ABSTRACT
In 2000, GIS and GPS were used together to map a 12-km portion of Walnut Creek located near Prairie City in Jesper County, Iowa (Schilling and Wolter, 2000). The objective of the mapping project was to locate channel features and identify spatial trends among alluvial system variables that could be used to identify and prioritize portions of the stream channel and watershed in need of further investigation or restoration. Using Trimble Pathfinder Pro XR GPS equipment, discrete locations (channel cross sections, debris dams, tile lines, tributary creeks, and cattle access points) were mapped to an accuracy of 1 m, whereas the continuous data (bank erosion rates, streambed materials, and thickness) were recorded to an accuracy of
5 m. To record continuous conditions, the GPS equipment was operated in continuous line mode with location recorded every 5 sec. GPS data were exported into a GIS format (ESRI Shapefile), using Pathfinder Office software. Field descriptions of the continuous line segments and discrete features were added to the GPS location information to create various GIS layers. Segment lengths varied from 10 to 50 m. Discrete channel features were located by pausing the continuous line mode of the GPS and taking points at feature locations. Stream survey data were used to model watershed conditions, identify water sampling points, and evaluate and select appropriate channel-rehabilitation measures.
