Background

Sinkholes are among the main features of karst areas, and are extremely widespread in Florida, one of the sites most known for their occurrence and the likely interaction with the built-up environment. The Tampa area, in turn, shows an high frequency of events, which origin derives from different types of sinkholes.

Purpose

The high frequency in the occurrence of sinkholes at Tampa and nearby areas points out the need to investigate the interactions among these phenomena and the anthropogenic environment, with particular regard to the effects that new sinkholes, or the evolution of those already known, might have on built-up areas.

Methods

The project was based on analysis of topographic maps, to identify those landforms related to occurrence of sinkholes. Production of thematic maps in GIS environment, and the related morphometric analysis, allowed to evaluate the main elements at the origin of the phenomena. Pluviometric analyses have been carried out on selected case studies to investigate the trigger of the sinkholes.

Results

The maps showing the distribution of depression density and sinkholes were compared with data compiled from the database of sinkholes maintained by the Florida Geological Survey. Our analysis demonstrated that the distribution of new sinkhole occurrences differs from that of existing sinkholes; this indicates that there are processes acting today that are influencing karst landscape formation, different from those acting in the past.

Products

Karst geomorphology maps in sample areas of the Tampa area. Publications in international journals or congress proceedings.

Conclusions

The indications coming out from the project, and their comparison with the sinkhole databases existing in Florida, point out to the role of anthropogenic actions in the development of new sinkholes, and the need to carry out detailed geological and geophysical surveys, before any engineering work is performed, in fragile territory such as Florida.