Morphometry and evolution of sinkholes on the western shore of the Dead Sea. Implications for susceptibility assessment

Abstract

Sinkhole development is a hazardous geomorphic process responsible for increasing economic losses worldwide. The highly dynamic eogenetic salt karst of the Dead Sea is one of the most striking examples of a human-enhanced sinkhole hazard. Since the 1980s, the shores of the Dead Sea have been affected by thousands of sinkholes while the lake level has been declining. Sinkholes pose a major threat, but their rapid development also offers an exceptional opportunity to study their evolution. Although the evolution of the morphometry and distribution of sinkholes provides essential data for hazard assessment, this kind of studies are almost lacking because of the typical slowness of the processes. Here we present multi-temporal cartographic sinkhole inventories of a sector in the western shore of the Dead Sea. The database was constructed using aerial and satellite imagery, high-resolution three-dimensional photogrammetric models, and fieldwork. Most of the depressions mapped were single, small, relatively shallow, subcircular, collapse sinkholes nested within large sagging basins. From 2005 to 2021, the 702 new sinkholes have been concentrated along a narrow N-S-oriented strip comprising tightly packed alignments and clusters. Sinkhole expansion by mass wasting and coalescence play an essential role in the evolution of the sinkhole landscape. An average subsidence rate of 45 cm/year has been calculated for the total area affected by sinkholes, providing an indirect estimate for the rate of subsurface salt dissolution. This research illustrates how multi-temporal geomorphic mapping and morphometric analyses provide an objective basis for the development of reliable spatial predictions for sinkhole evolution.