Surface and subsurface water contributions to streamflow from a mesoscale watershed in complex mountain terrain
AffiliationUniv Arizona, Sch Geog & Dev
KeywordsColorado Front Range
end-member mixing analysis
young water fraction
MetadataShow full item record
CitationZhang Q, Knowles JF, Barnes RT, Cowie RM, Rock N, Williams MW. Surface and subsurface water contributions to streamflow from a mesoscale watershed in complex mountain terrain. Hydrological Processes. 2018;32:954–967. https://doi.org/10.1002/hyp.11469
RightsCopyright © 2018 John Wiley & Sons, Ltd.
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AbstractAn understanding of surface and subsurface water contributions to streamflow is essential for accurate predictions of water supply from mountain watersheds that often serve as water towers for downstream communities. As such, this study used the end-member mixing analysis technique to investigate source water contributions and hydrologic flow paths of the 264km(2) Boulder Creek Watershed, which drains the Colorado Front Range, USA. Four conservative hydrochemical tracers were used to describe this watershed as a 3 end-member system, and tracer concentration reconstruction suggested that the application of end-member mixing analysis was robust. On average from 2009 to 2011, snowmelt and rainwater from the subalpine zone and groundwater sampled from the upper montane zone contributed 54%, 22%, and 24% of the annual streamflow, respectively. These values demonstrate increased rainwater and decreased snow water contributions to streamflow relative to area-weighted mean values derived from previous work at the headwater scale. Young water (2.3 +/- 0.8months) fractions of streamflow decreased from 18-22% in the alpine catchment to 8-10% in the lower elevation catchments and the watershed outlet with implications for subsurface storage and hydrological connectivity. These results contribute to a process-based understanding of the seasonal source water composition of a mesoscale watershed that can be used to extrapolate headwater streamflow generation predictions to larger spatial scales.
Note12 month embargo; published online: 19 February 2018
VersionFinal accepted manuscript
SponsorsNSF [DEB 1115068, DEB 0423662, DEB 1027341]; Niwot Ridge LTER [EAR 0724960]