Abstract
This study attempts to present the theoretical analysis on the erosion of beaches adjacent to a river mouth which has got reduction of sediment supply and along-shore shifting of the opening, based on the analytical solutions of one-line model. The erosion of the beach adjacent to one side of river mouth when the river mouth opening shifting to the other side is presented through superposition of an existing analytical solution. Similarly, superposition of analytical solution for the case river delta formation can explain the retreat of river delta shoreline due to the reduction of sediment supply and the advance after the recovery of sediment supply. An analytical solution, which describes the evolution of river delta shoreline in case the adjacent beaches are bounded by rigid boundaries at the ends (shore-perpendicular structures), is also introduced. Theoretical comparison on the evolution of river delta shoreline during the processes of formation, reduction and recovery for the cases with and without rigid boundaries is also made.
