The paper presents some results of a study conducted in 2015-2023 in an experimental area located in the Upper Oka Basin (Oryol District of the Oryol Region, Russia). Soil losses were studied, which were observed due to water erosion in a stream formed after spring heavy rains and in thalwegs of plowing furrows in an agricultural field with heavily, lightly and medium overplowed gray forest soils. The purpose of the study was to elaborate proposals for the increasing coefficients application to soil runoff estimations produced according to the equations developed by authors. The computational algorithm of the equations is based upon the accounting of in-soil caesium-137 radioactivity, the catchment area and the profile curvature of the topography relief. The equations were elaborated for caesium-137 radioactivity estimation (used as a marker of soil runoff) at plots with soils of varying washout (degradation) degrees. It has been established that increasing coefficients have to be applied to sectors of streams and plowing furrows found on satellite images or during visual inspection. The comparison results of soil loss observed in the stream and in the plowing furrows showed that soil loss in the stream in a sector of heavily overplowed soils exceeds soil loss in the plowing furrows by 1.7-2.0 times. It is proposed to apply the 1.7 increasing coefficient to soil runoff estimations in thalwegs of plowing furrows in areas with heavily overplowed soils with 1°-2° slope. The increasing coefficient for streams in these areas is higher - it reaches 2.0 or more. The increasing coefficient for streams in an area of lightly overplowed soils with 4°-6° slope, is 1.3-1.4. The study relevance is determined by the need to assess a soil loss observed due to water erosion, when ensuring adaptive land use management. It is concluded that the influence of the soil overplowing degree onto the water erosion development requires additional research. © 2025 Lomonosov Moscow State University. All rights reserved.