Effect of a density current on reservoir bottom relief and levels

Abstract

Durlng a study of the dynamics of the bottom stratified current in the Nurek reservoir during 1974Nurek reservoir during -1977 data were obtained on the formation of bottom deposits in the zone of action of the density current. The importance of comprehensive, on-site hydrophysical investigations of siltation, scouring of the bottom, and transport of the suspended load by a density current for the design and operation of reservoirs, ship canals, and other hydraulic structures determined the 8oals of the present work: i) a generallsation of the results of direct measuruments of siltation of the reservoir in the zone of action of the underflow density current during the period from 1974 through 1977; 2) an analysis of certain results of investigations of the main processes of mass exchange in the stratified current influencing the formation of bottom sediments on the basis of data from measurements taken in 1977.

Equipment for measuring current velocity, water temperature, and suspended sediment concentration in a reservoir

“…In different seasons the suspended sediment concentration S in the flow varied from 5 to 300.10 -5 g/cm ~, the differences of the water temperatures AT in the bottom flow and above its upper boundary was plus 0.6-minus 6eC. The rise of the level of the bottom of the axial line of the flow due to deposition of sediment was on average 7 m per year in the first stage of operation of the reservoir [5]. The density of the suspended material Ps = 2.5 g/cm 3, the particle size d did not exceed 70 ~m.…”

“…The thermophotonephelometer was used in investigations of the structure of the bottom flows in the Black Sea and Nurek reservoir [5,6]. More than I000 nephelometric profiles and vertical distributions of the water temperature were measured in sounding regimes without raising the detector on board during 24-h recording cycles on hydrological sections and planar surveys.…”