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Appurtenances in the irrigation network

Appurtenances in the open irrigation network include water outlets, dive culverts (siphons), dead and transit headwater gates, cofferdams made of flexible fabrics, irrigation pipes, screens, irrigation boards, and spillways.

In closed irrigation network, the following appurtenances are used: hydrants; slide valves; check and pressure relief valves (water-hammer alleviators); air eliminators; pressure controllers.

Water flows from delivery ditches through water outlets to temporary irrigation ditches, rigid and flexible conduits. Water outlets can be of stationary or portable types. Stationary water outlets are built from standard designs as a rule in the form of asbestos-cement pipes with a stop valve (cap valve) and in the form of open reinforced concrete or concrete sluices (gutters) with screw hoists. They are placed on side walls of permanent canals delivery ditches (at the head of temporary irrigation ditches) for passing water at a rate from 30 to 100 l/s and over. Water from open canals can be supplied to flexible conduits by flexible mobile siphon intake, culvert conduit; and from the gutter, by means of a special water outlet.

Siphons are used for water supply from permanent canals to irrigation border strip at a discharge of up to 500 l/s, to temporary irrigation ditches at a discharge of up to 100 l/s, and from temporary irrigation ditches to irrigation furrows. Big and medium siphons are made of sheet steel, aluminum, and polyvinyl chloride; small of polyethylene, rubber resin (caoutchouc), metal. Big siphons are charged by a vacuum pump; small ones are filled with water from a canal.

Dead and transit headwater gates or cofferdams are placed to raise the water level in temporary irrigation ditches and field ditches and to send water to irrigation border strips.

Dead boards are made trapezoidal shaped from one-and-half-millimeter-thick steel sheet and are used only under complete damming of water flow.

Transit mobile headwater gates are also made from sheet steel, but they have a hole of 200 mm and more in diameter cut for passing of transit water discharge; water through this hole flows out to a canvas hose 7090 cm long which is bolted on the gate. To adjust transit discharge, the hose section can be changed by using a cord. To shut off the transit flow fully, the hose is generally laid on the top of the gate. Transit headwater gates are to be placed when water from a temporary irrigation ditch is simultaneously supplied to several field ditches.

Dead and transit cofferdams made of ameliorative fabric are used also as headwater gates for water shutoff in temporary irrigation ditches and field ditches.

In some farms, water is still supplied to irrigation border strips and furrows with no special devices. Drainage cuts-furrows are cut in the borders of temporary irrigation ditches and field ditches with a spade, through which water runs to irrigation border strips. Then the drainage cuts are washed away, water discharge to the furrow becomes unstable and the soil is moistened non-uniformly. Making and closing of these drainage cuts is rather labor-consuming, and the number of simultaneously irrigated furrows is not large. Drainage cuts in earth can be consolidated by turf, but this work is labor-consuming too.

Labour productivity and irrigation quality significantly improve, if pipes, siphons, and holed covers are used.

At border irrigation on unleveled land plots, the borders made with a spade or irrigation boards made from sheet steel 1.5 mm thick, 20 cm high and 1.6 m long with rod-iron handles, d = 810 mm, 4550 cm long, have to be piled up across irrigation border strips for flooding the entire border strip.

Appurtenances in the closed irrigation network. To release water from closed pipelines to sprinkling machines, flexible conduits and temporary irrigation ditches, hydrants of different designs are built: in the form of standpipe, well, collapsible standpipe, etc. Special devices are mounted on the standpipes for coupling of flexible hoses.