Caspian rapid Sea level fluctuation and intensity of displacement of the shorelines in the Gorgan Bay and Miankaleh coast

Displacement of coastlines under the influence of hydrodynamic factors and rising sea levels cause serious damage to economic, social and environmental infrastructure, and rapid fluctuations in the Caspian Sea water level since the twentieth century have created adverse conditions for the coastal environment. The main objective is to assess the severity of changes in the shores of Gorgan Bay and Miankaleh coast as protected environmental areas of wildlife sanctuaries and biosphere reserves during a period coinciding with the decrease of the Caspian Sea water level during the years ۱۹۹۵-۲۰۱۹. The morphological conditions of the coastlines of Gorgan Bay and Miankaleh coast were investigated by field observations and analysis of satellite images. A total of ۱۰ study axes were selected around Gorgan Bay and Miankaleh and the intensity of shoreline movement by processing multi-time satellite images belonging to the years (۱۹۹۵-۲۰۱۹) in the GIS environment and with the help of digital software for coastal line analysis (DSAS), was calculated. Based on the shoreline movement, the study area was classified into three groups with shoreline changes (high, medium and low). The results show that the northeastern extremities of Miankaleh and the western extremity of Gorgan Bay have the highest coastline displacement and the central areas south of Gorgan Bay and the north-central part to the western part of Miankaleh coast have very little displacement. For comprehensive management of coastlines in the study area, focus on areas with high physical vulnerability is necessary and continuous control of quantitative and qualitative changes in coastal habitats affected by fluctuations in the water level of the Caspian Sea can reduce the existing challenges.

Keywords:

Caspian Sea , Fluctuations , Gorgan bay , shoreline relocation