A
piezometer is a small diameter observation well used to measure the
hydraulic headHydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...
of
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...
in
aquiferAn aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s. Similarly, it may also be a
standpipeA standpipe is a freestanding pipe fitted with a tap which is installed outdoors to dispense water in areas which do not have a running water supply to the buildings....
, tube, vibrating wire piezometer or manometer used to measure the
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
of a
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
at a specific location in a column.
Piezometers should ideally have a very short screen and filter zone, so that they can represent the hydraulic head at a point in the aquifer.
A
piezometer is a small diameter observation well used to measure the
hydraulic headHydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...
of
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...
in
aquiferAn aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
s. Similarly, it may also be a
standpipeA standpipe is a freestanding pipe fitted with a tap which is installed outdoors to dispense water in areas which do not have a running water supply to the buildings....
, tube, vibrating wire piezometer or manometer used to measure the
pressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
of a
fluidA fluid is a substance that continually deforms under an applied shear stress. All gases are fluids, but not all liquids are fluids. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
at a specific location in a column.
Piezometers should ideally have a very short screen and filter zone, so that they can represent the hydraulic head at a point in the aquifer. If the filter zone is located at a specific isolated depth, the piezometer is defined
punctual, or, if the piezometer has a filter on all its length, is defined
windowed. The windowed piezometer is cheaper than the punctual one, but cannot give information on vertical flows. The main problem with the piezometers is the time-lag between the variation of piezometric level in the aquifer and the respective variation in the piezometer. This time-lag is related to the piezometer (type, shape, etc.) and the soil. Modern piezometers with little time-lag are the piezometric cells, where the pressure on a
membraneArtificial membrane also known as synthetic membrane is a syntheticly created membrane which is usually intended for separation purposes in laboratory or in industry. Synthetic membranes have been successfully used for small and large-scale industrial processes since the middle of twentieth...
is measured by the pressure of gas (pneumatic piezometric cells), by vibrating thread extensimeters or by electrical extensimeters (
strain gaugeA strain gauge is a device used to measure the strain of an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable...
s piezometers).