Plateau Drainage
Perhaps one of the more surprising geomorphic forces at
work on the Karak Plateau is that associated with
fluvial processes. Though a typical year produces no
more than 340mm of precipitation (often considerably
less), much of it comes in the form of winter storms
that can generate flash floods and intense channel flow.
It is not uncommon to find among the bedload of dry
summer streambeds, rocks (e.g., basalt) with diameters
of up to 50cm that have been transported considerable
distances from their sources during winter storm events.
 The
figure to the left is a
"natural " color composite image prepared by draping
a satellite image (Landsat-7 ETM+ bands 1, 2, and 3)
over a DEM. Clearly visible are two of the most striking
features of the modern plateau, the deep canyons of the
Wādī al-Mūjib [
Photo]
and Wādī al-Hisā [
Photo]
that serve as the extreme northern and southern
boundaries of the plateau. These along with the Wādī al-Karak
(yellow dot), dominate drainage on the Plateau. The
Plateau drains through a combination of runoff flowing
directly into the canyons and their associated ephemeral
channels along with sapping processes. Major drainage
channels have been added to the image (black lines)
using a GIS.
 Faulting,
fracturing and underlying tectonic features exercise the
greatest influence on the Plateau's strongly linear
drainage network. The figure to the right is a
high-resolution (15 meter) satellite image (Landsat-7)
draped over a DEM that reveals the influence of faulting and
fracturing on the the formation of ephemeral channels
flowing into the Wādī Nykhayla that feeds into the Wādī
al-Mūjib in the northern Plateau. The Siwaqa Fault that
dominates the drainage system in this area is seen as
the linear displacement zone that extends vertically
from the bottom center of the image. This [
Photo], a high-resolution
(15m) ASTER satellite image of a region near the center
of the Plateau, shows an extensive dendritic network of
ephemeral channels.
In addition to surface process (i.e., streams and
channels), sapping also plays an important role on the
Plateau. As a geomorphic process, sapping leads to the
undermining and collapse of channel walls by weakening
and removing material where the subsurface groundwater
seeps through the channel wall. Sapping processes on the
Plateau have resulted in numerous theater-headed valleys
seen along the southern rim of the Wādī al-Mūjib
[
Photo].
The volute capitals of Mudaybi<sup>c</sup>
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