Results of Local Geodetic Monitoring of Lateral Erosion of the Oka River

The paper presents the results of geomorphological stationary works in the downstream of the Oka River bend near the “Kostino” village, center of the European part of Russia. Field observations of bank erosion rates at this survey site indicate an annual retreat of 1.67 m of the subaerial part of the bank. During two years of monitoring, spring floods completely flooded the stationary. In 2023, the maximum discharge of the Oka River was approximately 4700 m 3 /s and exceeded 2022’s value by 62%. We used unmanned aerial vehicles (UAVs) and obtained high-resolution surface rasters and calculated linear, area and three-dimensional erosion rates. The relief response to increased flood energy in the second year of observations was expressed in almost twofold acceleration of bank failure (by 95%). The concave bank sections, composed of sand and sandy loam, have undergone particularly intensive erosion in a number of places, which is confirmed by our monitoring of the channel bed. By surveying by season of the hydrological year, we found that subaerial bank erosion does not stop in summer and autumn, although it only reaches 20% of the full-year volume.