| چکیده انگلیسی مقاله |
This paper presents a comparative analysis of the sediment budgets of the Ob' and the Yenisei, based on the empirical measurements and simulations. The results of the work are numerical ratios accumulation, erosion, and runoff of sediments of the studied basins. The RUSLE model was used to calculate soil erosion by the GMTED 2010 DEM with a resolution of 250 m. The calculation of bank erosion was based on the use of GSWE automatic image decoding data and the calculation of the average height of the eroded bank with the ArcticDEM with a resolution of 2 m, in addition, the mean river depth was estimated by Shesi equation from the global databases of morphometric characteristics HYDROAtlas and GWRL. Sediment runoff was estimated by two methods. The first method was an assessment based on monitoring observations of the SSC of Roshydromet. The second method was based on data from field measurements of sediment runoff by MSU in 2018 and 2019 in the mouths of the Ob (Salekhard) and Yenisei (Igarka). In the second case, to calculate the sediment runoff, a method was developed for measuring the sediment runoff with the backscatter intensity of acoustic rays from the ADCP RiverRay 600 kHz. The transition from instantaneous measurements to average annual values was performed using the Makkaveev model, which is the quadratic dependence of sediment runoff from water discharge with erosion coefficient. For the Ob, this proportionality coefficient calculated values are from 0.42 to 1.05, and for the Yenisei is 0.68. Thus, the difference between total erosion (1250 Mt. yr-1 + 35 Mt. yr-1 for the Ob and 315 Mt. yr-1 + 21.9 Mt. yr-1 for the Yenisei) and sediment runoff in the mouths (63.5 Mt. yr-1 for the Ob and 32.5 Mt. yr-1 for the Yenisei) was used to calculate the total deposition of matter in the catchment area during the transport of sediments from sources to sinks, for the Ob total accumulations is 1269 Mt. yr-1, for the Yenisei is 334.5 Mt. yr-1. For the unregulated part of the Ob' catchment, the accumulation was 56.5 Mt. yr-1, and for the unregulated part of the Yenisei catchment was 43 Mt. yr-1. The coefficient of reduction of sediment runoff (1/SDR) downstream, based on new samplings of sediment runoff in 2018-2019 in the mouths of rivers, for the Ob and Yenisei both, was 2.3, and for the entire catchment area 20 and 30 respectively, this confirms the hypothesis of the accumulating regime of large rivers. |
