Farzaneh Gardounzadeh - MSc Student, Civil Engineering department, Sharif University of Technology, Tehran, Iran,
Mohammad Raei - Assistant Professor, Civil Engineering Department, Sharif University of Technology, Tehran, Iran

Caspian Sea with its particular circumstances including enclosed inland body of water which has no outflows, is known as a fragile and vulnerable aquatic environment. Therefore this body of water has a great environmental importance which in recent years has been threated by biological and hydrocarbon pollution entrance from offshore and inshore pipelines and structures due to sea accidents or decay although there are another hydrocarbon pollution sources according to Table 1 (Korotenko, Mamedov, Kontar, & Korotenko, 2004). By the way Caspian Sea is bordered by 5 countries Iran, Russia, Kazakhstan, Azerbaijan and Turkmenistan has 384,400 km2 surface area and two deep basin in the middle and near south coast (Figure 1). Because of Volga River in the north part of Caspian Sea, the major freshwater input, the salinity is zero and it increases by going southward up to 14 ppm (Korotenko et al., 2004; Korotenko, Mamedov, & Mooers, 2000, 2001). There are cyclonic circulations over deep part of the sea (Figure 1) (Korotenko et al., 2001).