NPDP Dam Dictionary

Browse by Letter:
All  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  


Term AKA Definition
Cairn A pile of stones used as a marker.
Caisson A box or chamber used in construction work under water.
Camber The extra height added to the crest of embankment dams to ensure that the freeboard will not be diminished by foundation settlement or embankment consolidation. The amount of camber is different for each dam and is dependent on the amount of foundation settlement and embankment expected to occur.
Canal A channel, usually open, that conveys water by gravity to farms, municipalities, etc.
Canal headworks The beginning of a canal.
Canal prism The shape of the canal as seen in cross section.
Capacity The load for which a generator is rated. The maximum load that a machine, station, or system can carry under existing service conditions. Equivalent terms: peak capability, peak generation, firm peak load, carrying capability. In transmission, the maximum load a transmission line is capable of carrying. See excess capacity and peaking capacity.
Catchment basin Unit watershed; an area from which all the drainage water passes into one stream or other body of water.
Cavitation The formation of partial vacuums in fast-flowing water caused by subatmospheric pressures immediately downstream from an obstruction or offset. Usually accompanied by noise and vibration.
Cavitation damage Damage caused when partial vacuums formed in a liquid by a swiftly moving solid body (e.g. a propeller) pit and wear away solid surfaces (e.g. metal or concrete). The attack on surfaces caused by the implosion of bubbles of water vapor.
Cellular gravity dam See hollow gravity dam.
Certified water right A State-issued document that serves as legal evidence that an approved application has been physically developed and the water put to beneficial use. The certificate establishes: priority date, type of beneficial use, and the maximum amount of water that can be used. Verification must be provided to the State through a survey conducted by an approved water-rights examiner. Even certified rights are subject to occasional review to ensure continued beneficial use.
Channel Natural or artificial watercourse of perceptible extent, with a definite bed and banks to confine and conduct continuously or periodically flowing water.
Check dam A small dam designed to retard the flow of water and sediment in a channel, used especially to control soil erosion.
Check structure A structure used to regulate the upstream water surface and control the downstream flow in a canal.
Check valve Any device which will allow fluid or air to pass through it in only one direction.
Chute Portion of spillway between the gate or crest structure and the terminal structure, where open- channel flow conditions will exist. A conduit for conveying free-flowing materials at high velocity to lower elevations.
Cipolletti weir A contracted weir of trapezoidal shape in which the sides of the notch are given a slope of 1 horizontal to 4 vertical
Clay The fine-grained portion of soil that can be made to exhibit plasticity (putty-like properties) within a range of water contents and that exhibits considerable strength when air-dry. Plastic soil which passes a No. 200 United States Standard sieve.
Climatic year Continuous 12- month period during which a complete climactic cycle occurs
Coarse gravel protection Gravel generally placed in a layer upon a finished surface to protect the finished surface from deterioration or erosion.
Coating The protective material applied to the outer surface of metalwork
Cobble Cobblestone A rock fragment, usually rounded or semirounded, with an average dimension between 3 to 12 inches; will pass a 12-inch screen, but not a 3-inch screen.
Cofferdam A temporary structure enclosing all or part of the construction area so that construction can proceed in the dry. A diversion cofferdam diverts a river into a pipe, channel or tunnel. See dam.
Cohesion The mutual attraction of soil particles due to molecular and capillary forces in the presence of water. Cohesion is high in clay (especially dry) but of little significance in silt or sand.
Cohesionless materials Cohesionless soil Soil materials that when unconfined have little or no strength when air-dried and that have little or no cohesion when submerged. Soil that has little tendency to stick together whether wet or dry, such as sands and gravels.
Cohesive soil Predominantly clay and silt soil, fine- grained particles, that sticks together whether wet or dry. A soil that when unconfined has considerable strength when air-dried, and that has significant cohesion when submerged.
Cold joint An unplanned joint resulting when a concrete surface hardens before the next batch is placed against it. Fresh concrete placed on harden concrete.
Collar The open end of a drill hole.
Collaring Starting a drill hole. When the hole is deep enough to hold the bit from slipping out of it, it is said to be collared.