A sinkhole that breached a confining clay layer illustrates the interconnectivity of the aquifers. The water-level drop in the surficial aquifer system and the coincident rise in the Upper Floridan.
*Water levels were recorded at a SWFWMD Regional Observation Monitoring Program wellsite that is less than 1,000 feet from the sinkhole
(Southwest Florida Water Management District, written communication, 1998).
The flow of subsurface water through sediments and eroded carbonate rocks affects how, where, and when sinkholes develop. Thus, formation of sinkholes is sensitive to changes in hydraulic and mechanical stresses that may occur naturally or as the result of human activity. Whether the stresses are imposed over geologic time scales by changes in sea level or over the time scale of human ground-water-resources development, they are expressed as changes in ground-water levels (hydraulic heads) and the gradients of hydraulic head. The hydraulic properties of the aquifers and the extent, composition, and thickness of overburden materials control how these stresses are transmitted. The chemistry of the ground water determines where dissolution and karst development occurs. Together, these hydrogeologic factors control the type and fre-quency of sinkholes that develop in west-central Florida.
Just as the hydrogeologic framework influences the development of sinkholes, the sinkholes influence the hydrogeologic framework. Understanding of the hydrogeologic framework can lead to land and water-resources management strategies that minimize the im-pact of sinkholes.