Karst system developed in salt layers of the Lisan Peninsula, Dead Sea, Jordan (original) (raw)
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Collapse and subsidence associated with salt karstification along the Dead Sea
Carbonates and Evaporites, 2001
Two types ofsinkholes are observed along the Dead Sea shore, Israel. The first is associated with vadose dissolution in Mount Sedom salt diapir. The second is associated with dissolution under the watertable along the retreating Dead Sea shore. The Dead Sea level is falling dramatically, mainly because of human activity. Simultaneously, the lake shores suffer tremendous impact since the late 1980s: The ground is collapsing and subsiding in hundreds of points along the lake, with people, roads and property being swallowed in the more catastrophic events. The collapse is believed to result from dissolution of salt by aggressive groundwater, following the retreat of Dead Sea level and the groundwater halocline. Geological evidence suggests that a previous major lake level fall occurred naturally-2000 BCE. This may provide a new explanation for a curious historical-geological phrase in the book of Genesis, suggested to record formation of collapse sinkholes which occurred in response to the historic falling lake level, associated with climatic desiccation. with recent environmental changes within the rift valley. In addition, past and present hazard to society is evaluated. We also combine field evidence of Holocene Dead Sea level
Self-accelerated Development of Salt Karst during Flash-floods along the Dead Sea Coast, Israel
Journal of Geophysical Research: Earth Surface, 2015
We document and analyze the rapid development of a real-time karst system within the subsurface salt layers of the Ze'elim Fan, Dead Sea, Israel by a multidisciplinary study that combines interferometric synthetic aperture radar and light detection and ranging measurements, sinkhole mapping, time-lapse camera monitoring, groundwater level measurements and chemical and isotopic analyses of surface runoff and groundwater. The >1 m/yr drop of Dead Sea water level and the subsequent change in the adjacent groundwater system since the 1960s resulted in flushing of the coastal aquifer by fresh groundwater, subsurface salt dissolution, gradual land subsidence and formation of sinkholes. Since 2010 this process accelerated dramatically as flash floods at the Ze'elim Fan were drained by newly formed sinkholes. During and immediately after these flood events the dissolution rates of the subsurface salt layer increased dramatically, the overlying ground surface subsided, a large number of sinkholes developed over short time periods (hours to days), and salt-saturated water resurged downstream. Groundwater flow velocities increased by more than 2 orders of magnitudes compared to previously measured velocities along the Dead Sea. The process is self-accelerating as salt dissolution enhances subsidence and sinkhole formation, which in turn increase the ponding areas of flood water and generate additional draining conduits to the subsurface. The rapid terrain response is predominantly due to the highly soluble salt. It is enhanced by the shallow depth of the salt layer, the low competence of the newly exposed unconsolidated overburden and the moderate topographic gradients of the Ze'elim Fan.
ISPRS Journal of Photogrammetry and Remote Sensing, 2017
This article presents and analyses the results obtained from Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques applied to ERS-1/2, ENVISAT, ALOS-PALSAR, COSMO-SkyMed, and Sentinel-1A datasets over the Lisan Peninsula, located in the southern part of the Dead Sea, Jordan. The novelty comes from the integration of three different wavelengths to study the dynamics of a salt dome. The monitoring activity entirely covers the period extending from 1992 to 2016. Five displacement maps have been produced, carefully checked and then fused to provide a total cumulated map of the displacements in the area. The ground movements have been analysed by comparison with in-situ tectonic observations collected by various authors since the mid-1980s. The study shows an episodic rising of the Lisan diapir. The presented results can be useful to update the knowledge of the displacement rates occurring in the area and to better comprehend the complex dynamics of the Lisan Peninsula.
Solid Earth Discussions
The fall of hydrological base-level is long established as a driver of geomorphological change in both fluvial and karst systems, but few natural occurrences occur on timescales suitable for direct observation. Here we document the spatiotemporal development of fluvial and karstic landforms along 20 the eastern coast of the hypersaline Dead Sea (at Ghor al-Haditha, Jordan) during a 50-year period of regional base-level decline from 1967 to 2017. Combining remote sensing data with close-range photogrammetric surveys, we show that the 35 m base-level fall has caused shoreline retreat of up to 2.5 km, and resulted in: (1) incision of new meandering or straight/braided stream channels and (2) formation of >1100 sinkholes and several salt-karst uvalas. Both alluvial incision and karst-related subsidence 25 represent significant hazards to local infrastructure. The development of groundwater-fed meandering stream channels is in places interlinked with that of the sinkholes and uvalas. Moreover, active areas of channel incision and sinkhole development both migrate seaward in time, broadly in tandem with shoreline retreat. Regarding theoretical effects of base-level fall, our observations show some deviations from those predicted for channel geometry, but are remarkably consistent with those for groundwater-30
Solid Earth, 2019
Enclosed topographic depressions are characteristic of karst landscapes on Earth. The developmental relationship between depression types, such as sinkholes (do-lines) and uvalas, has been the subject of debate, mainly because the long developmental timescales in classical limestone karst settings impede direct observation. Here we characterize the morphometric properties and spatio-temporal development of ∼ 1150 sinkholes and five uvalas formed from ∼ 1980 to 2017 in an evaporite karst setting along the eastern coast of the hypersaline Dead Sea (at Ghor Al-Haditha, Jordan). The development of sinkhole populations and individual uvalas is intertwined in terms of onset, evolution and cessation. The sinkholes commonly develop in clusters, within which they may coalesce to form compound or nested sinkholes. In general, however, the uvalas are not defined by coalescence of sinkholes. Although each uvala usually encloses several clusters of sinkholes, it develops as a larger-scale, gentl...
Exposure of tourism development to salt karst hazards along the Jordanian Dead Sea shore
Hydrology and Earth System Sciences
The Dead Sea shore is a unique, young and dynamic salt karst system. Development of the area began in the 1960s, when the main water resources that used to feed the Dead Sea were diverted towards deserts, cities and industries. During the last decade, the water level has fallen by more than 1 m per year, causing a hydrostatic disequilibrium between the underground fresh waters and the base level. Thousands of underground cavities have developed as well as hectometre-sized landslides. Despite these unfavourable environmental conditions, large tourism development projects have flourished along the northern coast of the Jordanian Dead Sea. In this work, which is based on a multi-method approach (analyses of radar and optical satellite data, in situ observations, and public science), we show that a 10 km long strip of coast that encompass several resorts is exposed to subsidence, sinkholes, landslides and flash floods. Geological discontinuities are the weakest points where the system can re-balance and where most of the energy is dissipated through erosional processes. Groundwater is moving rapidly along fractures to reach the dropping base level. The salt that fills the sediments matrix is dissolved along the water flow paths favouring the development of enlarged conduits, cavities and then the proliferation of sinkholes. The front beaches of the hotels, the roads and the bridges are the most affected infrastructure. We point out the importance for the land planners to include in the Dead Sea development schemes the historical records and present knowledge of geological hazards in the area.
Vulnerability of tourism development to salt karst hazards along the Jordanian Dead Sea shore
The Dead Sea shore is a unique young and dynamic evaporite karst system. It started developing in the 1960s, when the main water resources that used to feed the terminal lake were diverted towards deserts, cities and industries. The Dead Sea water level started to lower at an accelerating pace, exceeding 1 meter per year during the last decade, causing a hydrostatic disequilibrium between the underground fresh waters and the base level. This battery-like system provides the energy needed for the development of underground cavities, hectometre-size landslides, and vertical erosion of channels during flash-floods. The geological discontinuities are the weakest points where the system can re-balance and where most of the energy is dissipated through erosional processes. Groundwater is moving rapidly along these discontinuities to reach the dropping base level. The salt that soars the sediments matrix is dissolved along the paths favouring the development of enlarged conduits, cavities, and the proliferation of ground collapses (sinkholes). Despite these unfavourable environmental conditions, large touristic projects have flourished along the northern coast of the Jordanian Dead Sea. In this work, thanks to the application of remote sensing techniques combined with repeated field observations, we show that a 10 kilometres-long strip of land along the Dead Sea shore that encompass several touristic infrastructures is exposed to subsidence, sinkholes and landslides. Furthermore, we point out the importance of setting up an early warning system to warn the authorities prior to the triggering of hazardous events, limiting or preventing possible disastrous consequences related to hydrogeological hazards.
Geological Society of America Bulletin, 2006
More than a thousand sinkholes have developed along the western coast of the Dead Sea since the early 1980s, more than 75% of them since 1997, all occurring within a narrow strip 60 km long and <1 km wide. This highly dynamic sinkhole development has accelerated in recent years to a rate of ~150-200 sinkholes per year. The sinkholes cluster mostly over specifi c sites up to 1000 m long and 200 m wide, which spread parallel to the general direction of the fault system associated with the Dead Sea Transform. Research employing borehole and geophysical tools reveals that the sinkhole formation results from the dissolution of an ~10,000-yr-old salt layer buried at a depth of 20-70 m below the surface. The salt dissolution by groundwater is evidenced by direct observations in test boreholes; these observations include large cavities within the salt layer and groundwater within the confi ned subaquifer beneath the salt layer that is undersaturated with respect to halite. Moreover, the groundwater brine within the salt layer exhibits geochemical evidence for actual salt dissolution (Na/Cl = 0.5-0.6 compared to Na/Cl = 0.25 in the Dead Sea brine). The groundwater heads below the salt layer have the potential for upward cross-layer fl ow, and the water is actually invading the salt layer, apparently along cracks and active faults. The abrupt appearance of the sinkholes, and their accelerated expansion thereafter, refl ects a change in the groundwater regime around the shrinking lake and the extreme solubility of halite in water. The eastward retreat of the shoreline and the declining sea level cause an eastward migration of the fresh-saline water interface. As a result the salt layer, which originally was saturated with Dead Sea water over its entire spread, is gradually being invaded by fresh groundwater at its western boundary, which mixes and displaces the original Dead Sea brine. Accordingly, the location of the western boundary of the salt layer, which dates back to the shrinkage of the former Lake Lisan and its transition to the current Dead Sea, constrains the sinkhole distribution to a narrow strip along the Dead Sea coast.
2021
Karst groundwater systems are characterized by the presence of multiple porosity types. Of these, subsurface conduits that facilitate concentrated, heterogeneous flow are challenging to resolve geologically and geophysically. This is especially the case in evaporite karst systems, such as those present on the shores of the Dead Sea, where rapid geomorphological changes are linked to a fall in base level by over 35 m since 1967. Here we combine field observations, remote-sensing analysis, and multiple geophysical surveying methods (shear wave reflection seismics, electrical resistivity tomography, ERT, self-potential, SP, and groundpenetrating radar, GPR) to investigate the nature of subsurface groundwater flow and its interaction with hypersaline Dead Sea water on the rapidly retreating eastern shoreline, near Ghor Al-Haditha in Jordan. Remote-sensing data highlight links between the evolution of surface stream channels fed by groundwater springs and the development of surface subsidence patterns over a 25-year period. ERT and SP data from the head of one groundwater-fed channel adjacent to the former lakeshore show anomalies that point to concentrated, multidirectional water flow in conduits located in the shallow subsurface (< 25 m depth). ERT surveys further inland show anomalies that are coincident with the axis of a major depression and that we interpret as representing subsurface water flow. Low-frequency GPR surveys reveal the limit between unsaturated and saturated zones (< 30 m depth) surrounding the main depression area. Shear wave seismic reflection data nearly 1 km further inland reveal buried paleochannels within alluvial fan deposits, which we interpret as pathways for groundwater flow from the main wadi in the area towards the springs feeding the surface streams. Finally, simulations of density-driven flow of hypersaline and under-Published by Copernicus Publications on behalf of the European Geosciences Union. 3352 D. Al-Halbouni et al.: Dynamics of hydrological and geomorphological processes at the eastern Dead Sea saturated groundwaters in response to base-level fall perform realistically if they include the generation of karst conduits near the shoreline. The combined approaches lead to a refined conceptual model of the hydrological and geomorphological processes developed at this part of the Dead Sea, whereby matrix flow through the superficial aquifer inland transitions to conduit flow nearer the shore where evaporite deposits are encountered. These conduits play a key role in the development of springs, stream channels and subsidence across the study area.
Environmental geology, 2000
For the last four decades, the level of the Dead Sea has been subjected to continual variation which, among other important factors, has led to the occurrence of much subsidence and many sinkholes in the southern Dead Sea area. Sinkhole activities occurred repetitively and were observed in open farms, across roads, near dwellings and near an existing factory, thus causing a serious threat to the locals and farmers of the area and their properties. This paper presents the main results from detailed geological and geotechnical studies of this area. Aerial photo interpretation and borehole drilling aided these studies. Parallel geophysical investigations (vertical electrical sounding and seismic refraction) and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon. It was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the Dead Sea. The development of subsurface cavities is associated mainly with the variation in the level of the Dead Sea over the four past decades, the presence of regional salt intrusion under the surface of salt beds, the fluctuation of the water table and continuous dissolution and the active tectonism of the area. Moreover, this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future.