
Originally Posted by
Otsman
wow, if you look close, you can see all of the dried up riverbeds, that proves arabia was actually a very green place, sry, a little spam
http://en.wikipedia.org/wiki/Wadi
Wadis are the
streams in a
desert environment and generally are dry year round except after a rain. The desert environment is characterized by a sudden but frequent heavy rainfall. As rainfall occurs near hill ranges, wadis usually form near a hilly
terrain.
Those are actually "Wadis". While 99% of the year there is no rain, it still does occasionally fall. And when rain falls in the desert it's usually pretty heavy and forms these temporary streams called "wadis". That's what those are.. I believe.
Pics of Wadis: