Study of the relief transformation at arable lands becomes an actual problem due to the intensive use of interfluve sloped surfaces. This research examines the current state and dynamics of erosion network at arable slope in the upper Oka river basin. The riverbeds of modern streams are identified using the phytoindication analysis. The feature was detected out that these streams do not necessarily match with the ancient stream thalwegs. The radiocaesium analysis made it possible to show that soil washout magnitudes are comparable in the thalwegs of current and ancient streams, which are comparable in the length. Geomorphometric methods joined with the geoinformation analysis allow to quantify the role of current erosion network in transformation of the interfluve sloped surfaces relief.