWE and snow depletion and length of the snowmelt window using measured data with varied methods. New Hydrological Insights for the Region: Of 16 locations with the longest data record (1980 to 2018) in the region, more than half had significant declines in maximum SWE. Regional trends using all sites collectively showed a decline in maximum SWE of -0.4 cm/year. Maximum SWE was earlier at 10 to 13 of 16 sites, depending upon method. Trends at individual locations show a wide range in maximum SWE advancement (18 to 48 days). Regional maximum SWE advanced three weeks. Snowpack depletion was similarly early at more than half the sites. Although snowmelt occurs earlier, there was no change in the snowmelt window (days between peak SWE and no snow). The reduced maximum SWE may relate to reduced snowfall, increased sublimation or lower albedo associated with dust. We describe the ecological and social impacts of these observed shifts in snow amount and runoff timing for headwaters communities, water compacts, mountain ecosystems, and riparian vegetation.