North to South Variations in the Suspended Sediment Transport Budget within Large Siberian River Deltas Revealed by Remote Sensing Data

Abstract

This study presents detailed suspended sediment budget for the four Siberian river deltas, representing contrasting conditions between Northern and Southern environments. Two of the studied rivers empty their water and sediments into the marine located in the permafrost zone in the Arctic region (Lena and Kolyma), and the other two (Selenga and Upper Angara) flow into Lake Baikal located in the steppe and forest-steppe zone of Southern Siberia. For the first time, these poorly monitored areas are analyzed in terms of the long-term and seasonal changes of spatial patterns of suspended sediment concentrations (SSC) over distributaries systems. Remote sensing reflectance is derived from continuous time series of Landsat images and calibrated with the onsite field measurements of SSC. Seasonal variability of suspended sediment changes over deltas was captured for the period from 1989 to 2020. We identify significant variability in the sedimentation processes between different deltas, which is explained by particularities of deltas networks and geomorphology and the existence of specific drivers—continuous permafrost impact in the North and abundant aquatic vegetation and wetland-dominated areas in the South. The study emphasizes that differences exist between Northern and Southern deltas regarding suspended sediments transport conditions. Mostly retention of suspended sediment is observed for Southern deltas due to sediment storage at submerged banks and marshlands located in the backwater zone of the delta during high discharges. In the Northern (arctic) deltas due to permafrost impacts (melting of the permafrost), the absence of sub-aquatic banks and river to ocean interactions of suspended sediment transport is mostly increased downwards, predominantly under higher discharges and along main distributary channels. These results shine light on the geochemical functions of the deltas and patterns of sequestering various metals bound to river sediments.

Reemission of inorganic pollution from permafrost? A freshwater hydrochemistry study in the lower Kolyma basin (North‐East Siberia)

“…In further studies, a climate‐induced enhanced mobilisation of selected elements was highlighted (Frey & Mcclelland, 2009; Gabysheva et al, 2022; Holmes et al, 2012; Soromotin et al, 2022). In the case of Kolyma, a potential impact of climate change was signalled for the suspended sediment load in the recent decades, and mining impact was also observed (Chalov et al, 2018, 2021).…”

“…The described hydrochemical patterns including the water bodies of different status in hydrological system may be discussed also in Finally, it should be noted that dissolved elements are the most mobile in flowing waters. Therefore, their share in the transport of elements may be increasing in the total load along the river/oceanic transitional zone due to the higher losses of suspended load and bed load into the delta environments (Chalov et al, 2017(Chalov et al, , 2021Lisitsyn, 1995). Therefore, the dissolved elements calculation is important to further the comprehensive understanding of the changing Arctic rivers impact on marine environment.…”

“…Mann et al (2022) estimated also an increase of 50% (±25%) in Kolyma's mean annual runoff by 2100, in line with climate projections. Climate warming resulted also in an increase in Kolyma's sediment transport rates from 20 to 100 t km −2 year −1 in 1941–2000 (Chalov et al, 2018), which can be also attributed to mining impact (Walling & Fang, 2003) or changes due to permafrost thaw (Chalov et al, 2021).…”

“…Climate warming resulted also in an increase in Kolyma's sediment transport rates from 20 to 100 t km À2 year À1 in 1941-2000 (Chalov et al, 2018), which can be also attributed to mining impact (Walling & Fang, 2003) or changes due to permafrost thaw (Chalov et al, 2021).…”

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“…На очередном этапе на шей совместной работы было принято решение о прове дении исследования угледобывающего сектора Вьетнама с использованием результатов спутниковой съемки. С по явлением технологий дистанционного зондирования Зем ли из космоса спектр прикладных исследований значи тельно расширился, о чем свидетельствуют работы рос сийских и зарубежных исследователей [1,2,3,4,5,6,7,8]. Расстояние транспортировки вскрышных пород не пре вышает 2,5 км.…”