Surface Irrigation Underground Pipelines with Movable Risers
I N surface irrigation, the quantity of labor, water, and irrigated area can be optimized by using underground pipelines to distribute the water. Such systems offer the greatest possibilities for automating the irrigation process. In orchards and vineyards, where stationary, fixed irrigation pipeline systems for furrow irrigation are successfully employed, the vertical concrete pipe sections for distribution of the water can be mounted in the row of the trees. Thus, the standpipes do not interfere with machinery operations. Obviously, permanent standpipes are not suitable for irrigation of row crops. For row crops, it is desirable that no standpipes exist in the cropland in order to allow free movement of farm machinery. Also, the irrigation pipelines must be installed deep enough below the ground surface so as not to interfere with the variety of farm operations. Since 1958, many investigations have been undertaken regarding the fixed pipeline irrigation system of academician Shazov-Sheinkin in the USSR (Sheinkin 1965). The pipelines for distributing the water are placed about 16 in. beneath the soil surface. The water flow for each furrow passes through a V -̂in. diameter hole drilled in the crown of the asbestos-cement pipe. The water flows upward through the conical scour hole as shown in Fig. 1 and discharges into the furrow, with the flow rate being less than 8 gpm, while the pipeline pressure is 20 to 24 ft of water.