A holistic view of water sources in Kyiv, Ukraine using tap water, surface water, groundwater, and precipitation hydrogen (𝛿2H) and oxygen (𝛿18O) stable isotope ratios

The water supply for Kyiv (Ukraine) is a seasonally and spatially variable mixture of both ground and surface water. This water supply is vulnerable to the effects of climate change, pollution, and geopolitical conflict. Climate change has resulted in changing precipitation patterns, potentially altering the balance between ground and surface water utilization. Additionally, the ongoing conflict makes a holistic understanding of water resources and pathways critical for water management. This study uses water stable isotopes as tracers for water sources and the importance of different reservoirs in water management.

For this study tap water, surface water, groundwater, and precipitation were collected over 14 months (2019-2020) in Kyiv and nearby Boryspil, Brovary, and Boyarka and measured for hydrogen (𝛿²H) and oxygen (𝛿¹⁸O) stable isotope ratios. Precipitation data was used to capture seasonal variability in storm trajectories and create a meteoric water line. These results were then compared to surface, ground, and tap water to capture water sources and residence times.

The stable isotope values from the tap water for each district show a general seasonal trend in water sources, with more groundwater used in the supply in the winter for most districts. Spatially, groundwater use increases from south to north in the left-bank districts in Kyiv city and groundwater use generally decreases from south to north in the right-bank districts. As precipitation patterns shift and temperatures increase, the reliance on particular water sources may need to shift as well.

 Overall, 𝛿²H and 𝛿¹⁸O data provide a baseline expectancy for current water use throughout the year and, from this, deviations can be assessed early. A holistic view of the water system will be critical to assess changes due to infrastructure damage and/or other impact on water management in the Kyiv region.