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Water glossary



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Water Glossary - T

  • Tailwater recovery system: System modification to achieve greater efficiency in agricultural irrigation by collecting runoff for reuse in irrigation.

  • Tail-water runoff: Unused irrigation water or rain water that is collected at the base or end of an irrigated system or field in a ditch or impoundment. This water may be reused again for irrigation purposes, be left to evaporate, percolate into the ground, receive treatment, and (or) be discharged to surface-water bodies.

  • Total dissolved solids (TDS): The sum or all inorganic and organic particulate material. TDS is an indicator test used for wastewater analysis and is also a measure of the mineral content of bottled water and groundwater. There is a relationship between TDS and conductivity. People monitoring water quality can measure electrical conductivity quickly in the field and estimate TDS without doing any lab tests at all. See specific conductance.

  • Temperature: The degree of hotness or coldness.

  • Tensiometer: Type of soil moisture probe used to monitor soil moisture conditions to help determine when water should by applied.

  • Tertiary treatment: Removal from wastewater of traces or organic chemicals and dissolved solids that remain after primary treatment and secondary treatment.

  • TH: Total Hardness. The sum of calcium and magnesium hardness, expressed as a calcium carbonate equivalent.

  • Thalweg: The line of maximum depth in a stream. The thalweg is the part that has the maximum velocity and causes cutbanks and channel migration.

  • Thermal gradient: Temperature difference between two areas.

  • Thermal pollution: The impairment of water quality through temperature increase; usually occurs as a result of industrial cooling water discharges.

  • Thermal pollution: An increase in air or water temperature that disturbs the climate or ecology of an area.

  • Thermocline: Fairly thin zone in a lake that separates an upper warmer zone (epilimnion) from a lower colder zone (hypolimnion).

  • Thermoelectric power: Electrical power generated by using fossil fuel (coal, oil, natural gas or biomass), geothermal, or nuclear energy.

  • Thermoelectric power water use: Water used in the process of the generation of thermoelectric power. The water may be obtained from a public supply or may be self supplied. See also public supply and self-supplied water.

  • THM: Trihalomethanes. Toxic chemical substances that consist of a methane molecule and one of the halogen elements fluorine, bromine, chlorine and iodine attached to three positions of the molecule. They usually have carcinogenic properties.

  • Threshold level: Level established as the average rate of water use.

  • Threshold pollutant: Substance that is harmful to a particular organism only above a certain concentration, or threshold level.

  • Tiered pricing: Increasing block-rate pricing.

  • Time-of-day pricing: Pricing that charges users relatively higher prices during utilities' peak use periods.

  • Titration: An analytical technique to determine how much of a substance is present in a water sample by adding another substance and measuring how much of that substance must be added to produce a reaction.

  • Toilet displacement device: Object placed in a toilet tank to reduce the amount of water used per flush; for example, weighted plastic jugs filled with water or toilet dams that hold back a reservoir of water when the toilet is flushing.

  • Total solids: All the solids in wastewater or sewage water, including suspended solids and filterable solids.

  • Toxic: Harmful to living organisms.

  • Toxic water pollutants: Compounds that are not naturally found in water at the given concentrations and that cause death, disease, or birth defects in organisms that ingest or absorb them.

  • Toxicity reduction evaluation (TRE): A study conducted to determine the source(s) of toxicity in a discharge effluent so that these sources can be controlled sufficiently to allow a discharger to comply with their permit limits.

  • Toxicity test: The means to determine the toxicity of a chemical or an effluent using living organisms. A toxicity test measures the degree of response of an exposed test organism to a specified chemical or effluent.

  • Tragedy of the Commons: The idea that no one takes responsibility for things that everybody owns.

  • Transmission lines: Pipelines that transport raw water from its source to a water treatment plant.

  • Transmissivity: Refers to the rate at which limestone allows the transmission of water. Limestone can be highly porous, but not very transmissive if the pores are not connected to each other. Technically speaking, it is the rate at which water is transmitted through a unit width of aquifer under unit hydraulic gradient. Transmissivity is directly proportional to aquifer thickness, thus it is high where the edwards is thick and low where it is thin, given the same hydraulic conductivity.

  • Transpiration: Process by which water that is absorbed by plants, usually through the roots, is evaporated into the atmosphere from the plant surface. See also evaporation and evapo-transpiration.

  • Treated (wastewater) effluent: Water that has received primary, secondary, or advanced treatment and is released from a wastewater facility after treatment.

  • Treatment plant: A structure built to treat wastewater before discharging it into the environment.

  • Tributary: A stream that contributes its water to another stream or body of water.

  • Trickling filter: A wastewater treatment unit that contains medium material with bacteria. The stream of wastewater is trickled over the medium and the bacteria break down the organic wastes. Bacteria are collected on the filter medium.

  • Troposphere: The layer of atmosphere closest to the Earth, extending seven to ten miles above the surface, containing most of the clouds and moisture.

  • TS: Total Solids. The weight of all present solids per unit volume of water. It is usually determined by evaporation. The total weight concerns both dissolved and suspended organic and inorganic matter.

  • Tsunami: A Japanese term that has been adopted to describe a large seismically generated sea wave capable of considerable destruction in certain coastal areas, especially where sub-marine earthquakes occur.

  • Tube settler: Device using bundles of tubes to let solids in water settle to the bottom for removal by sludge.

  • Turbid: Thick or opaque with matter in suspension. Rivers and lakes may become turbid after a rainfall.

  • Turbidity: Cloudiness caused by the presence of suspended solids in water; an indicator of water quality.

  • Turbulent flow: A flow that contains may rapid fluctuations.

Water glossary