PREDICTING WATERSHED EROSION PRODUCTION AND OVER-LAND SEDIMENT TRANSPORT USING A GIS

Soil erosion from forested lands can seriously degrade stream water quality. Sediment production and over-land sediment transport models have been developed which predict ecosystem management impacts on soil erosion and movement across watersheds. The predictions of soil erosion are for whole watersheds, not for points within the watershed. Soil erosion and transport models are usually run independently. From a spatial perspective, the models are difficult to define and the output is difficult to interpret. Our research utilizes a user friendly, modular based, Geographic Information System (GIS) for predicting soil erosion and over-land sediment transport under a variety of management practices including road building, timber harvesting, burning, and creation of wildlife food plots, given a range of storm intensities broken into four seasons (i.e., spring, summer, fall, winter). Through the use of a GIS, model predictions of sediment can be spatially distributed across the watershed and displayed as map outputs of eroded soil deposition. The major objective of this paper is to demonstrate how a GIS and a modular modeling approach can be used by land managers to develop alternative management scenarios for cumulative effects assessment in forested watersheds. As improved soil erosion and transport models are developed, new models can be easily exchanged with current models using a GIS as an integrating database tool. ' INTRODUCTION is one method of characterizing these streams. Sediment load/movement is thought by agencies and Streams are an integral component of forest the public to be a key factor to evaluate in terms of ecosystems. Streams define landform, give relative forest management practices. Soil erosion due to road position to vegetation cover and animal habitats, and construction, log removal, and site preparation can be provide a conduit for material transfer. Defining water the major impact on water quality. Therefore, the quality by physical, chemical and biological conditions ability to estimate soil loss from the watershed due to