A 500-Year Tree-Ring Reconstruction of Truckee River Streamflow

Keywords: dendrochronology, streamflow, dendrohydrology, dendroclimatology, paleoclimatology
Session Type: Virtual Paper Abstract
Day: Monday
Session Start / End Time: 2/28/2022 03:40 PM (Eastern Time (US & Canada)) - 2/28/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 5

Abstract

Located on the Nevada-California border, the Truckee River Basin is an area of hydrologic extremes, subject to both multi-decadal droughts and devastating floods. However, its instrumental record is brief, and thus the full range of its variability is unknown. Hardman and Reil (1936) created the first reconstruction of Truckee River streamflow to address concerns regarding their contemporary drought. My research provides a modern parallel by placing the current post-2000 drought in its palaeoclimatological context. Incorporating their original 1930s tree cores as well as newly sampled material, I developed three new site chronologies which were then combined with other regional chronologies to produce a 1491-2003 reconstruction of Truckee River streamflow, an over 400-year extension of the instrumental record. Prolonged droughts and extreme high streamflow years are both in evidence; notably, however, this reconstruction shows a marked hydroclimatic shift centered around the 1850s. Previously, the Truckee River experienced decadal to multi-decadal periods of above average streamflow; subsequently, these have decreased in duration with only two high streamflow instances above three consecutive years occurring since 1900. As a further example, since the 1980s, no higher-than-average period has been shorter than four years. Whether this represents a fundamental shift to a new hydroclimatic regime remains unclear. With the combined influence climate change and rising global temperatures, it is also uncertain if the post-2000 drought is a new megadrought or a sign of aridification. Regardless, fewer long-term high streamflow episodes will have lasting impacts on water availability and sustainability in the Truckee River Basin.