| 摘要 |
An irrigation and drainage system for cultivated fields, croplands and the like for supplying and extracting water and similar liquids through a subsurface conduit network automatically responsive to the ground water table occurring above or below a predetermined subsurface reference level near the depth of the conduit network. A plurality of elongated subsurface perforated conduit lines are located throughout the field at a uniform depth below ground along one or more ground elevation contour line or lines for outflow or inflow of water through the conduit line perforations when the ground water level is respectively below and above the predetermined subsurface reference level. Distribution boxes having an adjustable weir and supply water and excess water connections are provided for the conduit lines at each elevation.
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