Coastal Zones

The formation of coastal geomorphological phenomena in terms of size and type is in direct relation with littoral drift. Sediment reservoir and the strength of tidal and shoreline currents control the formation and absence of geomorphological phenomena. In Caspian coastal area because of, first lack of stone capes or even sedimentary capes and second absence of tidal actions, some forms of coastal sedimentation have not developed. Due to considerable reservoir of sediment and the CCW general flow of Caspian Sea and the conditions of dominant wave coasts in most of Caspian coastal area, however, coastal sand dunes, spits and finally some lagoons, sheltered by the spits, have been formed. In this study, using IRS panchromatic images, Landsat8+ETM panchromatic images and available reports, the effect of sediment transport leading to formation of coastal reliefs in Anzali Lagoon located in the coastal area of Caspian Sea has been investigated. The results revealed that the northern boundary of Anzali Lagoon is in fact, a coastal dune which geomorphologically appears to be a spit. Furthermore, there are traces of five coastal sand dunes in this area. Longitudinal sand dunes are stretched from Tazeh Abad to Hassan Rood and the maximum longitudinal stretch is 4 km, which is located in Northwest of Bandar Anzali. In addition, accumulated volume of annual sediment transport in this situation is 300000 cubic meters; therefore, the net rate of littoral drift, moving from East to West is estimated to be 25000 cubic meters. Bandar Anzali area appears to have once been lowland resembling a cove and coastal sediment transport has formed spits growing Eastward which their heads have moved toward Southeast within this cove. Upon the fill-up of this lowland by these spits, the current shoreline has been created and the trend, shoreline and the longitudinal sand dunes have become west to east. Studies regarding the coastal changes revealed that Bandar Anzali area is subject to 0.8 mm annual land subsidence; therefore, this process is one of the reasons leading to controlling the littoral drift direction toward the lagoon.