Lee, C.K.; Yun, K.; He, G., and Park, B.W., 2021. Estimation of submerged coast by existing survey data and topographic survey. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 449–453. Coconut Creek (Florida), ISSN 0749-0208.
The purpose of this study is to investigate whether registered land located on a coast is submerged during high tide. The most important data when judging whether the registered coastal land is submerged are cadastral maps and topographic maps. In Korea, all land parcels have been registered in the land ledger and cadastral map in the 1910s. A land ledger is a document that contains the address, area, title, grade, and owner of the parcel, whereas a cadastral map is a graphical representation that contains the location and boundary of a parcel. Even if the boundary of the parcel changes at the site, the boundary of the cadastral map remains unchanged before the land register is modified officially by the request of the owner. For submerged land, two cases exist. Case 1 is after the land is submerged and left without restoration. Case 2 is after the land has been restored following its submersion. In case 1, the coastline of a submerged land can be surveyed by surveying in situ. However, in case 2, the coastline cannot be surveyed at the time it is submerged. In this study, a coastline is extracted using aerial images after it was submerged. When the coordinate systems of the cadastral and topographic maps are the same, changes in the land boundary can be determined easily by overlaying the two maps based on the absolute coordinate system. However, if the coordinate systems of the two maps are different, then another method is required. A simple method is to translate and rotate a map based on the boundary lines of features displayed on two maps to overlay another map at the appropriate location. In this study, a cadastral map is translated and rotated on a topographic map based on boundary lines of unchanged features on two maps to determine whether a coastal land is submerged. The proposed method renders it easy to determine whether land is submerged as well as the amount of parcel area submerged.