Effects of the Caspian Sea water level change on Boujagh National Park, southwest the Caspian Sea

Abstract

Nowadays, climate change and sea level rise are serious threats to the social, economical and environmental vulnerability of the ocean coasts all around the world, and the Caspian Sea rapid fluctuations during the third millennium have set different conditions on the environmental structure of coastal areas. The main target of this study is to evaluate the coastline morphology behavior and the deformation of habitats and ecological condition of Boujagh National Park (BNP) due to Caspian Sea level changing during the progression and regression phases between 1978-2019. Initially, based on the available scientific documents, familiarity with the study area was carried out and the axes of measurements were defined. In field operations, sedimentation and erosion units of coastal zones and also different habitats were identified and geographically determined. In the next step, the rate of deformation of coastal habitats was calculated and classified using satellite images and GIS, and ultimately, validity of the results was verified with field evidence. The comparison of regression amount in BNP indicated that maximum negative shoreline displacement (892 m) has occurred in the east part of Sefid-rud River mouth during 1978-1995. So that, the shoreline negative changing has reached to 850 m in the north- western of central part of study area, while 738 m in north- eastern of central part in the period of 1995- 2019. The inundation zone extent has declined 104 ha between 1995 and 2019. Also the sea regression amount of area was 111 ha in the period of 1978- 1995, while changed to 380 ha during 1995-2019. During the last 24 years, there have been widespread environmental alterations in the studied area and a large part of the coastal wetlands has been dried up. The most important habitats affected by the Caspian Sea fluctuations include coastal lagoons, dry and wet sandy beach, fluvial meadow and river estuary.