Ground Water Resources of British Columbia
Appendix 1 — Glossary of Terms
ALLUVIAL DEPOSITS — The general name for all sediments, including clay, (ALLUVIUM) silt, sand, gravel or similar unconsolidated material deposited in a sorted or semi-sorted condition by a stream or other body of running water, in a stream bed, floodplain, delta or at the base of a mountain slope as a fan.
AMBIENT GROUND WATER FLOW — The rate of flow and direction of flow of ground water under unpumped, natural conditions.
ALLUVIAL FANS — A fan shaped deposit of detrital material deposited by a stream where it emerges from a steep mountain slope or from an upland onto a less steeply sloping terrain.
ANION — A negative electricity charged ion such as a nitrate or chloride ion.
AQUIFER — An aquifer is a formation, group of formations or part of a formation containing enough saturated permeable material to produce significant amounts of water to wells and springs. (See also confined aquifers or artesian aquifers and unconfined aquifers.)
AQUIFER DEPLETION — Aquifer depletion occurs when ground water is withdrawn from an aquifer at a rate greater than it can be replenished.
AQUIFER VULNERABILITY — A measure of how vulnerable an aquifer is to contamination.
AQUIFER VULNERABILITY MAPPING — Mapping the vulnerability of an aquifer to contamination from sources. Vulnerability mapping does not consider the type of land use above an aquifer, only the intrinsic vulnerability of the aquifer, typically based on the type, thickness, and extent of geologic materials overlying an aquifer, depth to water, and type of aquifer materials.
ARTESIAN AQUIFER — See Confined Aquifer.
ARTESIAN WELL — A well obtaining its water from an artesian or confined aquifer in which the water level in the well rises above the top of the aquifer. The water level in a flowing artesian well rises above the land surface.
BASE FLOW — The sustained low flow in a stream. Generally base flow is the inflow of ground water to the stream.
BEDROCK — Rock underlying soil and other unconsolidated material.
BRECCIA — Fragments of rock, generally angular in a fine grained matrix, or a matrix of cementing material. Breccias include tectonic brecccias, clastic brecccias and volcanic breccias.
BRECCIATED ZONE — A zone converted into a breccia.
CAPTURE ZONE — The land area that contributes ground water to or recharges a pumping well.
CATION — A positive electrically charged ion such as a sodium or calcium ion.
CIRQUE — A large size amphitheatre shaped hollow which has been excavated by ice action in mountainous regions.
CLASTIC ROCK (DETRITAL ROCK) — A sedimentary rock composed of fragments of pre-existing rocks or organic structures.
COEFFICIENT OF STORAGE — See Storage Coefficient.
COLLECTOR WELL — Constructed with horizontal lengths of screened collector pipe radiating out from a central vertical well.
COLLUVIAL DEPOSITS — Weathered, unconsolidated materials transported and deposited by gravity.
CONFINED AQUIFER — Confined is synonymous with artesian. A confined aquifer or an artesian aquifer is an aquifer bounded both below and above by beds of considerably lower permeability than that existing in the aquifer itself. The ground water in a confined aquifer is under pressure that is significantly greater than that existing in the atmosphere.
CONFINING BED — A bed of impermeable material stratigraphically adjacent to one or more aquifers. Confining bed is now used to replace terms such as "aquiclude", "aquitard" and "aquifuge".
CONTAMINANT — Solute which, through human action, intrudes into the hydrologic cycle.
CONTAMINANT PLUME — Contaminants which encroach into a ground water system are moved down gradient. The area of the aquifer containing the degraded water which resulted from the migration of a pollutant is called a contaminant plume.
CONTAMINATION — Impairment of natural water quality by chemical or bacterial pollution as a result of human activities. The degree of contamination allowed before an actual hazard to public health is created will depend upon the intended end use, or uses of the water.
CRETACEOUS — The most recent geologic period in the Mesozoic Era.
DISCHARGE AREA — An area where ground water and water in the unsaturated zone is released to the ground surface, to surface water or to the atmosphere.
DRAWDOWN — The variation in the water level in a well prior to commencement of pumping compared to the water level in the well while pumping. In flowing wells drawdown can be expressed as the lowering of the pressure level due to the discharge of well water.
DRIFT (GLACIAL) — Glacial drift includes all rock material in transport by glacier ice, the deposits made by glacier ice and all materials mainly of glacial origin deposited in the sea or in glacial melt water bodies including materials rafted in by ice bergs or transported indirectly in the water itself. Glacial drift therefore includes till, rock fragments and stratified drift.
DRILLED WELL — A well that is constructed with a drilling rig, such as an air rotary or cable tool drilling rig.
DRUMLIN — Irish term for a small hill. Consists of glacial drift shaped by ice action into a "hog- back", which is oval in plan and has its long axis pointing in the direction of ice movement. Drumlins often occur in groups.
DUG WELL — A well that is dug by hand or excavated by backhoe. Dug wells are usually shallow.
ESKER — A narrow long ridge like form comprised mainly of gravel and sand. These stratified glacio-fluvial deposits were formed in a stream bed flowing inside the ice of a glacier generally at the glacier bottom. The glacio- fluvial deposits were then left in place after the ice melted.
EVAPOTRANSPIRATION — Loss of water from a land area through transpiration of plants and evaporation from the soil.
FAULT — A fracture in the earth's crust along which dislocation has taken place so that the rocks on one side of the fault have been displaced in relation to those on the other side.
FLOODPLAIN — The flat land adjacent to a river, formed by deposition of fluvial materials.
FLOWING ARTESIAN WELL — A well where the water level is above the ground surface.
FLUVIAL DEPOSITS — Deposits related to a river or stream.
FRACTURE — A break or crack in the bedrock.
FRESH WATER - SALT WATER TRANSITION ZONE — The interface zone occurring between fresh water and saltwater underlying marine islands and coastal areas with ground water occurring below the surface of the ground in geologic formations under saturated conditions.
GEOMORPHOLOGY — Geomorphology is the science dealing with the origin and evolution of land forms.
GLACIAL DRIFT — See Drift (Glacial).
GLACIO-FLUVIAL DEPOSITS — Deposits related to the joint action of glaciers and melt water streams.
GROUND WATER — Water in the zone of saturation, that is under a pressure equal to or greater than atmospheric pressure.
GROUND WATER CATCHMENT AREA — An area contributing natural replenishment (recharge) of the ground water regime. It may include localized discharge areas.
GROUND WATER DIVIDE — The uppermost boundary of a ground water basin.
GROUND WATER MINING — Permanent depletion of ground water reserves.
GROUND WATER TABLE — That surface below which rock, gravel, sand or other material is saturated. It is the surface of a body of unconfined ground water at which the pressure is atmospheric.
HANGING VALLEY — Where the valley floor of a tributary stream lies or "hangs" above the floor of the main valley. Hanging valleys may occur where the main valley has been glaciated.
HARDNESS — When hard water is used with soap it will form an insoluble residue and hard water will form a scale in utensils in which the water has been allowed to evaporate. Hardness is mainly caused by calcium and magnesium ions. Hardness is generally expressed in mg/L calcium carbonate (Ca CO3).
HETEROGENEOUS DEPOSIT — Non-uniform structure and composition throughout the deposit.
HOMOGENEOUS DEPOSIT — Structure or composition of the deposit is uniform throughout.
HYDRAULIC CONDUCTIVITY — Hydraulic conductivity is a measure of the ability of a fluid to flow through a porous medium determined by the size and shape of the pore spaces in the medium and their degree of interconnection and also by the viscosity of the fluid. Hydraulic conductivity can be expressed as the volume of fluid that will move in unit time under a unit hydraulic gradient through a unit area measured at right angles to the direction of flow.
HYDRAULIC GRADIENT — The slope of the ground water level or water table.
HYDRAULIC HEAD — The level to which water rises in a well with reference to a datum such as sea level.
HYDROGEOLOGY — Study of ground water in its geological context.
HYDROGRAPH — A graphical plot of changes in elevation of water or flow of water with respect to time.
HYDROLOGIC CYCLE — The continued circulation of water between the ocean, atmosphere and land is called the hydrologic cycle.
ICE CONTACT DEPOSITS — Drift sediment deposited in contact with its supporting ice.
IGNEOUS ROCKS — Rocks that solidified from molten or partly molten materials, that is from a magma or lava.
IMPERMEABLE — Impervious to flow of fluids.
INCRUSTATION — Mineral matter deposited by water. One of the major causes of well failure is the chemical and biological incrustation of well screen through precipitation of calcium and magnesium carbonates or sulphate's. The precipitation of iron and manganese compounds and slime producing iron bacteria will also plug well screens.
INDURATED — A compact rock hardened and solidified by post depositional chemical and physical alterations.
INFILTRATION RATE — The rate at which water permeates the pores or interstices of the ground.
INTERMONTANE VALLEY — A valley located between or surrounded by mountain ranges, mountains or mountainous regions.
ISOTROPIC — Exhibiting properties with the same values in all directions.
KETTLE — A closed depression made in drift by a mass of underlying ice melting.
LACUSTRINE DEPOSITS — Sediments laid down in a lake. Includes gravelly deposits at the margin and clay in deeper water. Sediments commonly show seasonal banding or varve clays.
LEACHATE — Fluid percolating through a land fill.
LEVEL OF GROUND WATER DEVELOPMENT — The level of ground water use of an aquifer relative to the aquifer's ability to replenish itself.
LITHOLOGY — All the physical properties, the visible characteristics of mineral composition, structure, grain size etc. which give individuality to a rock.
MARINE DEPOSITS — Mostly silt and clay materials deposited under a marine environment.
MEDIAN — Being in the middle or in an intermediate position.
MELTWATER CHANNEL — A channel shaped by water coming from the melting of snow or glacier ice.
MESOZOIC — Geologic era preceding the Cenozoic Era. The Mesozoic Era was a time when the rocks of the Triassic, Jurassic and Cretaceous Systems were deposited.
METAMORPHIC ROCKS — Any rock derived from pre-existing rocks by mineralogical, chemical, and/or structural changes, essentially in the solid state, in response to marked changes in temperature, pressure, shearing stress, and chemical environment, generally at depth in the earth's crust.
MONADNOCK — From Mount Monadnock in New Hampshire (1893). A Monadnock is an isolated hill standing conspicuously above a peneplain. (A peneplain is a land surface worn down to an area of low relief by stream erosion and mass wasting.
MORAINE — An accumulation of unsorted unstratified glacial drift mainly till, deposited by glacial ice. Drift deposited in the flanks of a valley glacier form a lateral moraine. Glacial deposits which have accumulated at the front of a glacier form a terminal moraine. Deposits of drift which have been dragged along beneath the ice form ground moraine.
OBSERVATION WELL — A well constructed for the objective of undertaking observations such as water levels, pressure readings and ground water quality.
OROGENY — The deformation of the earth's crust to form mountains.
OUTWASH DEPOSITS — Stratified drift deposited by meltwater streams flowing away from melting ice.
OVERBURDEN — The layer of fragmental and unconsolidated material including loose soil, silt, sand and gravel overlying bedrock, which has been either transported from elsewhere or formed in place.
OVERLAND RUNOFF — That part of precipitation flowing overland to surface streams.
PALAEOZOIC — Geological era preceding the Mesozoic Era. The Palaeozoic is a major division of geologic time and it includes in descending order the Permain, Carboniferous, Devonian, Silurian, Ordovician and the Cambrian.
PERCHED WATER TABLE — A separate continuous body of ground water lying (perched) above the main water table. Clay beds located within a sedimentary sequence, if of limited aerial extend, may have a shallow perched ground water body overlying them.
PERMEABILITY — The property of a porous rock, sediment or soil for transmitting a fluid, it is a test of the relative ease of fluid flow in a porous medium.
PERMEABLE — The property of a porous medium to allow the easy passage of a fluid through it.
pH — A numerical measure of the acidity or alkalinity of water ranging from 0 to 14. Neutral waters have pH near 7. Acidic waters have pH less than 7 and alkaline waters have pH greater than 7.
PHYSIOGRAPHY — Physical geography.
PIEZOMETER — Pressure reading and measuring instrument connected to a short sealed off length of a drill hole or hydrogeologic unit.
PIEZOMETRIC SURFACE — Imaginary surface defined by the elevation to which water will rise in wells penetrating confined aquifers.
PLATEAU — An elevated land surface of large areal extent where the surface is nearly level.
PLEISTOCENE — The period following the Pliocene during which an ice sheet covered the greater part of North America. Named by Lyell in 1839.
POLLUTION — Contamination of the environment with objectionable or offensive matter.
POROSITY — The volume of openings in a rock, sediment or soil. Porosity can be expressed as the ratio of the volume of openings in the medium to the total volume.
POTENTIAL WELL YIELD — An estimate of well yield generally above the existing yield rate or test rate, but considered possible on the basis of available information, data and present well performance.
PUBLIC INVOLVEMENT — The process by which the views of all parties interested in a proposed government decision are integrated into the decision-making process. It is a dynamic process that attempts to identify, record, analyze and synthesize ideas, concerns, needs and values before recommendations are given to government decision makers.
PUMPING INTERFERENCE — The condition occurring when a pumping well lowers the water level in a neighbouring well.
PUMPING TEST — A test conducted by pumping a well to determine aquifer or well characteristics.
QUATERNARY — The period of geologic time that follows the Tertiary. The Quaternary includes the Pleistocene and Recent Periods and is part of the Cenozoic Era.
RADIUS OF INFLUENCE — The radial distance from a pumping well to the point where there is no drawdown of the water table or piezometric surface. This point marks the edge of the cone of depression around the pumping well.
RECHARGE AREA (GROUND WATER) — An area where water infiltrates into the ground and joins the zone of saturation. In the recharge area, there is a downward component of hydraulic head.
SALINE GROUND WATER — Ground water consisting of or containing salt.
SALT WATER INTRUSION — Movement of salty or brackish ground water into wells and into aquifers previously occupied by fresh or less mineralized ground water either through upconing or sea water encroachment.
SANDPOINT — A well pipe with a screen, equipped with a hardened, conical point at the bottom, that is driven into the ground to tap shallow ground water.
SANDSTONE — A sedimentary rock composed of mostly sand sized particles.
SANITARY SURFACE SEALS — A grouted annular space around the well casing which usually extends from the land surface to several metres deep. The sanitary well seal functions to prevent any contaminated surface and near surface water from seeping down the side of the well to the aquifer.
SATURATED ZONE — The subsurface zone in which all voids are ideally filled with water under pressure greater than atmospheric.
SEA WATER ENCROACHMENT — The lateral landward movement of sea water into wells and freshwater aquifers.
SEDIMENTARY ROCKS — Rocks formed from consolidation of loose sediments such as clay, silt, sand, and gravel.
SHALE — A fine-grained sedimentary rock, formed by the consolidation of clay, silt, or mud. It is characterized by finely laminated structure and is sufficiently indurated so that it will not fall apart on wetting.
SPECIFIC CAPACITY — The rate of discharge of a water well per unit of drawdown. Specific capacity can be expressed as L/s/m of drawdown.
SPECIFIC CONDUCTANCE (GROUND WATER) — The ability of a water sample to conduct an electric current. Specific conductance is related to the concentration of dissolved solids in a water sample. A rapid determination of TDS of a water sample can be made by measuring the electrical conductance.
STATIC WATER LEVEL — The level of water in a well that is not being influenced by ground water withdrawals. The distance to water in a well is measured with respect to some datum, usually the top of the well casing or ground level.
STORAGE COEFFICIENT — Volume of water stored or released from a column of aquifer with unit cross section under unit change in head.
SURFICIAL DEPOSITS — Deposits overlying bedrock and consisting of soil, silt, sand, gravel and other unconsolidated materials.
SUSTAINED YIELD — Rate at which ground water can be withdrawn from an aquifer without long-term depletion of the supply.
TERTIARY — Geologic period of the Cenzoic Era and that period prior to the Quaternary.
TILL — Till consists of a generally unconsolidated, unsorted, unstratified heterogeneous mixture of clay, silt, sand, gravel and boulders of different sizes and shapes. Till is deposited directly by and underneath glacial ice without subsequent reworking by meltwater.
TOPOGRAPHY — The configuration of a surface including its relief and the position of its natural features.
TOTAL DISSOLVED SOLIDS (TDS) — Concentration of total dissolved solids (TDS) in ground water expressed in milligrams per litre (mg/L), is found by evaporating a measured volume of filtered sample to dryness and weighing this dry solid residue.
TRANSMISSIVITY — Rate at which water is transmitted through a unit width of an aquifer under a unit hydraulic gradient. Transmissivity values can be expressed as square metres per day (m2/day), or as square metres per second (m2).
TRANSPIRATION — The process by which water absorbed by plants, usually through the roots, is evaporated into the atmosphere from the plant surface.
UNCONFINED AQUIFER — An aquifer in which the water table is free to fluctuate under atmospheric pressure.
UNCONSOLIDATED DEPOSITS — Deposits overlying bedrock and consisting of soil, silt, sand, gravel and other material which have either been formed in place or have been transported in from elsewhere.
UPCONING — Upward movement of salty or brackish ground water into wells and into aquifers previously occupied by fresh or less mineralized ground water.
UNSATURATED ZONE — The zone between the land surface and the water table. The pore spaces, interstices, contain water at less than atmospheric pressure, and also air and other gases. Perched ground water bodies (local saturated zones) may exist in the unsaturated zone.
VARVE — Laminated clays and fine grained sediments of glacial origin deposited in lakes during the retreat of glacial ice. Each lamina or varve has a thicker coarser layer and a finer layer which represent a years seasonal cycle of deposition. Varve is the Swedish word for cycle.
WATER BALANCE (HYDROLOGIC BUDGET) — A record of the outflow from, inflow to, and storage in a hydrologic unit like an aquifer, drainage basin etc.
WATERSHED — A catchment area for water that is bounded by the height of land and drains to a point on a stream or body of water, a watershed can be wholly contained within another watershed.
WATER TABLE — See Ground Water Table.
WELL DEVELOPMENT — This operation helps make water enter the well more easily and can make the difference between a satisfactory and an unsatisfactory well. Different techniques for well development can be used, the aim is to remove the smaller sized particles from the aquifer surrounding the well screen and to provide a coarser filter zone around the screen. The smaller sized particles are drawn into the well screen and can then be removed by bailing or pumping.
WELLHEAD PROTECTION — Protection of the recharge (or capture zone) area of a pumping well.
WELL INTERFERENCE — When the area of influence, or the cone of depression around a water well comes into contact with or overlaps that of a neighbouring well pumping from the same aquifer and thereby causes additional drawdown or drawdown interference in the wells.
WELL POINTS — Also referred to as sand points, gravel points,are used in shallow permeable unconfined (usually) aquifers generally less than 30 feet deep. Well points consist of a short length of screened pipe with a sharp point on the bottom end. As the pipe is driven into the ground, additional lengths of pipe are added to the top end. Sand points are also available with a check valve at the lower end to enable the pipe to be washed down in sand and fine gravel aquifers. Water can be pumped down the pipe and it passes out the check valve at the bottom and washes the sand up the hole to the ground surface.
WELL SEALS — Cover for the top of the well.
WELL SCREEN — A cylindrical filter used to prevent sediment from entering a water well. There are several types of well screens, which can be ordered in various slot widths, selected on the basis of the grain size of the aquifer material where the well screen is to be located. In very fine grained aquifers, a zone of fine gravel or coarse sand may be required to act as a filter between the screen and the aquifer.
WELL YIELD — The volume of water discharged from a well in litres per minute (L/min), litres per second (L/s) or cubic metres per day (m3/day).
ZONE OF SATURATION — See Saturated Zone.
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