Mapping variable—width streamside management zones for water quality protection

Streamside management is an essential part of maintaining water quality during forest operations. Maintaining forest cover and forest floor near streams has been found to minimize the impact of upslope mechanical treatments. Throughout the Southeastern US streamside management is a major component in forestry practice guidelines. Width of streamside management zone is determined in most of these guidelines as a variable, based on slope perpendicular to the stream. Although a variable width zone is advantageous for water quality protection it complicates forest operation planning. Geographic Information Systems aid management planning by accurately mapping areas where operations must be altered. In the case of streamside management zones, harvest plans must include these zones in cutting, skidding, site preparation, and road and deck placement. This paper will outline a procedure (macro language program) which allows accurate mapping of streamside management zones that vary with side slope. An accurate map of streamside management zones can be produced from a map of stream bottom position and a high resolution Digital Elevation Model. The model allows determination of the position and extent of streamside management zones during operation planning without need to resort to ground mapping during the planning stage. Model applications will be shown on small harvested watersheds. Streamside management zone mapping can also be used in the context of identifying water quality impairment on larger watersheds that include agriculture and urban development.