Abstract
In recent years, severe coastal erosion in river mouth delta has been observed worldwide. To discuss such development of river mouth delta and shoreline retreat, an analytical solution of a one-line model, which is based on linearlized diffusion equation, may be used. By superimposing the solutions, it is possible to study various conditions and useful for understanding the essential phenomenon. However, the existing analytical solution for development of river mouth delta is restricted for rivers pour into an infinite length of the sandy beach. For this reason, it is impossible to take into consideration the influence of the edge of the beach such as capes and coastal structures. In this research, therefore, a theoretical study on a river mouth delta, which develops in a finite length sandy beach, has been investigated. It is found that the influence of the boundary does not appear when the dimensionless time t* is less than 0.3, and the existing solution can be applied. When the dimensionless time is sufficiently large, it shows a simple delta development process in which the parabolic shaped shoreline moves in parallel. At this time, the longshore sediment transport rate decreases linearly from the river mouth to the boundary. This theory was verified using laboratory experimental data from Refaat (1990).
