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Groundwater-related subsidence is the subsidence (or the sinking) of land resulting from unsustainable groundwater extraction.It is a growing problem in the developing world as cities increase in population and water use, without adequate pumping regulation and enforcement.
Ground-penetrating radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables or masonry. [1]
Subsidence frequently causes major problems in karst terrains, where dissolution of limestone by fluid flow in the subsurface creates voids (i.e., caves).If the roof of a void becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface.
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In short, it is a web and computer program that takes satellite images, aerial photography, and GIS (Geographic Information System) data and superimposes all of this on a 3D globe.
Land subsidence is a global issue and has different causes. Some are natural, like earthquakes , and some are caused by humans. In the United States, land subsidence from over pumping has affected 45 states and accounts for changes in over 17,000 square miles of land which is an area almost 10 times the size of Glacier National Park in Montana ...
Groundwater use and pumping in the area was the major water use for farmers and agriculture in the 1920s, and over time, this over-pumping resulted in land subsidence and a decline in groundwater-level resources. In time, this resulted in major land subsidence by the 1970s with local areas having 0.30 to 8.5 m (1 to 28 ft) of subsidence.
A subsidence crater is a hole or depression left on the surface of an area which has had an underground (usually nuclear) explosion. Many such craters are commonly present at bomb testing areas; one notable example is the Nevada Test Site , which was historically used for nuclear weapons testing over a period of 41 years.