Terms of Hydrology (P)

pan coefficient :

Ratio of evaporation from a large body of water to that measured ...

pancake ice :

Pieces of newly-formed ice, usually approximately circular, and w ...

parameter :

Coefficient in some hydrological model, formula or other relation ...

partial contraction :

Reduced contraction resulting from the approach walls being so cl ...

partial duration series :

Series of values of independent events, such as floods, occurring ...

partial volume :

In soils, the ratio of the volume of a phase (air, water, solid m ...

partially penetrating well :

Well in which the length of water entry is less than the thicknes ...

particle size :

Dimension which is representative of the size of an individual pa ...

passive sensing system :

Sensing system that detects or measures radiation emitted by the ...

path line :

Curve described by a moving particle of water.

Pavlovsky's approximation :

Similar to Dupuit's approximation, except that the stream lines a ...

peak discharge :

Maximum instantaneous discharge of a given hydrograph.

peak-to-mean flow ratio :

Ratio of the peak discharge of a flow hydrograph, or a unit hydro ...

Pearson distribution :

Group of probability distributions of varying skewness and other ...

pendular water :

Water film surrounding solid particles at their points of contact ...

perched groundwater :

Groundwater body, generally of moderate dimensions, supported by ...

perched stream :

Stream that is separated from the underlying groundwater by a zon ...

Percolation :

Flow of a liquid through an unsaturated porous medium, e.g. of wa ...

perennial stream :

Stream which flows continuously all through the year.

perforated casing :

Casing, installed in a well, that has slots or perforations throu ...

periphyton :

Association of aquatic organisms attached or clinging to rooted w ...

permafrost :

Layer of soil or rock in which the temperature has been continuou ...

permeability coefficient :

Used for coefficient of hydraulic conductivity but not recommende ...

permeameter :

Instrument for measuring hydraulic conductivity.

persistence :

Tendency of a hydrological process or time-series to recur or con ...

pF :

Decimal logarithm of the capillary head expressed in cm.

pH :

Absolute value of the decimal logarithm of the hydrogen-ion conce ...

phreatic cycle :

Period of rise and the succeeding period of decline of a water ta ...

phreatic water :

Groundwater occurring in the zone of saturation and having a wate ...

phreatophytes :

Water-loving plants that grow mainly along stream courses and/or ...

piezometer :

Observation well in which the water table level or the piezometri ...

piezometric head :

(1) Elevation to which water will rise in a piezometer connected ...

piezometric surface :

Surface joining points which are at an elevation equal to the pie ...

Pitot tube :

Tube one end of which is open and held facing directly into a liq ...

pixel :

Abbreviation for "picture element". Smallest element on the groun ...

plane flow :

Flow the streamlines of which are contained in parallel planes.

playa :

Lake bed found in arid or desert regions in the lowest part of an ...

point data :

Observations at a geographical site, e.g. the site of a rain gaug ...

point gauge; point gage (A) :

Adjustable water-level gauge consisting of a pointed metallic rod ...

point precipitation :

Precipitation at a particular site.

polar orbit :

Orbit which passes directly over both geographic poles of the Ear ...

polder :

A mostly low-lying area artificially protected from surrounding w ...

polje :

Large, isolated depression, generally several kilometres long, co ...

Pollutant :

A substance which impairs the suitability of water for a consider ...

pollution :

Addition of pollutant to water.

polynya :

Water area enclosed in ice, generally fast ice; this water area r ...

Pond :

Small storage reservoir or body of water.

pondage :

Short-term holding back of water in a surface storage reservoir.

ponding :

(1) Natural formation of a pond in a water course. (2) Creation o ...

ponor :

Hole or opening in the bottom or side of a depression where a sur ...

porosity :

Ratio of the volume of the interstices in a given sample of a por ...

porous medium :

Permeable medium containing connected interstices which may be co ...

potamology :

That branch of hydrology dealing with surface streams and their r ...

potential evaporation :

Quantity of water vapour which could be emitted by a surface of p ...

potential evapotranspiration :

Maximum quantity of water capable of being evaporated in a given ...

powder snow :

Dry snow surface which is composed of loose, fresh ice crystals.

precipitable water :

Amount of water, expressed as a depth or as a mass, which would b ...

precipitation :

(1) Liquid or solid products of the condensation of water vapour ...

precipitation gauge; precipitation gage (A) :

General term for any device that measures the amount of precipita ...

precipitation intensity :

Amount of precipitation collected in unit time interval.

precipitation station :

Station at which observations of precipitation only are made. (TR ...

precision :

(1) Quality associated with the degree to which repeated computat ...

pressure head :

Height of a column of static water that can be supported by the s ...

pressure ice :

General term for floating ice which has been squeezed together an ...

primary data processing :

Processing of raw observational data such as cleaning, checking, ...

principal climatological station :

Climatological station at which hourly readings are taken, or at ...

principal hydrometric station :

Hydrometric station at which one or a number of elements are obse ...

probabilistic process :

Process in which the probability of occurrence of the variables i ...

probability :

Basic statistical concept either expressing in some way a "degree ...

probability distribution :

Distribution giving the probability of a value of a variate as a ...

probability of forecast :

The chance of occurrence of a quantified assessment (in real time ...

probability paper :

Graph paper designed in such a way that the cumulative probabilit ...

probable (possible) maximum precipitation (PMP) :

Amount of precipitation that is the statistical (physical) upper ...

probable error :

Measure of sampling variability equal to 0.6745 times the standar ...

propeller-type current meter :

Current meter the rotor of which is a propeller rotating around a ...

psychrometer :

Instrument used for measuring the water-vapour content of the atm ...

puddle :

Accumulation of melt water on ice, mainly due to melting snow but ...

pulse dilution gauging :

Determination of flow characteristics (velocity or discharge) by ...

pumped storage :

(1) Arrangement whereby electric power is generated during peak l ...

pumping test :

Pumping of water from a well at one or more selected discharge ra ...

pumping water level :

Elevation at which water stands in a well when the well is being ...

Purification :

Treatment of water (or sewage) to change harmful or undesirable p ...