The Cotton Creek Experimental Watershed (CCEW) was monitored intensively for three years in Phase I, with continued monitoring through the current Phase II, and is yielding valuable information on watershed function and the effects of forest management. The 17.4 km2 watershed lies 17 km south of Cranbrook. Elevations range from 1050 m to over 2000 m. Snow accumulation and melt dominate the hydrology as is typical in southeast BC.
Over 50% of the watershed is covered by lodgepole pine and CCEW is thus rated as a high risk watershed for Mountain Pine Beetle (MPB) infestation. Outbreaks of MPB in the watershed in the 1980s and 1990s resulted in salvage logging (see Fig. 1). MPB are currently infesting neighbouring catchments, and are beginning to establish within CCEW. The MPB infestation has been expanding to the point that further salvage logging is planned and is underway. Given this situation CCEW provides a unique opportunity to document the effects of MPB-related tree death and salvage logging on watershed processes and aquatic habitat.
CCEW is one of the only medium-sized watersheds that has detailed and dense field monitoring of hydrological processes, micro-meteorological processes, channel morphology, water quality and riparian processes. In contrast to long-term monitoring of streamflow and water quality at individual sites, as conducted in paired catchment experiments, we simultaneously monitor the variability and changes of streamflow and channel geomorphology in multiple, nested basins, and employ a stratified sampling approach to study snow accumulation, snow melt and runoff generation. The existing infrastructure involves a nested network of 12 gauges along the main channel measuring stream discharge, stream temperature and electrical conductivity. This network documents the effect of riparian zone management on water temperature and the effect of road density on surface runoff using hydrograph separation techniques. Climate stations at different elevations and aspects record air temperature, humidity, wind speed and direction, precipitation, incoming solar radiation and snow depth (Fig 2). A network of 60 groundwater wells monitors subsurface flow and the occurrence of surface saturation (Fig 3). Soil moisture is also monitored at all groundwater wells.
Bedload transport is measured at several bedload traps installed along the main channel and in several tributaries to record the spatial variability of annual bedload transport.
A GIS database was established based on available GIS data sources, but also includes additional data collected in the watershed. For example, a detailed terrain analysis was undertaken in 2005 and digitized to be used in a GIS. The GIS database also includes a high resolution DEM (10 m), terrain indices (e.g. slope, wetness index), longitudinal stream profiles, updated road network, GPS corrected road culvert locations and drainage direction, and 50 soil profile observations.
We propose to continue the CCEW study for the next three years (and beyond), during which time MPB should affect a substantial portion of the watershed (the area dominated by Pinus contorta is at high risk of MPB attack or is already under attack as red attack has been observed this summer at some plots). Because we have already collected extensive baseline date during the last 3 years, CCEW provides a unique opportunity to monitor changes in watershed processes prior to and during MPB infestation and following salvage logging. We do not expect salvage logging to occur in the watershed during the next 3 years (but probably afterwards), but since some extensive areas in the northern part of the watershed have already been salvage logged, the cumulative effect of disturbance varies among the subwatersheds and hence allows a spatial comparison of watershed function across a range of disturbance intensities.
The spatially distributed measurements of snow accumulation and melt, soil moisture and gro ...
Moore, R. Dan. 2010. Cotton Creek Phase II: Multi-scale, spatially explicit studies of Mountain Pine Beetle impacts on watershed function. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2010MR339
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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