CGRG Bibliography of Canadian Geomorphology
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Author : Beall, F.D.; and Krezek, C.C.
Date : 2006.
Title : Hydrological response of headwater streams to alternative harvesting practices.
Publication : Annual Scientific Meeting of the Canadian Geophysical Meeting, May 14-17, 2006. Banff Centre, Banff, Alberta. Abstracts Volume.
Issue :
Page(s) : 10-11.
Abstract
In the tolerant hardwood forests of Central Canada, clearcutting as a harvesting technique has been replaced by partial cutting systems, but little information is available on the impacts of these systems on the hydrology of low-order streams. At the Turkey Lakes Watershed (TLW), 65 km north of Sault Ste. Marie, ON, a harvesting practices experiment was initiated in 1997. Five headwater basins were included in the experiment: 2 reference basins, one basin clearcut harvested (all trees >10 cm removed, 92% basal area removal), one basin as a shelterwood cut (42% basal area removal) and one basin as a selection cut (29% basal area removal). Continuous streamflow monitoring of the harvested basins began in 1980 and continues to the present. Total annual runoff and runoff coefficient did not exhibit a response outside of the natural variability in the pre-harvest period. This was due to WY1997 having the lowest recorded precipitation at TLW and 3 of the 6 WYs post-harvest were the 3 driest years on record. Enhanced summer baseflow was evident in the clearcut basin from the reduction in the number of zero flow days from an average of 39 yr-1 to 0 yr--1 in the 2 years following harvest. The number of summer zero flow days returned to pre-harvest levels 4 years post-harvest. Flow duration curves (FDC) were constructed for all basins pre- and post-harvest. On an annual basis, the median flow (50% probability) decreased by ~60% in the reference basins post-harvest, while the median flow decreased between 4% (clearcut) and 34% (shelterwood) in the harvested basins. The change in median flow was most pronounced in the summer and winter, typically periods of low flow at TLW. These results highlight the difficulty of evaluating hydrological response in a period of climatic extremes.
Bibliography of Canadian Geomorphology