The H60 is a concept used in the Interior Watershed Assessment Procedure (IWAP; MoF 1999) by which the upper altitudinal zone within a watershed is weighted for its assumed contribution to peak flows. The approach assumes that there is a very direct and immediate link between snowmelt and surface flow, there being little lag in delivery of water from the snowpack to the stream. This project uses tracers and water chemistry to test the H60 concept by determining the location in the watershed that makes the dominant contribution to the water in the peak hydrograph. The key uncertainty being studied is the lag between snow melt and water entering the stream channel. The snowpack in three small watersheds was marked with two selected chemical tracers, namely deuterium and chloride, that are (i) detectable in very small quantities and (ii) move conservatively through the soil (i.e. are not adsorbed onto soil particles but move through inertly with the snowmelt water). Stream water was sampled continuously during the snowmelt season in order to determine the time at which water from particular locations in the catchment actually contribute to the peak-flow hydrograph. By this means a picture is beginning to emerge of the travel times of water in the watersheds and the contributions of different zones and altitudinal belts to the important peak flows. Delays in approval of the project meant that the important snowmelt season in 2004 was largely missed. However, the season was not lost altogether as the equipment and methods could be tested. The results indicate that both tracers work for the intended purpose, though there are problems with using chloride in research catchments as it interferes with other water quality studies.
David F. Scott.
Scott, David F., Giles, Tim R.; Gluns, David R.; Jordan, Peter; Scherer, Rob. 2005. Testing the H60 concept in the Interior Watershed Assessment Procedure by process hydrology studies. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Hydrology, British, Columbia
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