Evolution and Sedimentation Mechanisms of Estuarine Beach in the Nakdong River Estuary, Korea: Natural and Human Impact

Dadae Beach located in the Nakdong River estuary has been continuously evolving as the result of natural and anthropogenetic activities. Due to the geographic characteristics of an estuarine beach, in which the estuary, ocean, and human activities converge, it is very difficult to identify the factors shaping changes in the sedimentary environment and present quantitative results. Nevertheless, this study presents a survey of hydrological characteristics that reveals major depositional mechanisms and the factors impacting the sedimentary environment by analyzing morphological variations over the last five decades. We found that Dadae Beach has transformed from a marine system to an estuarine system through three major stages of evolution over the last five decades and has now reached a quasi-equilibrium state. The depositional mechanism contributing to the deposition of Dadae Beach is mainly driven by rainfall during the wet season. In addition, the strengthening of ocean energy during the dry season causes erosion. By proposing a new evolutionary history of Dadae Beach which had previously been considered a byproduct of the barrier island generation process of the Nakdong River, we suggest a novel conceptual model for estuarine beach evolution.