Assessment of the hydrogeological and ameliorative state of the Kilchen irrigation system territory

Abstract

Climatic changes, physical and moral deterioration of the main funds of land reclamation systems in Ukraine prompt a change in conceptual approaches and reform of the water management system for efficient use of irrigated lands. One of the components of the agricultural hydrotechnical reclamation development is the provision of an appropriate level of ecological and reclamation status of irrigated lands and territories adjacent to irrigation systems (first of all, an open network of canals). The purpose of these studies is to assess the modern technical and hydrogeological-ameliorative state of the Kilchen irrigation system (total area of 35.3 thousand hectares) for a long period of operation of more than 50 years. The main research methods were field diagnostic surveys of the technical conditions of the main structures and elements of the irrigation system (open channels in the earthen channel). The trends of changes in climatic conditions of the territory over the last decade are analyzed. Analytical processing of the stock materials data and field observations of changes in the groundwater level, its chemical composition and mineralization in 24 observation wells along the main channel was carried out. The main chemical composition of groundwater in the research area is characterized as sulfate and sodium-calcium with total mineralization in individual areas from 0.6-0.9 to 1.7-3.5 g/l. According to the known methods of R.O. Bayer and V.A. Kovda calculations of the predicted change in the level and critical depth of groundwater have been performed. The established terms of change vary between 9-11 years, provided that irrigation is intensified and the irrigation system is fully operational. Based on the forecasting results, groundwater mineralization is expected to decrease from 3.5 g/l to 2.27 g/l between 2021 and 2029. It was determined that the level of groundwater above the calculated critical levels in different years occupies from 30.7 to 51.0% of the territory in the area of operation of the Kilchen irrigation system. The reclamation state of part of the irrigated lands in 2021 with a total area of more than 13.000 ha was distributed according to the following criteria: 12.000 ha – favorable, 1.200 ha – satisfactory, about 50 ha – unsatisfactory due to the manifestation of soil salinization processes. As of 2021, of the soils on an area of about 10.000 hectares that were studied, almost 8.500 hectares of soils are non-saline, more than 1.200 hectares are slightly saline, and about 50 hectares are moderately saline. For comparison, in 2003, all soils on the same area were non-saline, which indicates the deterioration of the ecological and melioratic state of the territory and the decrease in the quality of irrigation water.