Water quality in the Dnipro–Donbas canal (Ukraine) under conditions of war and climate change

This paper presents the results of a comprehensive study on the transformation of the hydrochemical regime of water in the Dnipro–Donbas Main Canal. Following the destruction of the Kakhovka Hydropower Plant dam in 2023, the canal has become a critically important and virtually irreplaceable artery for maintaining water and food security in the Steppe zone of Ukraine. Based on a retrospective analysis of a ten-year monitoring dataset (2015–2024), the study reveals the complex dynamics of the agronomic suitability of irrigation water under the new operational reality. The assessment was conducted using both international (FAO, USSL) and national criteria. The results indicate that Electrical Conductivity (EC) fluctuated between 0.75 and 1.15 dS/m, while the Sodium Adsorption Ratio (SAR) remained low (1.2–3.5), and the Residual Sodium Carbonate (RSC) index varied from − 2.5 to 0.8 meq/L. These values confirm that the water generally exhibits a low sodicity and bicarbonate hazard (Class S1). However, the primary threat arises from periodic peak increases in mineralization and chloride concentrations; during low-water periods, up to 25% of samples were classified as Class II (limited suitability) according to national standards. These spikes are directly correlated with critically reduced canal flow rates and intensified evaporation, creating a salt concentration effect. The study substantiates the concept of “dual pressure”, reflecting the synergy between the anthropogenic destruction of infrastructure and global climate change. Predictive modeling for 2050, based on linear trend analysis and climate scenarios, suggests that without a radical shift in water management, these episodic risks will evolve into irreversible salinity-driven degradation of unique chernozem soils across tens of thousands of hectares. The research demonstrates the institutional inadequacy of conventional discrete monitoring approaches and argues for a transition toward intelligent water resources management. The implementation of automated real-time monitoring systems at key hydraulic nodes and the development of adaptive strategies for agricultural producers including the establishment of technological buffer storage reservoirs are proposed. The obtained results provide a fundamental basis for the development of a national strategy for irrigation restoration under conditions of prolonged military conflict and increasing environmental pressure on water resources.