Formation and Reduction Processes of River Deltas ; Theory and Experiments

Abstract

Beach erosion has recently been recognized as accelerating due to changes in sediment sources from rivers. This can be considered as reduction processes of river deltas. In this paper, the formation and reduction processes of river deltas are first investigated theoretically by introducing the non-uniformity of longshore sediment transport into the equation of continuity of shoreline change. Theoretical solutions to shoreline changes in the formation and reduction processes are derived from the simplified governing equations using the concept of one-line theory. By numerical results of the solutions, shoreline changes in the formation and reduction processes are well explained. Secondly, experiments both on the formation and reduction processes were carried out. The theoretical results of the processes compared favorably with the experimental ones, indicating that the processes can be well explained by specifying the predominant parameters.