مخاطرات محیط طبیعی (Nov 2021)
Monitoring Coastline Changes of the SE Caspian Sea Coasts, 1977 to 2017
Abstract
The coastline is one of the most rapidly changing landforms of coastal areas. It changes constantly because of the rising sea level due to natural conditions and the influence of human activities. The position of coastline usually changes following the tides. Therefore, quick and accurate measurements of dynamic coastline changes are of great significance to coastal management, sea level change research, environmental protection, and sustainable coastal development. The main purpose of this study is monitoring Caspian Sea coastline changes under the influence of sea level fluctuations during the period 1977-2017. In this regard, the Landsat satellite imageries collection, Google Earth, topographic maps and fieldworks has been used in an analytical-descriptive manner. Then, making the necessary corrections on images, combining and merging the bands with each other, the best and most appropriate band composition was selected to extraction the coastline. Then, according to the rate of changes in the region's shores, 7 littoral cells were defined in the region. In the next step, the coastline position was extracted by tracking the location of the high watermark through visual and spectral separation methods and entered the database as digital layers. The coastline changes are monitored in two time periods, from 1977-1996 and 1996-2017. The results show that during the first period, erosion was the dominant process in the region. The lowest erosion rate was about 2.46 km2 in the LC2 and the highest was about 168.80 km2 in the LC5 and only about 0.0159 km2 sedimentation occurred in the LC1. But during the second period, the predominant process in the region was sedimentation. The minimum and maximum sedimentation rates were about 1.40 km2 in the LC2 and about 72.55 km2 in the LC5, respectively. During this period, only about 0.68 square kilometers of erosion occurred in the LC1.
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