The existence of the ditch between the Tongzhou shoal and the Langshan shoal should have some influence on the formation of the shallow area of the east Tongzhou shoal watercourse. The ditch not only makes against to the protection of the nearby shoals, but also plays a significant role of dispersing or breaking up the mainstream. So, as to the navigational channel regulation project of the Tongzhou shoal, both restricting the ditch, protection the shoal and improving the hydrodynamics of the shallow area should be taken account in at the same time. Based on a well calibrated 2D hydrodynamic model, the currents distribution on the shoals, ditch, tidalflat and the watercourses are analyzed, and a suitable position for restricting the ditch currents and regulating the channel is proposed. The proposed layout is certified being of dual role of both stabilizing river regime of this reach and improving the scour capability of the shallow area through scenario study.