Malagasy erosion

This true-color image of Madagascar was captured by the MODIS sensor of NASA's Terra spacecraft on September 27, 2001. The country's topsoil erosion problem, due to heavy deforestation and overfarming of the land, is evident in the picture. There you can see, rivers choked with red sediment as they flow towards the Mozambique Channel (bottom) that separates Madagascar from mainland Africa (North is to the left in this view). Also visible is the large discharge of that sediment as the rivers fade into the channel. The tropical forests that can be seen running along the eastern coast once stretched much further into the country's interior. Once cleared of forest, the soil on the landscape is highly susceptible to erosion by rainwater. As the runoff from rainfall passes across recently cleared fields, it washes away the life-giving soil and carries to the rivers and out to sea. It is estimated that Madagascar has lost 80% of its forests over the past century. The red dots are where the slash and burn fires were detected during the time of the image.


Credit: Courtesy Kam Lulla, JSC. For more images of this type, see the "Human Imprints from Space" slide set (Gwynn, Wilkinson, and Lulla; Lunar and Planetary Institute #989)

For more info: http://images.jsc.nasa.gov/iams/images/earth/STS026/html/10001402.htm