ANALYZING APPROPRIATE SAMPLING SCHEMES FOR d18O IN HYDROGRAPH SEPARATIONS

d¹⁸O IS A WIDELY ACCEPTED CONSERVATIVE TRACER USED IN SEPARATING EVENT HYDROGRAPHS INTO NEW AND OLD WATER CONTRIBUTIONS TO STREAMFLOW. SNOWMELT EVENTS REQUIRE A LARGE NUMBER OF d¹⁸O MEASUREMENTS BECAUSE THE CONCENTRATION OF SNOWMELT IS TEMPORALLY VARIABLE THROUGHOUT A SPRING MELT. OBTAINING A LARGE NUMBER OF d¹⁸O SAMPLES IS LABOR INTENSIVE AND LABORATORY RESULTS ARE EXPENSIVE. THE NUMBER OF SNOWMELT d¹⁸O SAMPLES ANALYZED MAY BE MINIMIZED IF A SYSTEMATIC DIFFERENCE OR LACK OF DIFFERENCE IS OBSERVED BETWEEN SAMPLE LOCATIONS. SNOWMELT SAMPLES HAVE BEEN COLLECTED FROM TWELVE BUCKETS BURIED AT DIFFERENT ELEVATIONS AND ASPECTS IN A 0.2 KM² MOUNTAINOUS CATCHMENT WITHIN THE DRY CREEK EXPERIMENTAL WATERSHED NORTH OF BOISE, ID. THIRTY-SIX SAMPLES FROM 6 DIFFERENT DAYS DURING A MELT EVENT WILL BE ANALYZED FOR d¹⁸O AND THE BENEFITS OF HAVING A HIGH SPATIAL AND TEMPORAL SAMPLING DENSITY WILL BE EVALUATED. BY MINIMIZING THE NUMBER OF SAMPLES ANALYZED THE COST OF AN EFFECTIVE HYDROGRAPH SEPARATION MAY BE MINIMIZED.