Kharlamov O. Improvement of engineering systems for the protection of irrigated lands from drainless in the southern region of Ukraine

The thesis presents the scientific results of vertical and horizontal drainage on research and production sites in the conditions of runoff and low runoff slope, irrigation of agricultural lands, and homesteads of rural settlements within the North-Crimean, Kakhovka and North-Rogachik irrigation systems. The drainage functioning conditions of groundwater regime, regularities of drainless processes development, their spatial distribution, comparison of actual and calculated drainage runoff are established and the necessity of improvement of drainage systems is proved. It was established that vertical drainage with a linear scheme of wells placement protects areas from drainless during the period of stable operation, but remains virtually unable to influence the flooding of drainage depressions located in the zone of its impact during periods of heavy rainfall and snowmelt. Systematic closed horizontal drainage with collectors laying at depths up to 5.5-7.5 m and self-flowing drainage against the background of irrigation ensured the maintenance of the groundwater level at depths of 3-4 m and more and reliable protection of areas from drainless. During forced drainage, there is a decrease in the efficiency of drainage, which is caused by the unstable operation of drainage pumping stations and insufficient operation. Developed and scientifically substantiated improved designs of drainage systems based on the use of vertical and horizontal drainage of joint action, deep collectors with high water absorption capacity, and surface runoff absorbers. Proposed structures of vertical and horizontal drainage will ensure the maintenance of groundwater levels below critical depths, stabilization of the hydrogeological and reclamation situation, and reduce drainless and flooding risks of irrigated areas.