The water shed of the same is to an extent of approximately 59,400 square kilometers, and originates from the provinces of Kurdestan and Azarbayjan. It passes through the Zanjan province and flows into the Caspian Sea in Gilan province. The Sefid Rood Valley acts like a corridor connecting some of the southern parts of the Caspian Sea, which are humid and high pressure areas to the low pressure regions of the Iran Plateau.