When Cyclone Ditwah made landfall on November 28 2025, Sri Lanka experienced one of its deadliest environmental disasters in modern history.

President Anura Kumara Dissanayake declared it the “largest and most challenging natural disaster in our history”. Torrential rains triggered widespread floods and landslides, leading to more than 350 confirmed deaths, hundreds missing and over 1.4 million people affected nationwide.

Major road and rail systems were cut off, hydropower stations and water treatment plants failed, and thousands of families were forced into emergency shelters. Reservoirs overflowed, riverbanks collapsed and communities near the Mahaweli, Kelani, Malwathu Oya and Mundeni Aru river basins were inundated within hours.

These were not random failures. They were systemic. Many of the regions that flooded were vulnerable areas adjacent to coastal lagoons and low-lying river plains. Cyclone Ditwah was not an anomaly. It exposed the underlying fragilities of Sri Lanka’s existing flood-management and drainage infrastructure.

This follows on from the devastating tropical cyclone in 1978 and the Boxing Day 2004 tsunami disaster. Fifty years ago, flood infrastructure was not in a good state. Significant improvements........

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