Vasyl Turcheniuk

This study presents the results of long-term field experiments investigating the effects of subsurface heating and irrigation with discharged warm water (28–35 °C) on the hydrothermal, redox, biological, and salt regimes of Haplic Chernozem (Loamic, Endocalcaric) in the central Forest-Steppe zone of Ukraine. The experiments were conducted under contrasting hydro-meteorological conditions, allowing assessment of thermo-reclamation practices across a wide range of temperature and soil moisture regimes. Subsurface heating increased soil temperature by 7.3–11.1 °C at the depth of heating pipe installation, while the thermal effect gradually decreased with increasing distance from the heat source. Combined heating and irrigation created a more uniform temperature distribution within the root zone, reduced the depth and duration of soil freezing, and improved hydrothermal conditions throughout the growing season. The studied soils maintained predominantly oxidative conditions under all treatments. However, the combined application of heating and irrigation promoted a more homogeneous distribution and seasonal stabilization of soil redox potential throughout the profile. Soil heating also enhanced microbiological activity, thereby increasing cellulolytic activity, particularly during cold and dry periods when soil temperature and moisture limited microbial processes. Irrigation with slightly mineralized warm wastewater did not cause significant overall soil salinization but resulted in the redistribution of calcium and sodium within the soil profile. Subsurface heating intensified the seasonal dynamics of readily soluble salts, promoting their temporary accumulation near the heating pipes, whereas combined heating and irrigation facilitated subsequent leaching of excess salts into deeper horizons. The integrated application of subsurface heating and irrigation produced the highest and most stable perennial grass productivity, increasing biomass yield by 87–163% compared with the control, irrespective of meteorological conditions. These findings demonstrate that the integrated use of industrial waste heat for subsurface heating combined with irrigation represents a promising and environmentally sustainable thermo-reclamation technology capable of improving soil functioning and agricultural productivity, provided that long-term monitoring of soil water–salt regimes is maintained.

— A mathematical modeling approach was employed to establish a suite of indicators for assessing the efficiency of Danube rice irrigation systems. The proposed indicators facilitate the identification of rational management strategies, including methods, regimes, and schemes for regulating the natural and reclamation processes of irrigated lands. This takes into account the unique characteristics of rice systems while ensuring compliance with current environmental regulations and principles of sustainable development. Анотація – За результатами математичного моделювання обґрунтовано сукупність показників як критеріїв для оцінки ефективності функціонування Придунайських рисових зрошувальних систем. Обґрунтований перелік показників дає можливість визначити раціональні способи, режими та схем регулювання природно-меліоративного режиму на зрошуваних землях, з урахуванням специфіки рисових систем, що відповідають сучасним екологічним вимогам і забезпечують сталий розвиток таких систем.

The chapter considers an approach for assessing and forecasting the water needs of accompanying crops of rice crop rotation in changing modern conditions of rice irrigation system's functioning. The obtained results can be effectively used in the development of adaptive measures to the climate changes in the context of water, energy, and food crises, as well as in the justification of resource-saving regimes and technological solutions in projects of reconstruction and modernization of rice systems aimed at achieving the goals of optimizing the use of water and energy resources during their functioning. The chapter presents the results of a machine experiment on the predictive assessment of the water needs of accompanying crops in variable natural-agro-melioration conditions of the Danube area. The conditions of the water needs formation for various types of accompanying crops were determined according to accepted schemes of technologies and water regulation regimes on irrigated lands of rice systems. A comparison of the obtained results with real production data was carried out.

Rice systems in Ukraine are built on territories with saline soils, and with a complex hydrogeological situation. A method of calculating ecologically safe periods for growing dryland crops on saline soils is proposed, which will help to optimize the structure of rice rotations and prevent soil degradation. The considered technologies for leaching of saline soils, which make it possible to ensure qualitative soil desalination, to shorten the duration of leaching, to lower the level of groundwater, to improve the oxygen regime of the soil. The methods for calculating the technological parameters of capital and preventive soil leaching of saline soils have been developed. These methods allow improving the water permeability of the soil, attracting a natural thermal effect, reducing the volume of freshwater, and preventing the restoration of salts. It can be an important step in restoring fertility and increasing the productivity of rice systems in the face of water scarcity and climate change.

In view of global climate changes, the study of the ecological feasibility of hydromelioration systems and their impact on the natural environment is extremely relevant. Evaluation of the ecological effectiveness of water regulation of drained land for current and forecasted climatic conditions...

One of the rational ways of energy saving is to use the heat of wastewater from energy companies for open ground heating and cultivation crops. The most significant sources of heat are thermal and nuclear power plants that produce low-thermal waters of 28–35°C. Heating of the ground with the use of circulating warm water allows to increase temperature at all points of the soil profile. The maximum thermal effect from heating ground is observed at the depth of pipe heaters (7.3– 11.1°C). Ground heating allows to extend the growing season for crops by 3–4 weeks, which can expedite harvesting and thus maximise the harvest. In natural moisture conditions, ground heating does not lead to significant reduction of moisture reserves in the active layer throughout the growing period. There is a redistribution of moisture in a soil profile. It decreases in the zone of pipe heaters and redistributes toward the top. The formation of the nutrient regime changes, the content of mobile phosphorus and potassium, and nitrate nitrogen increases, whereas the content of ammonia nitrogen is reduced. Ground heating is a new special heat reclamation technique. It allows not only to control temperature of the agricultural crop environment, but also to dissipate heat in the ground, and promote the utilisation of waste heat and the stabilisation of the environment.

Based on the generalization of international experience in reforming water management systems, a list of basic imperatives and principles, as well as the most common methods and tools of water policy development, which have been tested and successfully implemented in many countries. In particular, the study considers a number of principles of state sectoral policies and management of reform processes, including: the application of systematic multi-disciplinary approaches to assessing the state of natural and technical social systems; adherence to the principles of sustainable development and integrated management; stakeholder participation at all stages of policy development and implementation; implementation of the principles of good governance; use of technological innovations, informatization and application of platform technologies. Emphasis is placed on the fact that existing and promising sectoral strategies in the field of water protection and use should be based on a common intersectoral vision and the formation of relevant broader intersectoral strategic goals that address important national tasks of improving and developing water management. An algorithm of the process of interaction between stakeholders and expert groups in the process of developing the Water strategy is proposed, which provides for: accumulation and analysis of data on the state of water resources and water use; performing a systematic analysis of the functioning of the industry; development of a general vision of the future state of water resources management; substantiation of strategy principles and development of indicators for quantitative assessment of strategy implementation results; determination of the main stages of the strategy and methods of their implementation; development of qualitative and quantitative scenarios of institutional changes in the water management complex, as well as the necessary technical and technological innovations for the long term. It is substantiated that in order to ensure a transparent and clear process of development and implementation of the main provisions of the Water strategy, it is necessary to organize the national water dialogue with the participation of leading scientific and educational institutions in the field of water management.

The article discusses the option for the application of the methodology for the solution of boundary value problems on the conformal mapping for the calculation of filtration process in the horizontal systematic drainage, provided that the drain is installed at a different depth. In particular, the case of methods combining fictitious areas and quasiconformal mappings for solving nonlinear boundary conditions problems for calculating filtration regimes in soils with free sections of boundaries (depression curves) and intervals of the “drainage” type. As an example, the authors designed a hydrodynamic flow grid, determined the values of the flows to the drain, established a section line and elicited other process characteristics. The algorithm for the numerical solution of model nonlinear boundary conditions problems of quasiconformal reflection in areas bounded by two equipotential lines and two flow lines, when for one of the sections, the boundary is an unknown (free) curve with fixed and free ends. The conducted numerical calculations prove that the problems and algorithms of their numerical solution, with a relatively small iterations number (k = 141) suggested in the paper, can be applied in the simulation of nonlinear filtration processes that arise in horizontal drainage systems. Total filtration flow obtained Q = 0.9 dm3·s–1; flow for drains Q1 = 0.55 dm3·s–1 and Q2 = 0.35 dm3·s–1 are quite consistent with practically determined values.