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Monitoring and modeling spatial patterns of snow-fed streamflow:
What physical processes are most important at different basin scales?
A recently-graduated student, Fred Lott, and a current postdoctoral researcher, Jeff Deems, have been comparing distributed model performance with satellite maps of snowcover and in situ measurements of stage and discharge at eight interior subbasins for the Tuolumne River watershed in Yosemite National Park.
Previous research by Jessica Lundquist on diurnal cycles revealed that diurnal streamflow timing depends critically on the heterogeneity of the snowpack, which varies with basin scale [Lundquist and Dettinger 2005 ; Lundquist et al. 2005 ]. This same heterogeneity must be included in a hydrologic model to capture the dates when snow disappears in a basin.
Further work revealed that differences due to topographic shading become much more pronounced when snow melts earlier in the year [Lundquist et al. 2004; Lundquist et al. 2006]. Thus topography and solar exposure must be modeled explicitly to understand how north- vs. south-facing basins will respond to climate change [Lott, Master's Thesis, 2008]. We are examining which model structure best represents these effects.
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