Glossary/water dictionary

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farm budget analysis

Analysis of a farm’s income (including that from off-farm employment opportunities) and expenditure.^

farm irrigation efficiency

The ratio or percentage of the irrigation water consumed by crops of an irrigated farm to the water diverted from the source of supply, measured at the farm head-gate.^

farmer’s labour return

Gross farm income minus interest on average farm capital.^

financial rate of return

The ratio of the net revenue and the sum-at-charge, expressed as a percentage, attained or estimated to be attained after the development period of a project.^


An overflow of water onto lands that are used or usable by man and not normally covered by water. Floods have two essential characteristics: the inundation of land is temporary; and the land is adjacent to and inundated by overflow from a river, stream, lake or ocean.^

flood control

The use of techniques to change the physical characteristics of floods. These techniques include purpose built-in river control structures. Management of inflow of floodwater into a region, as well as its outflow, in such a manner that any flooding is either kept to a minimum (return period, extent) or occurs at a planned moment and during a planned period.^

flood control works

Engineering structures: built to protect land and property from damage by flood, e.g. levees, banks or other works along a stream; designed to confine floodwater to a particular channel or direct it along planned pathways; or a flood control reservoir.^

flood frequency analysis

The estimation of the frequency of occurrence of floods at a site. Flood frequency analysis attempts to fit a probability distribution to flood discharge data and generalise the results for use at sites with no flood data. Many techniques are in use.^

flood irrigation

All types of irrigation that make use of rising water from flood for inundating areas without major structural works, e.g. flood recession, spate irrigation and wild flooding.^

flood plain

A strip of relatively flat and normally dry land alongside a stream, river or lake that is covered by water during a flood.^

flood spreading

The flooding of gravelly or otherwise relatively pervious lands in order to recharge a groundwater basin.^

flood stage

The elevation at which overflow of the natural banks of a stream or body of water begins in the reach or area in which the elevation is measured.^

flood, 100-year

A 100-year flood does not refer to a flood that occurs once every 100 years, but to a flood level with a 1% chance of being equaled or exceeded in any given year.^


The channel of a river or stream and the parts of the floodplain adjoining the channel that are reasonably required to efficiently carry and discharge the flood water or flood flow of a river or stream.^

flowing well/spring

A well or spring that taps groundwater under pressure so that water rises without pumping. If the water rises above the surface, it is known as a flowing well.^


Water that contains less than 1,000 milligrams per litre (mg/L) of dissolved solids; generally, more than 500 mg/L of dissolved solids is undesirable for drinking and many industrial uses.^

fully automatic irrigation system

An irrigation system or network on a farm, whereby the water requirements of the plants are met automatically. It makes use of devices that measure soil moisture (e.g. tensiometer) or other indicators of irrigation need (e.g. time elapsed since rainfall), and trigger a series of operations to convey the necessary water through the network at the proper time.^

furrow irrigation

A method similar to corrugation irrigation used in permeable soils. It consists in feeding narrow furrows very close to one another with small discharges so as to wet more easily all the soil situated between two rows of crops (often orchards). Furrows parallel to the rows may be laid mechanically with a drill plough.^