Investigation on the Effects of a Hurricane on the Piezometric Head and Lateral Hydraulic Gradient of a Network of Piezometric Sensors in Florida’s Sinkhole Study

Abstract

Hurricanes produce large amounts of precipitation over short periods of time. This sudden influx of rainfall rapidly changes subsurface hydrological conditions. The increase in rainwater, or recharge, of the surficial aquifer happens significantly faster than that of the confined aquifer, resulting in a rapid increase of head difference. In Central Florida, a relatively thick impermeable soil (i.e., Hawthorn Group) layer is present between the surficial and confined aquifers. The increase in head difference causes internal soil erosion, often a catalyst in the creation of sinkholes. In this study, to better understand the rapid change of head difference, a temporal analysis of piezometric head before, during, and after a hurricane event was performed. Additionally, the change in lateral hydraulic gradient, measured between two adjacent piezometric sensors, was considered and investigated over the same time interval. This study was applied to the Wekiva Parkway SR46 connector project in Central Florida. The results from the analysis indicate that Sensor 1-3 location may be at or near an area of recharge. Based on an increase in hydraulic gradient and low sinkhole resistance ratio (SRR), Sensor 1-2 location has the highest potential for internal soil erosion.