RESULTS OF FIELD OBSERVATIONS OF ENGINEERING DRAINAGE EFFICIENCY

Relevance of research. Engineering drainage is an important element of the system of territory protection against the harmful water effects, which enables to carry out agro-industrial production, ensure safety for population, prevents floods and salinization development etc. Considerable restoration of irrigation and drainage, which is planned to be carried out in the southern regions, requires more research in the experimental and production areas. The results of field studies will be widely used in the design of drainage, justification of its schemes, types and parameters. Purpose of research is to study the results of field observations of engineering drainage on the irrigated agriculture area for their further use in design. Research methodology and objects. On-site drainage studies were conducted in the pilot production areas (PPAs), which are located on agricultural lands both on major irrigation systems and in settlements. The studies cover the period from 1990 to 2019. The areas with horizontal and vertical drainage were selected for the study. Results of the study and main conclusions. Based on the results of the research, it was determined the conditions of the drainage systems functioning, the genesis and the causes of flood development, the mechanism of groundwater depth and the dynamics of ground water table fluctuations in the drainage areas and adjacent territories. It was established the efficiency of drainage in difficult natural and water management conditions on the main irrigation systems and in a number of settlements. It was found that in the conditions of low drained and drainless relief, closed horizontal drainage systems with the laying of the collector drains to a depth of 7.5 m and gravity drainage operated with the highest efficiency. Such drainage systems provided groundwater stabilization at depths of 3-4 m or more due to the operation of deep-laying collectors without the involvement of less deep field drains. The excavation revealed that high efficiency of horizontal drainage was facilitated by the use of geotextile drainage filters, which avoided critical siltation and penetration of root systems into the pipe cavity. The efficiency of vertical drainage was dependent on the mode of its operation and the technical condition of water wells and pumping power equipment. Vertical drainage requires the implementation of additional measures to protect the areas against flooding – laying of horizontal drainage, development of the collector network, use of water wells for collecting surface and drainage water.