Terms of Hydrology (E)

earthquake flood :

Flood in coastal areas, caused by sea waves after a submarine ear ...

ebb :

Falling tide.

echo sounder :

Instrument using the reflection of an acoustic signal from the bo ...

economic yield (of aquifer) :

Maximum rate at which water can be artificially withdrawn from an ...

ecosystem :

System in which, by the interaction between the different organis ...

Eddy :

Rotational movement occurring in flowing fluid.

eddy-correlation method :

Method of estimating evaporation by measuring short-period fluctu ...

effective permeability :

Permeability of a porous medium to a fluid which only partly fill ...

effective porosity :

Amount of interconnected pore space available for fluid transmiss ...

effective rainfall :

(1) That part of rainfall which contributes to runoff. In some pr ...

effective velocity :

Volume of water per unit time passing through a unit area of the ...

effective well radius :

Horizontal distance from the axis of a well to the outside of the ...

Effluent :

(1) Liquid flowing out of a container or other system. (2) Water ...

effluent seepage :

Diffused discharge of groundwater to the ground surface or to a r ...

electric analogue model; electric analog model (A) :

Analogue model based on the similarity between the flow of electr ...

electrical conductivity of water :

Ability of water to conduct an electrical current, expressed as t ...

electrolyte :

Substance which dissociates into two or more ions when dissolved ...

electro-osmosis :

Flow through porous media caused by differences of electric poten ...

emergency spillway :

Auxiliary spillway used in the event of floods exceeding the capa ...

empirical flood formula :

Formula expressing peak discharge as a function of catchment area ...

endorheic :

Draining into interior basins.

endorheic lake :

Lake without surface or subsurface outflow where the inflow water ...

energy balance :

Equation for estimating the evaporation from open water bodies, o ...

energy gradient :

Decrease or loss of total head along a conduit (or channel) per u ...

engineering hydrology :

That branch of applied hydrology which deals with hydrological in ...

Entrainment :

Process of picking up and carrying away of the material produced ...

enveloping curve :

Smooth curve which represents the boundary within which all or mo ...

environmental tracer :

Tracer which is found in the natural environment.

ephemeral lake :

Lake becoming dry during the dry season or in particularly dry ye ...

epilimnion :

Water above the thermocline in a stratified body of water. (ISO/6 ...

Epper effect :

Effect in which the wave crest produced by a current meter and it ...

equilibrium drawdown :

Drawdown of the water table, or of the piezometric surface near a ...

equilibrium line of glacier :

Line or zone on a glacier where a year's ablation balances a year ...

equipotential line (or surface) :

Line (or surface) along which the potential is constant.

erosion :

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

error :

(1) In the general sense: an avoidable mistake, e.g. copying erro ...

estavel :

Underground stream in a karstic region.

estuary :

That generally broad portion of a stream near its outlet.

Euphotic zone :

Upper layer of a water body where light penetration is sufficient ...

eutrophic lake :

Lake characterized by a great amount of nutrients and biogenic ma ...

Eutrophication :

Enrichment of water by nutrients, especially compounds of nitroge ...

evaporation (of water) :

(1) Emission of water vapour by a free surface at a temperature b ...

evaporation opportunity :

Ratio of the actual rate of evaporation from land and water surfa ...

evaporation pan :

Evaporimeter composed of a fairly deep tank or pan with a rather ...

evaporation rate :

Quantity of water which is evaporated from a given water surface ...

evaporimeter :

Instrument for measuring the amount of water evaporated into the ...

Evapotranspiration :

Quantity of water transferred from the soil to the atmosphere by ...

evapotranspirometer :

Instrument used for measuring evapotranspiration.

exorheic :

Draining into the ocean.

expected value :

Best approximation of the true value which may be the mean of sev ...

experimental basin :

Basin in which natural conditions are deliberately modified and i ...

exsurgence :

Spring or seep in karstic terrain not clearly connected with a si ...

extreme value distribution :

Probability distribution of the largest (smallest) observation in ...

extreme value series :

Hydrological series which includes the largest or smallest values ...