Twin-peaks in streamflow timing: Can we use forest alpine snow melt-out response to estimate?

Authors: DOSKOCIL, LENKA - Colorado State University; FASSNACHT, STEVEN - Colorado State University; Barnard, David; PFOHL, ANNA - National Oceanic & Atmospheric Administration (NOAA); DERRY, JEFFREY - Center For Snow & Avalanche Studies; SANFORD, WILLIAM - Colorado State University

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2025
Publication Date: 7/4/2025
Citation: Doskocil, L.G., Fassnacht, S.R., Barnard, D.M., Pfohl, A.K., Derry, J.E., Sanford, W.E. 2025. Twin-peaks in streamflow timing: Can we use forest alpine snow melt-out response to estimate? Water. 17(13). https://doi.org/10.3390/w17132017.
DOI: https://doi.org/10.3390/w17132017

Interpretive Summary: Snow-dominated watersheds have rivers fed by melting snow typically with a high water flow period in late spring/early summer. Estimating the timing and magnitude of the high flow period is important for managing water resources and planning activities like rafting. In some areas of Colorado, however, rivers have two separate peaks in water flow instead of one. This double peak is believed to be caused by the timing of snow melt at different elevations. We looked at the Uncompahgre River system in Colorado to test this idea. We used a weather-driven snowpack model to see how this pattern emerges across four snow-dominated headwater basins spanning subapline and alpine regions. Our analyses indicate that the timing of the second peak is easier to predict than the first streamflow peak, and more work is need to improve predictions of the first peak.

Technical Abstract: Snow-dominated watersheds experience a snowmelt-driven peak in streamflow that occurs in the spring or early summer. Some of the headwater basins in Colorado, USA have two or more peaks in streamflow, including the Uncompahgre River, a Colorado River tributary. The timing of peak streamflow is important for water management and recreational planning. As such, we examined the connection between the timing of each streamflow peak and readily available snow measurement information in the forest and alpine zones. These station data are the date of the initiation of snowmelt, 50% melt-out, and complete melt-out or the snow disappearance date (SDD). When it occurs before mid-June (14 of 20 years), the timing of the first peak is well correlated with the forested snow measurement station SDD. The second streamflow peak timing is well correlated with SDD from the alpine station except for very early (3 years) and very late (2 years) SDD. We also examine the spatial variability of snow disappearance and peak snow water equivalent (SWE) across the four seasonally snow-covered headwater sub-basins using a dataset from a coupled meteorological–snowpack model.