Description: What is a Subsidence Incident? Sinkholes are closed depressions in areas underlain by soluble rock such as limestone, dolostone, gypsum, or salt. Sinkholes form when surface sediments subside into underground voids created by the dissolving action of groundwater in the underlying bedrock. Other subterranean events can cause holes, depressions or subsidence of the land surface that may mimic sinkhole activity. These include subsurface expansive clay or organic layers which compress as water is removed, collapsed or broken sewer and drain pipes or broken septic tanks, improperly compacted soil after excavation work, and even buried trash, logs and other debris. Commonly, a reported depression is not verified by a licensed professional geologist to be a true sinkhole, and the cause of subsidence is not known. Such an event is called a subsidence incident. The Florida Geological Survey maintains and provides a downloadable database of reported subsidence incidents statewide. While this data may include some true sinkholes, the majority of the incidents have not been field-checked and the cause of subsidence is not verified.
Description: This dataset represents swallets (stream to sink features) discovered, researched and mapped by the Florida Department of Environmental Protection, Florida Geological Survey, Florida Swallet Survey. The Florida Swallet Survey was a mapping program funded by the Florida Department of Environmental Protection's Florida Springs Initiative. A swallet is a stream to sink feature, meaning there is a contribution area that concentrates runoff into identifiable streams that disappear underground at a specific point through a sinkhole. The streams may be either intermittent or continuously flowing. Data collected includes: GPS points from a Trimble ProXR and TSC-1 Data Logger; length and width of pools and basins using a range finder; pool depths, if possible, using a hand-held sonar depth finder; color, clarity and visibility of the water in the pool using a secchi disk; photos were taken and written assessments were made of the geology, topography, vegetation, and notations of anything within a 150-meter radius. This dataset represents swallet locations that were within the scope of the Florida Springs Initiative / Florida Swallet Survey project. As such, not all Florida swallets are included in this dataset, and it is by no means comprehensive.