BARRIERS TO FLOW: THE GEOMORPHIC EFFECTS OF ROAD NETWORKS IN URBAN WATERSHEDS

Road networks have become a defining characteristic of urbanized regions. Continued growth of road networks increases their intersections with surface waters (e.g., bridges, fords) and can lead to impairments associated with these intersections. However, the geomorphological implications of road networks are poorly characterized. Here, we analyze a comparative set of urban watersheds in Pittsburgh, PA and control catchments in surrounding areas to quantify the patterns of road/stream crossings and their influence on the longitudinal profiles of the drainage networks. Preliminary results indicate that there are clearly detectable influences on the longitudinal profile that likely influence patterns of urban sediment transport and riparian biogeochemistry. These results clarify important controls on urban fluvial geomorphology with fundamental implications for effective treatments of the “urban stream syndrome.”