Modern runoff of the major rivers of Ukraine into the Northwestern part of the Black Sea
Abstract
Introduction. Understanding the current water discharge of major Ukrainian rivers flowing into the Black Sea is essential for modelling hydrological and oceanographic conditions in its north-western part. Freshwater inflow has a strong influence on thermohaline structure, salinity gradients, circulation, and ecosystem functioning. Under climate change and increasing anthropogenic pressure, river runoff in southern Ukraine has undergone significant alterations, resulting in prolonged low-flow phases. This study assesses long-term and recent trends in water discharge in the lower reaches of the Dnieper, Southern Bug, Dniester, and Danube rivers - the main freshwater sources for the Black Sea coastal zone -and provides input data for a Climate-Smart Decision Support System (CSDS), contributing to SDG 6 (Clean Water and Sanitation) and SDG 13 (Climate Action).
Methods. The analysis is based on long-term hydrological records (1981–2021) and operational data up to 2024 obtained from the Hydrological Information Laboratory of Odessa I.I. Mechnikov National University and the Ukrainian Hydrometeorological Centre. Hydrological-genetic analysis of runoff time series, statistical trend evaluation, residual mass curves, and comparison of characteristic hydrological years (wet, normal, dry) were applied. For rivers with limited observations in the lower reaches, correlations between upstream discharge and downstream water levels were used to reconstruct typical intra-annual runoff patterns.
Results. All four rivers show a pronounced shift toward persistent low-flow conditions during the past decade. The Southern Bug has experienced a sharp discharge decrease since 2010, reaching less than one-third of the long-term mean by 2024. The Dnieper exhibits alternating wet and dry phases over the last 40 years; however, the 2010s–early 2020s are marked by the lowest runoff values, particularly in 2015 and 2020. The Dniester exhibits relatively regular phase alternation; however, a sustained low-flow period has persisted since 2013–2014. In the Danube delta, discharge variability remains cyclic, yet the period 2016–2024 is characterized by consistently reduced water volumes. Typical intra-annual runoff distributions for wet, normal, and dry years reveal decreased spring peaks and increased warm-season variability.
Conclusions. Major rivers supplying freshwater to the Black Sea coastal zone are currently in a prolonged low-flow phase, which must be considered in hydrodynamic and thermohaline modelling. These trends should be incorporated into numerical oceanographic models (e.g., D-Flow FM) when defining boundary conditions. Under present climatic conditions, dry-year runoff distributions are recommended, while wet-year scenarios should be applied for extreme events. The results provide a basis for CSDS development, supporting adaptive water management and informed decision-making in a climate context.
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References
Sryberko, A. V., Andrianova, O. R., & Tuchkovenko, Y. S. (2024). Thermohaline structure and methods of calculating its spatial distribution in the active layer of the Black Sea [Monograph]. Odessa State Environmental University.http://eprints.library.odeku.edu.ua/id/eprint/13054/ [in Ukrainian]
Tuchkovenko, Y. S., & Kushnir, D. V. (2024). Modeling the distribution of transformed waters of the Dnipro River in the Black Sea as a result of an artificial flood caused by the destruction of the Kakhovka Reservoir dam. Prospects for Hydroecological Research in the Context of Local and Global Consequences of Warfare: Proceedings of the 9th Congress of the Hydroecological Society of Ukraine (174–176). Dnipro: DNU. [in Ukrainian]
Tuchkovenko, Y. S., & Kushnir, D. V. (2024). Diagnosis and forecast of oceanographic conditions in the Black Sea. In Proceedings of the 79th Scientific Conference of ONU (10–13). ONU. http://liber.onu.edu.ua/pdf/79_Conf_2024_FH&E.pdf [in Ukrainian]
Wikipedia contributors. (n.d.). The Northwestern part of the Black Sea. Wikipedia. https://surl.lt/puxsbi [in Ukrainian]
Blöschl, G., et al. (2017). Changing climate shifts timing of European floods. Science, 357(6351), 588–590. https://doi.org/10.1126/science.aan2506
Blöschl, G., et al. (2019). Changing climate both increases and decreases European river floods. Nature, 573, 108–111. https://doi.org/10.1038/s41586-019-1495-6
Bertola, M., Blöschl, G., Bohac, M., et al. (2023). Megafloods in Europe can be anticipated from observations in hydrologically similar catchments. Nature Geoscience, 16, 982–988. https://doi.org/10.1038/s41561-023-01300-5
Loboda, N. S. (2015). Modeling the impact of climate change on river runoff characteristics in Ukraine. In Climate change and its impact on the economy of Ukraine (451–482). TES. [in Ukrainian]
Vyshnevskyi, V. I. (2000). Rivers and water bodies of Ukraine. Kyiv. [in Ukrainian]
Vyshnevskyi, V. I., & Kosovets, O. O. (2003). Hydrological characteristics of Ukrainian rivers. Kyiv. [in Ukrainian]
Grebin, V. V. (2010). Modern water regime of rivers of Ukraine. Kyiv. https://geo.knu.ua/wp-content/uploads/2021/03/10_n_lit_gidrol.pdf.pdf [in Ukrainian]
Gopchenko, Y. D., & Loboda, N. S. (2001). Assessment of natural water resources of Ukraine by the water–heat balance method. Scientific Works of UkrNDGMI, 249, 106–119. [in Ukrainian]
Loboda, N. S., & Kozlov, M. O. (2020). Assessment of Ukraine’s river water resources under RCP4.5 and RCP8.5 scenarios for 2021–2050. Ukrainian Hydrometeorological Journal, 25, 93–104. https://doi.org/10.31481/uhmj.25.2020.09 [in Ukrainian]
Loboda, N. S., Tuchkovenko, Y. S., Kozlov, M. O., & Katynska, I. V. (2021). Assessment of river water inflow into the Sasyk estuary-reservoir. Journal of Geology, Geography and Geoecology, 30(2), 315–325. https://doi.org/10.15421/112128
Lukianets, O. I., et al. (2021). Spatial patterns of changes in mean annual runoff in Ukraine. Ukrainian Geographical Journal, 1(113), 6–14. https://doi.org/10.15407/ugz2021.01.006 [in Ukrainian]
Ovcharuk, V. A., & Shakirzanova, Z. R. (Eds.). (2024). Extreme hydrological phenomena in Southern Ukraine: Calculations and forecasts. Odessa State Environmental University. http://eprints.library.odeku.edu.ua/id/eprint/13144/ [in Ukrainian]
Didovets, I., et al. (2020). Climate change impact on water availability of main river basins in Ukraine. Journal of Hydrology: Regional Studies, 32, 100761. https://doi.org/10.1016/j.ejrh.2020.100761
Snizhko, S., Bertola, M., Ovcharuk, V., Shevchenko, O., Didovets, I., & Blöschl, G. (2023). Climate impact on flood changes: An Austrian–Ukrainian comparison. Journal of Hydrology and Hydromechanics, 71(3), 271–282. https://doi.org/10.2478/johh-2023-0017
Obodovskyi, O. H., et al. (2019). Mean annual river runoff in the river basin districts of Ukraine. Hydrology, Hydrochemistry and Hydroecology, 3(54), 65–66. [in Ukrainian]
Grebin, V. V., & Lukianets, O. I. (2019). Mean annual runoff of the Dniester basin. In Rivers and Estuaries of the Black Sea Region Conference (46–48). Odesa. [in Ukrainian]
Obodovsky, A., Lukyanets, O., Moskalenko, S., Kornienko, V. (2020). Generalization of the average annual water runoff of the rivers according to the hydrographic zoning of Ukraine. Visnyk of V. N. Karazin Kharkiv National University. Series Geology. Geography. Ecology, (51), 158-170. https://doi.org/10.26565/2410-7360-2019-51-11 [in Ukrainian]
Ovcharuk, V., Gopchenko, Y., Kichuk, N., Shakirzanova, Z., Kushchenko, L., & Myroschnichenko, M. (2020). Extreme hydrological phenomena in Southern Ukraine. Proceedings of IAHS, 383, 229–235. https://doi.org/10.5194/piahs-383-229-2020
Kushchenko, L. V., et al. (2021). Minimum and ecological flow of rivers in Southern Ukraine. Ecological Sciences, 2(35), 30–36. https://doi.org/10.32846/2306-9716/2021.eco.2-35.5 [in Ukrainian]
Ovcharuk, V., & Gopchenko, Y. (2022). Engineering substantiation of hydrological calculations. In Ecological significance of river ecosystems (351–382). Elsevier. https://doi.org/10.1016/B978-0-323-85045-2.00018-2
Loboda, N. S., & Rozvod, M. R. (2025). Assessment of vertical zonality changes of annual runoff. Hydrology, Hydrochemistry and Hydroecology, 3(77), 20–32. [in Ukrainian]
Shakirzanova, Z. R., Ovcharuk, V. A., Dokus, A. O., Kushchenko, L. V., & Tymko, O. S. (2022). Probabilistic method for determining low-flow discharge. Visnyk of V. N. Karazin Visnyk of V. N. Karazin Kharkiv National University. Series Geology, Geography, Ecology, (57), 251–267. https://doi.org/10.26565/2410-7360-2022-57-19 [in Ukrainian]
Shakirzanova, Z. R., & Blaha, A. O. (2025). Forecast of river water availability during water scarcity in Southern Ukraine. In Climate Change Conference Proceedings (97–100). https://doi.org/10.32782/19092025 [in Ukrainian]
State Water Cadastre. (2017). River basin districts of the Dnipro basin: Long-term hydrological data (2016–2020). [in Ukrainian]
Afanasiev, S., et al. (2025). River Basin Management Plan of the Southern Bug (2025–2030). https://davr.gov.ua/fls18/PURB_PivdennyiBuh.pdf [in Ukrainian]
Vyshnevskyi, V. I., & Kutsyi, A. V. (2022). Long-term changes in the water regime of rivers of Ukraine. K., Naukova Dumka. [in Ukrainian]
Khilchevskyi, V. K., et al. (2009). Water resources and water quality of the Southern Bug basin. Nika-Tsentr. [in Ukrainian]
Ovcharuk, V. A. (2020). Maximum spring flood runoff of lowland rivers of Ukraine. Helvetyka. [in Ukrainian]
European Parliament. (2006). Directive 2000/60/EC of the European Parliament and of the Council establishing a framework for Community action in the field of water policy. [in Ukrainian]
Grebin, V. V., et al. (2013). Hydrographic zoning methods of Ukraine. Interpres. [in Ukrainian]
Tuchkovenko, Y., Kushnir, D., & Ovcharuk, V. (2024). Modeling the distribution of transformed waters of the Dnipro River in the Black Sea following the artificial flood caused by the Kakhovka dam destruction. Proceedings of the International Scientific and Practical Conference “Natural and Geographical Studies of Relief, Climate, and Surface Waters: Current State and Development Prospects” (October 2–4, Kyiv, Ukraine), 54. Kyiv: Taras Shevchenko National University of Kyiv. https://geo.knu.ua/wp-content/uploads/2024/09/2024-materials-of-the-international-scientific-and-practical-conference_min.pdf
Ovcharuk, V. A., Gopchenko, Ye. D., & Traskova, A. V. (2017). Standardization of characteristics of maximum spring flood runoff in the Dniester River basin, 252. Kharkiv: FOP Panov A. M. [in Ukrainian]
Gopchenko, Y. D. (2013). Dependence between water levels and discharges of the Dniester. Research Report No. 0114U001751. ODEKU. [in Ukrainian]
Gopchenko, Y. D., Loboda, N. S., & Ovcharuk, V. A. (2014). Hydrological calculations. TES. [in Ukrainian]
ODEKU. (2011). Assessment of water exchange in the channel–floodplain–liman system. Research report. [in Ukrainian]
TuchkovenkоY., Loboda, N., & Ovcharuk, V. (2024). Key aspects of seawater intrusion in the Dniester River during storm surges. Visnyk of V. N. Karazin Kharkiv National University. Series Geology. Geography. Ecology, (61), 272-287. https://doi.org/10.26565/2410-7360-2024-61-22
Mikhaylov, V. N. (2004). Hydrology of the Danube Delta. M., GEOS.
Shakirzanova, Z. R., & Romanova, Y. O. (2021). Water and salt regime of Lake Katlabukh. ODEKU. [in Ukrainian]
Romanova, Y., Shakirzanova, Z., Ovcharuk, V., Todorova, O., Medvedieva, I., & Ivanchenko, A. (2019). Temporal variation of water discharges in the lower course of the Danube River across the area from Reni to Izmail under the influence of natural and anthropogenic factors. Energetika, 65(2–3), 144–160.
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