GB1368017A - Method and installation for irrigation - Google Patents

Abstract

1368017 Irrigation systems P NIEDERWEMMER 5 Sept 1972 41156/72 Heading A1B Water (e.g. treated sewage) is supplied by surface ducts 1, 2 to an underground irrigation system. The system comprises pipes 3 each provided. with apertures in its lower surface and supported non-horizontally by a gravel layer 11 disposed on an impermeable layer 9 connected to the ducts 1, 2 to form a trough. Openings 12, 14 permit flow of water from the ducts 1, 2 to the gravel layer 11. The fields may be drained of flood water through the irrigation system. The pipes 3 may be of circular, semi-circular or semi-elliptical crosssection. The impermeable layer 9 may be a plastics or fabric sheet, or an emulsion of asphalt, bitumen or resin sprayed onto the soil. The concrete ducts 1, 2 contain valves (56 in Fig. 14) each comprising two slotted plates which are relatively movable to control the flow of water and which aerate the water. The valves may be closed to cause water to overflow the layer 9 and wash and desalt the irrigation zone. Steps may be. provided in the ducts 1, 2 to accommodate a gradient in the ground surface which is terraced. Storage tanks are provided at 57 in Fig. 14 for natural warming of subsoil water. The water may be further aerated by aerators 57 (Fig. 14) each comprising an upright perforated cylinder in which the water falls successively between three troughs having perforated bases. Artificial fertilizers may be introduced into the cylinder through the air holes in it. Mechanically-treated sewage liquid is passed under gravity through a single or double stage aerobic filter comprising filter material such as slag, stone or coke contained in exchangeable units. Hot air is supplied under pressure to the filter. The liquid passes from the filter into a settling tank having apertures in its side through which the purified liquid passes into a surface duct 1 or 2. In Fig. 14, the access roads 49, 50 between the fields, are planted with bushes and trees, and the main supply ducts 51, 52 are connected to the secondary ducts 53, 54 (like ducts 1, 2 in Fig. 1) connected to pipes 55 (like pipes 3 in Fig. 1). The pipes 55 may contain valves. Artificial fertilizers may also be added and their concentrations measured at 58.