Interpretive Glossary of Water-related Terms and Expressions - T

TD: Total depth of the drilled hole.

TDS: See total dissolved solids.

tertiary recovery: See under recovery.

tectonic: Pertaining to the deformation of the earth's crust and rock formations, resulting from external forces and events.

thermogenic methane: Thermogenic methane is created by the thermal decomposition of buried organic material. It is found in rocks buried at deeper depths within the earth and is produced from oil and gas wells. The COGCC has consistently found that biogenic gas contains only methane and a very small amount of ethane, while thermogenic gas contains not just methane and ethane but also heavier hydrocarbons such as propane, butane, pentane, and hexanes. COGCC. See methane, biogenic methane and flaming water.

thief level: When crossflow occurs, it is the level in a producing water well where water from an unauthorized aquifer merges with and is withdrawn along with waters from an authorized aquifer. See crossflow (2).

thief zone: When crossflow occurs, it is a zone at lower water pressure taking or accepting the waters cross flowing from one or more other aquifers at higher pressure. See crossflow (1).

tortuosity: Related to the crookedness and meandering of a porous and permeable pathway. A measure determined by the ratio of the actual length of the porous and permeable pathway between two points to the straight line length.

total consumptive use: The amount of water, regardless of its source, used by crops during the growing season. It is the amount of water that is physically removed from the stream's system and is not available for other users on the stream. Douglas Co.

total depth: TD. The total depth of the drilled hole.

total dissolved solids: TDS. The total dissolved mineral matter in water. A general indicator to the quality of the water. Often referred to in units of parts per million, ppm (wt./wt.), but usually measured in units of mg/liter (wt./vol.). Water with TDS of more than 500 mg/liter is considered to be of marginal health quality and might contain excessive amounts of undesirable ions such as calcium, magnesium, nitrate or sulfate. That in sea water is about 35,000 ppm.

transfer: The process of moving a water right originally decreed to one ditch to another ditch by court decree. A transferred water right generally retains its priority in the stream system and may or may not retain its right to divert its entire decreed amount. Douglas Co.

transmissivity: The expression of the potential flow capability of an aquifer. Transmissivity is a property that allows direct comparison of the unique flow rate potential for each aquifer. Transmissivity is the product of hydraulic conductivity and net saturated thickness. In the detailed analysis of Darcy’s equation found under hydraulic conductivity the hydraulic conductivity is shown to be a part of Darcy’s equation. The net saturated thickness is obtainable from petrophysical well logs. See the equation form for transmissivity developed in the discussion under hydraulic conductivity. Also see flux.

transpiration: The process by which water in plants is transferred as water vapor to the atmosphere. Douglas Co.

trap: Refers to a natural reservoir where the boundaries of porosity are determined by structure, permeability, or stratigraphy. Can capture migratory oil and/or gas due to the difference in density of crude oil and/or gas from that of formation water.

treat: To filter, aerate, and/or add chemicals to improve the quality of groundwater or reclaimed water. Most often to remove undesirable ions, bacteria, and other pollutants, generally to improve the quality of used or reused water.

treated: Describes water that has been subjected to filtration, aeration and/or chemical means to improve its quality.

tributary: A tributary is generally regarded as a surface water drainage system that ultimately connects with a river system.

tributary ground water: All water from the earth’s surface, such as from meteoric precipitation, rivers, lakes, and streams, that has penetrated the soil by infiltration and percolation, and has become part of the natural stream of an aquifer. Tributary ground water exhibits communication with the atmosphere and atmospheric pressure and sometimes exposure at the ground surface; and, therefore, is a water supply renewable by natural means. See unconfined aquifer in aquifer (1).

tubing: The small diameter pipe, connected to a pump, inside the casing of a well through which water or other fluids can be pumped or forced to the surface.


Compiled and Edited by Robert C. Ransom


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