Response of a coastal hydrogeological system to a rapid decline in sea level; the case of Zuqim springs – The largest discharge area along the Dead Sea coast

Abstract

Summary The almost instantaneous response of a natural on-shore groundwater system to an extremely rapid drop in the level of an adjacent lake is described in this study. The study is focused on the Zuqim (Feshcha) spring complex located on the northwestern shore of the Dead Sea, which exhibits a drop of tens of meters in its water level over the last few decades. In this exceptional “field lab”, fluctuations and trends in the flow regime are recognized, as well as the contemporaneous geochemical variations. Lithological facies variations have a pronounced effect on the underground flow regime. The following main processes were recognized: (a) slight shifting of the long-standing springs eastward, following the retreating shore; (b) extension of the hydrologic system southward without significant change in the total discharge of the entire spring complex. The new seepages are characterized by high variability in salinity; and (c) continuous refreshing of the spring water as a result of prolonged flushing of old trapped brines. The water of the Zuqim springs lie on mixing lines between two local brine types and diluted brine of the Lisan Lake – the precursor of the Dead Sea. Based on our findings, future development processes in the spring complex are predicted, which is essential because of their impact on the endemic ecosystem that relies on this water. In addition, continuation of the rapid drop in lake level is expected to cause intensification of erosional processes, such as deepening of flow gullies. Shifting of the entire hydrological system southward and migration along with the retreating shore is also expected to continue, as well as the continuous decrease in the water salinity.