THE RATE OF URBANIZATION AND VARIATION IN IMPACTS TO FLUVIAL SYSTEMS

The rapidly expanding cities of the 21^st century cause a more intense urbanization and are therefore likely to alter urban stream geomorphology distinctly from historical urbanization. Due to more intense development practice, sediment inputs to the stream should be greater and widening and incision more extreme than the majority of urban streams studied to date. Comparisons among sets of urbanized streams in the U.S have emerged, but these sets are generally limited to 20^th century urbanization, following a relatively homogeneous history of human activity. This presentation documents the broad spectrum of potential scenarios shaping global urban streams through meta-analysis of the literature. The data synthesis reveals important gaps in our comparative set of urban streams and therefore identifies additional combinations of land use history and urbanization rates necessary to clarify processes that drive changes in urban streams. The clarification of variability in stream responses to contrasting land use change regimes is fundamental to our ability to predict geomorphological change and thus our ability to mitigate this change in urban systems.