What was the primary purpose of constructing the Farakka Barrage?

Preservation and maintenance of Kolkata port for navigation was the primary purpose of constructing the Farakka Barrage. Main objective of the Farakka Barrage Project complex is to divert adequate quantity of Ganga waters to Bhagirathi-Hoogly river system through 38.38 km long feeder canal for preservation and maintenance of Kolkata Port by improving the regime and navigability of the Bhagirathi-Hoogly river system.