An integrated sediment management approach that includes the recovery of the amount of declined sediment supply is effective as a fundamental solution to coastal erosion. During planning, it is essential to analyze the transfer mechanism of the sediments generated from estuaries (the junction between a river and sea) to assess the amount and rate of sediment discharge (from the river to sea) supplied back to the coast. Although numerical models that interpret the tidal sand bar flushing process during flooding have been studied, thus far, there has been no study focusing on the formation and development processes of tidal sand bars. Therefore, this study aims to construct wave deformation, flow regime calculation, and topographic change analysis models to assess the amount of recovered sediment discharge and reproduce the tidal sand bar formation process through numerical analysis for integrated littoral drift management. The tidal sand bar formation process was simulated, and the wave energy and duration of action concepts were implemented to predict the long-term littoral movement. The river flux and wave conditions during winter when tidal sand bars dominantly develop were considered as the external force conditions required for calculation. The initial condition of the topographic data directly after the Maeupcheon tidal sand bar flushing during flooding was set as the initial topography. Consequently, the tidal sand bar formation and development due to nearshore currents dependent on the incident wave direction were reproduced. Approximately 66 h after the initial topography, a sand bar formation was observed at the Maengbang estuary.

Shoreline variations occurring in sea areas are caused by the combined effect of sediment transport due to the inflow and outflow of sediment caused by waves at the left and right boundaries of the sea area and the depth of movement limit. Although many studies have been conducted to understand the characteristics of sediment transport, assessment on valid sediment run-off supplied to the sea area from mountains and rivers in sea areas with river inflow and research on the sediment budget analysis considering the topographical characteristics of South Korean sea areas are insufficient. Therefore, the establishing mitigation measures considering comprehensive viewpoints is necessary to systematically respond to various natural and anthropogenic causes. Moreover, further research related to the setting and analysis of major parameters must be conducted for improving the prediction performance as well as the evaluation system for analyzing the sediment budget, which is a quantitative evaluation index for coastline management optimized for domestic waters. This study aimed to establish a comprehensive analysis system for analyzing the sediment run-off generated in domestic sea areas and develop a shoreline model (In-MPaS model) considering mixed grain sizes for advancing sediment run-off analysis. With the observation data, the parameters necessary for the numerical analysis were set, the sensitivity of the In-MPaS model according to the particle size distribution of the sediment constituting the sea area was evaluated, and the major parameters for improving the prediction performance were analyzed. Consequently, it was found that the prediction performance of the In-MPaS model improved in terms of valid sediment run-off as well as the sediments constituting the sea area (which was assumed to have mixed grain sizes rather than a single grain size(D50). In particular, considering the topographical properties that regulate sediment transport due to the island (Deokbong Mountain) at the foreside of the river mouth bar, the shoreline prediction performance was significantly improved with the application of groins, which exhibit structurally similar performance.