Analytical Brief
Ecological and Economic Justification for Measures to Restore the Water Flow in the Kyslytskyi Branch of the Danube and Forecast Scenarios in the Event of Delayed Implementation
The Kyslytskyi branch of the Danube River is a critical element of the hydrological system of the Danube Delta region. Its operation ensures the stability of the water regime for a number of strategically important natural and economic sites in the south of Odesa region, including Lakes Katlabuh, Safyany, and Kitay, the "Lung" landscape reserve, as well as irrigation networks and the drinking water supply for over 22 settlements.
In recent years, due to hydromorphological changes in the Kiliya branch of the Danube, there has been a critical decrease in water exchange between the Kyslytskyi branch and the main river channel. Additional negative factors include the siltation of the entrance cross-section and the formation of sedimentary deposits (two islands with a total area of about 17 hectares), posing the risk of hydrological isolation of the branch.
Ecological Importance of the Kyslytskyi Branch
Hydrological balance: the branch provides a natural inflow to Lakes Katlabuh (68 km², 131 million m³) and Kitay (60 km², 125 million m³), stabilizing their water levels.
Biodiversity: supports spawning and migration routes for fish species, including commercially important ones, and provides habitat for waterfowl and wetland fauna.
Ecosystem services: contributes to water self-purification, microclimate regulation, and soil moisture retention.
Economic Importance
Water supply: feeds the Kiliya drinking water intake.
Irrigation: sustains the operation of six pumping stations serving extensive agricultural areas.
Agricultural production: enables stable irrigation for grain, vegetable, and fodder crops in a zone of risky farming.
Social stability: helps maintain employment levels in rural communities and prevents degradation of productive lands.
Main Problems
Siltation and shallowing of the entrance cross-section of the Kyslytskyi branch.
Formation of sedimentary islands and peninsulas, reducing channel throughput.
Reduced water exchange with the main Danube channel, leading to deterioration of water quality in lakes.
Risk of hydrological isolation, potentially resulting in the branch’s desiccation and the drying of connected lakes.
Proposed Measures
Widening the entrance cross-section of the branch to increase water flow capacity.
Removal of bottom sediments and clearing of two islands with a total area of approximately 17 hectares.
Bank reinforcement to prevent further siltation.
Implementation of a monitoring system for hydrological and ecological parameters.
Technical and economic indicators of the project:
Length of the section: 25 km.
Volume of sediments to be removed: 2.0 million m³.
Estimated cost: UAH 300 million.
Implementation period: 2025–2026.
Included in the Danube River Basin Management Plan (2025–2030).
Forecast Scenarios
A timely intervention in 2025–2026 will ensure the restoration of full water exchange between the Kyslytskyi branch and the Kiliya branch of the Danube, stabilizing the hydrological regime of the lakes and preserving the region’s ecosystems and biodiversity. This will support sustainable agriculture, maintain the efficiency of irrigation systems, and minimize the risk of social tension related to water shortages.
In the case of partial implementation of the measures, only temporary improvements can be expected, accompanied by a high probability of repeated siltation of the branch’s entrance. Such a development will lead to gradual degradation of lake ecosystems, reduced biological productivity, and increased operational costs for irrigation and water supply systems. While water supply for settlements may be partially maintained, the risk of its deterioration in the medium term will remain high.
The most negative outcome is the scenario of inaction, which, within 5–7 years, will result in the complete hydrological isolation of the Kyslytskyi branch from the main channel. This will cause the desiccation of Lakes Katlabuh and Kitay, irreversible changes to wetland complexes, the disappearance of certain species of flora and fauna, and significant economic losses to the agricultural sector due to reduced irrigated areas, declining yields, and soil degradation. Social consequences will include worsening living conditions in more than 22 settlements, shortages of drinking water, increased migration flows, and heightened social tensions.