Forest Investment Account

Abstract of FIA Project Y051294

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Forest management in interior of British Columbia: moving beyond equivalent cut area

Author(s): Alila, Younes
Imprint: Vancouver, B.C. : University of British Columbia, 2005
Subject: Forest Investment Account (FIA), Hydrology, Forest, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program


Scientific investigations in forest hydrology has traditionally been dominated by paired watershed studies in which primarily streamflows are monitored before and after land-use changes and statistical tests are applied to judge if the hydrologic response of the watershed has changed. Since statistical tests would only tell whether to reject or accept the hypothesis that land-use changes affected the hydrologic response of the watershed; the question of why or why not is commonly left to speculations. Because internal hydrological process knowledge is not known with this black-box approach, forest hydrology is embroiled in controversies that never seem to get resolved. We propose a new process based experimental approach combined with physically based modeling to understand the changes of hydrological processes and quantify their effects on streamflow at multiple scales. In this approach, watersheds need to be instrumented in a way that internal processes can be studied over various spatial scales and the resulting experimental data and process knowledge can guide and justify the hydrological modeling. In this paper, we demonstrate the proposed dialog between field hydrologists and the modeler during the set-up process of a new experimental watershed, a snow dominated 18.5 km2 drainage located in the Kootenays, Southeastern British Columbia, Canada. The mountainous watershed is forested to the headwaters with moderately steep hillslopes and a mosaic of forest stands of various age classes. We measure discharge, stream temperature, and electric conductivity at 10 nested sub-basins and two perennial springs. We monitor the climatological variability with two complete climate stations and five additional precipitation/air temperature stations. We track the spatial snow cover with 50 snow sensors and measure snow water equivalent every two weeks at several snow courses. This paper explores in detail the value of the discharge measurement networks to capture the natural and anthropogenic hydrological variability in the watershed. We compare the spatial variability of the response dynamic during rainfall and snowmelt events. We use the detailed meteorological measurements with soil, topography and forest cover information to determine if the observed streamflow variability is driven by meteorological, anthropogenic, and/or natural variability. The resulting process understanding will then be used to guide our detailed instrumentation of internal catchment processes focusing on runoff generation mechanisms and its relation to land-use management.

For further information, please contact Younes Alila, University of British Columbia (

Updated September 08, 2005 

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