MAXIMIZING DIGITAL RESOURCES: COMBINING GIS TECHNOLOGY AND FIELD WORK FOR DEPICTING LOW-ORDER STREAMS IN THE OZARK MOUNTAINS

For sound land management planning, federal land managers require knowledge of hydrologic features across the landscape. In a digital format this information can represent important resource information used to identify areas for protection, restoration, and regulatory compliance. The objective of this project was the development of a digital representation of the stream network for the Boston Mountain Ecoregion of the Ozark Highlands that could be used for planning and implementation of land management activities.

Stream delineation was performed on a 5 meter DEM for a 61,240 acre study area representative of the Boston Mountain Ecoregion. This analysis was performed in ArcMap and ArcCatalog 9.1 using the tools available through the Spatial Analysis extension on the toolbar. A flow accumulation grid was developed and three separate models were determined with accumulation threshold values of 2500, 3420, and 5,000 cells. Each model was evaluated against 864 GPS located hydrologic features across the study area. Next the models were validated through field assessments at 40 different locations. Each location consisted of three sites corresponding to the separate models. Stream channel characteristics were documented at each site. These characteristics were then used to determine which threshold values best correlated to on-the-ground expressions of ephemeral and intermittent stream channels.

The product of this study is a GIS shapefile which represents small ephemeral and intermittent stream channels, with a known tolerance, which can be used to enhance the National Hydrologic Data Set. The resulting model is a tool intended to be incorporated into land management planning activities. This study uses current data collection technologies (Lecia ADS40 Sensor), high resolution DEMs, and field validation to calibrate this tool for use in the Boston Mountains. Upon completion of the validation process it was determined that stream delineation using a flow accumulation process with a threshold value below 20 acres provided an adequate stream model for land management purposes.