Automatic discretization and parameterization of watersheds using a digital elevation model

Karen Finney, Rob James, Nandana Perera, Tiehong Xiao and Mike Gregory


Characterization of both overland and channelized flow is crucial for understanding the sources and fate of catchment runoff.  It is essential that care is taken when delineating catchments to ensure that these two types of flow are distinguished from one another. Unfortunately due to the level of complexity associated with large watersheds, obtaining complete and detailed watershed data necessary to characterize the hydrological process is not always possible. To represent stream response in a watershed the sheet flow, channelized flow, flow path slope and contributing area must first be taken into account.

This paper examines the SWMM hydrology setup and parameterization for TRCA’s Don River flood forecasting model using an automatic watershed delineation, parameterization and discretization tool developed in PCSWMM.  In addition, two scenarios, with varying parameterization and hydrologic and hydraulic resolutions, will be compared using observed rainfall and flow data.

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