Chennai does not forget its floods. It forgets what made them inevitable. Each northeast monsoon brings familiar photographs: inundated streets, stranded vehicl. Yet the deeper question is ordinary: what happened to the land that once held the water?Rainfall matters, enormously, and Cyclone Arnab last week was no exception. During Cyclone Michaung in December 2023, the India Meteorological Department recorded 291.6 millimetres in 24 hours at Perungudi on December 4.