This study is an analysis of the possibility of harnessing backwater in open river channels to create waterways in the area of the river mouth. To accomplish this, simplified methods of analysing non-uniform flow have been assessed, with the use of Rühlmann’s, Tolkmitt’s and Bresse’s equations. It was demonstrated that Bresse’s method is the best of the three – the results obtained by using it to determine the range of backwater from the receiving body are much closer to true values than for the other two, and it is the only method that meets the physical criterion of backwater size with the boundary condition of Chezy depth tending to 0. The carried out analyses demonstrated that it is possible to create high-class waterways in lower reaches of rivers by modifying the geometry of their channels, namely the depth and slope of their bottom