Improvement of coastal GIS data by precise determination of MSL in south Iranian coast Iraj Jazireeyan Faculty of Geodesy and Geomatics Eng., Iran Email: jazirian@kntu.ac.ir , alesheikh@kntu.ac.ir Ali Asghar Alesheikh Faculty of Geodesy and Geomatics Eng. Abstract National Cartography Center of Iran (NCC) collecting local records of sea level variation and sea-level change in south of Iran in Persian Gulf .For studying and analyzing sea level variations requires an accurate determination of local sea-level changes. This paper examines two approaches for getting better estimates of local sea-level change. First, South Iranian coast case studies are used to illustrate localized differences in sea-level change records adjacent to historic tide-gauge sites. Second, the paper illustrates the use of an inexpensive GIS-based for determining coastal vulnerability assessment. The paper discusses the potential impact of change on various types of South Iranian coasts and demonstrates the importance of recognizing different sea-level histories, together with an understanding of coastal processes in order to assess coastal stability.