Evaporite rocks underlie about 35 to 40 percent of the United States, though in many areas they are buried at great depths. Since Florida is prone to sinkholes, it is a good place to use to discuss some different types of sinkholes and the geologic and hydrologic processes that form them. The processes of dissolution, where surface rock that are soluble to weak acids, are dissolved, and suffusion, where cavities form below the land surface, are responsible for virtually all sinkholes in Florida.
Dissolution of the limestone or dolomite is most intensive where the water first contacts the rock surface. Aggressive dissolution also occurs where flow is focused in preexisting openings in the rock, such as along joints, fractures, and bedding planes, and in the zone of water-table fluctuation where groundwater is in contact with the atmosphere.
Rainfall and surface water percolate through joints in the limestone. Dissolved carbonate rock is carried away from the surface and a small depression gradually forms. On exposed carbonate surfaces, a depression may focus surface drainage, accelerating the dissolution process. Debris carried into the developing sinkhole may plug the outflow, ponding water and creating wetlands. Gently rolling hills and shallow depressions caused by solution sinkholes are common topographic features throughout much of Florida.
Cover-subsidence sinkholes tend to develop gradually where the covering sediments are permeable and contain sand. In areas where cover material is thicker, or sediments contain more clay, cover-subsidence sinkholes are relatively uncommon, are smaller, and may go undetected for long periods.
Cover-collapse sinkholes may develop abruptly over a period of hours and cause catastrophic damages. They occur where the covering sediments contain a significant amount of clay.
Over time, surface drainage, erosion, and deposition of sinkhole into a shallower bowl-shaped depression. Over time, surface drainage, erosion, and deposition of sediment transform the steep-walled sinkhole into a shallower bowl-shaped depression.
New sinkholes have been correlated to land-use practices, especially from groundwater pumping and from construction and development practices. Sinkholes can also form when natural water-drainage patterns are changed and new water-diversion systems are developed. Some sinkholes form when the land surface is changed, such as when industrial and runoff-storage ponds are created.
The substantial weight of the new material can trigger an underground collapse of supporting material, thus causing a sinkhole. The overburden sediments that cover buried cavities in the aquifer systems are delicately balanced by groundwater fluid pressure. The water below ground is actually helping to keep the surface soil in place.
Groundwater pumping for urban water supply and for irrigation can produce new sinkholes in sinkhole-prone areas. If pumping results in a lowering of groundwater levels , then underground structural failure, and thus, sinkholes, can occur. Do you think you know about groundwater?
Quiz icon made by mynamepong from www. Follow me to the Land Subsidence website! Groundwater is one of our most valuable resources—even though you probably never see it or even realize it is there. There is water somewhere beneath your feet no matter where on Earth you live. Groundwater starts as precipitation, just as surface water does, and once water penetrates the ground, it continues moving, sometimes quickly and sometimes very slowly.
Eventually groundwater emerges A huge amount of water exists in the ground below your feet, and people all over the world make great use of it. But it is only found in usable quantities in certain places underground — aquifers. More than 2, claims were reported in Florida in but that figure jumped to almost 6, claims in There is no geological explanation for the rise and state insurance officials believe many claims are questionable. There must be structural damage to a home for a policyholder to claim a loss from a sinkhole, but insurance officials say claims are often paid without that proof.
Daily 12 Today. By Mike Schneider August 13, Workers prepare to pull vehicles from a sinkhole that opened up on a residential street in the South Deering neighborhood on April 18, in Chicago, Ill. As the foam expands, it compacts the soil. Void filling : This is another sinkhole repair method. It involves filling up spaces and gaps underneath the concrete. We use a high density, lightweight material called polyurethane.
It is injected into drilled holes. It expands as a foam, covering the area in seconds. Facebook Twitter LinkedIn Pinterest. Leave A Reply Cancel reply Comment. Privacy Protected. Your information will remain confidential. Call Now. Go to Top. However, there are definite regions where sinkhole risk is considerably higher. In general, areas of the state where limestone is close to surface, or areas with deeper limestone but with a conducive configuration of water table elevation, stratigraphy, and aquifer characteristics have increased sinkhole activity.
Reports of sinkholes show up in Florida newspapers so often, they deserve their own section. But Kromhout says, despite popular perception, that there does not seem to be an increase in sinkholes across the state. Then again, Kromhout says he isn't aware of any studies that have assessed sinkhole frequency over time.
The U.
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