Forecast Assessment of Water Regime Efficiency and Changes in Water Consumption on Drained Lands of Western Polissya of Ukraine in a Changing Climate

Abstract The forecast data on the impact of changing weather and climatic conditions on evaporation, water demand, and crop yield on drained lands in Western Polissia of Ukraine at different stages of their development are presented. They serve as the basis for creating the project water management regimes and forming the operational water management regimes, which are implemented by selecting and justifying the necessary water management methods, types, structures, and operation modes of drainage systems, and to calculate their parameters. Computer simulation modeling of various climatic scenarios was planned to accomplish the objective. The forecast was made through a machining experiment based on the implementation of a corresponding complex of forecast-simulation models regarding the main regime-technological variable parameters of drainage systems, local climatic conditions, water regime, water management technologies, and productivity of drained lands for schematized natural, agrotechnical, and meliorative conditions. Vegetation values of total evaporation and water demand formation of drained lands were determined for the long-term forecast module of water supply regarding variable climatic and agro-meliorative conditions. The technological efficiency of different irrigation technologies (subsoil irrigation, sprinkler irrigation) of drained lands was evaluated. The research showed that in the Western Polissia of Ukraine, the water supply module for irrigating drained lands varies significantly depending on the type of crops, drained soil (mineral, peat), irrigation technologies, and heat and moisture supply conditions during the vegetation period. Compared to the existing normative values of 0.5…0.75 l/s·ha, its range of variation is 0.5…3.9 l/s·ha. In this case, the water demand for cultivated crops increases almost two to three times, necessitating the transition from periodic to regular irrigation of drained lands.