Modification of Kinematic Wave Cascading Model for Low Impact Watershed Development (Paperback)

The Kinematic Wave (KW) method has been widely applied to the urban stormwater hydrological model. These models require the conversion of a real catchment to its equivalent rectangular cascading plane. Without field data and engineering guidelines for the calibration process, it is a challenge to properly translate the irregularity of the real catchment into the rectangular shape unit-width overland flow process. This research has developed catchment shape factors and shape curve functions with three mathematical approaches: parabolic function, exponential function, and trigonometry Sin function. In order to evaluate the capability of the shape factor modification on stormwater hydrograph prediction, and to test the sensitivity of the KW shape function to the level of modeling detail, this study applied the derived mathematical shape functions to a real urban watershed, the Upper Harvard Gulch Watershed (UHGW). With the UHGW stream gage verification, this study concluded that the parabolic function provides a consistent and stable basis for watershed shape conversion. In addition, the difference of the catchment's site layout and KW overland flow path are also discussed in this study since these factors change the model predicted peak flow rate and runoff volume. The overland flow discharge and flow depth relationship were developed based on principle of continuity and momentum. This research provides the Kinematic Wave cascading model and runoff volume analysis numerical techniques to model a level spreader system for the purpose of comparison between effective imperviousness and traditional area weighted method imperviousness.