Morphological Changes of Sefidrud Delta, North Iran, Using Rremote Sensing & GIS Techniques

The mouth of Sefidrud River is characterized by a birdsfoot delta which is actively prograding into Northeastern portion of Caspian Sea, a coastal lagoon approximately 60 km north of Rasht, Iran. Sefidrud River has a catchment\´s area of 56700 km², which is the biggest sub-catchments of draining into southern Caspian Sea. Remote sensing and GIS techniques have been used to detect the morphological changes of Sefidrud delta over the last three decades (1975-2005). For this purpose different satellite data from different date including LANDSAT MSS, TM & ETM+ and IRS have been digitally processed. First, IRS-Pan data were georeferenced with respect to 1:25000 topographic maps using a Universal Transverse Mercator (UTM) projection. All the required data sets were registered to the IRS-Pan image. Further more the data were imported into GIS environment for analyzing and possible change detection. It was performed manually by visual interpretation on the basis of image elements techniques. The updated features were digitized on screen and overlaid with the previous data. Results of the study showed that the Caspian Sea level rise (2.6 m between "1975-2005") affected the coast of Sefidrud delta promontory strongly and it\´s promontory moved to eastward about 2 km as a maximum shoreline change over the last three decades. The study revealed that this severe erosion is due to coastal processes, sediment deficiency and sea level rise or/and subsidence. Coastal instability at Sefidrud promontory has almost continued during the last century. Severe erosion was determined along other cells over the Sefidrud delta coasts. The present study emphasis on the requirement of the geospatial information for coastal changes detection in Caspian Sea.