We examine the current problems of Lake Baikal level regulation. A comparative analysis is made of the changes in the lake level, the range of its fluctuations and in the intra-annual amplitude for the 120-year-long period of observations in natural and regulated conditions. The period 2014–2017 with an extremely low water level is analyzed. It is pointed out that the inconsistency between existing legislation and the water resource management system within the Baikal and Angara drainage basins has also contributed to the decline in sustainability of the water economy, along with the climatic factors. It was found that while generally quite well complying with the requirements of water users and water consumers in conditions of normal and almost normal water availability, it cannot meet the regulatory needs and restrictions in periods of extreme water availability. The risks and contradictions in the regulation of the Lake Baikal water level in low- and high-water years are considered. Quantitative assessments are made of the possible maximum levels in Lake Baikal during floods for different restrictions of water flow in the downstream water. The estimates of expected areas of flooding are given. It is pointed out that along with water management and socio-economic risks, climatic and environmental factors should also be taken into account in the lake level regulation. An analysis is made of the environmental requirements which were taken into account when setting the limited meter range of Lake Baikal level regulation (Decree of the Government of the Russian Federation of 3.26.2001 No. 234). There is an inconsistency in these requirements and, in some cases, the impossibility of meeting them. Quantitative assessments are made of the implications of the re-enforcement of Decree No. 234 on January 1, 2021. It is shown that the enforcement of this decree in full necessarily involves violating the requirements of water users. The years of elevated water levels are necessarily accompanied by flooding of the city of Irkutsk. It is suggested that the “social” option of regulating the level of Lake Baikal water level regulation be used in order to avoid infringement of existing legislation and flooding by the downstream water. Special research work should be done to determine a reasonable range of Lake Baikal water level regulation having regard to the current environmental and socio-economic factors.

This paper examines the operation of the water management system in the Angara River basin in periods when the water level conditions deviate from the norm. Analysis of the actual water management regimes in reservoirs constituting the Angara cascade over the last 30 years shows that in high- and especially low-water years, the needs of water users are not satisfied with reliability, and the statutory requirements are not fulfilled to the full extent. Analysis of the water management system operation in the Angara River basin in the best-known low-water years confirms this. Aside from climatic changes in the basins of Lake Baikal and the Angara River, the main causes of this situation are the current legal framework and the water management system based on it. This article also discusses other causes of the overall decrease in reliability and stability of the water management system. A universal stability indicator is proposed: a statutory water provision range for each water user is determined taking the existing conditions and restrictions into account. The possible and permissible operation regimes for reservoirs of the Angara cascade have been modeled for various variants based on the statistical streamflow data collected over a 115-year monitoring period. For each of the modeled variants, water provision estimates were obtained taking the statutory requirements and restrictions into account. Since the climate and hydrological parameters in the basins of Lake Baikal and the Angara River have significantly changed over the last 2 decades, an additional scenario was produced for a prolonged low-water period. The results made it possible to identify the most efficient (sustainable) reservoir operation variant that satisfies the needs of water users and consumers in water resources in a better way and complies with the main current requirements and restrictions. To enhance the stability of the water management system in the Angara River basin, it is recommended to amend and supplement the existing legal framework.

The paper is concerned with a methodological approach to monitoring the state of atmospheric parameters in the catchment area of Lake Baikal, including real-time analysis of actual distributed data with the determination of analog years according to the preset proximity of comparative indicators and the most probable long-term predictive distributions of surface temperatures, precipitation, pressure, and geopotential with a lead time of up to 9–12 months. We have developed the information-analytical system GeoGIPSAR to conduct the real-time analysis of spatial and point data by various processing methods and obtain long-term prognostic estimates of water inflow into the lake.

The paper provides a system of consistent models to study the integrated use of water resources of reservoirs and operating conditions of hydropower plants that constitute the Angara cascade. The system includes many different simulation and optimization models (hydrological, hydraulic, water management, and the hydropower cascade operation control) taking into account the hydrological, climatic and territorial features of the water systems of the Baikal, Angara and Yenisei basins; and the role of the Angara cascade in the operation of the Siberian electric power system. The paper presents a brief description of the models, their parameters, criteria and constraints, and their interaction principles. The models are designed to determine the long-term operating conditions of the Angara cascade of hydroelectric power plants. To this end, it is proposed to use global climate models with the data on the state of the atmosphere and ocean based on which the most probable characteristics of meteorological indices in the region are determined, to make estimates (scenarios) of inflows into the cascade reservoirs in the form of ranges of probability distributions for a period of up to one year. The results of modeling the long-term operation of individual hydroelectric power plants and the entire Angara cascade are presented for 2019–2020. Relying on the assumed long-term water scenario, the estimated water availability scenarios make it possible to evaluate the expected electricity output, the average used capacity and other parameters of the hydroelectric power plants operation, to form prospective energy balances in the power system, and to determine the the prospective load of thermal power plants.

The decision of Mongolia’s Government to implement the projects for the construction of hydropower plants (HPPs) in the transboundary basin of the Selenga River caused the need to study their possible impact on the Russian part of the basin and Lake Baikal. To assess the impact of planned in Mongolia HPPs on the territory of the Russian Federation (water resources and ecosystem), we have studied the expected changes in the yearly hydrological regimes due to flow regulation. A methodology developed at the Melentiev Energy Systems Institute (MESI) allows integrating various models (hydrological, energy, environmental, etc.) into a single system. We have employed this system to model the parameters of the planned HPPs reservoirs and their regulation modes, as well as the deviations of hydrological regimes of Selenga River due to the HPPs construction from those under natural conditions. The concept of “environmental flow” is used to assess changes in the intra-annual hydrological regime of a river. We determine the boundaries of the environmental flow for each month based on an analysis of a variety of biotic and abiotic restrictions for the entire river bed from the border of the Russian Federation to the Selenga River delta.