A Multicentury Perspective on the Relative Influence of Seasonal Precipitation on Streamflow in the Missouri River Headwaters

Abstract

AbstractThe impacts of warming temperatures and declining snowpack on seasonal water yields in the Missouri River Headwaters are not well understood, revealing a gap in our understanding of regional hydroclimate and drivers of streamflow within the Upper Missouri River basin. This study presents the first annually resolved tree‐ring reconstruction of spring precipitation for the Missouri River Headwaters. This reconstruction along with existing tree‐ring reconstructions of 1 April snow water equivalence (SWE) and water year streamflow are used to detect variable influences of winter and spring precipitation on streamflow over past centuries, and relative to the modern period. The results suggest that spring precipitation has been a more consistent influence on water year streamflow in the Missouri River Headwaters over past centuries than winter snowpack. The strong relationship between 1 April SWE values and water year streamflow in the Missouri River Headwaters observed over much of the 20th century is not found to be a consistent feature of these multicentury paleorecords. Instead, the climatic influences on streamflow within the Missouri River Headwaters are likely more variable than 20th‐century instrumental records indicate.