EXAMINING THE EFFECTS OF RESOLUTION AND ROADS ON DEM-DERIVED DRAINAGE NETWORKS

Understanding the extent of perennial and ephemeral streams in steep, complex terrain is important for understanding regional water quality. Previous work has shown that higher resolution digital elevation models (DEMs) can more accurately map perennial drainage networks in mountainous headwater watersheds. Furthermore, site-specific analysis has shown that paved roads can greatly reduce the threshold contributing area for surface-flow initiation. In this work, we address questions regarding these observations using the new 1.0-meter resolution North Carolina DEM. First, can channel initiation points be accurately identified remotely using these new data? Second, how variable are the threshold channel initiation contributing area values across the landscape? And finally, how much do roads expand and alter these mountain-drainage networks? We used a combination of remote hydrologic geospatial analyses paired with field observations to address these questions. Preliminary evidence suggests channel initiation points can be identified with the high-resolution DEM, contributing areas vary greatly depending on topography and road-presence, and that paved roads add significant surface flow and alter watershed boundaries when they exist near drainage divides.