Three hundred years of snowpack variability in southwestern British Columbia reconstructed from tree‐rings

• Published in: Hydrological processes 2020-12, Vol.34 (25), p.5123-5133
• Main Authors: Mood, Bryan J., Coulthard, Bethany, Smith, Dan J.
• Format: Article
• Language: English
• Subjects: Annual; British Columbia; Climate change; dendroclimatology; Drought; Duration; Economics; El Nino phenomena; hydrology; La Nina; Oscillations; paleoclimate; Reconstruction; Snow; Snow-water equivalent; Snowfall; Snowpack; Spectral analysis; Spectrum analysis; Stream discharge; Stream flow; Surveying; Variability; Water management; Water resources; Water resources management
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.13933

Recent snow droughts in southwestern British Columbia (BC), Canada, have reduced seasonal streamflow during the typically dry late‐spring and summer months, leading to socio‐economic and ecological impacts that draw attention to the impending consequences of climate change. Knowledge of annual winter snowfall variability within this region is largely derived from a sparse network of short‐duration (≤50 years) snow survey stations. In this paper, we develop an annual April 1 snow water equivalent (SWE) reconstruction from living tree‐ring chronologies that offer a perspective on long‐term natural snowpack variability. The dendrohydrological model estimates the first principal component April 1 SWE for the southwestern regions of BC to 1711. Spectral analysis identified dominant multidecadal April 1 SWE variability over the pre‐instrumental period. The reconstruction successfully captures known instrumental period influences of La Niña oscillations on reconstructed SWE, suggesting that our tree‐ring based the reconstruction has the potential to provide insights on pre‐instrumental ocean–atmosphere links with southwestern BC snowpack dynamics. Runs analysis suggests pre‐instrumental snow droughts have been more than twice as long in duration and severity than during the observed period which indicates the instrumental record may not capture the full range of April 1 SWE variability. The reconstruction provides the first high‐resolution description of SWE over the past 300 years in southwestern BC and is of immediate use to regional water resource managers. April 1 snow water equivalent reconstructed from tree‐rings in southwestern British Columbia reveals snow droughts (sub‐20th percentile) can be longer in duration and higher in magnitude than the instrumental record may show.