Aug 24, 2013

Effects of changes in winter snowpacks on summer low flows: case studies in the Sierra Nevada, California, USA

Godsey, S. E., Kirchner, J. W., Tague, C. L.
Hydrological Processes
  • States as the climate warms over the next century, the volume of the annual Sierra Nevada snowpack is expected to decrease by ~40–90%
  • Analyzes records of snow water equivalent (SWE) and unimpaired stream flow records in eight snow-dominated catchments in the Sierra Nevada spanning 10–33 years
  • Findings suggest  that annual minimum flows in some catchments could decrease to zero if peak SWE is reduced to roughly half of its historical average
  • Finds that for every 10% decrease in peak SWE, annual minimum flows decrease 9–22% and occur 3–7 days earlier in the year
  • Finds in two of the study catchments, Sagehen and Pitman Creeks, seasonal low flows are significantly correlated with the previous year's snowpack as well as the current year's snowpack
  • Explores how future warming could affect the relationship between winter snowpacks and summer low flows
  • Results suggest that a 10% decrease in peak SWE will lead to a 1–8% decrease in low flows