Why is the Sahel Desert shrinking?

The Sahel is a particularly drought-prone area, and this increases the process of desertification, meaning the way a desert grows. Between 1968 and 1973, Africa was hit by a particularly bad drought which made the already vulnerable Sahel prone to desertification. Human activities also caused erosion, adding to the problem. During the last few decades the Sahel has expanded southward again according to satellite imaging and local reports. This has been due to the government's efforts at reforestation. Unfortunately, the Sahara has also followed in its wake.