Deep groundwater mediates streamflow response to climate warming in the Oregon Cascades

Abstract

Recent studies predict that projected climate change will lead to significant reductions in summer streamflow in the mountainous regions of the Western US. Hydrologic modeling directed at quantifying these potential changes has focused on the magnitude and timing of spring snowmelt as the key control on the spatial-temporal pattern of summer streamflow. We illustrate how spatial differences in groundwater dynamics can also play a significant role in determining streamflow responses to warming. We examine two contrasting watersheds, one located in the Western Cascades and the other in the High Cascades mountains of Oregon. We use both empirical analysis of streamflow data and physically based, spatially distributed modeling to disentangle the relative importance of multiple and interacting controls. In particular, we explore the extent to which differences in snow accumulation and melt and drainage characteristics (deep ground water vs. shallow subsurface) mediate the effect of climate change. Results show that within the Cascade Range, local variations in bedrock geology and concomitant differences in volume and seasonal fluxes of subsurface water will likely result in significant spatial variability in responses to climate forcing. Specifically, watersheds dominated by High Cascade geology will show greater absolute reductions in summer streamflow with predicted temperature increases.

A hydrogeologic framework for characterizing summer streamflow sensitivity to climate warming in the Pacific Northwest, USA

“…Several recent studies have demonstrated the important role of geologically controlled deep groundwater in mediating streamflow response to climatic variability and warming in the PNW Tague et al, 2008Tague et al, , 2013Tague and Grant, 2009;Mayer and Naman, 2011;Waibel et al, 2013). Historical streamflow analysis across the western US underscores the importance of both climatic and geologic controls on streamflow response to climate change (Safeeq et al, 2013).…”

Linking Climate Change and Groundwater

“…Seasonal streamflow is altered because the snowpack acts as a reservoir for water storage (Barnett et al 2008;Cayan et al 2001;Hunt et al 2013;Mote et al 2005;Stewart et al 2004;Tague et al 2008). For example, Eckhardt and Ulbrich (2003) predicted a smaller proportion of the winter precipitation will fall as snow due to warming trends in mountainous regions of central Europe and that the spring-snowmelt peak will likely be reduced while the flood risk in winter will probably increase.…”

“…Spatial differences in groundwater dynamics in mountainous regions also can play a substantial role in determining streamflow responses to warming (Tague et al 2008;Tague and Grant 2009). Tague et al (2008) suggested that groundwater dynamics, such as subsurface drainage, are as important as topographic differences in snow regimes in determining the response of mountain landscapes to climate change.…”

“…Tague et al (2008) suggested that groundwater dynamics, such as subsurface drainage, are as important as topographic differences in snow regimes in determining the response of mountain landscapes to climate change. The changes in streamflow, shifting spring and summer streamflow to the winter, will likely increase competition for reservoir storage and in-stream flow for endangered species (Payne et al 2004) and lead to summer water shortage throughout the western United States (Tague et al 2008) and other similar semiarid and arid regions globally.…”

An Eco-Hydrological Model-Based Assessment of the Impacts of Soil and Water Conservation Management in the Jinghe River Basin, China

“…RHESSys has been used for a wide variety of hydrological and ecosystem biogeochemical cycling applications [22][23][24][25][26]. A full description of the RHESSys process representation is given in [21].…”