The objective of the research is to test operation efficiency of siphon-vacuum drainage in working conditions, to solve intensification problems of drainage at vacuumizing. The research object is experimental-pilot section of vacuum drainage of siphon action in the Mugan-Salyan massif (Azerbaijan Republic) characterizing by the absence of slope. The description of proposed design of drainage systems and the principles of their operation are given. Operation of the siphon drainage system was studied in natural conditions that is in the irrigation season of cotton grown at the entire area of experimental site. Based on natural study high efficiency of siphon-vacuum drainage was revealed. Results obtained at the experimental site have shown that drain discharge and drainage modulus closely linked with the value of actual head pressure in the middle of drain spacing. During vegetation irrigations maximal water discharge was 11.1 l/sec, and the minimal one – 2.8 l/sec. Drainage modulus is one of the main evaluation criteria of drainage network efficiency. At the experimental site drainage modulus varied from 0.14 to 0.55 l/(sec•ha). Before the drainage system operation, depth of groundwater table was 120–150 cm from the ground level. Start of pumping units for drainage system operation provided the creation of depression curves of ground water to drains; while the depth of groundwater in the middle part of drain spacing lowered to 250–280 cm. The study results have shown that the rate of groundwater level lowering increased significantly at the background of siphon drainage. This fact suggests the possibility of significant increase in the intensity of soil leaching and reducing the duration of ameliorative activities in the certain hydro-geological conditions.
Keywords: drainage, groundwater level, siphon, plunger, tray, pump, outfall drain, drainage flow.
