This paper shows a method of river channel excavation plan considering unsteady flood flow using a numerical quasi-3D unsteady flood flow and 2D bed variation analysis model based on the observed temporal changes in water surface profiles in the downstream area of the Tone River. At first, we verified accuracy of the numerical model comparing calculation results with the observed temporal changes in water surface profiles, observed flow hydrograph and the bed variation before and after floods. The numerical model enable more efficient and effective river channel excavation plan.
