Optimization of operating modes of the water management complex based on determining the synergetic cost of the water resource

The article develops a methodology for optimizing the operating regimes of a water management system, taking into account the influence of the natural reservoir of water resources - the Kamenskaya floodplain. The foundation of the research is the assessment of the synergistic cost of water resources as an integrated indicator of reliability, environmental friendliness, and socio-economic efficiency. The aim of the work is to create a methodology that reconciles the interests of the power industry, navigation, and ecology to enhance the energy efficiency of water management systems. To achieve this goal, methods of water-energy nexus analysis, calculation of hydropower plant (HPP) firm power, an optimization block for HPP operating regimes, as well as the application of marginal utility theory and the profit maximization criterion (MR = MC) were used. The methodology is based on a combination of optimization approaches and economic principles, enabling the consideration of conflicting interests among various stakeholders in water management activities. The scientific novelty lies in the proposal of unique techniques with no global equivalents: calculation of firm power, determination of marginal water costs, and the use of indifference curves for balancing the interests of water users. The developed approach allows for the justification of electricity tariffs for a given generation output, as well as solving the inverse problem - determining the optimal power production level for a given tariff. The research results are applicable to the management of water management systems, especially under conditions of stochastic energy sources, such as hydropower. The proposed methodology can be used to improve energy efficiency, ensure environmental sustainability, and comply with non-power requirements during the operation of hydraulic structures. The obtained data were validated using the case study of the Novosibirsk HPP. The conclusions demonstrate the high practical significance of the proposed techniques, their applicability in the real-world operation of complex water management systems, and their potential for integration into sustainable water sector development strategies.