UNDERGROUND IRRIGATING DRAIN PIPE LINE IN FARMING LAND WITH TILLED GROUND AND COMBINED CULVERT

摘要

PURPOSE:To widen the area of arable land by a method in which a water level- regulating open tank is provided on the downstream side of a drain pipe connected to a culvert at a water level lower than the culvert, and a water supply pipe is connected through a water pressure-regulating open tank to the upstream side. CONSTITUTION:A lower stage gate 16 in a water level-regulating open tank 5 is closed, an upper stage gate 15 is vertically adjusted to determine a water level for irrigation, and water is supplied from the water supply pipe 6. The water goes into a water pressure-regulating open tank 13, and the pressure of water being supplied is reduced in a pressure-reducing valve 14 and the irrigating water level is regulated and held under the atmospheric pressure. A drain pipe 4 is filled with the water, and the water goes from a material culvert 2 in to a bullet culvert 1, passes through cracks and large holes, and goes up to the upper part of the arable land to an adequate water level for irrigation on the ground's surface. When the water level is lowered, and the upper gate 15 is lowered, the supply of water from the pipe 6 is stopped by the valve 14. Hereupon, the water is overflowed from the gate 15 and the water level is lowered.