Hydrological regime of the foundation of the Charvak dam after ten years of operation

1. The complex natural conditions and characteristics of the operating regime of the Charvak reservoir determined the duration and complexity of the process of the formation of the hydrogeological (hydrodynamic, temperature, hydrochemical) regime in the dam foundation and abutment. 2. The process of restructuring of the natural hydrogeological conditions, which began with the start of the staged filling of the reservoir in 1970, developed in subsequent years with a variable intensity, determined by the values of the annual increase and drawdown of the head on the dam, and originally had an unsteady cyclic character in which a recurrence of the main characteristics of the seepage flow was not observed from cycle to cycle at comparable elevations of the upper pool level. The extent and rate of the changes that occurred gradually decreased. 3. By the end of the period under consideration, after 10 years of permanent industrial operation of the dam at high reservoir levels, relative stabilization of the hydrodynamic, temperature, and hydrochemical regimes of the subsurface waters in the stretch of the hydro development with approach to a steady cyclic type is observed. 4. The process of a gradual increase of the difference of heads and the general nonunformity of its reduction on the curtain also, apparently, stabilized at the attained level. No substantial change in the established picture of the distribution of heads is expected. The curtain is gradually limiting seepage in the foundation and abutments of the dam, which is indicated by the relative stability of the discharge of the drainage devices of the hydro development. The general hydrogeological conditions that have formed after 10 years of operation of the Charvak dam are evaluated as normal, do not at present arouse apprehension, but require constant checking and continuous systematic observations of the seepage processes.