It is baked and dried out by the sun.

It is not in condition to absorb or retain much of the run-off water, consequently, the rain water finds little to stop it as it swirls down the slopes.

In torrents it rushes down the stream beds, like sheets of water flowing down the steep roof of a house.
Conditions are very different in a region where forest cover is abundant.

In the forests, the tops of the trees catch much of the rain that falls.

The leaves, twigs, branches and trunks of the trees also soak up considerable moisture.