Historical analysis of tropical and non-tropical induced flooding within the James River Basin, Virginia

This paper identifies flooding patterns within the James River Basin based strictly on flood frequency and causative weather events. By analyzing USGS river gauge data, NWS mapping products, and the HURDAT2 data set in a common time domain, floods are characterized by their source. These sources of flooding are categorized with a novel system of storm designations, including non-tropical, Atlantic tropical, Gulf tropical, Atlantic hybrid, Gulf hybrid, and bypassing storms. Associated tables delivering flood joint and marginal probabilities resulted from the analysis. Non-tropical storms are most often the source of flooding in all three regions of the basin and account for most of the floods recorded.

In examining the results of this study, it is apparent that non-tropical and tropical sourced flooding, with or without concurrent frontal activity, all have the potential to create various floods across the basin. While some tropical cyclones, like Hurricane Camille (1969), caused flooding events in all three regions of the James River Basin, others, such as Hurricane Floyd (1999), only caused flooding in the eastern portions of the basin. Much of this results from the influence of frontal systems, which can alter the path of the storm and, thus, the precipitation, hence the use of the “hybrid” storm designation used in this study.