Water terms starting with S

303 terms

Significant hazard A downstream hazard classification for dams in which 1-6 lives are in jeopardy and appreciable economic loss (rural area with notable agriculture…
Significant Wave Height The average height of the one-third highest waves of a given wave group.
Sill 1.The lower horizontal part of a window frame or window opening; also the accessory member which extends as a weather barrier from frame to outside face…
Silt (rock flour) The fine-grained portion of soil that is nonplastic or very slightly plastic and that exhibits little or no strength when air dry.
Silting Filling with soil or mud deposited by water.
Siltstone A sedimentary rock made mostly of silt-sized grains.
Simulid Group of two-winged flying insects who live their larval stage underwater and emerge to fly about as adults.
Single-stage pump A pump that has only one impeller.
Sink Any process, activity, or mechanism which removes a greenhouse gas, an aerosol, or a precursor of a greenhouse gas or aerosol from the atmosphere.
Sinkhole A steep-sided depression formed when removal of subsurface embankment or foundation material causes overlying material to collapse into the resulting void.
Sinuosity The ratio of the length of a river's thalweg to the length of the valley proper. A measure of a river's meandering. Rivers with a sinuosity less than 1.
Siphon A pipe connecting two canals. A tube or pipe through which water flows over a high point by gravity.
Siphon Spillway A spillway with one or more siphons built at crest level. This type of spillway is sometimes used for providing automatic surface-level regulation within…
Siphon tube Relatively short, light-weight, curved tube used to convey water over ditch banks to irrigate furrows or borders.
Siphonage A partial vacuum created by the flow of liquids in pipes.
Site In archeology, any location of past human activity.
Site Specific Hydrologic Prediction System (SSHP) The WFO hydrologic forecast model for small rivers and streams that uses RFC soil moisture state variables, stage and precipitation data.
Site-Specific A term used to describe any process or enzyme which acts at a defined sequence within a DNA or RNA molecule.
Skewed Tilted images. See De-skewing.
Skimmer gate A gate at the spillway crest whose prime purpose is to control the release of debris and logs with a limited amount of water.
SKIP A non-digging bucket or tray that hoists material
Skiving To dig in thin layers.
Slab A concrete pad that sits on gravel or crushed rock, well-compacted soil either level with the ground or above the ground.
Slaking The process of breaking up or sloughing when an indurated soil is immersed in water.
Slate Fine-grained metamorphic rock formed by "baking" and recrystallizing shale or mudstone and which splits easily along flat, parallel planes.
Sleet Precipitation that consists of clear pellets of ice; sleet is formed when raindrops fall through a layer of cold air and freeze.
Slide A small landslide.
Slide gate A steel gate that upon opening or closing slides on its bearings in edge guide slots. A gate that can be opened or closed by sliding in supporting guides.
Slide Gate (Sluice Gate) A gate that can be opened or closed by sliding it in supporting guides.
slope An inclined surface usually defined by the ratio of the horizontal distance to the vertical distance, i.e. 2:1 (2 horizontal units to 1 vertical unit).
Slope Protection The protection of an embankment slope against wave action or erosion.
Slough A long, narrow stretch of water such as a small stream or feeder tributary off a lake or river.
Slug Large initial amount. A unit of mass which will undergo an acceleration of 1 foot per second squared when a force of 1 pound is applied to it.
Sluice An opening for releasing water from below the static head elevation.
Sluice gate A gate that can be opened or closed by sliding in supporting guides.
Sluiceway An opening in a diversion dam used to discharge heavy floating debris safely past the dam.
Sluicing A method of compacting soil where the soil is washed into placed with a high velocity stream of water.
Slurry Watery mixture of insoluble matter which is pumped beneath a dam to form an impervious barrier. Cement grout.
Slurry trench A narrow excavation whose sides are supported by a mud slurry filling the excavation. Sometimes used incorrectly to describe the cutoff itself.
Small power producer (SPP) Under the Public Utility Regulatory Policies Act (PURPA), a small power production facility (or small power producer) generates electricity using waste…
Small Stream Flooding Flooding of small creeks, streams, or runs.
Smolts Adolescent salmon 3 to 7 inches long.
Snow Precipitation that consists of frozen flakes formed when water vapor accumulates on ice crystals, going directly to the ice phase.
Snow Accumulation and Ablation Model A model which simulates snow pack accumulation, heat exchange at the air-snow interface, areal extent of snow cover, heat storage within the snow pack…
Snow Core A sample of either freshly fallen snow, or the combined old and new snow on the ground.
Snow Density The mass of snow per unit volume which is equal to the water content of the snow divided by its depth.
Snow Depth The combined total depth of both the old and new snow on the ground.
Snow Pillow An instrument used to measure snow water equivalents. Snow pillows typically have flat stainless steel surface areas.
Snow Stake A 1-3/4 inch square, semi-permanent stake, marked in inch increments to measure snow depth.
Snow Stick A portable rod used to measure snow depth.
SNOw TELemetry (SNOTEL) An automated network of snowpack data collection sites. The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS)…
Snow Water Equivalent The water content obtained from melting accumulated snow.
Snowboard A flat, solid, white material, such as painted plywood, approximately two feet square, which is laid on the ground, or snow surface by weather observers…
Snowmelt Flooding Flooding caused primarily by the melting of snow.
Snowpack The total snow and ice on the ground, including the new snow, the previous snow and ice which has not melted.
Social Science The branch of science that studies society and the relationships of individuals within a society.
Social value (psychological value) Concept that the existence of wilderness provides a condition that could allow an individual to achieve control over stressful conditions, thus…
Sodic soil Contains sufficient exchangeable sodium to interfere with the growth of most crop plants.
Sodicity The exchangeable-sodium content of the soil. High sodium content.
Soil Sediments or other unconsolidated accumulations of solid particles produced by the physical and chemical disintegration of rocks, and which may or may not…
Soil cement A mixture of water, cement, and natural soil, usually processed in a tumble and mixed to a specific consistency, then placed in lifts and rolled to…
Soil classification Systematic arrangement of soils into classes of one or more categories or levels of classification for a specific objective.
Soil conservation Protection of soil against physical loss by erosion and chemical deterioration by the application of management and land-use methods that safeguard the…
Soil Conservation Service The former name of a branch of the United States Department of Agriculture, renamed the Natural Resources Conservation Service (NRCS).
Soil Conservation Service (SCS) The Soil Conservation Service, now known as the NRCS (National Resources Conservation Services).
Soil Moisture Water stored in soils.
Soil subsidence The lowering of the normal level of the ground, usually due to overpumping of water from wells.
Soil-cement bedding A mixture of soil, portland cement, and water placed for pipe bedding.
Solid head buttress dam A buttress dam in which the upstream end of each buttress is enlarged to span the gap between buttresses.
Spacing In blasting, the distance between holes in a row. Apparent spacing is the spacing as outlined by the delay pattern.
Spalling (spall) The loss of surface concrete usually caused by impact, abrasion, or compression. To break off from a surface in sheets or pieces.
Spatial concentration The dry weight of sediment per unit volume of water-sediment mixture in place, or the ratio of the dry weight of sediment to the total weight of…
Spawn The location or process of monsters (or items) appearing when they are created in the world.
Spawning beds Places in which eggs of aquatic animals lodge or are placed during or after fertilization.
Special examination A field review performed on a high- or significant-hazard dam to address an identified visible dam safety deficiency or to investigate significant changes…
Special features Area containing ecological, geological, or other features of scientific, educational, scenic, or historical value.
Special populations Those individuals or groups that may be institutionalized and have needs that require special consideration in emergencies.
Species Organisms in the same genus that have similar characteristics.
Specific Gravity The ratio of the mass of a body to an equal volume of water.
Specific weight The weight per unit volume.
Specific Yield The ratio of the water which will drain freely from the material to the total volume of the aquifer formation.
Spectrum intensity The integral of the pseudo-velocity response spectrum taken over the range of significant structural vibration periods of the structure being analyzed.
Spigot The plain end of a cast-iron pipe. The spigot is inserted into the bell end of the next pipe to make a water tight joint.
Spile (forepole) A plank driven ahead of a tunnel face for roof support.
Spills Water releases that cannot be put to use for project purposes (includes floodflows).
Spillway A passage for surplus water to flow over or around a dam.
Spillway channel An open channel or conduit conveying water from the spillway inlet downstream.
Spillway chute A steeply sloping spillway channel that conveys discharges at super-critical velocities.
Spillway Crest The lowest level at which water can flow over or through a spillway.
Spinning reserves Available capacity of generating facilities synchronized to the interconnected electric system where it can be called upon for immediate use in response…
Splitter wall A wall or pier parallel to the direction of flow in a channel that separates flows released from different sources as a means of energy dissipation.
Spoil Dirt or rock which has been removed from its original location. Excavated material.
Spring The point at which the water table meets Earth's surface, causing water to flow from the ground.
Springline An imaginary horizontal reference line located at midheight, or halfway point, of a circular conduit, pipe, tunnel, or the point at which the side walls…
Sprinkler irrigation A method of irrigation in which the water is sprayed, or sprinkled, through the air to the ground surface.
stability Tendency of systems, especially ecosystems, to persist, relatively unchanged, through time; also, persistence of a component of a system.
Staff Gage A vertical staff graduated in appropriate units which is placed so that a portion of the gage is in the water at all times.
Staff gauge A graduated scale on a plank or metal plate used to indicate the height of the water in a canal.
Stage The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has…
Stage I Precipitation Processing The first level of precipitation processing, occurring within the WSR-88D computer and performed for each volume scan of the radar.