Terms of Hydrology (O)

observation well :

Well used for measuring the static head of groundwater, and speci ...

off-line :

Equipment used or processing performed not under direct control o ...

old snow :

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

oligosaprobic :

Description of a body of water which is characterized by the pres ...

oligotrophic :

Description of a body of water poor in nutrients and containing m ...

oligotrophic lake :

Lake deficient in plant nutrients and usually having abundant dis ...

on-line :

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

on-line hydrological forecasting :

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

open channel flow :

Flowing water having its surface exposed to the atmosphere.

optimal design :

System design based on the selection or combination of all pertin ...

optimal yield :

Amount of water which can be withdrawn annually from an aquifer, ...

orographic precipitation :

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

oscillatory wave :

Wave in which each individual particle oscillates about a point w ...

osmosis :

Passage of a solvent from a dilute solution to a more concentrate ...

osmotic pressure :

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

Outfall :

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

outflow :

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

outlet :

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

outliers :

Small number of members of a sample so far separated in value fro ...

overdraft :

Amount of water withdrawn from a water resources system in excess ...

overflow :

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

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 n ...

oxidation :

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