Formation, propagation, and internal structure of bed density flow in the nurek hydroelectric plant reservoir

Transport of suspended sediments in the Nurek hydroelectric station reservoir by a density current and calculation of siltation of the reservoir

“…The concentration of suspended sediment in the current in this period was close to the flood concentration and reached a value of 3"i0 -s g/cm s. The total measurement time in this section was 7 h. The results of investigations of current equilibrium conducted simultaneously with measurements on the section coincide with the data in [2], i.e., the thickness of the current h and the average values of the velocity ufn the vertical and turbidity S at the initial site remained constant 12 h with an accuracy of • During movement of the flow along the outer slope of the mouth bar (Bz-Bs) erosion of the bottom by the density current was observed in addition to the previously observed [i, 2] effects of an increase in thickness and density stratification and, therefore, the siltation calculations given below are only for the stretch located after site B3. Figure 3a shows the change along the axis of the bottom current in the value of Ap(S)/~o(S, T) characterizing the portion of the total difference of densities due to the increased turbidity of the current, i.e., the quantity AS(x) (Fig.…”

“…Investigations conducted during 1974-1976 [2] showed that the thickness of the current when formed remains constant with an accuracy of • until it dies out (in the section in Fig. 2 h =const in stretch Bs-Bg).…”

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Investigations of the distribution of suspended sediments in the upper pool of the reservoir for the Nurek hydroelectric station, which were carried out in [1973][1974][1975], showed that a bottom density current exists [1][2]. It was established that the bottom current transports the bulk of suspended sediments in the reservoir and, consequently, the pattern of the distribution of the density current also determines the deposition process of the suspended particles and the formation of bottom deposits.

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“…Owing to the presence of a concurrent flow of the overlying water layers in the reservoir toward the dam the velocity of the bottom current (Fig. Figure 5 shows the bottom profiles and levels in the longitudinal section of the reservoir during the period from October 1974 through October 1975 [2]~ A comparison of the results of calculating ~(x) by means of relationships given above with the data of direct measurements (Fig. Consequently, Eqs.…”