In-Situ Overland Flow Collection System For Sierran Watersheds
C. Denton, W.W. Miller*, D.W. Johnson, P.S.J. Verburg, and G.L. Dana

We have developed a versatile intermediate scale (50 to 100 m2 or more) in-situ overland flow collection system to capture surface runoff during natural events. Our design is easily applied to a wide range of terrain common to natural watershed settings including areas that receive considerable amounts of winter snowfall. Cumulative runoff from 13 Sierran study sites over a 7-month period ranged from a low of 3.9 L (0.08mm) to a high of 21.6 L (0.43 mm) on slopes of <10% in areas of no visible erosion or surface runoff during both snowmelt and summer precipitation. Importantly, this approach clearly gets us one step closer to directly linking nutrient loading from surface runoff to tributary and lake water quality in that we found NH4+-N concentrations as high as 86.2 mg L-1 and ortho-PO4 as high as 28.7 mg L-1 P in the surface runoff. Soil solution and snowmelt extracts were > 3 and 2.5 orders of magnitude lower, respectively. These findings are highly pertinent to hydrologic and nutrient transport models in the Tahoe Basin.Return to results