Erosion from Deforestation Turns Madagascar’s Rivers Red15.4S 48.0E
The Sofia River (above) and the Betsiboka River (below) are red in color due to sediments originating in the central highlands, where red lateritic soils predominate. The Betsiboka River discharges its sediments into the Bombetoka Bay, which then connects to the Mozambique Channel.
The red waters of the river demonstrate soil erosion, one of Madagascar’s greatest environmental problems, caused by deforestation in the central highlands. Such soil erosion is widespread exceding 400 tons/ha per year in some areas.
Soil erosion has also made the Betsiboka Estuary into one of the world’s fast-changing coastlines. The land has been cleared and incredible rates of erosion have occurred due to about 100 years of extensive logging in rainforests and coastal mangroves.
After every heavy rain, exacerbated by tropical cyclones, the bright red soils are washed from the hillsides into the streams and rivers, clogging the coastal waterways with sediment.