Commentary to the textbook Hydrology and Hydrochemistry, published in 2025

The article presents and analyses the textbook «Hydrology and Hydrochemistry» published by Professors V.K. Khilchevskyi and V.V. Greben of Taras Shevchenko National University of Kyiv in 2025. The first comprehensive textbook on this subject published in Ukraine outlines the basics of hydrology (Part I) and hydrochemistry (Part II). The textbook is based on the modern terminology set out in the relevant regulatory documents: DSTU 3517:2024 «Land Hydrology. Terms and definitions of basic concepts» DSTU 2439: 2018 «Chemical elements and simple substances. Terms and definitions of basic concepts, names and symbols». The scientific and methodological developments of the «Hydrological Dictionary» and «Hydrochemical Dictionary», the educational and methodological complex «Hydrochemistry», as well as modern developments in water resources research, published at the Department of Hydrology and Hydroecology of Taras Shevchenko National University of Kyiv during 2022-2025, were useful. The study of the educational component «Hydrology and Hydrochemistry» is also supported by methodological guidelines for practical work issued by the Department of Hydrology and Hydroecology in 2025. The study guide is structured in two parts: I – Hydrology; II – Hydrochemistry. The hydrological block is structured into 8 sections: 1) Origin of natural waters. the subject of study of hydrology, its formation and development; 2) Distribution of water on the globe, its cycle; 3) Hydrology of rivers; 4) Hydrology of lakes; 5) Hydrology of reservoirs; 6) Hydrology of groundwater; 7) Hydrology of oceans and seas; 8) The concept of water resources. Water resources of Ukraine. The hydrochemical block also has 8 sections: 9) General characteristics of the chemical composition of natural waters. formation and development of hydrochemistry; 10) Factors of formation of the chemical composition of natural waters; 11) Data systematisation. classification of waters by chemical composition and salinity; 12) Hydrochemistry of precipitation; 13) Hydrochemistry of rivers, lakes and reservoirs; 14) Chemical composition of groundwater; 15) Hydrochemistry of oceans and seas; 16) Water quality assessment. Protection of water from pollution. The textbook is intended for students studying under the educational programme ‘Ecology’ of the speciality ‘Ecology’ (field of study – Natural Sciences, Mathematics and Statistics). However, it will also be useful for educational programmes of the Earth Sciences speciality, which study issues related to natural waters.