Forests, Lands, and NR Operations

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Equivalent Clearcut Area as an Indicator of Hydrologic Change in Snow-dominated Watersheds of Southern British Columbia

Author(s) or contact(s): R. Winkler and S. Boon
Source: Forests, Lands, and NR Operations
Subject: Clearcutting, Hydrology, Natural Disturbance, Recovery, Watershed
Series: Extension Note
Other details: Published 2017. Hardcopy is available.


Forest disturbance, whether natural or as a result of timber harvesting, directly affects stand-scale hydrologic processes through changes in interception, evaporation, and transpiration. The potential effects of forest disturbance on streamflow are often evaluated by examining the total area disturbed and the location(s) in a watershed where forest cover has been (or will be) altered. The assumption is that the greater the disturbed area, the greater the potential for hydrologic change. It is also assumed that these changes will diminish over time as the forest regrows. The extent of disturbance, accounting for regrowth, is referred to as the equivalent clearcut area (ECA). This note describes ECA, including its origin, development, and use, how it is calculated, and its applicability to forest development planning and watershed assessment. This note focusses on ECA in snow-dominated interior British Columbia watersheds where spring peak flows are a key hydrologic concern. However, the discussion applies wherever ECA is used, although the methods of calculation and seasons considered may vary.

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Updated MARCH 10, 2017