Terms of Hydrology (H)

hail :

Precipitation of small balls or pieces of ice (hailstones) with a diameter ...

halocline :

Layer in a stratified body of water in which the salinity gradient is at a ...

hanging dam :

Piling up of frazil under an ice cover on a river, which reduces the cross ...

hard pan :

Dense hard layer near the surface in subsoil, which obstructs penetration o ...

hard water :

Water in which relatively high amounts of minerals, mainly of calcium and m ...

hardness (of water) :

That property of water, due mainly to bicarbonates, chlorides and sulphates ...

head loss :

Decrease of total head, expressed in units of height, due to energy dissipa ...

headrace :

Channel or flume which brings water to a water wheel or turbine.

headwaters :

Streams from sources of a river.

heat balance :

Balance of the gains and losses of heat for a given system (e.g. body of wa ...

heat capacity :

Ratio of heat absorbed (or released) by a system to the corresponding tempe ...

heat-capacity method :

Method for determining soil moisture by measuring the heat capacity of soil ...

heavy water :

Water enriched in water molecules containing heavier (stable and radioactiv ...

Hele-Shaw analogue; Hele-Shaw analog (A) :

Analogue based on the similarity between two-dimen- sional plane groundwate ...

high water :

(1) Highest water level reached during a flood or a reservoir operation. (2 ...

histogram :

Univariate frequency diagram with rectangles proportional in area to the cl ...

historical data :

Hydrological and meteorological data of events which occurred in the past.

hoarfrost :

Deposit of ice crystals, generally assuming the form of scales, needles, fe ...

hodograph method :

Method for showing two-dimensional groundwater flow problems by mapping the ...

homothermy :

Situation in which the temperature of a water body does not vary with depth ...

hook gauge; hook gage (A) :

Adjustable water-level gauge, used in the accurate measurement of the eleva ...

humid zone :

Zone in which precipitation exceeds potential evaporation.

hydraulic conductivity :

Property of a saturated porous medium which determines the relationship, ca ...

hydraulic grade line :

Line joining the elevations to which water would rise in piezometric pipes ...

hydraulic gradient :

(1) In a closed conduit: the slope of the hydraulic grade line. (2) In open ...

hydraulic jump :

Sudden transition of water level in an open channel from a depth less than ...

hydraulic mean depth :

Ratio of the wetted cross-sectional area to the wetted perimeter of a strea ...

hydraulic radius model :

Model comparing flow through soils to flow through pipes of variable cross ...

hydraulic resistivity :

Reciprocal of the hydraulic conductivity.

hydraulic structures :

Technical installations by means of which measures are taken in water manag ...

hydraulics :

Branch of fluid mechanics dealing with the flow of water (or other liquids) ...

hydrodynamic dispersion :

Spreading of a solute in flow through porous media, resulting from molecula ...

hydrogen-ion concentration :

Concentration of hydrogen ions in milliequivalents per litre of solution, g ...

hydrogeochemistry :

Science which deals with the chemical composition of natural waters, its ch ...

hydrogeological boundary :

Lateral discontinuity in geological material, marking the transition from t ...

hydrogeology :

That branch of geology which deals with groundwater and especially its occu ...

hydrograph :

Graph showing the variation in time of some hydrological data such as stage ...

hydrographical degradation :

Degeneration of a hydrographical network in the flat parts of a catchment, ...

hydrographical network :

Aggregate of rivers and other permanent or temporary watercourses, and also ...

hydrography :

Science dealing with the description and measurement of open bodies of wate ...

hydrological advisory :

Information on an expected hydrological phenomenon which is considered to b ...

hydrological cycle :

Succession of stages through which water passes from the atmosphere to the ...

hydrological drought :

Period of abnormally dry weather sufficiently prolonged to give rise to a s ...

hydrological element :

Some hydrological phenomenon such as water level (stage) , discharge or pre ...

hydrological forecast :

Statement of expected hydrological conditions for a specified period and fo ...

hydrological forecasting :

Forecasting hydrological characteristics in space and time.

hydrological network :

Aggregate of hydrological stations and observing posts situated within any ...

hydrological observation :

Direct measurement or evaluation of one or more hydrological elements, such ...

hydrological observing station :

Place where hydrological observations or climatological observations for hy ...

hydrological regime :

Variations in the state and characteristics of a water body which are regul ...

hydrological station for specific purposes :

Hydrological station established for the observations of a specific element ...

hydrological warning :

Emergency information on an expected hydrological phenomenon which is consi ...

hydrological year :

Continuous 12-month period selected in such a way that overall changes in s ...

hydrology :

(1) Science that deals with the waters above and below the land surfaces of ...

hydrolysis :

Chemical reaction of water in which water as a reactant produces a bond rup ...

hydrometeor :

Liquid or solid water particles falling through or suspended in the atmosph ...

hydrometeorology :

Study of the atmospheric and land phases of the hydrological cycle, with em ...

hydrometric station :

Station at which data on water in rivers, lakes or reservoirs are obtained ...

hydrometry :

Science of the measurement and analysis of water including methods, techniq ...

hydrophyte :

Plant which normally grows in water or which requires a large amount of moi ...

Hydrosphere :

That part of the Earth covered by water and ice.

hydrostatic pressure :

(1) Isotropic pressure exerted by water at rest. (2) In soil water: (syn. n ...

hyetograph :

(1) Map or chart displaying temporal or areal distribution of precipitation ...

hygrometer :

Instrument for measuring the relative amount of moisture in the atmosphere, ...

hygroscopic coefficient :

Quantity of moisture contained in a soil in equilibrium with an atmosphere ...

hygroscopic moisture :

(1) Moisture held in the soil in the zone of aeration in equilibrium with t ...

hygroscopicity :

Capacity of a porous medium to absorb atmospheric moisture.

hypolimnion :

Water below the thermocline in a stratified body of water. It is remote fro ...

hysteresis (in stage-discharge relation) :

Variability of the stage-discharge relation at a gauging station subject to ...