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a network of channels and drains constructed on marshy or excessively wet land. It is the key element of a drainage system and consists of regulating, protecting, and conducting networks with drainage outlets, manholes, overfalls, chutes, bridges, pipe crossings, and other such structures. The type of drainage network is determined by the cause of excess water and by agricultural use of the land.
The regulating network ensures the removal of excess water from the root zone of the soil, thus improving the soil’s water, gas, and heat regimes and creating conditions for the efficient operation of farm machinery and utilization of fertilizers. On marshy mineralized soils or swamps where excess water is due to precipitation and which require rapid surface drainage, the regulating network consists of permanent open and closed collectors arranged at regular intervals throughout the area. Open collectors are generally ditches and are used to drain natural grass meadows, peat bogs, afforested areas, and floodplain meadows. Closed, or subsurface, collectors are trenches with perforated, usually ceramic or plastic pipes covered by soil or by a material that filters well, such as sand or organic material such as corn cobs and straw. When excess water is due to upward seepage, the regulating network usually consists of a system of ditches and pipes; when the cause of wetness is confined ground-water, deep channels may be used in addition to ditches and pipes.
When draining peat bogs where the water source is ground-water and which have a 2–3 m layer of peat and a mineral bottom composed of nonsilted sands that filter well, the regulating network is built in the form of individual deep open channels dug into the sand or a system of such widely spaced channels.
The protective network is intended to protect an area from the influx of surface water and groundwater from the drainage basin, running water, and bodies of water. Uphill channels (at the foot of slopes) catch the runoff from higher areas; uphill-catch channels catch surface slope runoff and groundwater flow; catch channels intercept groundwaters; levees are built to protect land from streams and bodies of water.
The conducting network receives excess water from the regulating and protective networks and transports it to the nearest body of water—river, reservoir, or lake. It consists of open main channels of various orders, which are installed along the lowest places in the area being drained. When drainage is accomplished by ditches and pipes, open or closed collectors are used that empty into the main channel and occasionally into the body of water. The sides and bottom of the channel are reinforced with porous concrete tiles, sod, and brushwood, which improves operation and durability.
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S. F. AVER’IANOV