Preprints
https://doi.org/10.5194/hess-2021-437
https://doi.org/10.5194/hess-2021-437

  20 Aug 2021

20 Aug 2021

Review status: this preprint is currently under review for the journal HESS.

Diel streamflow cycles suggest more sensitive snowmelt-driven streamflow to climate change than land surface modeling

Sebastian A. Krogh1,2,3, Lucia Scaff4, Gary Sterle2, James Kirchner5,6, Beatrice Gordon1, and Adrian Harpold1,2 Sebastian A. Krogh et al.
  • 1Department of Natural Resources and Environmental Science, University of Nevada, Reno, 89557, USA
  • 2Global Water Center, University of Nevada, Reno, 89557, USA
  • 3Departamento de Recursos Hídricos, Facultad de Ingeniería Agrícola, Universidad de Concepción, Chillán, 3812120, Chile
  • 4Global Water Futures, Canada First Research Excellence Fund (CFREF), University of Saskatchewan, Saskatoon, SK S7N 3H5, Canada
  • 5Department of Environmental Systems Science, ETH Zurich, CH-8092 Zurich, Switzerland
  • 6Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland

Abstract. Climate warming may cause mountain snowpacks to melt earlier, reducing summer streamflow and threatening water supplies and ecosystems. Few observations allow separating rain and snowmelt contributions to streamflow, so physically based models are needed for hydrological predictions and analyses. We develop an observational technique for detecting streamflow responses to snowmelt using incoming solar radiation and diel (daily) cycles of streamflow. We measure the 20th percentile of snowmelt days (DOS20), across 31 watersheds in the western US, as a proxy for the beginning of snowmelt-initiated streamflow. Historic DOS20 varies from mid-January to late May, with warmer sites having earlier and more intermittent snowmelt-mediated streamflow. Mean annual DOS20 strongly correlates with the dates of 25 % and 50 % annual streamflow volume (DOQ25 and DOQ50, both R2 = 0.85), suggesting that a one-day earlier DOS20 corresponds with a one-day earlier DOQ25 and 0.7-day earlier DOQ50. Empirical projections of future DOS20 (RCP8.5, late 21st century), using space-for-time substitution, show that DOS20 will occur 11 ± 4 days earlier per 1 °C of warming, and that colder places (mean November–February air temperature, TNDJF <−8 °C) are 70 % more sensitive to climate change on average than warmer places (TNDJF > 0 °C). Moreover, empirical space-for-time based projections of DOQ25 and DOQ50 are about four and two times more sensitive to earlier streamflow than those from NoahMP-WRF. Given the importance of changing streamflow timing for headwater resources, snowmelt detection methods such as DOS20 based on diel streamflow cycles may constrain hydrological models and improve hydrological predictions.

Sebastian A. Krogh et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-437', Jessica Lundquist, 05 Oct 2021
    • AC2: 'Reply on RC1', Sebastian Krogh, 13 Nov 2021
  • RC2: 'Comment on hess-2021-437', Anonymous Referee #2, 08 Oct 2021
    • AC1: 'Reply on RC2', Sebastian Krogh, 13 Nov 2021

Sebastian A. Krogh et al.

Sebastian A. Krogh et al.

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Short summary
We present a new way to detect snowmelt using daily cycles in streamflow driven by solar radiation. Results show that warmer sites have earlier and more intermittent snowmelt than colder sites, and the timing of early snowmelt events is strongly correlated with the timing of streamflow volume. A space-for-time substitution shows greater sensitivity of streamflow timing to climate change in colder than in warmer places, which is then contrasted with land-surface simulations.