Kim, C.W.; Shim, W.J., and Yim, J., 2019. Multi-decadal shoreline change interpreted from aerial photographs in Ilgwang Beach, South Korea. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 316-320. Coconut Creek (Florida), ISSN 0749-0208.

The aim of this study is to use multi-temporal aerial photographs spanning a period of 70 years from 1948 to observe shoreline changes at Ilgwang beach in the northeastern part of Busan, which is an area that has excellent economic, social, and natural attributes. Photographs were enhanced using geometric correction, and the shoreline and beach width were extracted using a wet/dry line. Decadal changes were statistically analyzed using the Digital Shoreline Analysis System, 4.3 (DSAS). The sediment budget of the watershed was calculated using the Revised Universal Soil Loss Equation (RUSLE) and a correlation analysis was then conducted against beach width. The impact of typhoon Thelma which occurred in 1987 was strongly observed, and its occurrence prevented any clear trends in shoreline changes from being observed between 1948 and 2017, although a dike constructed on northern part of the beach caused strong deposition in transect 1 from 2009. In addition, the beach width was found to be relatively narrow at the both end of the beach and in the center where a small stream flows. The annual rate of change in beach width was 0.31 m in the northern part, 0.23 m in the central part, and 0.25 m in the southern part meaning sedimentation. The sediment budget of the watershed was positively correlated with beach width; and this result highlights the importance of proficient watershed management with respect to beach management. It was evident that the artificial structure constructed in the middle part of the beach had an influence on sediment transport, and changes related to the typhoon were evident; these results indicate that shoreline changes are affected by various factors, including the human impact on the watershed and natural conditions, and it is thus necessary to use a spatially integrated management approach that involves all these factors.