SPACEPHOTOS

The theme of this photograph—soil erosion—is depicted with two colors—dark green, the remaining vegetated areas (primarily grasslands), and various shades of brown, sediments transported into the Bay of Mahajamba. The bay, named for the Mahajamba River that flows into its southern part, is also entered by the Sofia River from the east. The mouth of Mahajamba Bay is not visible in this photograph; however, the heavy sediment loads carried through the estuary sometimes create sizable sediment plumes in the Mozambique Channel. This region along the northwest coast of Madagascar, the world’s fourth largest island, indicates the country’s major problem—overpopulation and destruction of forests. At the beginning of the 20th century the island had an estimated 90 percent vegetative cover, mostly forests; now approximately 100 years later, only 10 percent of the forests remain. With 80 percent of the population engaged in farming and the island’s population doubling in 30 years (population increased from 5.4 to 11.2 million from 1960 to 1989), the stress on the land has been tremendous. The area shown in this picture is largely savanna—short grass with scattered trees. Chief agricultural activities are growing sugarcane and raising cattle. Annual rainfall amounts range from 40 to 80 inches (100 to 200 centimeters).