Geologists studying remote sensing images of Arabia have found a dry
riverbed covered by desert sands. The 850-kilometre channel begins in the
Hijaz Mountains of western Saudi Arabia and ends in a delta that covers
more than two-thirds of Kuwait, says Farouk El-Baz, director of the centre
for remote sensing at Boston University. Parts of the ancient channel had
been mapped as ‘wadis’, but no one had recognised it as a large river system
because large dune fields cut across it.
Arabia has had wet periods at times over the past 200 000 years. Water
last flowed in what El-Baz calls the ‘Kuwait River’ between 5000 and 11
000 years ago; some stretches of the river may have been up to 5 kilometres
wide. Then as the region became one of the driest in the world, blowing
sands covered the channel. The river runs along a fault, so that there should
still be ground water deep in the channel. El-Baz says this water might
be tapped by wells several hundred metres deep. Sand-covered parts of the
old channel may contain the remains of prehistoric settlements, from the
time before the river dried.
El-Baz sees signs to the south of three other dry rivers that would
have drained other parts of Arabia. He has asked NASA to use a shuttle-based
radar experiment to study the region later this year; the radar can penetrate
the sand to study the rocks and channels beneath.
