Snowpack management on Marmot watershed to increase late season streamflow

The forested portion of Twin subbasin of the Marmot Creek Experimental Watershed in Alberta, Canada, was harvested in a honeycomb pattern of 1-tree height diameter circular clearings during 1977-79. Our goal for this treatment was to alter hydrograph shape in favour of late season streamflow. Our research on plot studies elsewhere indicated that at peak snowpack, this size clearing would contain 38 percent more snow than under uncut forest and that it would ablate 24 percent slower than either that under uncut forest or that accumulated in clearcuts larger than 3 to 5 tree heights across. These snow research findings suggested that the water yield from a catchment harvested in such tiny clearings might occur later in the water year -- a quite different time distribution than has been reported from harvests consisting of larger size clearcuts. For the first three years since treatment, 28 percent (50 mm) more snow water equivalent accumulated in the clearings than under adjacent treed patches. There has been no increase in total snowpack on the treated catchment. Annual water yield increased by 36 mm in 1980, 16 mm in 1981. There are insufficient data at this time to evaluate the effect on recession flow.