Interpretation of Location Condition and Topographical Changes around the Jangamjinseong Fortress in Seocheon using Geographic Information System

The Jangamjinseong fortress is a naval base where the Geumgang river and meet the West Sea. It is a gateway to the inland of Korean peninsula and a strategic point up the Hangang river, and is the site of large-scale wars of various eras, including the battles of Baekgang, Gibeolpo and Jinpo. Humangsan mountain, where the Jinseong is located, and Jeonmangsan mountain, where the Janghang Refinery Chimney is located, both belong to the Janghang Breccia Formation in Cretaceous, and rise like a huge dome, forming a unique topography. Quaternary intertidal zone was widely formed in front of the Jinseong, and historical maps from the 18th and 19th centuries, as well as topographical maps from the Japanese colonial period, show that the area’s topography has continuously changed due to land reclamation. The absolute sea level on the west coast is currently at its highest, but the relative sea level around AD 500 was about 2 m higher than it is now, and is interpreted to have gradually lowered since then. Thus, if a basic model using geographic information system is built based on the current topography around the Jangamjinseong fortress and the paleotopography is simulated through sea level fluctuations, it is difficult to predict topographic changes even if the sea level rises by 2 m due to the reclaimed land and seawall. However, inside the sea wall, low-lying areas were distributed along the coastline at about 3 m above sea level, so the flooded area was searched under the assumption of artificial flooding. As a result, the low-lying area between mountains of Jeonmangsan and Humangsan was flooded and took the form of a bay, and the Jinseong is located on the eastern side of the bay, where ships can enter directly to dock. Therefore, when viewing the Jangamjinseong fortress from the sea, it is difficult to see because it is obscured by the Jeonmangsan mountain, and it has a natural fortress topography that makes it easy for ships to enter and exit using the current. This is a simulation of the topography using an artificial flooding model, so it is necessary to review its reliability with the paleotopography. If sea level changes through sedimentary layer analysis of tidal zone, remote sensing and archaeological excavations are carried out, the topographical change and location condition of the Jangamjinseong fortress will be able to be interpreted more clearly.