Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2023, Vol. 20, No. 3, pp. 323-329
Changes in Sulak River plume parameters after mudflows in the mountains of Dagestan
O.Yu. Lavrova
1 , K.R. Nazirova
1 , Ya.O. Alferyeva
2 , D.M. Soloviev
3 , E.V. Zhuk
3 1 Space Research Institute RAS, Moscow, Russia
2 Lomonosov Moscow State University, Moscow, Russia
3 Marine Hydrophysical Institute RAS, Sevastopol, Russia
Accepted: 30.06.2023
DOI: 10.21046/2070-7401-2023-20-3-323-329
Measurements of Sulak River plume parameters in the Caspian Sea conducted from 2 to 7 June 2023 concurrently with satellite survey allowed tracing changes in water turbidity (WT) and suspended particulate matter (SPM) concentration in the near-mouth zone after the arrival of mudflow masses into the sea. Heavy rains in the mountains of Dagestan on 31 May 2023 caused mudflows which entered in particular the Sulak River. Two days later, on 2 June, mud masses together with river water flowed into the Caspian Sea. In the near-mouth zone, WT values exceeded 1000 NTU, which was beyond the allowable threshold of a portable turbidimeter employed for turbidity measurements. On 2, 4, 5 and 7 June, quasi-synchronously with satellite imaging, measurements were conducted from a small boat using various oceanographic equipment. They were accompanied with water sampling for further determination of SPM concentration and mineral composition. The linear dependence revealed between WT and SPM concentration made it possible to calculate WT which could not be measured in situ: it amounted to 1247 NTU at SPM concentration of 1097.4 g/m3. Satellite data were used to compile WT maps using the Dogliotti 2015 algorithm. The results of satellite observations and in situ measurements showed that, within two days, WT and SPM concentration at the nearest to the river mouth station dropped 6-fold and continued to decrease to the average values for this area in early June. Determined by X-ray phase analysis, the mineral composition of suspended solids on the day of mudflow arrival into the sea was represented mainly by clay minerals, their content reaching 75 %. Later, by 7 June, the mineral composition returned to the average values and the content of clay minerals did not exceed 44 %.
Keywords: satellite remote sensing, plume, turbidity, suspended particulate matter concentration, mineral composition of suspended solids, Sentinel-2 MSI, Landsat-8 OLI, Landsat-9 OLI-2, Sulak River, Caspian Sea, in situ measurements, mudflows
Full textReferences:
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