Morphologic characterization of urban watersheds and its use in quantifying hydrologic response

The morphology of urban watersheds and the effects of urbanization on the structure of the drainage system have not been studied extensively. The overarching objectives of this study are to develop methodologies to characterize the morphology of urban drainage systems and to use this characterization to model the hydrologic response of the watershed. These objectives are accomplished through: (a) an exploration of applications of morphologic theories in the characterization of urban watersheds and the impacts of urbanization; (b) the development and testing of a methodology to generate urban terrains in which the effects of artificial conduits are represented; and (c) the development and testing of a new rainfall-runoff model called the U-McIUH (Urban Morpho-climatic Instantaneous Unit Hydrograph), in which the hydrologic response is identified from the spatial structure of the watershed and the properties of the storm event.;The approach adopted reveals significant impacts of urbanization on the internal structure of natural watersheds at different scales. This finding is relevant when building stormwater models intended to compare the pre- and post-development catchment response. These morphologic impacts should be incorporated into stormwater models through the redefinition of model parameters that characterize both the channelized and unchannelized portions of the catchment when the urbanized scenario is simulated. This research also shows the importance of incorporating artificial conduits into urban terrain for hydrologic modeling. A new method to incorporate the artificial conduits into the DEM proved to be superior to other previously available methods because it better represents the flow directions and paths. Finally, the new rainfall-runoff model fills an existing gap in the field of distributed stormwater modeling. It provides a more thorough treatment of the flows in minor conduits and unchannelized portions of the watershed, which enhances the simulations of runoff accumulation that are traditionally used in conceptual models. The model is parsimonious and uses a simplification of kinematic wave routing to compute travel times that considers the dependence of the unit hydrograph on rainfall intensity and the effect of upstream contributions on the travel times. This simplification reduces the complexity of the model computations while still producing reasonable model performance.