A team of faculty and students measured discharges at several critical places along Adyar river to collect real-time data during the cyclone. Equipped with ‘Acoustic Current Profiler’, two teams of students and faculty measured currents and flow depths across the width of the river to get its integrated flow rate.

Explaining the significance of the project, K Phanindra Reddy, Commissioner, Revenue Administration, Disaster Management and Mitigation, said the data collected by the teams in close coordination with Tamil Nadu State Disaster Management Authority (TNSDMA) would be useful to operationalise the Real-Time Flood Forecasting (RTFF) and Spatial Decision Support System (SDSS) being coordinated by TNUIFLS under the World Bank-assisted Tamil Nadu Sustainable Urban Development Project (TNSUDP).

Elaborating on the technical aspects, Prof Balaji Narasimhan said, “As part of robust flood management, rating curves at critical sections of the rivers are especially important to understand the volumetric flow rate for different flow depths. Once a rating curve is developed, an integrated network of water level sensors could be used to monitor river discharges remotely and automatically at these critical river stretches.” Preliminary model runs showed that catchments of Somangalam, Manimangalam, Adhanur, and Guduvanchery alone could have contributed to up to 70 per cent to 80 per cent of flood flows realised in Adyar river.

Such critical data and a reservoir inflow forecasting system through numerical models could have helped mitigate the impact of 2015 floods. Unlike Chembarambakkam reservoir that has flood gates to regulate water level, the tanks in these catchment areas did not have control measures in 2015. Realising this lacuna, the PWD has begun installing sluice gates in many small tanks to regulate storage in advance, the statement added.

This project was conceived after mega floods hit Chennai in December 2015. IIT-Madras along with IIT-Bombay, Anna University and the National Centre for Coastal Research (NCCR) developed a pilot flood forecasting system with funding support from the Principal Scientific Advisor.