Fluvial adjustment of the Lower Jordan River to a drop in the Dead Sea level

Abstract

Water utilization in the upper part of the Jordan Basin has led to a significant reduction in inflow to the Dead Sea. Over the last 70 years, a drop of about 22 m in mean sea level has occurred and has resulted in a continual adjustment of the Lower Jordan River. The impacts of this lowering on the channel morphology of the Lower Jordan River were examined using aerial photographs. Until the late 1970s, the drop in the sea level was small but still led to channel extension. Since the early 1980s, a rapid drop in sea level took place leading to major changes in channel morphology and deep incisions. The greatest change in channel width was recorded near the river mouth. Between 1850 and 1980, there were only insignificant changes in channel sinuosity, but subsequently, a 25% increase of channel sinuosity has been recorded. Most of changes in the channel sinuosity were recorded in the newly exposed area. Over the last 30 years, the active channel width has narrowed by almost four times. Until the late 1980s, the channel was relatively stable with minor bank collapses and only one bar detected near the Jisr Abdallah. During the 1990s, a number of bars developed along the channel. The downcutting is in parallel with the sea level drop resulting in the development of terraces along the lower part of the study reach. In 1983, the channel incision reached 8 km upstream and by 1993 it was about 11 km.