Terms of Hydrology (S)

safe yield :

Amount of water (in general, the long-term average amount) which ...

Salinity :

Measure of the concentration of dissolved salts, mainly sodium ch ...

salt content :

Concentration of dissolved salts in water.

salt water :

Water in which the concentration of salts is relatively high (ove ...

saltation :

Stream transportation of sediments by intermittent leaps or bound ...

salt-water intrusion :

Phenomenon occurring when a body of salt water invades a body of ...

salt-water wedge :

Wedge of salt water caused by salt water moving under a freshwate ...

sampling distribution :

Distribution of a statistic in all possible samples which can be ...

sandbox model :

Physical model simulating a porous medium in which the flow domai ...

sanding-up :

Accumulation of sand at the bottom of a well, container, etc.

saprobic :

Associated with dead or decaying organic matter. (ISO/6107)

saturated zone :

Part of the water-bearing material in which all voids, large and ...

saturation vapour pressure; saturation vapor pressure (A) :

Maximum possible partial pressure of water vapour in the air or a ...

scanner :

Device that scans and by this means produce an image.

scanning line :

Narrow strip on the ground swept by the instantaneous field of vi ...

scour :

Erosive action - in particular, pronounced local erosion - of wat ...

S-curve :

Hydrograph that would result from an infinite series of sequentia ...

sea-water intrusion :

Penetration of sea water into a coastal aquifer.

secondary data processing :

Analysis of processed data from one single observational series o ...

secondary hydrometric station :

Hydrometric station which is established only for a limited numbe ...

sediment :

Material transported by water from the place of origin to the pla ...

sediment concentration :

Ratio of weight of dry solids to the weight of a water/sediment s ...

sediment discharge :

Discharge of sediments of a stream at a given cross section.

sediment grading :

Grading of the sediment carried by rivers according to particle s ...

sediment sampler :

Sampling device for determining the concentration of sediment loa ...

sediment yield :

Total sediment outflow from a watershed or past a given location ...

Sedimentation :

Process of settling and depositing by gravity of suspended matter ...

sedimentation diameter :

Diameter of a sphere of the same specific weight and the same ter ...

sediment-carrying capacity :

Maximum sediment quantity per unit time which can be transported ...

sedimentology :

Deals with erosion, transport and deposition of sediments as rela ...

Seepage :

(1) Slow movement of water in a porous medium. (2) Loss of water ...

seepage face :

That part of the soil surface, at a level below the free water ta ...

seepage spring :

Spring which issues from a permeable medium over a relatively lar ...

seepage velocity :

Discharge of seepage water through an unsaturated porous medium, ...

seiche :

Oscillation of the surface of a lake or similar body of water, ca ...

semi-arid zone :

(1) Zone in which in some years precipitation is insufficient to ...

semi-pervious boundary :

Boundary between a pervious and a semi-pervious layer.

sensitivity :

The relationship of the change of a response to the corresponding ...

serial correlation :

Correlation between members of a sample of a time (or space) seri ...

serial correlation coefficient :

Sample value of the parent autocorrelation coefficient. (DST)

settling :

Movement downwards of particles suspended in water.

settling velocity :

Terminal fall velocity of solid particles during their sedimentat ...

sewage :

Water supply from a community after it has been fouled by various ...

shale ice :

Mass of thin and brittle ice plates formed by breaking up of thin ...

sharp-crested weir :

Weir with sharp horizontal crest which is so shaped that the wate ...

sheet erosion :

More or less uniform removal of soil from an area by rain-drop sp ...

sheet flow :

Flow in a relatively thin sheet, of nearly uniform thickness, ove ...

shifting bed :

Stream bed, the topography of which changes with time.

shifting control :

Control in which there is a change in stage-discharge relationshi ...

shoal :

(1) Submerged bar of sand, resulting from natural deposition on a ...

shore ice :

Basic form of fast ice, representing a compact ice cover attached ...

shore-line :

Line of intersection of the sea or lake with the land. The region ...

short-term hydrological forecast :

Forecast of the future value of an element of the regime of a wat ...

shower :

Precipitation, often short-lived and heavy, falling from convecti ...

shuga :

Accumulation of spongy white ice lumps, a few centimetres across, ...

sidelooking airborne radar (SLAR) :

All weather, day/night remote sensor particularly effective in im ...

significance :

An effect is said to be significant if the hypothesis that the ef ...

sill :

(1) Low structure built under water in order to adjust the depth ...

Silt :

(1) Inorganic granular finer soil materials, classified according ...

silt content :

Ratio of weight of silt to weight of water, inclusive of silt.

silting-up :

Process of filling up or raising the bed of a watercourse or body ...

Simulation :

Reproduction or representation of an event or sequence of related ...

sink :

In fluid dynamics, point (or line) where stream lines converge.

sink hole :

Place where water disappears underground in a limestone region. I ...

siphon :

Closed conduit, a portion of which lies above the hydraulic grade ...

skewness :

Asymmetry in a frequency or probability distribution.

Skimming :

Diversion of surface layers of water from a stream or conduit by ...

sleet :

Precipitation of snow and rain together or of snow melting as it ...

slope (of water surface) :

Inclination of the water surface expressed as the difference in e ...

slope-area method :

Method of estimating discharge by application of open-channel hyd ...

Sludge :

Accumulated solids separated from various types of water as a res ...

slush :

Snow which is saturated and mixed with water, found on land or ic ...

slush ice :

Ice mass consisting of transformed frazil ice, partly as bunches ...

snow :

Precipitation of ice crystals, most of which are branched, someti ...

snow board :

Marker at least 40 cm by 40 cm which is laid on a previous accumu ...

snow course :

Line laid out and permanently marked, along which snow is sampled ...

snow cover :

Snow accumulated on the ground. (TR)

snow coverage :

Ratio of the snow covered area to the total area of a basin.

snow density :

Mass of snow pack per unit volume. The mass includes liquid water ...

snow depth :

Vertical distance between the surface of a snow layer and the gro ...

snow ice :

Ice formed by freezing of a mixture of snow and water.

snow melt :

(1) Transformation of snow into liquid water. (2) Water from melt ...

snow pack :

Field of naturally packed snow that ordinarily melts slowly and y ...

snow patch :

Isolated area of snow, lying above or below the regional snow-lin ...

snow pillow :

Device filled with antifreeze solution and fitted with a pressure ...

snow stake :

Graduated fixed stake to facilitate the measurement of snow depth ...

snow survey :

Determination of the total amount of snow covering a catchment ar ...

snow tube :

Snow-gauge composed of a cylinder, closed at one end, which is us ...

snowdrift :

(1) Mass of snow heaped up by wind and deposited along an irregul ...

snowfall :

Depth of fresh snow deposited during a given recent period.

snowflakes :

Agglomerations of snow crystals.

snow-gauge; snow gage (A) :

Apparatus designed to measure the amount of fallen snow.

snow-line :

(1) Climatic snow-line: lowest altitude of a continuous layer of ...

snow-melt flood :

Considerable flood rise in rivers occurring every spring and caus ...

snow-pack yield :

Amount of water, not retained by the snow pack, that reaches the ...

sodium absorption ratio (SAR) :

Ratio for irrigation waters, used to express the relative activit ...

soft water :

Water without significant hardness.

soil drainage :

Movement of free water contained within a soil by flowing under t ...

soil moisture :

Moisture contained in the portion of the soil which is above the ...

soil moisture content :

Percentage of water in soil, expressed on a dry-weight basis or b ...