Throw a 145-mph tropical cyclone accompanied by 10 inches of rain against a low-lying coastline, and you get flooding that New Orleanians can easily understand.
The most recent such incident, outlined in NASA's Earth Observatory science feature, is the horseshoe-shaped path of the Indian Ocean Tropical Cyclone Giovanna, which made landfall on the narrow east coast plain of Madagascar as a Category 4 storm on Feb. 9.
Giovanna cut across the island’s mountainous plateau center before entering the channel separating it from Mozambique, and then curved south and back east around the island’s southern tip, churning back into the Indian Ocean, where it’s still producing 30-mph winds today.
Giovanna has killed at least 23 people in Madagascar and left about 190,000 homeless in the last week, according to news sources.
The sediment-choked Onibe River on Saturday was delivering a thick plume of sediment to the Indian Ocean, similar to the sediment delivered to the Gulf of Mexico by the rain-swollen Mississippi River last fall.
But Madagascar’s narrow range of topography, dropping from 9,436 feet to sea level over just 75 miles, results in fast-moving water picking up huge amounts of mud and debris as Giovanna exited the area