Drought Glossary

acre-foot

the volume (as of irrigation water) that would cover one acre to a depth of one foot.

basal

the foundation or underlying cause.

basin

the entire tract of country drained by a river and its tributaries.

carrying capacity

the maximum number of individuals that a given environment can support without detrimental effects.

center pivot irrigation

central pivot irrigation is a form of overhead (sprinkler) irrigation consisting of several segments of pipe (usually galvanized steel or aluminium) joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. The system moves in a circular pattern and is fed with water from the pivot point at the center of the circle.

condensation

the change of water from its gaseous form (water vapor) into liquid water. Condensation generally occurs in the atmosphere when warm air rises, cools and looses its capacity to hold water vapor. As a result, excess water vapor condenses to form cloud droplets.

climate

the general or average weather conditions of a certain region, including temperature, rainfall, and wind. On Earth, climate is most affected by latitude, the tilt of the Earth's axis, the movements of the Earth's wind belts, the difference in temperatures of land and sea, and topography. Human activity, especially relating to actions relating to the depletion of the ozone layer, is also an important factor.

cubic meters per second

a unit of flow rate used for rivers. Equal to that of a cube with sides of one meter (~39.37 in) in length exchanged or moving each second. Equivalent to 25,566.497 acre feet per year

desalinization

desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other minerals from water.

drainage divide

topographic separation between neighboring watershed basins. This imaginary line determines the direction of flow to different river basins. Usually the divide between watershed basins is on a hilltop or ridge-line, but in low lying areas can be more difficult to determine.

drought

climatic condition where water loss due to evapotranspiration is greater than water inputs through precipitation.

hydrological drought

hydrological has to do with water, or hydrology the study of the movement, quality or distribution of water.

meterological

meterological events are weather events. Meterological drought is the first stage of drought when the precipitation amount is less than normal for that region.

mitigate

to reduce, lessen, or alleviate. Also used in terms of prevention of drought.

no-till farming

it is a way of growing crops from year to year without disturbing the soil through tillage.

nucleation

small particles introduced into a fluid can cause a phase transition. Nucleation particles, usually dust, often trigger cloud formation.

orographic uplifting

air masses that move over mountain ranges are forced upward which causes cooling as it rises. This cooling can cause condensation and cloud formation.

palmer drought severity index

the PDSI was developed by Wayne Palmer in the 1960s and uses temperature and rainfall information in a formula to determine dryness. It has become the semi-official drought index.

precipitation

the primary mechanism for transporting water from the atmosphere to the surface of the earth. There are several forms of precipitation, the most common of which for the United States is rain. Other forms of precipitation include; hail, snow, sleet, and freezing rain.

reservoir

a reservoir is, most broadly, a place or hollow vessel where something (usually liquid) is kept in reserve, for later use. Most often, a reservoir refers to an artificial lake, used to store water for various uses. Reservoirs are created first by building a sturdy dam, usually out of cement, earth, rock, or a mixture. Once the dam is completed, a stream is allowed to flow behind it and eventually fill it to capacity.

run-off

runoff is the movement of landwater to the oceans, chiefly in the form of rivers, lakes, and streams. Runoff consists of precipitation that neither evaporates, transpires nor penetrates the surface to become groundwater. Even the smallest streams are connected to larger rivers that carry billions of gallons of water into oceans worldwide.

salinity

salinity is the saltiness or dissolved salt content of a body of water. On land, salinity influences the kinds of plants that will grow either in a water body, or on land fed by a water resource (or by a groundwater).

snowpack

the amount of snow that falls and remains in an area in a given winter. The snowpack determines how much run-off and water will be available the following season.

spillway crest

the elevation at which a reservoir is full, when it reaches the level on its dam over which the water would begin to spill.

stakeholder

anyone who has a stake or interest in the outcome of the project, as well as anyone one who is affected by the project.

tributary

a stream that flows into a river, a larger stream, or a lake.

vulnerability

the extent to which changes could harm a system. In other words, it's the extent to which a community can be affected by the impact of a hazard such as drought.

water consumption

the complete removal of water from some type of source, like groundwater, for some use by humans. This water is not returned to the source.

water withdrawal

the removal of water from some type of source, like groundwater, for some use by humans. The water is subsequently returned some period of time later after its is used. The quality of the returned water may not be the same as when it was originally removed.

watershed

area of land where all the water that is under it or drains off of it goes into the same place.

weather

the state of the atmosphere at a specific time and place. Usually includes information about precipitation, temperature, winds and relative humidity.