The article deals with the processes of slope erosion, leading, in particular, to emerging a gully, its most dangerous type. The concentration of this process’ products in certain places on the slope leads to increased soil destruction and formation of narrow extended gaps, which quickly turn into wide ones. The ravine continuously increases in size as the destroyed soil is constantly carried out of it. Any known methods of combating this, to one degree or another, boil down to creating protective barriers which prevent liquid products of planar soil washout from entering the ravine. That is why the author examines the pattern of erosion products’ streamlines on a flat slope where an extended gully is being formed. The concentration of streambeds at the top generates soil destruction to an even greater degree and causes the transformation of the gap into a gully. However, independent of the length, only part of the liquid flowing down the slope gets into it. The stream area to the left and right of the axis is limited by specific (edge) lines; therefore, by constructing a linear barrier that blocks the flow of liquid erosion products within these lines, one can significantly slow down or even stop the growth of the ravine