Hydrological Observation Circle (HOC) is a Circle under Narmada & Tapi Basin Organization of Central Water Commission, headquartered at Gandhinagar. The HOC came into existence in April 1995 when it started functioning at Vadodara under Chief Engineer, NTBO, Vadodara. Subsequently, it is shifted to Gandhinagar on 7th July 2004. Under the Circle, there are 2 Divisions viz.

• Mahi Division (with 4 Sub-Divisions) with headquarters at Gandhinagar
• Tapi Division (with 5 Sub-Divisions), with headquarters at Surat.

Functions of HOC

The following are the main functions of HOC:

• Collection, collation and publication of Hydrological, Hydro-meteorological, Sediment and Water Quality data of the west flowing rivers in the state of Gujarat, Rajasthan, Madhya Pradesh and Maharashtra.
• Operation and modernization of Flood Forecasting systems on the west flowing rivers in the state of Gujarat, Rajasthan, Madhya Pradesh and Maharashtra.
• Operation and maintenance of Regional Data Processing and Storage Center.