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.
This figure 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.
Karak Plateau
Faulting, fracturing and underlying tectonic features exercise the greatest influence on the Plateau's strongly linear drainage network. The next figure 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.
Mujib ephemeral
This is a high-resolution (15m) ASTER satellite image of a region near the center of the Plateau, shows an extensive dendritic network of ephemeral channels.
South Mujib ephemeral ASTER satellite image
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.
Mujib sapping