Probable Maximum Precipitation Evaluation for a West Virginia Watershed, United States

Abstract

Estimates of probable maximum precipitation (PMP) are necessary for designing the maximum reservoir storage necessary to prevent dam overtopping. Recent investigations in Ohio, Virginia, and Pennsylvania implied that reducing PMP rainfall estimates in West Virginia may be appropriate; however, additional studies in this data-deficient region with changing climate are necessary before any reductions are contemplated. The objective of this study was to re-evaluate PMP for the Lake Tuckahoe watershed in West Virginia. The 6-h, 26-km2 (10 sq mi) PMP was evaluated for current (2019) and projected (2100) climates and compared with the design PMP. Then, the impact of the PMP alternatives was determined for Howard Creek Dam, which was selected to be a case study of a region delineated as a data-deficient region. The estimated current (2019) PMP is 4% greater than the design PMP, and the projected (2100) PMP is 14% greater than the design PMP. Analysis of the dynamic nonstationary climate anticipated for the Howard Creek Dam, designed for a stationary climate, showed inadequate storage that will increase the likelihood of dam overtopping. Therefore, this study cannot support a reduction in PMP for the Lake Tuckahoe watershed and similar surrounding watersheds.