Kim, J.; Choi, J.; Choi, C., and Hwang, C., 2017. Forecasting the potential effects of climatic and land-use changes on shoreline variation in relation to watershed sediment supply and transport.This study investigated the potential effects of future climatic and land-use changes on sediment supply and shorelines in the Hoeya River estuary, Korea. Historical shoreline variations were determined along Jinha and Solgae Beaches for the period 1975–2013 using the Digital Shoreline Analysis System. Sediments during future periods were simulated in this watershed under the Representative Concentration Pathways 4.5 and 8.5 scenarios using the soil and water assessment tool model. Subsequently, this study analyzed the correlations between the beaches and the sediment supply. For the natural beaches BS-I (0.805) and BS-II (0.700) in 1975–2013, the river-supplied sediment was closely correlated to shoreline changes. The area of beach sediment for future periods was assessed based on R-squared values. The artificial beach BS-III (0.203), which had remained relatively stable in 1975–92, showed shoreline erosion following this period. This beach is now artificially supplied with sediment because of a training dike. In 1986, because of the presence of a dam, a decrease in the discharge volume of suspended solids from the watershed caused a clear erosional trend in artificial beach BS-IV (0.432) from 1975. Artificial activity in the study area has caused major changes to the shoreline, but the R-squared values are relatively low. In the future, the area of the natural beach will increase during spring and winter and will decrease during summer and autumn. Furthermore, these seasonal trends in future periods may be amplified by seasonal variability in the wave direction. These results are expected to improve the understanding of shoreline changes that contribute to sediment supply and transport in river watersheds, which has significant implications for the effective management of the coastal environment.