Prediction annual rates of shoreline change Caspian sea

The coastal zone is one of the nation’s greatest environmental and economic assets. In coastal regions the natural forces that cause shoreline changes are embodied in waves، currents، wind and other factors. Gorganroud River Delta is located in 53°57 to 54° 1 E and 36°56 to 37° N in Southeast of Caspian sea. In this study، gibbosity of Gorgan River delta at the river mouth has been studied. The Gorganroud river basin from the Caspian Sea catchment basin is located a large part of it in Golestan and Mazandaran provinces. The total flow rate of Gorgan Bay Rivers Catchment is about 500 cubic meters and total of their discharge is 3. 5 million tons per year. The beach is average slope of 0. 1 percent that Denotes the slope of the study area is very low. The aim of this study was to evaluate the rate of change of coastline and its predictions with two different methods. The reason of selection area of Gorganroud coastline is a very large amount of change over different periods of time. This research is mainly based on an analytical method is based on using mathematical and statistical methods that Using topographic maps 1/250000 and 1/50000 is characterized general delimitation of the study area. Initially the satellite images of TM، MMS،ETM sensors were obtained from Landsat and Images coastline in 2005 and 2013 from the Google Earth software. The shorelines with digitization of images were extracted and converted into a linear files in Software ARCGIS9. 3. To investigate the rate of annual change of the coastline، two methods have been applied. Methods used to evaluate the rate of annual change in shoreline and Predict the rate of change in the next years were Based on the use of transect. According to the curve enormous coastline، Cuts perpendicular to the coastline drawn at even intervals of 500 meters To analysis the rate of change within Gorgan River Delta. The first of the methods used is End Point Rate (EPR). The End Point Rate is calculated by dividing the distance of shoreline movement by the time elapsed between the oldest and the most recent shoreline. The major advantages of the EPR are the ease of computation and minimal requirement of only two shoreline dates. The major disadvantage is that in cases where more data are available، the additional information is ignored. The second method for Changes Rate prediction is The Average of Rates (AOR). The Average of Rates method calculates separate end point rates for all combinations of shorelines when more than two are available. A minimum time criterion is introduced to filter the available shorelines and it is a function of measurement errors and the magnitude of the rate of change. The main advantages of this method are that all “good” data that pass the minimum time criterion are used and the sensitivity of the method to substantial shifts in trends and data variability. The main disadvantages are that small time differences between the shorelines produce a long minimum time span and there is not a computational norm for modelling the minimum time span equation. The largest distance is between shorelines between the years 2001 -1975 that use in SCEmethod. Based on the maximum distance between the coastline is shown in transect of 11 with distance of 3938 meters. The results of the NSM method is shown that maximum distance between the shorelines is in transect of 11 with distance of 3200 meters. The results of the EPR shows that Most changes in the coastline is In the middle of a Gorganrood river delta The range of 63. 7 – 84. 2 meters per year. The results of the AOR shows The range of 60. 4 – 90. 8 meters per year. According to Sea water level measurement station of the Caspian Sea to Baku and Anzali Since 1882 sea level change is more than 3 meters. This change is Significant impact on a coastline profile and its surrounding landuse. Evaluation of methods to assess shoreline change rate indicates that EPR and AOR methods Are considered Due to cyclical changes. Considering the Delta jut into the sea and Annual average rate of change 40. 2 meters، with EPR method، gibbosity Gorganroud River at the mouth of the river have been added to the coastline the past 112 years.