Assessing climate change impacts on alpine stream-flow and vegetation water use: mining the linkages with subsurface hydrologic processes

✍ Scribed by Christina L. Tague

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 117 KB
• Volume: 23
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.7288

✦ Synopsis

Within the most recent Intergovernmental Panel on Climate Change (IPCC) report, some of the most well-researched and already observable impacts of climate change are changes in seasonal stream-flow patterns associated with earlier snowmelt and the reduction in snow accumulation, as evidenced by studies in the European Alps, Himalayas, and western North America (reviewed by Kundzewicz et al., 2007). In addition to stream-flow responses to warming, alpine ecosystems are also highly vulnerable to warmer temperatures (Diaz et al., 2003). Many of these observed and projected ecosystem responses are linked to hydrologic processes, including changes in water availability and growing season length associated with earlier snowmelt and potential increased water stress associated with changes in atmospheric drivers of evapotranspiration (Barnett et al., 2005; Betts et al., 2007; Bales et al., 2006). There are a variety of science research initiatives directed towards improving the understanding and predictability of the responses of alpine systems to climate change. Organizations such as Mountain Research Initiative (MRI) (http://mri.scnatweb.ch/, Drexler, 2008) comprise global and regional networks of research. Within the USA, organizations such as Consortium for Integrated Climate Research in Western Mountains (CIRMOUNT) (Diaz et al., 2008) and projects including Western Mountain Research Initiative (WMI) (http://www.cfr. washington.edu/research.fme/wmi/, Baron et al., 2006) and the recently funded National Science Foundation (NSF) Sierra Critical Zone Observatory are designed to explicitly address climate change impacts in mountain environments. Most of these initiatives are linked to intensive field monitoring sites. Thus, while the focus of these studies is often the assessment of climate change impacts, they are also clearly opportunities to advance hydrologic science in general. Studying climate change in alpine environments has several features that are perhaps unique in their support of hydrologic analysis. Firstly, snow accumulation and melt (a key hydrologic input from a streamflow or vegetation water use perspective) vary relatively systematically within watersheds across multiple scales (e.g. Daly et al., 2000; Nolin and Daly, 2006). Climate change studies have also led to a concerted effort to characterize spatial-temporal patterns of snow accumulation and melt in alpine environments, at plot to regional scales (e.g. Molotch et al., 2004;Jain et al., 2008;Trujillo et al., 2007). While significant uncertainties remain, substantial gradients in spatial-temporal patterns of snow observed in alpine regions are perhaps resolved with better accuracy (over large areas) than more subtle gradients in other hydrologic variables or in other regions. These relatively strong gradients in snow accumulation and melt may be easier to measure than gradients in other hydrologic variables (evapotranspiration, soil moisture, precipitation in non-alpine regions or stream-flow in ungaged watersheds). In many alpine regions, such as the western USA, snowmelt is also the dominant water input. Given that snowmelt varies both in space (often with elevation in a particular watershed) and in time (with