The height of a damless water intake structure threshold

Abstract

More than 80% of the annual water consumption in Uzbekistan comes from large transboundary rivers such as the Amu Darya and Syr Darya. The rest of the water is formed on the territory of the Republic. Almost all year round, the turbidity of the Amu Darya and Zaravshan rivers is 3÷5 g/l, reaching 15÷18 g/l during flood periods.in most cases, water from the rivers is taken into irrigation channels using damless water intake structures. In order to prevent the ingress of bottom sediments from rivers into channels, thresholds have been constructed at water intake structures, the height of which is set constructively. As a result, bottom sediments pass through thresholds and move along the bottom of channels, reducing their cross-sections, as well as filling the chambers of pumping stations and pressure basins of hydroelectric power plants with sediments. After getting into the flow parts of pipelines and hydraulic machines (pumps and hydraulic turbines), they lead to abrasive wear, as well as other negative consequences. A lot of work has been done to prevent sediment from entering through water intake structures, but so far none of these proposals has provided an effective solution. In the laboratory of the Tashkent Institute of irrigation and agricultural mechanization engineers, a series of experiments were conducted on a glass hydraulic tray to determine the height of bottom sediments, taking into account their heterogeneity. Based on experiments, the dependence on determining the height of the ridge is derived. Based on the obtained dependence, a method for determining the height of the threshold of a damless water intake structure is proposed. This technique was experimentally tested on a laboratory tray. Specifying the threshold height will lead to optimization of capital costs for the construction of the threshold of the water intake structure, as well as reduction of operating costs for cleaning channels from sediment and repair work of hydraulic machines from hydroabrasive wear.