Evaluation of the effectiveness of drainage systems within the Desantne Village Council in Kiliya district of Odessa region

Relevance of research. Irrigated agriculture in the steppe regions of the southern Ukraine was naturally accompanied by negative phenomena. Among the most significant of them is  flooding on agricultural land as a result water imbalance of the active water exchange zone when using irrigation. A significant part of this water as filtration losses from the irrigation network and directly when watering land goes to the aeration zone and reaches the surface of groundwater, increasing its supply. As a result, the groundwater level increases, the amplitude of which increases depending on the depth of groundwater, the intensity of irrigation, the distance from the irrigation network, the method of irrigation and other factors. In recent years, the number of actually irrigated areas located on irrigated lands is significantly reduced and at the same time the area of "dry" drainage is increasing. Therefore, one of the most pressing problems for today is the analysis of the condition of drainage and discharge network throughout Ukraine. Thus, the purpose of the research is to study the drainage and discharge network of the south-west of Odesa region to determine the current condition and prospects for its further use. The objectives of the research include monitoring of groundwater levels for the period of 1991 - 2019, determining the condition of the drainage and discharge network within the Desantne village council in Kiliya district of Odessa region. Theoretical methods of scientific research were used: monitoring, observation, analysis, survey, evaluation, comparison, generalization. The results of the study of closed drainage systems in the Desantne village council in Kiliya district of Odessa region showed that their effectiveness is insufficient. Recently, due to the cessation of irrigation at the research and production sites, groundwater level has fallen below the drains, the drainage has stopped operating and has been in a dry condition for a long time. The groundwater level in the drainage areas was at the depths of mainly 3.5-4.3 m. 24% of the inspection wells were destroyed, and 38.6% of them had no reinforced concrete cover rings. For a long time the closed horizontal drainage has been in unsatisfactory technical condition. Main conclusions: Drainage on irrigated lands should optimize the water-salt regime of soils, while moisture and salt reserves during the growing season in the root zone should be strictly dosed and ensure high crop yields as well as suitable hydrogeological and reclamation conditions on irrigated lands and adjacent areas. Introduction of large-scale parcellation of land and the land of reclamation funds as well as paid water use should not lead to the deterioration of the technical condition of the collector-drainage network. Drainage systems, as a means of groundwater level reducing, are especially relevant in land reclamation and flood protection of rural settlements. In the southern regions of Ukraine this problem was dealt with by Bayer R., Zelenin I., Lyutaev B., Miedviediev O., Miedviedieva O., Romashchenko M., Savchuk D. and others. Most systems were built on irrigation arrays in the Soviet times, ie 30-50 or more years ago. Redistribution and parcellation of agricultural land have led to the decline of the systems and the deterioration of their efficiency. Such works allow to analyze the operation of each drainage systems and make reasonable conclusions about their further use in terms of economic and environmental feasibility.