23. Sediment Laden Drainages, Betsiboka River, Madagascar
The Betsiboka is Madagascar’s main river, flowing for a total of 525 kilometers (325 miles) from north of Tananarive. The river is navigable for at least 130 kilometers (80 miles) inland and the lower reaches pictured here are noted for their extensive rice fields. While the red sediment being transported provides an attractive and informative example of a river estuary, it is a symptom of an ecological disaster for Madagascar: Felling and clearing of the islan’'s natural cover of tropical forest has been so extensive that soil erosion has been vastly accelerated and much of the sediment visible in the river represents an irreplaceable natural asset.
Brick red lateritic soils, the result of tropical weathering, are responsible for the strong color of the sediments. Most of the deforestation in Madagascar has taken place over the last 20 years, the same period during which observations from space have become established. Recent observations show that very little of the original forest remains.
STS-51A, November 1984. Picture #19-34-039.