More than 80 percent of known land subsidence in the U.S. is a consequence of groundwater use, and is an often overlooked environmental consequence of our land and water-use practices. Increasing land development threatens to exacerbate existing land-subsidence problems and initiate new ones. Subsidence detection and mapping done by the USGS is needed to understand and manage our current and future land and water resources in areas where subsidence is a problem or may be in the future.
BACKGROUND
Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to removal or displacement of subsurface earth materials. The principal causes include:
- aquifer-system compaction associated with groundwater withdrawals
- drainage of organic soils
- underground mining
- natural compaction or collapse, such as with sinkholes or thawing permafrost
Subsidence is a global problem, and in the United States more than 17,000 square miles in 45 States have been directly affected by subsidence1.
ROLE OF SCIENCE
The occurrence of land subsidence is seldom as obvious as it is in the case of catastrophic sinkholes or mine collapses. Where groundwater depletion is involved, subsidence is typically gradual and widespread. The detection of regional-scale subsidence has historically occurred with the identified movement of key benchmarks. Gazing out over the San Joaquin Valley, California, today one would be hard-pressed to recognize that some of the land surface was nearly 30 feet higher fewer than 75 years ago.
The tool of choice used to detect and map land-surface deformation is known as interferometric synthetic aperture radar (InSAR). InSAR uses repeat-pass radar images from Earth-orbiting satellites to monitor subsidence and uplift at incredible detail. Once subsidence is identified and mapped, assessments of the InSAR data can be done to improve our understanding of the subsidence processes. A combination of scientific understanding and careful natural-resource management can minimize the subsidence that results from developing our land and water resources.
RELATED USGS RESEARCH
- How much does sinkhole damage cost each year in the United States?
- Land Subsidence: Cause & Effect
- Water Science School - Land Subsidence
ADDITIONAL RESOURCES
Examples of research USGS does concerning land subsidence, sinkholes, and related science.
Simulating Land Subsidence
Using Numerical Models to Simulate Subsidence
Sinkholes
Is a sinkhole related to land subsidence? How? Learn more with some of our most frequently asked questions.
What is the difference between a sinkhole and land subsidence?
Sinkholes are just one of many forms of ground collapse, or subsidence. Land subsidence is a gradual settling or sudden sinking of the Earth’s surface owing to subsurface movement of earth materials. The principal causes of land subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, and thawing permafrost. Land...
How many sinkholes open up in a year?
There is no database of sinkhole collapses for the United States, so these data are unavailable. Some individual state geologic surveys track reported collapses within their state. Many sinkhole collapses are not reported to authorities or news organizations, and many occur in rural areas where they are unobserved. Learn more: USGS Water Science School - Sinkholes
What is a sinkhole?
A sinkhole is a depression in the ground that has no natural external surface drainage. Basically, this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes are most common in what geologists call, “karst terrain.” These are regions where the types of rock below the land surface can naturally be dissolved by groundwater...
- Overview
More than 80 percent of known land subsidence in the U.S. is a consequence of groundwater use, and is an often overlooked environmental consequence of our land and water-use practices. Increasing land development threatens to exacerbate existing land-subsidence problems and initiate new ones. Subsidence detection and mapping done by the USGS is needed to understand and manage our current and future land and water resources in areas where subsidence is a problem or may be in the future.
Sources/Usage: Public Domain.Approximate point of maximum subsidence in the San Joaquin Valley, California. The land surface subsided roughly 9 meters from 1925 to 1977 due to aquifer-system groundwater withdrawals. Signs on the telephone pole indicate the former elevations of the land surface in 1925 and 1955. (Credit: Richard Ireland) BACKGROUND
Land subsidence is a gradual settling or sudden sinking of the Earth's surface due to removal or displacement of subsurface earth materials. The principal causes include:
- aquifer-system compaction associated with groundwater withdrawals
- drainage of organic soils
- underground mining
- natural compaction or collapse, such as with sinkholes or thawing permafrost
Subsidence is a global problem, and in the United States more than 17,000 square miles in 45 States have been directly affected by subsidence1.
ROLE OF SCIENCE
The occurrence of land subsidence is seldom as obvious as it is in the case of catastrophic sinkholes or mine collapses. Where groundwater depletion is involved, subsidence is typically gradual and widespread. The detection of regional-scale subsidence has historically occurred with the identified movement of key benchmarks. Gazing out over the San Joaquin Valley, California, today one would be hard-pressed to recognize that some of the land surface was nearly 30 feet higher fewer than 75 years ago.
The tool of choice used to detect and map land-surface deformation is known as interferometric synthetic aperture radar (InSAR). InSAR uses repeat-pass radar images from Earth-orbiting satellites to monitor subsidence and uplift at incredible detail. Once subsidence is identified and mapped, assessments of the InSAR data can be done to improve our understanding of the subsidence processes. A combination of scientific understanding and careful natural-resource management can minimize the subsidence that results from developing our land and water resources.
RELATED USGS RESEARCH
- How much does sinkhole damage cost each year in the United States?
- Land Subsidence: Cause & Effect
- Water Science School - Land Subsidence
ADDITIONAL RESOURCES
- Science
Examples of research USGS does concerning land subsidence, sinkholes, and related science.
Simulating Land Subsidence
The California Water Science Center has been involved in multiple studies simulating land subsidence associated with groundwater withdrawal. The simulations can be used to estimate the magnitude, location, and timing of subsidence. They can also be used to evaluate management strategies to mitigate adverse effects from subsidence while also optimizing water availability.Using Numerical Models to Simulate Subsidence
The California Water Science Center has been involved in multiple studies simulating land subsidence associated with groundwater withdrawal. The simulations can be used to estimate the magnitude, location, and timing of subsidence. They can also be used to evaluate management strategies to mitigate adverse effects from subsidence while also optimizing water availability.Sinkholes
It is a frightening thought to imagine the ground below your feet or house suddenly collapsing and forming a big hole in the ground. Sinkholes rarely happen, but when they strike, tragedy can occur. Sinkholes happen when the ground below the land surface cannot support the land surface. They happen for many reasons; read on to educate yourself about sinkholes. - Multimedia
- Publications
- News
- FAQ
Is a sinkhole related to land subsidence? How? Learn more with some of our most frequently asked questions.
What is the difference between a sinkhole and land subsidence?
Sinkholes are just one of many forms of ground collapse, or subsidence. Land subsidence is a gradual settling or sudden sinking of the Earth’s surface owing to subsurface movement of earth materials. The principal causes of land subsidence are aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, and thawing permafrost. Land...
How many sinkholes open up in a year?
There is no database of sinkhole collapses for the United States, so these data are unavailable. Some individual state geologic surveys track reported collapses within their state. Many sinkhole collapses are not reported to authorities or news organizations, and many occur in rural areas where they are unobserved. Learn more: USGS Water Science School - Sinkholes
What is a sinkhole?
A sinkhole is a depression in the ground that has no natural external surface drainage. Basically, this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes are most common in what geologists call, “karst terrain.” These are regions where the types of rock below the land surface can naturally be dissolved by groundwater...