High rates of sediment transport by flashfloods in the Southern Judean Desert, Israel

Abstract

A system has been installed to automatically monitor rainfall, streamflow, bedload discharge and suspended sediment concentration in the arid to hyper-arid setting of Nahal Rahaf, Southern Judean Desert in Israel. The Rahaf gauging station is located in a relatively steep, wide channel with an unsteady bed driven by flash floods. It is an attempt to deploy modern automatic equipment for continuous sediment transport monitoring in harsh, arid fluvial environments. Unit bedload discharges are the highest recorded hitherto, suggesting they may represent an upper end member in the worldwide climate–bedload discharge relationship. Suspended sediment concentration is much higher than is typical of perennial fluvial humid environments. There is high correlation between suspended sediment concentration and water discharge on an event scale, with diverse intra-event relations. The sediment yield of individual events is large, but the small number of floods limits the mean annual sediment yield to low values in this arid environment. This also has environmental implications, as large-scale quarrying requires a long period of self-restoration in such an arid fluvial setting. Copyright © 2005 John Wiley & Sons, Ltd.