Kinematic Wave Model of Urban Pavement Rainfall-Runoff Subject to Traffic Loadings

Rainfall-runoff quantity and quality relationships are impacted by both the built environment in particular “impervious” paved surfaces and anthropogenic activities such as traffic. Through the capture, analysis, and modeling of eleven discrete rainfall-runoff events, the impacts of the paved urban surface and traffic were examined with respect to the temporal delivery of storm water runoff quantity. A kinematic wave model accurately captured the significant aspects of typical urban runoff events such as time to peak, total volume of flow and peak discharge from a 300-m² paved surface subject to traffic. Abstractions associated with traffic, represented as the volume-based runoff coefficient, were estimated based on the relationship between runoff and vehicular traffic. It was found that for high intensity storms, with less than 10 vehicles/L of runoff volume (VRV), the runoff coefficient asymptotically approached a maximum value between 0.6 and 0.9. For low intensity storms, with more than 10 vehicles/L (as VRV), the runoff coefficient asymptotically approached a lower maximum value between 0.2 and 0.4. The kinematic wave theory also gave predictions of the time of concentration that were more accurate than other, more common methods currently in use including those by the FAA and the Soil Conservation Service. Prediction of the rainfall-runoff process impacted by the built environment and traffic permits determination of urban pavement hydrographs to determine the unsteady loadings of in situ treatment strategies under a variety of storm conditions. Such unsteady loadings are necessary inputs for selection, design and analyses of in situ storm water unit operations and processes that are developing for the control of both urban runoff quantity and quality.