Dead Sea Level Research Articles

Influence of flood events on the response of steep and coarse-grained channels to base-level lowering in an arid setting

The Dead Sea level has been undergoing a continuous and rapid lowering, presently ∼ 1.1 m/yr, providing a real time laboratory to examine the response of drainage systems to base level drop. There is a gap of knowledge concerning the impact of floods on the fluvial system in an environment of continuous base level lowering. Such knowledge is of pronounced importance due to the world-wide reduction of natural water recourses caused by human and climate impacts. We relate the effects of flash floods on morphological changes in small, steep and coarse-grained alluvial channels as a response to a rapid base level fall. We studied the steep (7–9 %) David and Qedem channels draining to the Dead Sea by (i) monitoring flow events using depth transducers and (ii) topographic changes by repeat drone-based photogrammetric surveys to quantify fluvio-morphological dynamics, and (iii) analyzed boulder-related bedforms and their distance from the thalweg. Altogether 15 monitored flow events of varying magnitude led to a wide range of fluvio-morphological changes. Considerable erosion occurred as expressed by bank collapse and channel bed incision. Small events displayed incision with morphological changes limited to the downstream reach, while larger events caused morphological changes throughout the entire channel. Substantial deposition at the outlet occurred together with local mechanisms of deposition upstream. The extents of erosion and net volumes of change highly correlated with event peak-discharge and event water volume. Frequent thalweg deflections occurred, some of which were related to the interaction with boulders. Boulder ribs displayed processes of formation/destruction in multiple phases, often occurring in larger events. The examined aspects illustrate the unique dynamics of a continuously unstable fluvial system under a flash-flood hydrological regime and its impact on fan delta incision and sediment transport processes.

Seawater softening by nanofiltration enables ecofriendly Dead Sea level stabilisation while creating the basis for cost-effective inland desalination

Increased water extraction led to accelerated shrinkage of the Dead Sea, seriously damaging the environment and posing an economic risk for industry and tourism. The surrounding countries are willing to avert this looming crisis; however, previous approaches became infeasible due to economic, political and ecological hurdles. Motivated by this issue, we propose an alternative sustainable concept based on nanofiltration. We carried out basic design and cost estimations, showing that nanofiltration permeate produced from seawater allows environmentally friendly Dead Sea recharge, minimising gypsum precipitation, algae blooms and groundwater contamination potential on the conveyance routes. Dead Sea level stabilisation with nanofiltration permeate from Med Sea water costs between 0.54 and 0.7 $/m3 at 7 % weighted average cost of capital, significantly lower than treating Red Sea water (0.76 to 0.86 $/m3). Furthermore, providing NF permeate at the Dead Sea in transboundary exchange with Israel allows Jordanian and Palestinian inland desalination for regional potable water production. In the Jordan case, potable water costs at the major demand center, Amman, range between 1.56 and 1.76 $/m3, significantly lower than the national supply from the Red Sea. This study promises a new, feasible solution for trilateral research and implementation cooperation on the Dead Sea issue.

A mechanistic approach for interpreting hydroclimate from halite‐bearing sediments

ABSTRACTEstablishing accurate palaeo‐hydroclimatic reconstructions from lacustrine and marine archives is a long‐standing challenge in palaeoenvironment studies. Closed‐basin evaporites, and especially halite, record episodes of extremely arid conditions during rapid climate change. However, the complex limnological behaviour of deep hypersaline water bodies and the stochastic nature of the hydroclimatic regime and its variations limit detailed palaeo‐hydroclimatic interpretations from such records. Therefore, a mass‐balance model was developed to explore hydrology–limnology–sedimentology relationships in hypersaline environments under both deterministic and stochastic approaches that generates synthetic halite–mud sequences. Applying the model to the Holocene Dead Sea halites yields novel insights into palaeoenvironmental conditions in the Levant. The deterministic framework indicates that: (i) under a series of similar hydroclimatic cycles, the thickness of each subsequent halite interval decreases, due to the depletion of dissolved‐ions storage in the brine; (ii) halite deposition requires lake levels to drop below the minimal lake level of the preceding cycle; (iii) the time interval between halite deposition and the hydrological minimum is increasingly longer in subsequent cycles. Thus, counter‐intuitively, halite deposition mostly takes place as water discharge increases, providing that the water balance is still negative. The stochastic approach produced random sequences comparable to the observed Dead Sea sedimentary record. It demonstrates that some hydrological minima are not represented by halite deposition at all. Furthermore, the thickness and number of halite beds at each hydrological cycle vary substantially, depending on the specific hydrological conditions realized. Finally, these results imply that the major Dead Sea level drop at the pre‐Holocene deglaciation (ca 14 ka bp), previously assumed to be a record minimum, could not have been as pronounced as suggested, and must have been milder than the subsequent drop at the early Holocene (ca 11–10 ka bp).

Eventual Increase in Solar Electricity Production and Desalinated Water through the Formation of a Channel between the Mediterranean and the Dead Sea

Currently, the Israeli energy industry faces the challenge of a considerable increase in solar electricity production. As a relatively isolated system, the significant expansion of solar electricity may cause problems with electricity quality. Electrical storage installation can resolve this problem. In Israel’s situation, the optimal solution could be the creation of a channel between the Mediterranean and the Dead Sea. The channel can solve three closely related problems: the increased production of desalinated water for domestic, industrial, and agricultural needs; the prevention of a permanent Dead Sea level decline and its imminent disappearance; the development of hydro-pumping electrical storage stations; and the creation of numerous PV facilities in the Negev area for national electricity generation. However, detailed analysis should be conducted for the estimation of the possible increase in solar electric generation with consideration of a stochastic PV outcome and the potential ability to use the Dead Sea for the brine discharge of electrical hydro-storage plants.

Dead Sea level decline pushed a sensitive ecosystem out of equilibrium, causing the relocation of a colonial bird breeding site

ABSTRACT Capsule Dead Sea Sparrows Passer moabiticus transferred their historical breeding colony location, following geo-ecological and hydrological changes, to a new, less arid zone within a nature reserve. Aims To find biotic and abiotic factors affecting the choice of nest sites by Dead Sea Sparrows, in order to locate potential breeding areas and plan in advance for their protection. Methods Mapping old and new nest sites of Dead Sea Sparrows within Einot Tzukim nature reserve, Dead Sea Valley, and using anthropogenic and geo-ecological GIS layers, we created a map of the potential preferred breeding colony area. Results We found the biotic and abiotic factors affecting nest site preference of Dead Sea Sparrows, which included areas far from human activity, areas close to historic springs, and areas affected by a major fire. New areas in the reserve exposed by the retreating Dead Sea were inhabited by the birds, which gradually transferred their breeding centre to a less arid zone within the reserve. Conclusion When managing colonial breeding sites, it is crucial to understand the role of both natural and anthropogenic influences in order to prioritize sites for conservation and management. Producing a preference map, based on such data, can help managers locate potential breeding areas and plan in advance for their protection.

Identifying plausible historical scenarios for coupled lake level and seismicity rate changes: the case for the Dead Sea during the last 2 millennia

Abstract. Studies of seismicity induced by water level changes in reservoirs and lakes focus typically on well-documented contemporary records. Can such interactions be explored on a historical timescale when the two data types suffer from severe uncertainties stemming from the different nature of the data, methods and resolution? In this study, we show a way to considerably improve the correlation between interpolated records of historical Dead Sea level reconstructions and discrete seismicity patterns in the area, over the period of the past 2 millennia. Inspired by the results of our previous study, we carefully revise the historical earthquake catalog in the Dead Sea to exclude remote earthquakes and include small local events. For addressing the uncertainties in lake levels, we generate an ensemble of random interpolations of water level curves and rank them by correlation with the historical records of seismic stress release. We compute a synthetic catalog of earthquakes, applying a Mohr–Coulomb failure criterion. The critical state of stress at hypocentral depths is achieved by static poroelastic deformations incorporating the change in effective normal stress (due to the best-fit water level curve) superimposed on the regional strike-slip tectonic deformations. The earthquakes of this synthetic catalog show an impressive agreement with historical earthquakes documented to have damaged Jerusalem. We refine the seismic catalog by searching for small local events that toppled houses in Jerusalem; including all local events improves the correlation with lake levels. We demonstrate for the first time a high correlation between water level changes and the recorded recurrence intervals of historical earthquakes.

Criteria for the recognition of clastic halite: The modern Dead Sea shoreline

AbstractSedimentological studies of modern halites have focused on shallow water to subaerially‐exposed saline pans, where in‐place crystal growth, dissolution and cementation textures dominate. Clastic halite transported and deposited by waves and unidirectional currents as bedload is poorly known. This paper: (i) describes and interprets the diagnostic sedimentary features of clastic halite from a modern outcrop exposed along the north‐western coastline of the Dead Sea; and (ii) provides criteria for recognition of clastic halite in the rock record. The 2 m thick halite unit at Nahal Og was deposited within the last four decades at water depths <30 m as Dead Sea levels fell ca 30 m. Clastic halites consist of frameworks of sorted crystals with point contacts and no preferred growth fabrics. Halite cumulates, deposited as suspended load, precipitated in the water column and sank to the brine bottom. The excellent sorting and purity of halite crystal layers are unique to cumulates. Small‐scale ripple cross‐stratified thin beds and intraclast conglomerates were deposited from bedload. Halite bedload deposits (composed of halite flat pebbles, ooids, rafts, single clear crystals, cumulate crystals, mud intraclasts and rounded mudballs, foraminifera, gypsum) reflect wave transport and deposition via oscillatory flow above wave base, or by unidirectional flow in the breaker and surf zones. In addition, waves on the Dead Sea coast generate longshore currents. Thin beds produced by wave‐influenced oscillatory transport of halite are symmetrical in cross‐section. Less common cross‐stratified units with asymmetrical cross‐sections indicate unidirectional currents. Clastic halite, especially as a bedload deposit, has rarely been identified in ancient evaporites. Shoreline deposits from ancient halites, however, must contain wave‐reworked and current‐reworked layers and should be common in saline giants, given their enormous size and potential for generating waves and currents. Documentation of modern clastic halite may lead to a better understanding of ancient hypersaline environments on Earth.

Dynamics of turbidity in gypsum-precipitating brines: The case of the Red Sea – Dead Sea project

Authigenic processes in aqueous environments, such as mineral precipitation, can create turbidity which may have undesired effects on the natural environment and in industrial processes. Turbidity is often used to monitor such environments, as a mean to determine water quality and to follow the industrial processes. However, turbidity develops and grows or dissipates with time as the processes underlying its development advance. This dynamic nature of turbidity has yet to be studied.The proposed pilot Red Sea – Dead Sea project (RSDSP) is to desalinate seawater from the Gulf of Aqaba/Eilat and convey the reject brine, with or without additional seawater, to the Dead Sea to slow down the rate of its water level decline. The pilot is considered environmentally safe and will be used as a mean to determine if increased inflow volumes to stabilize the Dead Sea level will not negatively affect the lake. The mixing of the two very different solutions will lead to gypsum precipitation in the Dead Sea. In a large-scale project, if this gypsum remains in suspension, it may result in increased turbidity and whitening of the Dead Sea's surface water, thereby impacting the lake's appearance, its energy balance, and its touristic and mineral industries.We have studied the dynamic nature of turbidity as gypsum crystals form, grow and sink out of the water column in enriched mixtures of Dead Sea brine with seawater from the Red Sea. Our laboratory experiments suggest that precipitation from simple mixtures is likely to proceed without creating a significant spontaneous increase in turbidity. Turbidity did however develop in sulfate-enriched mixtures that had higher initial oversaturation. In these enriched solutions increased turbidity was observed, which developed faster and to higher values with increasing initial oversaturation. A linear relationship was found between the mass of gypsum precipitated and turbidity. However, this relationship was not universal; a unit mass of precipitated gypsum resulted in higher turbidity when the gypsum precipitated from mixtures having higher %wt of Dead Sea.This study shows that under laboratory conditions, mixtures of Dead Sea - seawater or Dead Sea – reject brine, do not develop turbidity due to gypsum precipitation. However, precipitation process in large scale natural systems can differ from those in the lab. Therefore, our findings cannot unequivocally conclude whether a whitening of the Dead Sea would develop following the implementation of the full scale RSDSP. Nevertheless, it does set forth the factors that need to be monitored during the pilot stage. Moreover, the study also demonstrates that: 1) authigenic processes do not lead to a one-to-one relationship between particulate matter and turbidity; and 2) turbidity readings must first be calibrated before used as a monitoring tool to identify and quantify gypsum formation (e.g., in desalination plants) or for the determination of induction times (e.g., in experiments).

From straight to deeply incised meandering channels: Slope impact on sinuosity of confined streams

AbstractMeandering channels and valleys are dominant landscape features on Earth. Their morphology and remnants potentially indicate past base‐level fluctuations and changing regional slopes. The prevailing presence of meandering segments in low‐slope areas somewhat confuses the physically based relationships between slope and channel meandering. This relationship underlies a fundamental debate: do incised sinuous channels actively develop during steepening of a regional slope, or do they inherit the planform of a preexisting sinuous channel through vertical incision? This question was previously explored through reconstructed evolution of meandering rivers, numerical simulations, and controlled, scaled‐down laboratory experiments. Here, we study a rare, field‐scale set of a dozen adjacent perennial channels, evolving in recent decades in a homogeneous erodible substrate in response to the Dead Sea level fall (> 30 m over 40 years). These channels are fed by perennial springs and have no drainage basin or previous fluvial history; they initiated straight and transformed into incising meandering channels following the emergence of the preexisting lake bathymetry, which resulted in increased channel lengths and regional slopes at different rates for each channel. This field setting allows testing the impact of changing regional slope on the sinuosity of a stream in the following cases: (a) relatively long and low‐gradient shelf‐like margins, (b) a sharp increase in the basinward gradient at the shelf‐slope transition, and (c) gradually steepening slopes. Under a stable and low valley slope, the channels mainly incise vertically, inheriting a preexisting sinuous pattern. When the regional slope steepens, the channels start to meander, accompanying the vertical incision. The highest sinuosity evolved in the steepest channel, which also developed the deepest and widest valley. These results emphasize the amplifying impact of steepening regional slope on sinuosity. This holds when the flow is confined and chute cutoffs are scarce.

Sedimentology and stratigraphy of a modern halite sequence formed under Dead Sea level fall

AbstractHalite sequences in the geological record accumulated in deep hypersaline basins. However, such halite sequences are interpreted based on modern analogues of halite deposition in shallow hypersaline environments. Recently, halite deposition in the deep, hypersaline Dead Sea has been studied together with its coeval environmental and limnogeological forcing. This is the closest modern analogue for deep environments. Therefore, stratigraphy, sedimentology and petrography of a well‐dated, high‐resolution modern Dead Sea halite sequence are explored. The sequence was deposited during a ca 30 m lake‐level decline since the onset of modern halite deposition in 1980, and was compared with sub‐annual lake levels, precipitation and flood records. The sedimentology of the sequence documents the trend of shallowing water depth, including individual floods. The sequence base is composed of alternating bottom growth‐cumulate halite annual couplets, typical of deep hypolimnetic water deposition. Up‐sequence, the annual couplets disappear and towards its top are composed of cumulate layers with dissolution features, typical of shallow epilimnetic water deposition. Halite deposition rate is reduced by 60% at the shallow lakefloor compared with the deep lakefloor, mainly due to the summer undersaturation that leads to depocentre ‘halite focusing'. The top of the sequence contains shoreline deposits, halolites (halite ooids) and polygonal surface cracks, indicating subaerial exposure. This study shows petrographic indicators for summer thermal dissolution (partially dissolved crystals), which are distinct from dissolution features by winter floods that generate a regional truncation surface. Spatial variations in halite thickness and facies, indicating much thinner and spatially limited halite units compared to modelled halite units based on mass balance considerations were also observed. These observations provide criteria for: (i) recognizing water depths and shallowing lake‐level trends from halite sequences throughout the geological record; and (ii) interpreting palaeolimnology, water column structure and the relations between stratigraphic horizons and corresponding shorelines.

Displacement of springs and changes in groundwater flow regime due to the extreme drop in adjacent lake levels: The Dead Sea rift

Lake-level fluctuations brought on by climatic changes and anthropogenic factors may affect the flow regime in adjacent aquifers that discharge toward those lakes. Such fluctuations may also cause displacement of springs that discharge these aquifers. Using a calibrated numerical model, an extreme example of such phenomenon is observed in the Dead Sea rift valley and the adjacent Eastern Mountain Aquifer of the Judea and Samaria Mountains. Lake levels along the Dead Sea rift have changed dramatically and rapidly by hundreds of meters, followed by changes in the lake areas by hundreds of square kilometers. Simultaneously, the aquifer exhibited spring displacements, both on large and small scales. Currently, 50% of the aquifer water discharge in the Zuqim zone, and 10% north of the Dead Sea. But in the past, only 30% discharged at Zuqim and 40% north of the Dead Sea. There is evidence for such an occurrence in the past, and it is likely to recur in the future, based on the predicted progressive decline of the current Dead Sea level. This may have an impact on wetland habitats along the coast.

Mediterranean – Dead Sea Channel for Preserving Dead Sea Level and Increasing Solar Energy Production

Mediterranean – Dead Sea Channel for Preserving Dead Sea Level and Increasing Solar Energy Production

Mean, variance, and trends of Levant precipitation over the past 4500 years from reconstructed Dead Sea levels and stochastic modeling

AbstractA novel quantitative assessment of late Holocene precipitation in the Levant is presented, including mean and variance of annual precipitation and their trends. A stochastic framework was utilized and allowed, possibly for the first time, linking high-quality, reconstructed rises/declines in Dead Sea levels with precipitation trends in its watershed. We determined the change in mean annual precipitation for 12 specific intervals over the past 4500 yr, concluding that: (1) the twentieth century was substantially wetter than most of the late Holocene; (2) a representative reference value of mean annual precipitation is 75% of the present-day parameter; (3) during the late Holocene, mean annual precipitation ranged between −17 and +66% of the reference value (−37 to +25% of present-day conditions); (4) the driest intervals were 1500–1200 BC and AD 755–890, and the wettest intervals were 2500–2460 BC, 130–40 BC, AD 350–490, and AD 1770–1940; (5) lake-level rises and declines probably occurred in response to trends in precipitation means and are less likely to occur when precipitation mean is constant; (6) average trends in mean annual precipitation during intervals of ≥200 yr did not exceed 15 mm per decade. The precipitation trends probably reflect shifts in eastern Mediterranean cyclone tracks.

Sinuosity evolution along an incising channel: New insights from the Jordan River response to the Dead Sea level fall

AbstractThe geomorphic evolution of the Jordan River in recent decades indicates that interaction between incision and high‐magnitude floods controls sinuosity changes under increasing mouth gradients during base‐level fall. The evolution of the river was analyzed based on digital elevation models, remotely sensed imagery, hydrometric data, and a hydraulic model. The response varies along the river. Near the river mouth, where incision rate is high and a deep channel forms, overbank flooding is less likely. There, large floods exert high shear stress within the confined channel, increasing sinuosity. Upstream, near the migrating knickzone channel gradients also increase, incision is more moderate and floods continue to overtop the banks, favoring meander chute cutoffs. The resulting channel has a downstream well‐confined meandering segment and an upstream low‐sinuosity segment. These new insights regarding spatial differences along an incising channel can improve interpretations of the evolution of ancient planforms and floodplains that responded to base‐level decline. © 2018 John Wiley & Sons, Ltd.

Meandering and Land Use /Cover Change Detection in the Lower Jordan River (LJR), 1984-2016, Using GIS and RS

The objective of this study is to monitor and analyze the meandering, and changes in land use / land cover (LULC) caused by the large reduction of water flow of the lower Jordan River (LJR), resulting from climatic conditions, and conflict over water resources between Syria, Jordan, Israel and the Palestinian Authority in the upper part of the Jordan River Basin (JRB). These circumstances have led to dramatic decline in the Dead Sea level by a vertical distance of -39 m during the monitoring period. This has resulted in the scarcity of water resources, changes affecting the geomorphology of the river as well as the vegetated area and the spatial distribution of riparian vegetation in the (LJR). These changes were examined using Landsat TM, ETM, all images acquired in August 1984, 2000, and 2016, and a topographic map (TM) was used as a base map. The multi-temporal images were geometrically and radio metrically calibrated to each other and used as input for an automatic change detection procedure. The results of the interpretation showed that there was an elongation in the active channel length of about 741.8 m within the monitoring period as a result of the Dead Sea retreat, and about 2.65 km caused by meandering. The direction of the migration rates varied towards west and east, with the dominant direction towards the west and the annual average migration rate for west and east was 0.325 m, with a total lateral migration during the study period about only 17.875m in both directions west and east. River meandering has increased from 1.8 m to 2.1 m in the time period. With respect to (LULC), the difference image indicated that significant positive changes in green vegetation have occurred between 1984 and 2016; this is due to the expansion of water storage by canals, and dams in all riparian counters, with an increase in water ponds. The Normalized Difference Vegetation Index (NDVI) showed that the riparian vegetation area increased by 36.9% during the monitoring period, indicating the stability of the valley floor. DOI: http://dx.doi.org/10.5755/j01.erem.74.2.20917

Shear wave reflection seismic yields subsurface dissolution and subrosion patterns: application to the Ghor Al-Haditha sinkhole site, Dead Sea, Jordan

Abstract. Near-surface geophysical imaging of alluvial fan settings is a challenging task but crucial for understating geological processes in such settings. The alluvial fan of Ghor Al-Haditha at the southeast shore of the Dead Sea is strongly affected by localized subsidence and destructive sinkhole collapses, with a significantly increasing sinkhole formation rate since ca. 1983. A similar increase is observed also on the western shore of the Dead Sea, in correlation with an ongoing decline in the Dead Sea level. Since different structural models of the upper 50 m of the alluvial fan and varying hypothetical sinkhole processes have been suggested for the Ghor Al-Haditha area in the past, this study aimed to clarify the subsurface characteristics responsible for sinkhole development.For this purpose, high-frequency shear wave reflection vibratory seismic surveys were carried out in the Ghor Al-Haditha area along several crossing and parallel profiles with a total length of 1.8 and 2.1 km in 2013 and 2014, respectively. The sedimentary architecture of the alluvial fan at Ghor Al-Haditha is resolved down to a depth of nearly 200 m at a high resolution and is calibrated with the stratigraphic profiles of two boreholes located inside the survey area.The most surprising result of the survey is the absence of evidence of a thick (> 2–10 m) compacted salt layer formerly suggested to lie at ca. 35–40 m depth. Instead, seismic reflection amplitudes and velocities image with good continuity a complex interlocking of alluvial fan deposits and lacustrine sediments of the Dead Sea between 0 and 200 m depth. Furthermore, the underground section of areas affected by sinkholes is characterized by highly scattering wave fields and reduced seismic interval velocities. We propose that the Dead Sea mud layers, which comprise distributed inclusions or lenses of evaporitic chloride, sulfate, and carbonate minerals as well as clay silicates, become increasingly exposed to unsaturated water as the sea level declines and are consequently destabilized and mobilized by both dissolution and physical erosion in the subsurface. This new interpretation of the underlying cause of sinkhole development is supported by surface observations in nearby channel systems. Overall, this study shows that shear wave seismic reflection technique is a promising method for enhanced near-surface imaging in such challenging alluvial fan settings.

Investigations into the Holocene geology of the Dead Sea basin

This paper discusses the geological history and paleoclimate of the Dead Sea region based on drill hole data. A composite stratigraphic column for the Holocene period, of multiple lime carbonate and halite sedimentation, has been constructed for the southern Dead Sea basin. Integration of stratigraphic data with geochronology has shed new light on our understanding of Holocene sedimentation rates, tectonics, diapirism, the formation of sinkholes, lake levels, and paleoclimate. During this period, the southern basin has subsided at a rate of 8.5–11 m/ka, while the subsidence of the northern basin may have reached 25–30 m/ka. The Holocene has been divided into 13 major climatic intervals, starting with a very arid climate from ~ 11,700 to ~ 8800 BP, where halite precipitated in both basins, with the Dead Sea possibly reaching a level of ~ − 419 m msl. After ~ 8800 BP, there was a very intense pluviatile period, with the formation of alluvial fans opposite wadi channels reaching up to 45 m in thickness. An attempt has been made to construct a new Dead Sea-level curve, based on the mineralogical data and corrected for diapirism under the Lynch Straits and tectonic subsidence. The previous lake-level curves were based on elevations of shore-line facies in a tectonically active basin with differential subsidence. A new hypothesis is presented for sinkhole formation in both the northern and southern basins, which is considered to be initiated and controlled by active faulting, with the dissolution of the halite by artesian, undersaturated waters, more than the receding Dead Sea level. The brine level is rising in the southern basin. The findings from this research can act as a model for understanding the development of ancient and modern evaporites worldwide.

Using Combined Close-Range Active and Passive- Remote Sensing Methods to Detect Sinkholes

In the Dead Sea region of Israel, sinkholes collapse can be observed easily due to the large number of sites. The continuous decrease in Dead Sea level over the last 30 years, caused a substantial increases the sinkhole activity (more than 3,000 sinkholes upper layer collapse). Sinkholes of up to 50 m diameter are found to be clustered in sites with variable characteristics. In this research, we have developed methods for prediction of sinkholes appearance by using mapping and monitoring methods based on active and passive remote-sensing means. These methods are based on measurements from several instruments including field spectrometry, geophysical ground-penetration radar (GPR) and a frequency domain electromagnetic (FDEM) instrument. Field spectrometry was used to compare the spectral signatures of soil samples collected near progressing sinkholes and those taken in regions with no visible occurrence of sinkholes. Active remote sensing showed higher electrical conductivity and soil moisture in the former regions. Measurements were taken at different time points to monitor the progress of an embryonic sinkhole. The research steps included (i) review of previous published literature, (ii) mapping of regions with an abundance of sinkholes in various stages, and areas that are vulnerable to them, (iii) data analysis and development of warning indicators, accessible information to the scientific community. The result derived from this research indicates the possibility to build a pre-warning tool to detect the formation of sinkholes.

Natural versus human control on subsurface salt dissolution and development of thousands of sinkholes along the Dead Sea coast

One of the most hazardous results of the human-induced Dead Sea (DS) shrinkage is the formation of more than 6000 sinkholes over the last 25 years. The DS shrinkage caused eastward retreat of underground brine replaced by fresh groundwater, which in turn, dissolved a subsurface salt layer, to generate cavities and collapse sinkholes. The areal growth rate of sinkhole clusters is considered the most pertinent proxy for sinkholes development. Analysis of Light Detection and Ranging (LiDAR), Digital Elevation Models (DEMs), and Interferometric Synthetic Aperture Radar (InSAR) allows translation of the areal growth rate to a salt dissolution rate of the salt layer, revealing two peaks in the history of the salt dissolution rate. These peaks cannot be attributed to the decline of the DS level. Instead, we show that they are related to long term variations of precipitation in the groundwater source region, the Judea Mountains, and the delayed response of the aquifer system between the mountains and the DS rift. This response is documented by groundwater levels and salinity variations. We thus conclude that while the DS level decline is the major trigger for sinkholes formation, the rainfall variations more than 30 km to the west dominate their evolution rate. The influence of increasing rainfall in the Judea Mountains reaches the DS at a typical time-lag of four years, and the resulting increase in the salt dissolution rate lags by a total time of 5–6 years.

Do People Live at Sea Level and the Dead Sea Level Have Different Patterns of Anti-Hypertensive Drugs

Do People Live at Sea Level and the Dead Sea Level Have Different Patterns of Anti-Hypertensive Drugs