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The dam monitoring system checks the level of the water because this creates different pressures on the dam, also in relation to the air and water temperature. All these parameters are controlled and compared with the deformation and stress applied on the structure of the dam, measured with extensimeter, pendulum, reverse pendulum, piezometer, etc.
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 ...
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.
These sensors work by sending in small electromagnetic waves into the subsurface level, and receiving information as these waves are returned. [12] Key components of studying land subsidence in the Central Valley include large and small scale monitoring, studying topography in relation to groundwater, and a multi-agency approach.
Tectonic subsidence is the sinking of the Earth's crust on a large scale, relative to crustal-scale features or the geoid. [1] The movement of crustal plates and accommodation spaces produced by faulting [2] brought about subsidence on a large scale in a variety of environments, including passive margins, aulacogens, fore-arc basins, foreland basins, intercontinental basins and pull-apart basins.
The Intergovernmental Council for the International Hydrological Programme (IHP) created a Working Group on Land Subsidence for liaison of IHP subproject 8.4, "Investigation on land subsidence due to ground-water exploitation." in April 1975. [2] This first WGLS was composed by: Mr. Joseph F. Poland, Chairman. U.S. Geological Survey, USA. (Chair)
Interferometric synthetic aperture radar, abbreviated InSAR (or deprecated IfSAR), is a radar technique used in geodesy and remote sensing.This geodetic method uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite [1] [2] [3] or aircraft.
where is the tectonically driven subsidence, is the decompacted sediment thickness, is the mean sediment density, is the average depth at which the sedimentary units were deposited, and are the densities of the water and mantle respectively, and the difference in sea-level height between the Present and the time at which the sediments were deposited.