Water — page 2 of 31

Water terms

101. Age tank (day tank) A tank used to store a chemical solution of known concentration for feed to a chemical feeder.
102. Agglomerate An ice cover of floe formed by the freezing together of various forms of ice.
103. Aggradation Geologic process wherein streambeds, floodplains, sandbars, and the bottom of water bodies are raised in elevation by the deposition of sediment; the…
104. Aggregate 1. A clump or mass formed by gathering or collecting units. 2. A body of loosely associated cells, such as a friable callus or cell suspension. 3.
105. AGM annual geometric mean.
106. Agricultural drainage The process of directing excess water away from root zones by natural or artificial means, such as by using a system of pipes and drains placed below…
107. Agrochemical Synthetic chemicals (pesticides and fertilizers) used in agricultural production.
108. AHS Archaeological and Historical Services.
109. AIPC American Indian Program Council.
110. Air quality Measure of the health-related and visual characteristics of the air to which the general public and the environment are exposed.
111. Air release valve A valve, usually manually operated, which is used to release air from a pipe or fitting.
112. Air slaking The process of breaking up or sloughing when an indurated soil is exposed to air.
113. Air Vent A pipe designed to provide air to the outlet conduit to reduce turbulence and prevent negative pressures during release of water.
114. Air waves Air borne vibrations caused by explosions.
115. Air-space ratio Ratio of volume of water that can be drained from a saturated soil or rock under the action of force of gravity to total volume of voids.
116. Air-void ratio The ratio of the volume of airspace to the total volume of voids in a soil mass.
117. Airborne Snow Survey Program Center (NOHRSC) program that makes airborne snow water equivalent and soil moisture measurements over large areas of the country that are subject to…
118. Airborne Snow Water Equivalent Measurement Theory A theory based on the fact that natural terrestrial gamma radiation is emitted from the potassium, uranium, and thorium radioisotopes in the upper eight…
119. AIRFA American Indian Religious Freedom Act.
120. AIS automated information system
121. AISC American Institute of Steel Construction.
122. aka also known as.
123. ALB Albuquerque Projects Office (Albuquerque, NM).
124. Albedo The ratio of light reflected by a surface to the light falling on it.
125. ALC Agency Location Code - an eight (8) digit code assigned to U.S. government agencies by the Department of Treasury.
126. Alert (Automated Local Evaluation in Real Time) A flood warning system consisting of remote sensors, data transmission by radio, and a computer software package developed by the National Weather Service…
127. ALERT Flood Warning System A cooperative, community-operated flood warning system; the acronym stands for Automated Local Evaluation (in) Real Time.
128. Alert Stage The elevation, or stage, of a stream at which need-to-know officials (e.g., county sheriff, civil defense officials, bypass gate operators) are notified…
129. Alevin A young fish which has not yet absorbed its yolk sac.
130. Algae Simple plant organism (typically a single cell) commonly found in water.
131. Algae bloom A heavy growth of algae in and on a body of water as a result of high phosphate concentration from farm fertilizers and detergents.
132. Algal bloom Rapid and flourishing growth of algae. Sudden, massive growths of microscopic and macroscopic plant life, such as green or bluegreen algae, which develop…
133. Algicide Any substance or chemical specifically formulated to kill or control algae.
134. Aliquot Portion of a sample.
135. Alkali A soluble mineral salt.
136. Alkali-aggregate reaction (AAR) A deterioration of concrete by which the alkali in the cement paste in the concrete reacts chemically with the silica or carbonate present in some…
137. Alkali-carbonate reaction (ACR) Reaction of alkalis which occurs between certain argillaceous dolomitic limestones and the alkaline pore solution in the concrete and causes expansion and…
138. Alkali-silica reaction (ASR) Reaction of alkalis with aggregate with various forms of poorly crystalline reactive silica: opal, chert, flint and chalcedony and also tridymite…
139. Alkali-silicate/silica reaction (ASSR) Reaction of alkalis with strained quartz is thought to be one reactive component of aggregates causing this reaction.
140. Alkaline Having a pH of 7.0 or above. The condition of water or soil which contains a sufficient amount of alkali substances to raise the pH above 7.0.
141. Allelopathy The secretion of chemicals, such as phenolic and terpenoid compounds, by a plant's roots, which inhibit the growth or reproduction of competitor plants.
142. Allochthonous Exotic species of a given area. Also refers to deposits of material that originated elsewhere, e.g., drifted plant material on the bottom of a lake.
143. Allopatric In the context of natural populations of animals or plants, inhabiting distinct and separate areas.
144. Allowable bearing capacity The maximum pressure that can be permitted on foundation soil, giving consideration to all pertinent factors, with adequate safety against rupture of the…
145. Allowable pile bearing load The maximum load that can be permitted on a pile with adequate safety against movement of such magnitude that the structure is endangered.
146. Alluvial Formed by the action of running water; of or related to river and stream deposits.
147. Alluvial fan A fan-shaped depositional landform consisting of alluvial deposits that formed where a flowing stream slows and spreads out (depositing its load)…
148. Alluvium Deposits of clay, silt, sand, gravel, or other particulate materials that have been deposited by a stream or other body of running water in a streambed…
149. ALP Animas-La Plata Project.
150. Alternating current (AC) (AC) An electric current that reverses its direction at regularly recurring intervals.
151. Alternatives Courses of action that may meet the objectives of a proposal at varying levels of accomplishment, including the most likely future conditions without the…
152. Alum A type of immune adjuvant (a substance used to help boost the immune response to a vaccine). Also called aluminum sulfate.
153. AM area manager.
154. AMA adaptive management area.
155. Ambient Surrounding natural conditions or environment at a given place and time. Environmental or surrounding conditions.
156. Ambient Temperature The temperature of a medium, such as gas or liquid, which comes into contact with or surrounds an apparatus or building element.
157. Ambursen dam A buttress dam in which the upstream part is a relatively thin flat slab usually made of reinforced concrete.
158. AMCR alternative management control review.
159. Ammonium One form of nitrogen that is usable by plants.
160. AMP Abbreviation for adenosine monophosphate.
161. Amperage The strength of an electric current measured in amperes. The amount of electric current flow, similar to the flow of water in gallons per minute (gpm).
162. Ampere (amp) A unit of electric current or rate of flow of electrons. One volt across 1 ohm of resistance causes a current flow of 1 ampere.
163. Amperometric Based on the electric current that flows between two electrodes in a solution.
164. Amphibian A cold-blooded, smooth-skinned vertebrate of the class Amphibia, such as a frog, toad, or salamander, that characteristically hatches as an aquatic larva…
165. Amplification 1. Creation of many copies of a segment of DNA by the polymerase chain reaction. 2. Treatment (e.g.
166. AMR acquisition management review.
167. AMWUA Arizona Municipal Water Users Association.
168. Anabranch A diverging branch of a river which re-enters the main stream.
169. Anadromous Fish that live most of their adult life in saltwater but spawn in freshwater.
170. Anaerobic An environment or condition in which molecular oxygen is not available for chemical, physical or biological processes.
171. Anchor block. See thrust block.
172. Anchor Ice Submerged Frazil ice attached or anchored to the river bottom, irrespective of its formation.
173. Anchor Ice Dam An accumulation of anchor ice which acts as a dam and raises the water level.
174. Ancillary services Those services necessary to support the transmission of electric power from seller to purchaser, given the obligations of control areas and transmitting…
175. Andesite Volcanic rock (or lava), characteristically medium dark in color and containing 54 to 62 percent silica and moderate amounts of iron and magnesium…
176. Angle of external friction (angle of wall friction) Angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting between soil and…
177. Angle of internal friction (angle of shear resistance) The angle between the axis of normal stress and the tangent to the Mohr envelope at a point representing a given failure-stress condition for solid…
178. Angle of obliquity The angle between the direction of the resultant stress or force acting on a given plane and the normal to that plane.
179. Angle of repose Angle between the horizontal and the maximum slope that a particular soil or geologic material assumes through natural processes.
180. Angle of wall friction Angle between the abscissa and the tangent of the curve representing the relationship of shearing resistance to normal stress acting between soil and…
181. Angler-day The time spent fishing by one person for any part of a day.
182. Anion A negatively charged ion in an electrolyte solution, attracted to the anode under the influence of a difference in electrical potential. See cation.
183. Anisotropic mass A mass having different properties in different directions at any given point.
184. Anisotropy The difference in the property of a system with changes in direction. In this case, anisotropy refers to the difference in the temperature of the cosmic…
185. Annex (functional) An emergency operations plan element that describes the jurisdiction's plan for functioning in that component area of activity during emergencies.
186. Annual energy cost Variable costs relating to energy production in a year, usually espressed in mills per kilowatt-hour.
187. Annual failure probability The probability of the load multiplied by the probability of failure.
188. Annual Flood The maximum discharge peak during a given water year (October 1 - September 30).
189. Annual inspection (AI) Annual inspections of a dam and appurtenant facilities are conducted by the local operating office.
190. Annual load factor This factor is equal to energy generated in a year divided by the product of the peak demand for that year and the number of total hours in a year.
191. Annual operating cost This is a general term which is sometimes called annual operating expense and includes all annual operation and maintenance expense, wheeling, purchased…
192. Annual work plan Annual budget document that describes proposed work to be performed at a specific Bureau of Reclamation project, and details the amount of funds required.
193. Annualized loss of life The sum of the probability of dam failure multiplied by the annual probability of the loading and the estimated number of lives that would be lost…
194. Annular Ring-shaped.
195. Annular space A ring-shaped space located between two circular objects, such as two pipes.
196. Anode The positive pole or electrode of an electrolytic cell, vacuum tube, etc. (see also sacrificial anode).
197. Anoxic Without oxygen.
198. ANSI American National Standards Institute - a private, non-profit organization that administers and coordinates the U.S.
199. Antecedent flood A flood or series of floods assumed to occur prior to the occurrence of an inflow design flood (IDF).
200. Antecedent Precipitation Index (API) (API) An index of moisture stored within a drainage basin before a storm.