Water Intake Works

a hydraulic-engineering installation for obtaining water from a source of supply (river, lake, reservoir, and so on) for purposes of hydroelectric power engineering, water supply, or irrigation. Water intake works are intended to ensure the delivery of water into a conduit (a canal, pipeline, tunnel, and so on) in specified amounts, of the proper quality, and according to a water-consumption chart.

Intake works for hydroelectric power plants (often called water receptacles) are built mostly on rivers and are part of hydraulic power systems. They are classified in two basic types, low-pressure and bottom. Low-pressure water intake works are built on mountain rivers and draw water from ponds backed up by relatively low dams (6-10 m). In case of large fluctuations of the water level in the reservoir, bottom intake works are used. Depending on the natural conditions of the area and the overall configuration of the hydraulic power system, the intakes can be of the dam, shore, or tower type. A tower intake is a free-standing tower that is situated in the headrace; it usually has several intake openings at different heights and is connected to the shore or the crest of the dam.

Intake works for water-supply systems (water receptacles) are classified according to the type of source (river, reservoir, lake, marine, and so on). The most widespread river water intake works are of the shore, channel, floating, and scoop types. They may also be combined with first-stage pumping stations or installed separately from them. A shore water intake, which is used on relatively steep river banks, consists of a large-diameter concrete or reinforced-concrete pit, with the forward wall projecting into the river. Water enters it through apertures protected by gratings and then passes through screens that effect a preliminary mechanical cleaning of the water. Channel water intake works are usu-ally used where the river banks are low; they have intakes that extend into the channel of the river. Such intakes vary widely in design. Water is delivered from the intake by gravity-flow pipes to a shore sump, which is often combined with a first-stage pumping station. Floating water intake works are pontoons or barges on which pumps for drawing water directly from the river are installed. The water is delivered to shore by a pipeline with flexible joints that is laid on a connecting trestle. In scoop intake systems the water is first brought from the river to a pond (artificial basin), at the end of which the intake system itself is situated. The pond serves to precipitate sediments and combat floating and bottom ice.

Irrigation water intake works may or may not involve a dam. Intake works without dams consist of an artificial channel (canal) that branches off from the river at a certain angle and diverts part of the stream flow. In order to prevent the deposition of bottom sediment in the irrigation canal, the intake is situated on a concave river bank so that surface currents, which carry less sediment, are diverted into the intake works, whereas the bottom currents are deflected by pumps into the riverbed. Where the riverbed is unstable and the current flows at appreciable speeds, a diversion intake (spur) is erected in the upstream part of a damless intake system to furnish the amount of water needed. The diversion barrage is usually made of local materials (rock or brush). In cases of heavy discharge, surface and bottom intake works with dams are used as part of hydraulic-engineering complexes and are equipped with scrubbing equipment, gratings, sluices, and settling pond to hold back suspended alluvium. From the standpoint of design, dam-type intake works for purposes of irrigation are analogous to those used in hydroelectric power engineering.