Faculty of Civil Engineering, Shahrood University of Technology
Department of Civil Engineering, Faculty of Engineering, University of Guilan
Due to the great importance of sea level changes especially for coastal regions, identifying and studying the factors affecting these variations makes it easier to predict changes of sea level and will help to determine the riparian zone and changes in coastal lines. In this research, precipitation-evaporation is studied based on ERA-Interim model of ECMWF in order to estimate changes in Caspian Sea (CS) level and the validity of the results is evaluated in a period between 1980 to the end of 2015. Recorded data about the rivers entering the CS were also studied for better prediction of changes in water level. According to satellite and software analyses, in average evaporation has increased with a rate of 0.89 Km3/year, while precipitation and rivers discharge have decreased by the rates of 1.09 Km3/year and 1.41 Km3/year, respectively during the 36 years. The standard deviation of the sea level change caused by Volga discharge (normally entering 249.13 Km3/year into the sea alone) is closer to the recorded standard deviation obtained from change of CS level than the other two factors. Also, the lowest and the highest correlation coefficients relative to the recorded sea level changes were calculated considering simultaneous effect of precipitation-evaporation, and simultaneous effect of all parameters, respectively. As a conclusion, it can be said that the main reason for decreasing the CS level during recent years could be attributed to the rise of evaporation in comparison to precipitation and inlet rivers discharges.