Home – Home – Jornals – Earth’s Cryosphere 2023 number 1

This paper reports on the hydrogeological conditions and groundwater regime in the Lena River floodplain near Yakutsk. The published and archive materials, including field data collected by the authors in 2013-2021, were analyzed. Data from more than 70 boreholes were examined to characterize permafrost and hydrogeological conditions in the area. Data on groundwater level monitoring in the reclaimed area of the floodplain were also used. Over 250 sample analyses were interpreted to characterize the chemical composition of surface and ground waters. The results suggest that suprapermafrost waters in the high floodplain are recharged both by infiltration of river water and by a transit water flow under the river channel hydraulically connected to floodplain taliks. The seasonal and spatial variability of the chemical composition of waters was revealed in the Lena River and in the studied taliks. The surface and ground waters of the Quaternary aquifer on the east bank of the Lena River are characterized by the lowest total dissolved solids (TDS) concentration (0.1-0.3 mg/L) and by the magnesium-calcium chloride-bicarbonate composition. These waters are recharged by fresh water of the supra- and interpermafrost taliks of the Bestyakh terrace and by the riverbed taliks under small rivers. In the vicinity of Yakutsk, TDS concentrations in the Lena River and in the Quaternary aquifer increase to 0.5-1.3 g/L due to high mobility of chloride and sulfate ions migrating with the surface and suprapermafrost runoff from the low terrace, where the city is located.