NASA MODIS Image of the Day: September 24, 2012 – Madagascar
In late summer, 2012 fires speckled the landscape of Madagascar. Most fires burn in the dry western region, although several also appear on the coastal plain of humid eastern Madagascar. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite acquired this true-color image on September 10. Red marks indicate the location of ‘hotspots’ – areas where the thermal detectors on MODIS indicate temperatures higher than the background. When accompanied by smoke, such hotspots strongly indicate burning fires. Although not easily seen at low resolution, smoke is visible at higher resolutions of this image. Given the number and widespread distribution, these fires are likely primarily the result of the practice of “tavy”, a type of slash and burn agriculture practiced for centuries in Madagascar. Traditionally fire is used to clear small plots of forest, which is then planted with rice. After a year or two of cultivation, the field is allowed to go fallow before it is once again burned and cultivated. Over time, especially when used by a growing population in a dwindling forest, such practices deplete the soils and destroy the forest ecosystem. Soils can become so depleted that even native plants fail to thrive in the fallow years, leaving the land vulnerable to erosion. Much of the soil in western Madagascar is reddish in color, and the erosion has been said to make some rivers appear to be bleeding at times, as the red sediment washes from the land towards the sea. When viewing this image at higher resolution, most of the rivers in the western areas, especially near the fires, appear a sediment-laden tan color. A few rivers in the northern section, including the waters near the delta of the Betsiboka River are tinged with red. Sediment can be seen along the entire coast, and it appears rusty-red in several locations.
