Researchers from Moscow State University named after MV Lomonosov have calculated the sediment formation pathways of the three major Siberian rivers, the Ob, Yenisei and Lena. The scientists’ work was published in the journal Catena.
Along with water, heat, and solutes, rivers carry particulate matter, also called fluvial sediment, to the Arctic. They contain dangerous compounds – heavy metals – and permafrost melting products. At the same time, rivers are increasingly “feeding” the Arctic seas.
Russian geographers modeled the processes of erosion (destruction of the soil) and erosion of the banks in the catchments of three rivers – regions where water enters them and occupies 14% of the Eurasian territory. They also estimated the amount of sediment deposited on slopes, floodplains and reservoirs.
It turned out that the catchment area of the Ob is largely subject to erosion – one and a half times more intense than the catchment areas of the Lena and Yenisei. Experts explain this by the fact that the upper reaches of the Ob are more suitable for agriculture, which intensifies the processes of soil destruction.
Channel erosion turned out to be greatest in the Lena: twice that in the Ob and almost ten times that in the Yenisei. According to geographers, this can be explained by the degradation of permafrost, which contributes to greater sediment flow.
Based on the results of the calculations, the researchers concluded that channel erosion in the lower reaches of rivers – adjacent to the ocean – contributes more to sediment formation than nearby soil erosion. At the same time, current river flow volumes cannot cope with the amount of material entering rivers as a result of erosion of soils and river banks. Therefore, more than 90% of all sediment does not reach the undercurrents and remains on slopes, floodplains and river beds.
Source: Ferra
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