Verifying calculated flow accumulation patterns of mapped and unmapped forest streams by culvert location

Access to reliable surface water drainage information is important to forest operations planning in road layout and construction, culvert location and size, cutblock and harvest trail layout, site preparation and regeneration, and off-road navigation. A GIS-based process leading to an improved map of surface drainage is described and tested for the University of New Brunswick forest. This process predicts flow accumulation by combining the predictive ability of a digital elevation model (DEM) with additional information provided by mapped hydrographic features. Previously unmapped flow channels were reliably mapped with this process; 88% of predicted culvert locations were within 40 m of the actual location. Total channel length mapped increased 11.7 times over the existing maps. Key words: digital elevation model, forest operations planning, surface hydrology, flow accumulation