Thermal analyses of ice in designing the series of Bureya HPP

Abstract

Areas of open water in ice are analyzed in the tailrace of an HPP. The site of the Lower Bureya HPP under design is located 90 km below the Bureya HPP. The total volume of the reservoir will be 2 km 3 , and the surface area 155 km 2 . The reservoir will be regulated daily with a drawdown prism of 1m . The average depth of the reservoir will be 27 m, the width 635 m, and the flow velocity 0.01 – 0.02 msec at the dam. At flow rates of 600 – 800 m 3 sec, the reservoir will be filled in 40 – 30 days, respectively. Based on Avakyan’s classification [1], therefore, the reservoir will be a shallow water body of significant flowage. Based on its characteristics, maximum inflow in the upper reaches will approximate riparian conditions. The icing and thermal regimes in the section in question are formed under the influence of continuous filling of the Bureya Reservoir. The first hydraulic generating set at the Bureya HPP was started in June 2003; at the present time, six of the generating sets are in service. The Bureya Reservoir is a very large and very deep water body, and its degree of water exchange is average. According to 2003 – 2008 observations, the expanse of ice-free water below the Bureya HPP had increase every year from 33 – 37 km in the initial winter to 90 – 95 km during the winter of 200607, but had decreased to 70 km in the last winter. Below the basic edge of the ice in a section 5–7k mlong, the ice cover was unstable with a chain of small open areas. Analysis of Water Temperature in Reservoir Behind Lower Bureya HPP. The winter regime of the reservoir was calculated in accordance with the VNIIG method (in a section free of ice) [2], and by Rossinskii’s method [3] (under an ice cover). Water temperatures averaged over the depth at the midpoint of each month were obtained for characteristic conditions as a result of the analysis (Table 1). The water temperature near the dam of Lower Bureya HPP will range from 2.9°C in November to 0.7°C in April in a warm winter with heavy precipitation, and from 2.3 to 0.6°C, respectively, in a cold winter with light precipitation. The area of ice-free water was calculated from Bydin’s formula [4] hS t i 11 ,