Beach sediments, morphodynamics, and risk assessment, Caspian Sea coast, Iran

Abstract

Protection of ocean and marine coastal regions is a vital part in any coastal management program for sustainable development. Erosion processes have developed in areas with high population density and economic exploitation. Hydrodynamic forces (waves and currents) are important agents for changing coastal processes and advancing erosion. This paper discusses coastal erosion vulnerability along the southern coasts of the Caspian Sea. Evaluation of beach erosion and instability and assessment of hazards are the most important objective. This research focused on six selected stations, each including six sites, with measurements in October 2004. Sedimentary samples and beach geometric characteristics have been measured at all 36 sites. A Universal Ranking System Model (URSM) was created by defining indexes including characteristics of all factors potentially contributing to beach erosion risk. A value for erosion potential was assigned to every index, and Fuzzy theory was used to translate linguistic phrases to mathematical language. All data pertinent to beach erosion was input into Arc View GIS, and the URSM ranking model applied. As a result, the relative risk of erosion at each beach was determined. By dividing the study area into five morphological zones, zones with high vulnerability were highlighted. Erosion and shoreline changes by hydrodynamic processes vary from region to region in the Caspian Sea. The Miankaleh area along the southeastern coast is the most stable area, and Nashtaroud region in western Mazandaran is the most vulnerable area along the southern Caspian Sea coast.