Afluente (Tributary)

Watercourse flowing into a larger watercourse or into a lake.

Agua subterránea (Groundwater)

Subsurface water occupying the saturated zone.

Aguas negras (Sewage)

Water supply from a community after it has been fouled by various uses. It may be a combination of the liquid or water-carried domestic, municipal and industrial wastes, together with such groundwater, surface water and storm water as may be present.

Aguas residuales (Waste water)

Water containing waste, i.e. liquid or solid matter discharged as useless from a manufacturing process.

Alerta de avenida (Flood warning)

Advance notice that a flood may occur in the near future at a certain station or in a certain river basin.

Alerta hidrológica (Hydrological advisory)

Information on an expected hydrological phenomenon which is considered to be dangerous. (TR)

Almacenamiento (Storage)

(1) Impounding of water in surface or underground reservoirs, for future use. (2) Volume of water stored.

Año hidrológico (Hydrological year)

Continuous 12-month period selected in such a way that overall changes in storage are minimal so that carryover is reduced to a minimum.

Aportación anual (Annual flow)

Total volume of water that flows during a year, usually referring to the outflow of a drainage area or river basin.

Aridez (Aridity)

(1) Condition in which evaporation always exceeds precipitation. (2) Characteristic of a climate relating to insufficiency or inadequacy of precipitation to maintain vegetation.

Avenida (LT) (Flood)

(1) Rise, usually brief, in the water level in a stream to a peak from which the water level recedes at a slower rate. (2) Relatively high flow as measured by stage height or discharge. (3) Rising tide.

Avenida de diseño de aliviadero (Spillway design flood)

(1) Flood used for the design of a dam spillway. (GHP) (2) Maximum flood flow that could be passed without damage or serious threat to the stability of engineering structures. (GHP)

Balance energético (Energy balance)

Equation for estimating the evaporation from open water bodies, or the evapotranspiration from land surfaces, in which the increase in energy stored in the body of water is the residual between the incoming energies (solar radia- tion, long-wave atmospheric radiation, net advected energy into the body of water) and the outgoing energies (reflected solar and long-wave radiations emitted by the body of water, energy of evaporation, energy conducted from the body of water as sensible heat, and energy advected by the evaporated water) . (GHP)

Balance hídrico (Water balance)

Inventory of water based on the principle that during a certain time interval, the total water gain to a given catchment area or body of water must equal the total water loss plus the net change in storage in the catchment or body of water. (TR)

Banco de arena (Shoal)

(1) Submerged bar of sand, resulting from natural deposition on a river bed. (2) Part of the area covered by water (sea or lake or river) where the depth is small.

Banco de nieve (Snow patch)

Isolated area of snow, lying above or below the regional snow-line, which may last throughout the summer.

Barranco (Gully)

Channel deeply eroded by water which flows only due to storm-water runoff and/or during the melting of snow.

Barrera de hielo (Ice jam)

Accumulation of ice at a given location which, in a river, restricts the flow of water.

Biomasa (Biomass)

Total mass of living material in a given body of water. (ISO/6107)

Bombeo (Pumping)

The act or process of pumping or the action of a pump.

Calidad del agua (Water quality)

Physical, chemical, biological and organoleptic properties of water.

Cambio climático (Climatic change)

Significant change observed in the climate of a region between two reference periods.

Cañada (Coulee)

Commonly, in the northern plains of the western United States, any gully, dry wash, or intermittent stream valley of considerable size.

Canal (Canal)

Man-made open channel, usually of regular cross- sectional shape.

Cañón (Canyon)

Deep valley with high, steep slopes, often with a river flowing along its bottom.

Capacidad (Capacity)

(1) Maximum volume that can be contained by a reservoir. (2) Maximum rate of flow that can be carried by any conveying structure.

Captura (Capture)

Collecting spring water into pipes or canals.

Cascada (Cascade)

Small waterfall or one of a series of small falls.

Catarata (Waterfall)

Vertical fall or the very steep descent of a stream of water.

Caudal (Discharge)

Volume of water flowing through a river (or channel) cross-section in unit time. (TR)

Caudalímetro (Flowmeter)

Instrument for measuring the rate of flow in a conduit or open channel.

Ciclo del agua (Water cycle)

Succession of stages through which water passes from the atmosphere to the earth and returns to the atmosphere: evaporation from the land or sea or inland water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.

Ciclón tropical (Tropical cyclone)

Cyclone of tropical origin of small diameter (some hundreds of kilometres) with minimum surface pressure in some cases less than 900 hPa, very violent winds, and torrential rain sometimes accompanied by thunder-storms.

Colmatación (Clogging)

Deposition of fine particles such as clay or silt at the surface and in the pores of a permeable porous medium, e.g. soil, resulting in a reduction of permeability.

Congelación (Freeze-up)

Formation of ice cover on a water surface due to seasonal cooling.

Conservación de recursos hídricos (Water conservation)

Measures introduced to reduce the amount of water used for any purpose, and/or to protect it from pollution.

Consumo de agua (Consumptine use)

Quantity of surface and groundwater absorbed by crops and transpired or used directly in the building of plant tissue, together with that evaporated from the cropped area, expressed in units of volume per unit area. Also includes all activities where the use of water results in a loss of the original water supplied, such as industrial or community consumption.

Contaminación (Pollution)

Introduction into water of any undesirable substance not normally present in water, e.g. micro-organisms, chemicals, waste or sewage, which renders the water unfit for its intended use.

Corriente de agua (Stream)

(1) Body of water, generally flowing in a natural surface channel. (2) Water flowing in an open or closed conduit, a jet of water issuing from an orifice, or a body of flowing groundwater.

Cuenca (Basin)

Drainage area of a stream, river or lake.

Decantación (Subsidence)

(1) Settling of sediment carried in the flow of a stream. (2) Lowering in elevation of a considerable area of land surface, due to the removal of liquid or solid underlying material or removal of soluble material by means of water.

Decrecida (Reccesion)

Period of decreasing discharge as indicated by the falling limb of a hydrograph starting from the peak.

Depósito regulador (Forebay)

Small reservoir or pond located at the head of a penstock or a pipeline. It may be used to store water in relatively small quantities to take care of variations in the demand for water which occur over short periods of time, usually not exceeding several hours.

Depuración (Purification)

Tratamiento del aguaTreatment of water (or sewage) to change harmful or undesirable physical properties and remove harmful and undesirable chemical substances and living organisms. (o aguas residuales) para modificar las propiedades físicas así como eliminar sustancias químicas y organismos vivos, dañinos o no deseables.

Desagüe (Drainage)

Removing of water from the soil or from an enclosure.

Desbordamiento (Overflow)

Excess water which spills over the ordinary limits of a surface water or groundwater reservoir.

Desembalse (Drawoff)

Water withdrawn from a surface reservoir.

Desembocadura (Outfall)

(1) Lowest point on the boundary of a drainage system. (2) Point where waste water or drainage is discharged.

Deshielo (Thaw)

Melting of snow and ice at the earth's surface, following a temperature rise above 0°C.

Desplazamiento de hielo (Ice run)

Movement of ice or slush ice with the current of a stream.

Detritos (Detritus)

(1) In a biological context: organic particulate matter. (ISO/6107) (2) In the context of sewage treatment practice: coarse debris denser than water but capable of being transported in moving water. (ISO/6107)

Drenaje (Drainage)

Removal of surface water or groundwater from a given area by gravity or by pumping.

Dureza (del agua) (Hardness of water)

That property of water, due mainly to bicarbonates, chlorides and sulphates of calcium and magnesium, which prevents the production of abundant lather with soap.

Ecosistema (Ecosystem)

System in which, by the interaction between the different organisms present and their environment, there is a cyclic interchange of materials and energy. (ISO/6107)

Embalse (Reservoir)

Body of water, either natural or man-made, used for storage, regulation and control of water resources.

Erosión (Erosion)

Wearing away and transport of the soil by running water, glaciers, wind or waves.

Escarcha (Hoarfrost)

Deposit of ice crystals, generally assuming the form of scales, needles, feathers or fans and which forms on objects whose surface is sufficiently cooled, generally by nocturnal radiation, to bring about the sublimation of the water vapour contained in the ambient air.

Estación de bombeo (Pumping station)

Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another.

Estación de tratamiento de agua potable (Drinking Water Treatment Plant)

También conocida como estación potabilizadora de agua (EPA), al conjunto de estructuras en las que se trata el agua de manera que se vuelva apta para el consumo humano.

Estación depuradora de agua residual (Waste Water Treatment Plant)

También llamada planta de depuración o planta de tratamiento de aguas residuales (PTAR), tiene el objetivo genérico de conseguir, a partir de aguas negras o mezcladas y mediante diferentes procedimientos físicos, químicos y biotecnológicos, un agua efluente de mejores características de calidad y cantidad, tomando como base ciertos parámetros normalizados.

Estación hidrométrica (Hydrometric station)

Station at which data on water in rivers, lakes or reservoirs are obtained on one or more of the following elements: stage, streamflow, sediment transport and deposition, water temperature and other physical properties of water, characteristics of ice cover and chemical properties of water. (TR)

Estratificación (Stratification)

The existence or formation of distinct layers in a body of water identified by differences in thermal or salinity characteristics or by oxygen or nutrient content.

Estuario (Estuary)

That generally broad portion of a stream near its outlet.

Eutrofización (Eutrophication)

Enrichment of water by nutrients, especially compounds of nitrogen and phosphorus, that will accelerate the growth of algae and higher forms of plant life. (ISO/6107)

Evaporación (de agua) (Evaporation of water)

(1) Emission of water vapour by a free surface at a temperature below the boiling point. (2) Amount of water evaporated.

Explotación de recursos hídricos (Water management)

Planned development, distribution and use of water resources.

Filtración (Filtration)

Process of passing a liquid through a filtering medium for the removal of suspended or colloidal matter.

Fosa séptica (Disposal well)

Well used for the disposal of polluted or drainage water, brines, etc.

Fuente (Source)

(1) Origin of river. (2) In fluid dynamics, point (or line) where stream lines diverge.

Fusión de nieve (Snow melt)

1) Transformación de nieve en agua líquida. 2) Agua procedente de la fusión de la nieve.

Géiser (Geyser)

Intermittent thermal spring throwing up a column of hot water.

Gestión de cuencas (Watershed management)

Controlled use of drainage basins in accordance with predetermined objectives.

Glaciar (Glacier)

Accumulation of ice of atmospheric origin generally moving slowly on land over a long period.

Glaciar de valle (Valley glacier)

Glacier which flows down a valley.

Granizo (Hail)

Precipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 mm, sometimes more, falling either separately or agglomerated into irregular lumps.

Helada (Frost)

Covering of ice, in one of its many forms, produced by the sublimation of water vapour on objects colder than 0°C.

Hidráulica (Hydraulics)

Branch of fluid mechanics dealing with the flow of water (or other liquids) in conduits and open channels.

Hidrogeología (Geohydrology)

That branch of hydrology which deals with groundwater, taking into account the geological conditions.

Hidrología (Hydrology)

(1) Science that deals with the waters above and below the land surfaces of the Earth, their occurrence, circulation and distribution, both in time and space, their biological, chemical and physical properties, their reaction with their environment, including their relation to living beings.

Hidrometeorología (Hydrometeorology)

Study of the atmospheric and land phases of the hydrological cycle, with emphasis on the interrelationships involved. (GHP)

Hidrometría (Hydrometry)

Science of the measurement and analysis of water including methods, techniques and instrumentation used in hydrology.

Hidrosfera (Hydrosphere)

That part of the Earth covered by water and ice.

Hielo (Ice)

Solid form of water.

Humedad absoluta (Absolute humidity)

Mass of water contained in a unit volume of moist air.

Iceberg (Iceberg)

Large mass of floating or stranded ice, more than 5 m above sea-level, which has broken away either from a glacier or from an ice-shelf formation.

Impermeable (Impermeable)

Having a texture that does not permit water to move through it perceptibly under static pressure ordinarily found in subsurface water. (IGH)

Intensidad de precipitación (Precipitation intensity)

Amount of precipitation collected in unit time interval.

Inundación (Flooding)

(1) Overflowing by water of the normal confines of a stream or other body of water, or accumulation of water by drainage over areas which are not normally submerged. (2) Controlled spreading of water for irrigation, etc.

Inundación por escorrentía local (Drainage flood)

Flood which results from rainwater ponding at or near the point where it falls because it is falling faster than the drainage system (natural or man-made) can carry it away. (TR)

Inversión (Turnover)

(1) Action of turning over of a water body, e.g. a lake, whether or not stratified, due to a change in ambient temperature and/or wind action. (2) Volume of water involved in the renewal of the total storage of a reservoir or aquifer.

Inyección de agua (Water bleeding)

Water forced through a crack in an ice cover.

Isobata (Isobath)

Contour line (or surface) of equal depth of the water table below the ground surface.

Isograma (Isogram)

On a diagram or chart, the line of equal value of a hydrological or meteorological element.

Isohipsa freática (Water table isohypse)

Line connecting all points on a water table which have the same elevation above a given datum.

Isolínea (Contour -line)

Line on a map indicating the locus of points at which a certain property is constant (e.g. elevation, salinity) .

Lago (Lake)

Inland body of water of considerable size.

Lecho del río (River bed)

Lowest part of a river valley shaped by the flow of water and along which most of the sediment and runoff moves in interflood periods.

Limo (Silt)

(1) Inorganic granular finer soil materials, classified according to soil texture and soil separates classification, e.g. 0.02 to 0.002 mm in diameter according to the International Society of Soil Science, or 0.05 to 0.005 mm in diameter according to the US Bureau of Soils. (2) Unconsolidated sediment, belonging to the finest fraction, most of the particles of which are smaller than sand and larger than clay particles.

Llovizna (Drizzle)

Fairly uniform precipitation composed exclusively of fine drops of water (less than 0.5 mm diameter) very close to one another.

Lluvia (Rain)

Precipitation of liquid water, either in the form of drops of more than 0.5 mm diameter, or of smaller, widely scattered drops.

Malecón (Floodwall)

Wall built to confine a stream to prevent flooding.

Manantial (Spring)

Place where water flows naturally from a rock or soil onto land or into a body of surface water.

Manto de nieve (Snow pack)

Field of naturally packed snow that ordinarily melts slowly and yields water during the early summer months.

Marea (Tide)

Periodic rise and fall of water in the seas or in large lakes due to the gravitational attraction of the Moon and the Sun. (TR)

Masa de agua (Water body)

Mass of water distinct from other masses of water.

Morfología fluvial (Fluvial morphology)

Science of the formation of beds and flood plains and of forms of streams by the action of water.

Muestra de agua compuesta (Composite water sample)

Two or more samples or subsamples, mixed together in appropriate known proportions (either discretely or continuously) , from which the average result of a desired characteristic may be obtained. The proportions are usually based on time or flow measurements. (ISO/6107)

Muestreador de aguas (Water sampler)

Device used to obtain a sample of water, either discretely or continuously, for the purpose of examination of various defined characteristics. (ISO/6107)

Necesidades de agua (Water need)

Quantity of water required, over a given period, to satisfy fully a known or estimated requirement.

Nevada (Snowfall)

Depth of fresh snow deposited during a given recent period.

Neviza (Firn)

Snow which has become granular and dense under the action of various processes of melting and refreezing or sublimation and crystallization.

Nivel (Stage)

Elevation of the free-water surface of a body of water relative to a datum level.

Nivel freático (Phreatic surface)

Surface within the zone of saturation of an unconfined aquifer over which the pressure is atmospheric.

Nutriente (Nutrient)

Substance, element or compound necessary for the growth and development of plants and animals.

Obras hidráulicas (Hydraulic structures)

Technical installations by means of which measures are taken in water management for the utilization of water resources and protective measures taken against harmful effects of water.

Observación hidrológica (Hydrological observation)

Direct measurement or evaluation of one or more hydrological elements, such as stage, discharge, water temperature, etc. (TR) "

Onda (Wave)

Disturbance in a body of water propagated at a constant or varying speed (celerity) , often of an oscillatory nature, accompanied by the alternate rise and fall of surface fluid particles.

Ósmosis (Osmosis)

Passage of a solvent from a dilute solution to a more concentrated one through a semi-permeable membrane, i.e. one which is permeable only to the solvent.

Pantano (Marsh)

Lowland flooded in the rainy season, and usually watery at all times.

pH (pH)

Absolute value of the decimal logarithm of the hydrogen-ion concentration (activity) . Used as an indicator of acidity (pH < 7) or alkalinity (pH > 7) .

Pie de la interfaz (Toe of interface)

Line of intersection between the bottom of an estuary or a coastal aquifer and the freshwater/sea-water interface in it.

Piezómetro (Piezometer)

Observation well in which the water table level or the piezometric head can be measured.

Pixel (Pixel)

Abbreviation for "picture element". Smallest element on the ground distinguishable on an image acquired by remote sensing.

Playa (Beach)

Belt or zone which extends along the water line, occupied by unconsolidated material, moving sand or shore drift. The shore inland from the water line to the place where there is a marked change in material or physiographic form, or to the line of permanent vegetation.

Política hídrica (Water policy)

Collection of legislation, legal interpretations, governmental decisions, agency rules and regulations, and cultural responses which guide a country's actions concerning the quantity and quality of water.

Polución (Pollution)

Addition of pollutant to water.

Pozo (Well)

Shaft or hole sunk, dug or drilled into the earth to extract water.

Precipitation (Precipitation)

(1) Liquid or solid products of the condensation of water vapour falling from clouds or deposited from air on the ground. (2) Amount of precipitation (as defined under (1) ) on a unit of horizontal surface per unit time.

Presa (Dam)

Water-retaining earthwork used to confine streamflow within a specified area along the stream or to prevent flooding due to waves or tides.

Previsión de abastecimiento (Water supply forecast)

Statement of the expected volume of available water, with associated time distribution and probability whenever feasible, for a specified period and for a specified area. (TR)

Qanat (Kanat)

Subsurface gallery for water supply starting from below the water table and sloping downwards to the ground surface with a gradient flatter than both the water table and the ground surface.

Recarga de un acuífero (Groundwater recharge)

Process by which water is added from outside to the zone of saturation of an aquifer, either directly into a formation, or indirectly by way of another formation.

Recesión de aguas subterráneas (Groundwater recession)

Decreasing rate of groundwater discharge to surface water bodies during periods of no recharge, connected to the depletion of ground water storage, and expressed by groundwater recession curve. (IGH)

Recursos hídricos (Water resources)

Water available, or capable of being made available, for use in sufficient quantity and quality at a location and over a period of time appropriate for an identifiable demand.

Red de canales (Channel network)

Arrangement of natural or man-made drainage channels within an area.

Red de drenaje (Drainage parttern)

Arrangement of natural or man-made drainage channels within an area.

Régimen hidrológico (Hydrological regime)

Variations in the state and characteristics of a water body which are regularly repeated in time and space and which pass through phases, e.g. seasonal.

Región climática (Climatic region)

Region in which there is a relatively uniform climate, according to specific criteria.

Reserva de agua subterránea (Groundwater storage)

Quantity of water in the saturated zone of an aquifer. (IGH)

Residuo (Residual)

(1) If a model is fitted to data, the difference between model-computed and data values. For example, in a linear regression, the difference between an observed value and the value determined from the equation. (2) Difference between the true and observed values of a variable.(2) Difference between the true and observed values of a variable.

Riachuelo (Creek)

Natural stream of water, normally smaller than, and often tributary to, a river. (AU)

Riego (Irrigation)

Artificial application of water to lands for agricultural purposes.

Río (River)

Large stream which serves as the natural drainage channel for a drainage basin.

Rocío (Dew)

Deposit of water drops on objects at or near the ground, produced by the condensation of water vapour from the surrounding clear air.

Salinidad (Salinity)

Measure of the concentration of dissolved salts, mainly sodium chloride, in saline water and sea water.

Salinización del suelo (Soil salinization)

Detrimental process through which the concentration of soluble salts in a soil can increase as water is removed from the soil by evaporation and transpiration.

Salmuera (Brine)

Very concentrated salt solution (conventionally above 100 000 mg/l) often produced by evaporation or freezing of sea water.

Sedimentation (Sedimentation)

Process of settling and depositing by gravity of suspended matter in water.

Sequía (Drought)

Prolonged absence or marked deficiency of precipitation.

Sifón (Siphon)

Closed conduit, a portion of which lies above the hydraulic grade line. This results in a pressure less than atmospheric in that portion and hence requires that a partial vacuum be created to start flow. A siphon utilizes atmospheric pressure to effect or increase the flow of water it carries. It may occur naturally in karstic regions.

Sifonamiento (Boil)

Upward flow of water in a sandy formation due to an unbalanced water pressure resulting from a rise in a nearby stream, or from removing the overburden in making excavations.

Sistema de abastecimiento de agua (Water supply system)

All storage reservoirs, pumps, pipes and works required for providing water of a desired quantity and quality to the different sectors of consumption.

Sistema de explotación de recursos hídricos (Water resources management system)

Group of water engineering structures and related water bodies serving one or more purposes and managed as a unified whole.

Sobreexplotación (Overdraft)

Amount of water withdrawn from a water resources system in excess of the optimal yield.

Sobreexplotación de aguas subterráneas (Groundwater overexploitation)

Withdrawal from a groundwater reservoir in excess of the average rate of replenishment.

Sumidero (Sink)

In fluid dynamics, point (or line) where stream lines converge.

Termosmosis (Thermo-osmosis)

Flow through porous media caused by differences of temperature.

Tifón (Typhoon)

Cyclone of tropical origin of small diameter (some hundreds of kilometres) with minimum surface pressure in some cases less than 900 hPa, very violent winds, and torrential rain sometimes accompanied by thunder-storms.

Tormenta (Storm)

(1) Wind with a speed between 23 and 26 m/s. (2) Heavy fall of rain, snow or hail, whether accompanied by wind or not, associated with a separable meteoro- logical event.

Transpiración (Transpiration)

Process by which water from vegetation is transferred into the atmosphere in the form of vapour.

Turbidez (Turbidity)

Condition of a liquid due to fine, visible material in suspension, which impedes the passage of light through the liquid.

Umbral (Sill)

(1) Low structure built under water in order to adjust the depth of a river. (2) Invert of a gate or weir opening. (3) Low structure built across the inlet of a diversion channel or at an outlet, to reduce or prevent the flow until the water stage reaches the crest of the structure.

Vertedero (Weir)

Overflow structure which may be used for controlling upstream water level or for measuring discharge or for both. (TR)

Vertido (Spill)

Flow from a reservoir over or through a spillway.

Vía de agua (Waterway)

(1) Navigable width of a river, channel, lake, etc. (2) Width of opening for the passage of water, e.g. between piers.

Vida útil de un embalse (Reservoir life expectancy)

Period of time a reservoir can be expected to be economically usable determined by reduced capacity due to sedimentation processes.

Viscosidad (Viscosity)

Property of a fluid to resist shearing in the presence of velocity gradients. It is usually expressed as a coefficient. (TR)

Vórtice (Whirlpool)

Large eddy or vortex in a water body.

Zanja (Ditch)

Man-made small open channel constructed through earth or rock for the purpose of conveying water.

Zona árida (Arid zone)

(1) Zone in which precipitation is lacking to the extent that irrigation must be practised to support cultivation. (2) Zone in which average evaporation exceeds precipitation.

Zona de aireación (Zone of aeration)

That portion of the lithosphere in which the interstices are filled partly with air and partly with water.

Zona eufótica (Euphotic zone)

Upper layer of a water body where light penetration is sufficient to support effective photosynthesis. (ISO/6107)

Zona húmeda (Humid zone)

Zone in which precipitation exceeds potential evaporation.

Zona saturada (Saturated zone)

Part of the water-bearing material in which all voids, large and small, are filled with water. (IGH)

Zona semiárida (Semi-arid zone)

(1) Zone in which in some years precipitation is insufficient to maintain cultivation. (2) Zone in which evaporation frequently exceeds precipitation.

Zonalidad de los fenómenos hidrológicos (Zonality of hydrological phenomenal)

Changes of hydrological characteristics mainly with altitude, latitude and local conditions.