Overview
During extreme rain events, officials in Kerala must decide when and how much water to release from reservoirs. While the water level is visible on a screen, crucial information—rainfall, river flow, downstream capacity, and coastal conditions—is scattered across many agencies. The article argues that Kerala already has abundant data; the real challenge is to make these data interoperable so that decisions are timely and evidence‑based.
Key Developments
- By December 2025, KSDMA operated 100 automated weather stations.
- The CWRDM launched the Reservoir Assessment Tool‑Kerala for near‑real‑time reservoir monitoring.
- The IMD supplies rainfall forecasts, while INCOIS provides wave and tide predictions.
- The CWC study of the 2018 floods highlighted the limited capacity of the Thottappally spillway as a bottleneck.
Important Facts
In the 2018 floods, the CWC estimated that 1.63 billion cubic metres (BCM) of runoff was generated by four river systems, but Vembanad Lake could carry only about 0.6 BCM. The spillway’s effective discharge was around 630 cubic metres per second, far below its design capacity of 1,800 cubic metres per second because of siltation. Consequently, roughly 1 BCM of water stayed in the basin, raising lake levels and flooding low‑lying areas.
The lesson is clear: a reservoir release cannot be judged in isolation; downstream river capa