year 13, Issue 1 (Spring 2023 2023)                   E.E.R. 2023, 13(1): 29-52 | Back to browse issues page

XML Persian Abstract Print


Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:

Alizadeh S, Yamani M, Sarvati M, Ghahroudi Tali M. Analyzing the degree of vulnerability along the coast line of the west of the Caspian Sea (Talesh to Anzali). E.E.R. 2023; 13 (1) :29-52
URL: http://magazine.hormozgan.ac.ir/article-1-753-en.html
Faculty of Geography, University of Tehran, Tehran , myamani@ut.ac.ir
Abstract:   (1872 Views)
  1. Introduction
Coastal areas are highly vulnerable, because they are involved with both sea hydrodynamic processes and human activities. Coastal geomorphology is considered as a prominent way to analyze coastal processes. Paleontology researches demonstrate tens of meters fluctuation in water level of the Caspian Sea. The shores of the Caspian Sea have variable topography and land use including lowlands (estuaries of rivers, gulfs and progradation) and sandy uplands. There is a slight slope in lowlands which cause flooding of lands when the sea level rises and also increased piezometric level of coastal aquifers. One the most important issues which must be considered in future development planning of coastal areas, is a proper space between constructions and sea that let natural processes be done. In fact, to determine the potential to deal with coastal hazards, it is necessary to prepare a coastal vulnerability map and identify areas with high vulnerability potential and strengthen and determine management approaches to protect investigated beaches. The investigated region is a 93.4 kilometer coastline in three cities including Talesh, Rezvanshahr and Anzali.
  1. Methodology
To identify the level of vulnerability of the coastal areas of Gilan province in relation to hydrodynamic issues, the use of effective geomorphological factors is one of the methods of evaluating the level of vulnerability of the coastal areas in dealing with these processes. In this research, four variables were used in the form of 12 sub criteria  , using the hierarchical analysis method, to achieve the vulnerability index of the coastal area of ​​Talesh to Anzali cities. According to the mentioned references and the purpose of the study, the desired variables include sea level changes, land topography, geomorphology and land use. Landsat satellite images, topographic maps 1:25000 and digital model of 12.5 meters height of the research area as well as SAGA, IDRISI, ENVI, DSAS and Arc GIS software were used for analysis.
  1. Results
The highest influence coefficient belongs to the factor of sea eustatic changes and then to the geomorphology variable. The most vulnerable coasts are those in which there are regression (more than 50 meters), the least distance and the highest density of agricultural use, the greatest distance and the lowest density of construction use, the lowest height and the slowest slope and the direction of the slope towards the land, the lowest density and the greatest distance from estuaries of rivers. The least vulnerable coasts are those in which there are progradation, the greatest distance and the lowest density of agricultural use, the least distance and the highest density of construction use, the highest height and the steepest slope and the direction of the slope towards the sea, the highest density and the least distance from estuaries of rivers. The largest coastal area belongs to areas with high and very high vulnerability including coastal areas of Anzali, Rezvanshahr, Asalem and some regions of Talesh. The smallest coastal area belongs to areas with very low vulnerability including coastal areas of Leisar and Pareh Sar. Generally, the coasts with low vulnerability are those around the breakwater of Pareh Sar and also those strengthened by the land currents. Therefore 56.2 kilometers out of 93.4 kilometers (60 percent) of investigated area, require a special attention to determine management approaches to protect coasts, prevent coastal erosion and nourishing the beach.
  1. Discussion & conclusions
According to eustatic changes of the sea, areas with high vulnerability have the most length (58 kilometers) which have more than 50 meters regression, and the least vulnerability belongs to coasts with progradation. The estuaries of rivers are one of the prominent geomorphic forms in the studied area. In the area, there are 12 main rivers leading to the Caspian Sea which carry a considerable amount of sediment to coastal areas. This nourishes the coasts around estuaries and reduces vulnerability of the area. The most vulnerability in this respect, belongs to coasts of Bandar Anzali and areas between the Cities of Leisar and Talesh. Height, slow slope and the direction of slopes towards the land are the vulnerable factors of the beach, because they cause flooding in lands when the sea level rises. In terms of topology, there are no good conditions for natural protection of the beach in all the investigated areas, except a few beaches around the village of Rostam Mahalleh, located between the cities of Talesh and Asalem. In the coasts which have been submerged over the past 45 years, the backshore land use, which is mainly agricultural land, has been pushed back. Despite same sea level changes, the changes of coastlines are different. So that the backshore agricultural areas have an over 50 meters regression, while backshore areas with human structures have been more stable. For example, the beach of Pareh Sar breakwater has progressed in past 45 years despite the advance of sea water during the years. Therefore, it can be stated that the backshores with agricultural areas are more vulnerable than areas containing constructions. In terms of land use factor, the most vulnerability belongs to the coasts of Leisar and Asalem.

 
Full-Text [PDF 1687 kb]   (549 Downloads)    

Received: 2022/09/18 | Published: 2023/04/28

Add your comments about this article : Your username or Email:
CAPTCHA

Send email to the article author


Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

© 2024 CC BY-NC 4.0 | Environmental Erosion Research Journal

Designed & Developed by : Yektaweb