Rules governing use of water resources and operating procedures should be approved individually for each reservoir.In the summer of 2007 during passage of the spring flood, facilities for the distribution of mass information, for example, television, repeatedly attracted the attention of the public to a situation where a number of population centers located in the tail race of the Zeya hydroproject would be partially inundated. Unsubstantiated statements concerning improper actions of operating personnel at the Zeya HPP, and even as though the flooding had been induced by "human hands" were sounded in the reports.Let us point out that the historical maximum flow rate in the area of Zeya, which had been reestablished in the detailed design [1] on the basis of information relative to water levels published in [2], had been attained in 1886 at 16,600 m 3 /sec. The continuous flow rate of 15,200 m 3 /sec at the site of the Zeya HPP on 19 July 2007 occupies second place after the absolute maximum over the entire period of available information (121 years); this is an unusual event. The Zeya hydroproject most likely prevented one of the most damaging floods, which could have occurred on the Zeya River, and in the middle course of the Amur River under modern conditions in the Far East.Let us stress that the reservoir behind the Zeya HPP plays a significant role in preventing and reducing damages sustained from riparian floods: the 0.01% probability that the maximum design flow rate will be exceeded in the Zeya River is reduced by nearly a factor of three, appreciably diminishing the frequency and area of spring floods in the Zeya and Amur Valleys.The purpose of this paper is, however, to inform specialists and journal readers of the fact that it actually occurred, and for whatever the reasons may be, and that we must, in our opinion, strive to render a similar situation prohibitive in the future.Minor flooding had also occurred during passage of the spring flood through the Zeya hydroproject in 2006; we therefore deem it necessary to relate this information to the hydrotechnical community. Basic Terms and Definitions Adopted in the PaperWater Regime -the variation in the water levels and flow rates within the river over time, which exert an influence on the hydrotechnical complex in question;Conditions for Runoff Formation -basic runoff conditions, which determine the formation of maximum flow rates and highest water levels in the rivers;Extent to Which Hydrology Is Studied -existence of hydrological stations and posts, which are operated by the Rosgidromet and other organizations, and are located in the river basin and its tributaries;Maximum Runoff -a conventional term adopted in lieu of the "maximum flow rate" concept during high water in the rivers, the channels of which abut sections designed for water-development works. The assigned probability that the highest water level will be exceeded is defined in terms of the maximum flow rate of water with respect to the hydraulic characteristics of the channel in the form...

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In the last few years sharp problems have arisen in connection with reconstruction of hydraulic developments built during the pre-and postwar years, intended for increase in the capacity of hydroelectric plants, improvement of their operating reliability, and restoration of structures damaged in the process of prolonged operation. For reconstruction, as a rule, in addition to the need for replacing the hydropower, hydromechanical, and electromechanical equipment because of obsolescence and physical wear, in many cases it is necessary to change the configuration of the internal passages of a hydroelectric plant, its repair with full or partial replacement of the metal liners, and repair of individual, heavily loaded elements of the components of basic structures, in particular: spillays, penstocks, concrete in the zone of variable water level, etc. Installation of modern electrical engineering equipment calls, in many cases, for changes in the planning of auxiliary rooms, by removing different walls or floors.At the present time, design, preparatory, and in several cases basic construction-erection work is being carried out for In the engineering practice of this country, such work is not of a massive nature, and until recently it was carried out basically by hand, using pneumatic drills, concrete breakers, and other similar tools. This calls for substantial time expenditures (according to the ENiP Norms and Rules, the demolition of 1 m 3 of reinforced concrete requires up to 40 manhours, the actual time expenditures being even higher). Moreover, prolonged work with manual pneumatic tools adversely affects human health. Taking into account the massive nature of reinforced concrete demolition work in the process of reconstruction and repair of hydraulic developments, as well as the short periods established for the carrying out of this work, the need has arisen for mechanization of these processes, using Russian and foreign experience with similar work or with work in related branches, in particular in rock excavation.