Abstract
The purpose of this study was to analyse different scenarios of water resources use to assess the variability of water levels in the aquatic environment of the Small Aral Sea. The following methods were employed during the study: method of mathematical modelling; method of hydrological calculations; comparative analysis; analysis of hydrological data. The methods were chosen for their reliability and applicability to hydrological studies, enabling accurate water level predictions, assessment of resource management options, and analysis of hydraulic structures impact. Based on the results of the calculation of the filling of the Small Aral Sea, it was established that the time required to reach water levels of 50 and 44 metres was between 2 and 15 years. Using the method of mathematical modelling used for forecasting, it was found that the period of water level restoration in the Small Aral Sea under the application of the single-level option could be 26 years on average. The most effective approach for the Northern Aral Sea is the two-tier approach with the marks of the normal headwater level of 42 m and for the Saryshyganak Bay − 50 m, which helped to optimise the use of water resources and reduce water consumption for evaporation. The findings of this study can be applied in practice by hydrologists, hydraulic engineers, resource scientists, environmental engineers, ecologists, ecologists-hydrobiologists, specialists in water management and environmental monitoring.