Glossary
Agronomy The applied aspects of both soil science and the several plant sciences, often limited to applied plant sciences dealing with crops.
Alluvial Deposited by rivers in low-lying areas and flood plains.
Annuals Plants that live for one growing season.
Aquifer A layer of rock which holds and allows water to move through it, and from which water can be extracted. Confined aquifers have a layer of rock above them which are impermeable to water.
Bedrock Unweathered hard rock at the base of a soil profile.
Biophysical Relating to biological and physical processes.
Bore A hole of uniform diameter (usually 150 mm to 160 mm) drilled vertically into the ground to tap an aquifer. It contains a pipe through which groundwater can be pumped or can flow to the surface by artesian pressure (see also pressure and hydraulic pressure).
Break of slope The line across a landscape at which the surface slope is reduced and where the hydraulic conductivity of the underlying material or the hydraulic gradient decreases.
Catchment The area of land from which rainwater or snow melt drains into a reservoir, pond, lake or stream.
Colluvial (deposits) Deposits of loose material that have been carried by gravity and are usually found at the foot of slopes or cliff lines.
Deep drainage Where water drains from below the root-zone into underlying aquifer systems.
Discharge Flow of groundwater from the saturated zone to the earth surface.
Discharge area The area in which there is upward movement of groundwater and where groundwater is discharged from the soil surface. Groundwater escapes via springs, evaporation, transpiration and surface drainage (see also recharge area).
Drain A channel for the purpose of interception and removal of excess surface or sub-surface water to a stable outlet.
Ecosystem A community of organisms, interacting with each other, plus the environment in which they live and with which they also interact such as a pond or forest.
Electrical conductivity Ability of a substance to conduct electricity.
Episodic recharge Where recharge occurs as a result of a small number of intense or prolonged rainfall events, rather than steadily over a long period.
Evaporation The process of water changing from a liquid to a vapour.
Extrapolate To estimate a quantity which depends on one or more variables by extending the variable/s beyond their established ranges.
Fallowing The land management practice of leaving land without vegetative cover for a period of time before sowing another crop. Its purpose is to allow nutrients and water to accumulate in the soil.
Flowtube model A catchment-scale groundwater model.
Geology/geologic Science of learning about the earth: its origin, structures, composition, historical changes and processes.
Geomorphology Science of describing and interpreting landform patterns and processes of landscape formation.
Geophysics The science of studying the earth's physical properties such as magnetism, conductivity and density.
Groundwater All free water below the surface in the layers of the Earth's crust.
Hazard Anything that can cause harm to an asset.
Hydraulic conductivity The physical property of the aquifer which determines the rate of movement of water.
Hydraulic gradient The slope on the watertable (change in hydraulic pressure over distance in the direction of flow) which determines the rate of movement of groundwater.
Hydraulic pressure The pressure exerted by water over an area, usually causing some movement or flow of water from one area to another.
Hydrogeology The study of groundwater movement.
Hypersaline More saline than seawater.
Inundation Flooding, overflowing or deluge.
Non-market value Value placed on environmental changes which are usually not valued through market transactions. An attempt is made to estimate in dollar terms the loss suffered by the community by such changes.
Perched aquifer/watertable A watertable above the main watertable level where impermeable soil or rock prevents the water from percolating through to the main groundwater body.
Permeability The capacity of a substance (for example, soil or rock) to allow water to pass through it. Sand, for example, is said to have high permeability.
Perennial Plant that lives for several years (annuals live for only one growing season).
Pressure In confined aquifers (those under a confining layer), the groundwater is stored under pressure. When it is intercepted (e.g. by a bore), the groundwater rises under pressure to a level above the top of the aquifer.
Recharge A component of rainfall that drains below the root zone of vegetation and joins the groundwater.
Recharge area The area where water can enter and move downward to the groundwater. Recharge areas are usually permeable in the upper slopes and are often on shallow soils.
Regolith Weathered or sedimentary material that is over bedrock.
Remnant vegetation Vegetation remaining after an area has been cleared.
Risk An estimation of the expected amount of harm that will occur to an asset.
Root zone Near-surface part of a soil profile where roots are active.
Seeps/seepage Where there is permanent or seasonal appearance of water at the soil surface causing soil salinity either directly through saline water or by evaporative concentration. Non-saline seepages also occur.
Spectra/spectrum A continuous range of frequencies within which waves have some specified common characteristics (as in radio-frequency spectrum, visible spectrum).
Topography The detailed description and analysis of the features of a relatively small area, district or locality.
Transpiration The process by which water is extracted from the soil, transmitted through plants, and evaporated from the leaves.
Water balance A state of equilibrium when rainfall or irrigation water in a landscape is accounted for by the sum of run-off, plant water use, evaporation, recharge and changes in soil moisture content.
Waterlogging Waterlogging occurs when the watertable rises into the root zone. It results in anaerobic (absence of free oxygen) conditions which reduce plant growth and may kill plants.
Watertable The watertable is the upper surface of groundwater. The soil profile is fully saturated below the watertable and unsaturated above it.
Weathering Chemical, physical and biological decomposition of rocks. This can result in the formation of a soil profile.
Table of Contents for the Australian Dryland Salinity Assessment 2000
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