The article discusses the methods of determining the longitudinal slopes of rivers, their advantages and disadvantages are noted. Various methods of determining the longitudinal slopes of rivers are analyzed. It is revealed that the weighted average slope adopted by the hydrometeorological service, determined by the graphoanalytic method, does not fully reflect the essence of the influence of slopes on the speed of water movement. It is noted that it is expedient to use the differential equation of uneven motion to determine the slopes of the water surface in the lower reaches of lowland rivers. The criterion ratio of slopes characterizing the stability of the riverbed in the longitudinal direction is revealed. The hydraulics-morphological method of determining the level and longitudinal slope of the free flow surface, as well as quantitative criteria for the movement of river flows, has been continued.

https://doi.org/10.1088/1755-1315/1045/1/012009

About the longitudinal slopes of flat rivers

The accumulation of sediments in reservoir is always a problem. Over time, these accumulations occupy the volume meant for water management, dramatically reducing the reservoir's effectiveness. The environment of the river basin below the reservoir undergoes significant changes. In this regard, assessing changes in volumetric W-H characteristics, particularly in reservoirs built on high turbidity rivers, is critical. The Mataghis Reservoir on Tartar River was chosen as the object of study. The quantity of accumulated sediments was established by original measurements and was calculated in three hydrologic ways at distinct stages of operation. The actual graphs showing the reservoir's W-H volumetric characteristics were made two decades after commissioning and are still in use. According to the findings, over 70 per cent of the reservoir volume has been filled with sediments over the course of the reservoir's thirty-year operation. A theoretical model of the sediment buildup process in basins has been created. Separate parameters have been created for the deposition of bottom sediments entering the reservoir and suspended particles in the flow. Based on them, the patterns of distribution of accumulated sediments according to the length and height of the reservoir were drawn out. The vertical pulsation velocity and the results of studies for determining the minimum rate of soil particle flow were used. To solve sedimentation problems in operating and newly constructed reservoirs, a methodology for evaluating changes in the amount of collected water and changes in the volume of water control, as well as a theoretical method for projecting their future behavior, can be applied

Study of sediment deposition processes and assessment of the change in the W-H characteristics of the madaghis reservoir

Hydraulic resistances of eroded riverbed and assessment of their sustainability

The Amu Darya river carries a large amount of up to 15 kg/m3 of suspended matter containing up to 85-90% suspended and 10-15% bottom sediments, which pose a serious threat to the hydroelectric power station and irrigation systems operating in its basin. In case of dam water intake, head sump tanks are provided in the composition of waterworks. So, in the composition of Right-Bank and Left-Bank, sedimentation tanks with mechanical cleaning to protect the channels were built at the Takhiatash hydroelectric complex Kaskelenskaya and Selinsky irrigation system. It is established that the hydraulic and alluvial modes of operation of these settling tanks depend on the water, alluvial, and backwater modes of operation Takhiatash waterworks. It is noted that due to low water conditions, this hydroelectric power plant operated for a significant part of the year with fully closed gates in all spans, producing intensive siltation of the upper stream. These processes led to a change in the alluvial mode of operation of the settling tanks. At the same time, due to low water and excessive design dimensions, in the first years of operation, these settling tanks were heavily silted up, the bottom mark rose to 17.2 m (above the design 165 m). Properly designed settling tanks should prevent siltation of main and distribution channels while respecting the transport capacity of the channels located below. It is proved that some well-known methods for calculating settling tanks, due to their complexity and bulkiness, cannot be used in calculating siltation modes of settling tanks under operational conditions that require simplification or finding a simpler relationship. A simple method is developed for calculating the dynamics of sediment deposition in irrigation sump tanks based on the probability of turbulent pulsation motion. Recommended: for normal operation of irrigation septic tanks, it is necessary to carry out systematic monitoring of the output turbidity and intensity of treatment, as well as water supply according to the water consumption schedule.

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Kadirbek Nazarbekov

Papers

Hydraulic calculation of irrigation settling tanks of Amu Darya irrigation systems