Hydrometric and Geochemical Evidence of Streamflow Sources in the Upper Dry Creek Experimental Watershed, Southwestern Idaho

Publication Date


Type of Culminating Activity


Degree Title

Master of Science in Geology



Major Advisor

James McNamara


In order to investigate the sources contributing to streamflow in the Upper Dry Creek Experimental Watershed (UDCEW), hydrometric and geochemical data were collected in the 2000/2001 cold-season in a highly instrumented 0.02 km2 headwater catchment within the semi-arid Dry Creek Watershed (DCW). Data collected included precipitation, snowmelt, streamflow, meteorological data, and basin water samples. This data was used to evaluate the concentration-discharge (C-Q) relationships, hydro graph separation, and to complete End-Member Mixing Analysis (EMMA) for the two major snowmelt events occurring in the 2000/2001 cold-season.

The flow sources considered in this study include precipitation, regional groundwater, and soilwaters. The hydrometric and geochemical data provided evidence that all water contributing to streamflow in UDCEW can be accounted for by cold-season precipitation occurring in the basin and that there is no contribution to streamflow by a regional groundwater source. The EMMA analysis showed that three end-members including snowmelt, and two soilwater sources, contribute to cold-season streamflow. The sampled soilwater end-members did not explain the observed streamwater chemistry, so a hypothesized soilwater end-member was suggested. Both EMMA and the two-component hydro graph separation indicate that the major flow source area contributing to streamflow is direct interception of snowmelt.

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