Satellite-based Tracking of Reservoir Operations for Flood Management during the 2018 Extreme Weather Event in Kerala, India
Abstract. In parts of the world characterised by high precipitation and steep topography, hydroelectric dams often play the dual role of power generation and flood control. Improper and uncoordinated management of such dams during extreme and unexpected precipitation events can have disastrous consequences. As such, there exists a growing need for a reliable, transparent, and publicly available reservoir assessment and information system that can help water managers better prepare for such natural events. A fully satellite sensor-based framework offers a potentially viable approach towards this goal. The Reservoir Assessment Tool (RAT 3.0), which utilises high frequency remote sensing-based surface area and reservoir storage estimation alongside hydrological modelled inflow is tested and analysed for the 2018 Kerala floods in India. The effectiveness of RAT 3.0 was gauged by considering how well a fully satellite sensor-based framework was able to capture the rapidly evolving dynamics of the flood and reservoir state. Application of RAT 3.0 in monitoring the state of 19 reservoirs in Kerala during the flood event showed very promising results. In general, RAT 3.0 was found to be able to capture the temporal trend of the reservoir storage and pinpoint the sudden shift in filling or release decisions made by the dam operator. This translated to reliable updating of downstream flood risk in near real-time for improving flood preparedness, even though the absolute magnitudes were sometimes found to be in need of bias correction. A customised form of RAT 3.0 tailored for hydropower dams operating during high precipitation events in mountainous regions is proposed as an outcome of this study.