Effects of clearcut timber harvesting on annual water yields in the Carnation Creek watershed, British Columbia
Date
1996
Authors
Eakins, Kelly Aileen
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Abstract
Changes in annual water yield after clear-cut timber harvesting are investigated at Carnation Creek on the west coast of Vancouver Island, British Columbia. The paired basin method was used to determine annual, seasonal and monthly changes in water yield between treated basins H (12 ha) and J (24 ha) and control sub-basins C (145 ha) and E (265 ha). Water yield increased 20% and 28% at Hand J watersheds, respectively and was matched by corresponding decreases in evapotranspiration. Water yield increases were lowest the first year after harvesting and peaked six years later. Wet season (October - March) water yields increased 20% at H watershed and 25% at J watershed while dry season (April-September) increases were 14% at H watershed. Increases in annual water yield after timber harvesting are attributed to reduced evapotranspiration and interception losses allowing more water for streamflow. These findings support results reported from studies in the Pacific northwest region and provide quantitative information on the effects of clear-cut timber harvesting on the west coast of Vancouver Island.