Due to very heavy rainfall during the month of September in upper catchment of the river Ponnaiyar in Karnataka and Andhra Pradesh, the Krishnagiri dam attained its FRL in September 2017 and started releasing water downstream.
Due to this, the downstream reservoirs also got sufficient inflow and Sathanur Dam was very near its Full Reservoir Level. In such situation, on 29th November 2017, one of the shutters of the Krishnagiri dam got damaged and water started flowing through the damaged shutter.
The project authorities and the district authorities have also opened additional spillway to avoid pressure on the damaged shutter. The district authorities had also warned all the downstream districts regarding the situation arising out of the damage to shutter. The information was analysed in Central Water Commission (CWC) with the available data as well as data collected from Project authorities.
Sathanur Dam is downstream of Krishnagiri Dam. As the Sathanur dam was already near its FRL, anticipating the flow from the damaged shutter of Krishnagiri reservoir, Sathanur Project authorities started releasing water from 29th November 2017 evening. The average discharge since 29th November was approximately 64 cumec (2260 cumec). This has reduced the reservoir levels at Sathanur Dam.
The Krishnagiri reservoir was constructed across the Ponnaiyar River near Periyamuthur village about 10 km from Krishnagiri town in Krishnagiri district, Tamil Nadu. The execution of the KRP dam was started on Mar 1955, completed and opened for irrigation on Nov 1957. The Gross Storage capacity of the reservoir is 47.156 MCM. The Sathanur Dam was completed during the year 1957 near Thiruvannamalai town in Thiruvannamalai district of Tamilnadu. The Gross Storage capacity is 228.91 MCM. CWC has started inflow forecasting activities at Sathanur Dam from 2017 North East Monsoon season onwards.
The intervening catchment between Krishnagiri Dam and Sathanur Dam is about 2,000 sq.km. Distance between the two dams is 117 km.