Terms of Hydrology (O)

observation well :

Well used for measuring the static head of groundwater, and specially to ob ...

off-line :

Equipment used or processing performed not under direct control of the cent ...

old snow :

Deposited snow, the transformation of which into firn is so far advanced th ...

oligosaprobic :

Description of a body of water which is characterized by the presence of on ...

oligotrophic :

Description of a body of water poor in nutrients and containing many specie ...

oligotrophic lake :

Lake deficient in plant nutrients and usually having abundant dissolved oxy ...

on-line :

Part of a computer system is on-line if it is directly under the control of ...

on-line hydrological forecasting :

The process of hydrological forecasting in which at least one of the compon ...

open channel flow :

Flowing water having its surface exposed to the atmosphere.

optimal design :

System design based on the selection or combination of all pertinent variab ...

optimal yield :

Amount of water which can be withdrawn annually from an aquifer, basin or r ...

orographic precipitation :

Precipitation caused by the ascent of moist air over orographic barriers.

oscillatory wave :

Wave in which each individual particle oscillates about a point with little ...

osmosis :

Passage of a solvent from a dilute solution to a more concentrated one thro ...

osmotic pressure :

Extra pressure which must be applied to a solution in order to prevent flow ...

Outfall :

(1) Lowest point on the boundary of a drainage system. (2) Point where wast ...

outflow :

Flow of water out of a stream, lake, reservoir, container, basin, aquifer s ...

outlet :

Opening through which water flows out or is extracted from a reservoir or s ...

outliers :

Small number of members of a sample so far separated in value from the rema ...

overdraft :

Amount of water withdrawn from a water resources system in excess of the op ...

overflow :

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

overland flow :

Flow of water over the ground before it enters a definite channel.

overturn :

Reversal of layers in thermo-stratified water bodies.

ox-bow :

Abandoned part of a former meander, left when the stream cuts a new, shorte ...

oxidation :

Chemical process which can lead to the fixation of oxygen or the loss of hy ...