Abstract: In his study of jet-assisted hydraulic jump in rectangular channel, France investigated the stability of the hydraulic jump and the effectiveness of the jet over a wide range of operating conditions. He observed that the stabilization of the jump is dependent on a number of parameters like the Froude number, channel bed slope, etc. but concluded however that the angle of inclination of the jets has the most pronounced effect. In the present research researchers develop a mathematical model for dredging a rectangular open channel with hydraulic jump and abrupt change in slope using the conditions of geometrical and dynamical similarities. Applying the model to a numerical example, new parameters of the new (excavated) channel are determined and compared with those of the original channel.