A number of small hydroelectric stations are presently operating under conditions of the high mountains of Pamir, in the territory of the Gorno-Badakhshan Autonomous Region. The experience in operating these hydrostatlons shows that difficulties related to shuga [frazll slush] occur during their operation, which leads to a reduction of power production and emergency shutdowns.Thus, a marked increase of the water level occurs in the diversion canal of the Khorog hydrostation on the Gunt River as a consequence of clogging of the cross section by shuga, which is accompanied by a reduction of water flow to the turbines of the hydrostation.The diversion canal of the Aksu hydrostatlon in the Eastern Pamir becomes completely clogged with shuga, which leads to long shutdowns of the hydrostation.The Namangut hydrostation on the Pyandzh River experiences complications in winter operation in connection with a accumulations in the lower pool of masses of shuga being discharged along the chute of the idle spillway.The difficulties experienced by small hydrostations of Pamir in the winter are a consequence of insufficient knowledge about the ice and thermal regime and absence of reliable methods of engineering forecast of shuga and ice phenomena on rivers in high-mountain regions. The results of investigations of the hydraulic, ice, and thermal regime of streams and lower pools of hydrostations located in flatland territories are generalized in [I]. However, owing to the differences in the hydraulic and morphometric conditions of flow in flatland and mountain rivers, the results obtained cannot be completely applied to the mountain rivers.
When piezometric tubes are joined by a common header they show a value close to the average pressure in the flow.The velocity tubes show the value of the specific kinetic energy of the flow and the Pitot tubes show the value of the total specific energy of the flow. A differential manometer connected to two header Pitot tubes installed in two cross sections of conduits of the investigated hydraulic system show the loss of energy between these cross sections.According to the design of the Rogun hydroelectric station, about 20 tributaries of the Vakhsh River will empty into the reservoir. Only three of them (Obigarm, Muzhikharv, and Dashtigurgon) have permanent observation stations of the hydrometeorological service, the data of which on the runoff and especially the sediment load are quite scant and irregular, the kinematic structure was not analyzed. For the other tributaries the hydrological and hydrodynamic characteristics were not studied earlier. In connection with this, the Mathematical Institute together with the Computer Center of the Academy of Sciences of the Tadzhik SSR and the Central Asian Branch of the All-Union Planning, Surveying, and Scientific-Research Institute (Sredazgidroproekt) carried out on-site investigations on the right-and left-bank tributaries of the Vakhsh River. With consideration of the characteristics of the hydrological regime and climate of the region, the most detailed investigations of the kinematic structure were carried out in the low-flow period, when the danger of rockfalls and mudflow phenomena decreased.Sites of existing stream-gauging stations were used for the observations, and in the case of their absence sites on straight stretches of the channels were selected. The "Inguri-5" apparatus, consisting of five current meters and a counting mechanism with five pulse counters, were used for measuring the velocity characteristics. Some hydraulic characteristics of tributaries of the Vakhsh River and stability parameters calculated from the July-August 1988 field data are given in Table 1.The Froude numbers Fr = Vav/~(Vav is the average velocity in the cross section, hay is the average depth, g is the acceleration of gravity) vary in the range 0.10-0.73; the minimum values occur for the Obigarm River and the maximum for the Obi-Shur River. During passage of the spring floods (April-May) the Froude numbers exceed unity: 1.1 for the Muzhikharv River; 1.3 for the Obi-Shur River, etc. The Reynolds numbers calculated in terms of Vav, hay exceed 105; the mean velocities of the turbulent flow were determined as the arithmetic mean values of the instantaneous velocities for various averaging intervals. The ratios of the average depths to the average diameters of the channel sediments hay/day vary from 2.8 (for the left-bank rivers Obi-Tagikamar, Obi-KhodzhavaUsho, etc.) to 10 (for right-bank tributaries). According to various classifications [1-4], the investigated tributaries belong primarily to mountain--piedmont rivers and partially to mountain rivers. On the basis of the field da...
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