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The USGS Nansemond pipe extensometer.

By Virginia and West Virginia Water Science Center
The USGS Nansemond pipe extensometer.
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Detailed Description

The USGS Nansemond pipe extensometer (59D 39) showing the triangular table in green and the instrument bridge in yellow above the extensometer. The piers that support the table extend down 65 feet. The movement of the table relative to the extensometer is how land-surface movement is measured.

Sources/Usage

Public Domain.

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Close up photo of the nansemond extensometer, showing the counter-weight, fulcrum arm, and pressure gauge.

The Virginia Extensometer Network

Borehole extensometers are instruments that monitor land subsidence caused by aquifer compaction. They provide precise, high-resolution measurements of changes in aquifer-system thickness. These changes in aquifer-system thickness contribute to vertical land motion (VLM) across the Virginia Coastal Plain, and are driven primarily by groundwater level decline due to human water usage. The Virginia...
By
Chesapeake Bay Activities, Virginia and West Virginia Water Science Center
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The Virginia Extensometer Network

Borehole extensometers are instruments that monitor land subsidence caused by aquifer compaction. They provide precise, high-resolution measurements of changes in aquifer-system thickness. These changes in aquifer-system thickness contribute to vertical land motion (VLM) across the Virginia Coastal Plain, and are driven primarily by groundwater level decline due to human water usage. The Virginia...
Learn More
link
Five methods of monitoring subsidence and sea level rise: extensometers, InSAR, wells, GPS surveying, and tidal stations.

Land Subsidence on the Virginia Coastal Plain

Land subsidence is a loss of ground elevation, often experienced as the ground slowly sinking over the course of years. In eastern Virginia, high rates of groundwater use is a major factor in the land subsidence affecting the area. The Virginia-West Virginia Water Science Center, with the help of our partners, has been monitoring land subsidence in the Virginia Coastal Plain since 1979 using a...
By
Virginia and West Virginia Water Science Center
link

Land Subsidence on the Virginia Coastal Plain

Land subsidence is a loss of ground elevation, often experienced as the ground slowly sinking over the course of years. In eastern Virginia, high rates of groundwater use is a major factor in the land subsidence affecting the area. The Virginia-West Virginia Water Science Center, with the help of our partners, has been monitoring land subsidence in the Virginia Coastal Plain since 1979 using a...
Learn More

Nansemond Extensometer

Inside the Nansemond extensometer shed. Above the extensometer sits the green and yellow instrument table.
Nansemond Borehole Extensometer
Nansemond Borehole Extensometer
Close up photo of the nansemond extensometer, showing the counter-weight, fulcrum arm, and pressure gauge.
The USGS Nansemond Extensometer
The USGS Nansemond Extensometer
Virginia Extensometer Drilling Site
Virginia Extensometer Drilling Site
Virginia Extensometer Drilling Site
The USGS Nansemond drilling site.
USGS Nansemond drilling site.
USGS Nansemond drilling site.
The USGS Nansemond research station.
The USGS Nansemond research station.
The USGS Nansemond research station.
The USGS Nansemond pipe extensometer with a total depth of 1,960 feet.
The USGS Nansemond pipe extensometer
The USGS Nansemond pipe extensometer
The USGS Nansemond pipe extensometer.
The USGS Nansemond pipe extensometer.
The USGS Nansemond pipe extensometer.
The USGS Nansemond research station.
The USGS Nansemond research station
The USGS Nansemond research station
An analog dial gage (left) and a digital linear potentiometer (right with blue barrel).
Analog dial gage (left) and a digital linear potentiometer (right)
Analog dial gage (left) and a digital linear potentiometer (right)
Pivot block where the USGS Nansemond extensometer connects to the fulcrum arm.
USGS Nansemond extensometer Pivot Block.
USGS Nansemond extensometer Pivot Block.
Installing the linear potentiometer on the USGS Nansemond extensometer.
Installing the linear potentiometer on the USGS Nansemond extensometer
Installing the linear potentiometer on the USGS Nansemond extensometer
Connecting drill stem to the top head drive on the USGS Research Drilling program’s rig.
Connecting drill stem to the top head drive on the USGS Research Rig
Connecting drill stem to the top head drive on the USGS Research Rig

USGS Extensometer Drilling in Virginia

Along the Atlantic Coast, a 2000+ ft deep hole has been drilled by the USGS to assess the issues of groundwater pumping, relative sea-level rise, and land subsidence. This video shows the drilling of the first extensometer to measure land subsidence in the North Atlantic Coastal Plain in 30+ years. Land subsidence has been observed at various locations in the southern Chesapeake Bay region at...

By
Water Resources Mission Area, Virginia and West Virginia Water Science Center, Communications and Publishing

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