Homayoun Khoshravan - Associated professor of the water research institute, Caspian Sea national research study center; Tehran, Iran
Parisa Poursafari Yekrang - Laboratory Research Expert in Water Engineering Department, Guilan University& PhD Candidate in Environmental Engineering water wastewater TehranUniversity

The shifting of coastlines under the influ ence of hydrodynamic factors and the increase in sea level havecaused serious damage to economic, social, and environmental infrastructure, and the rapid fluctuations inthe Caspian Sea water level since the ۲۰th century have created unfavorable condition s for the environmentof coastal areas. The main objective was to assess the severity of changes in the shores of Gomishan Lagoonduring a period coinciding with the decrease in the Caspian Sea water level during the years ۱۹۹۵ ۲۰۱۹.Morphological conditio ns were investigated using field observations and satellite image analysis. Theintensity of coastline displacement was calculated by processing multi time belonging to the years (۱۹۹۵۲۰۱۹) GIS environment and using Digital Shoreline Analysis System (DSAS Based on shorelinemovement, the study area was classified into three groups according to shoreline changes ( medium,and low). The results show that the northern extremities of Gomishan Lagoon have the highest amount ofshoreline displacement and the amount of shoreline displacement gradually decreases in the central andsouthern areas. The only exception is the negative movement of the shoreline, overlooking the mouth ofGorganrud River, which has retreated landward by ۱۵۰ cm in ۲۴ years, to ۸۷۸ m The average annualdisplacement of the coastline in the study area was ۱۹۵ m, with maximum and minimum displacements of۳۴۴ m and ۳۷ m, respectively. Additionally, the coastline retreats approximately ۵۰ m each year at themouth of Gorgan River.

Caspian Sea, Fluctuations, Gomishan Lagoon, Shoreline displacement