Investigation of the impacts of local-scale hydrogeologic conditions on sinkhole occurrence in East-Central Florida, USA

Sinkholes occur when surface soils gradually subside or suddenly collapse into subsurface cavities and voids due to raveling and erosion of surficial soils caused by dissolution and washing-off of underlying soluble carbonate bedrock. Sinkhole occurrence is related to local-scale hydrogeologic conditions (groundwater recharge rate and hydraulic head difference between water table and potentiometric level). Historical data have shown that sinkholes are more likely to occur in the beginning of wet season and the frequency of occurrence varies seasonally. In this study, the East-Central Florida region, which is vulnerable to sinkhole hazard, is selected as the study area, and the relationships between temporal and spatial distributions of observed sinkholes and hydrogeologic conditions are quantitatively investigated. The analysis results indicate that the seasonality of sinkhole occurrence is due to the seasonal variation of rainfall and groundwater level, and sinkholes are most likely to occur when the local-scale head difference stays constant at a peak value after a sharp increase over a short period of time. In space, sinkhole density increases linearly with increases in groundwater recharge rate and hydraulic head difference.