Dead Sea Level Research Articles

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

Background: people live at various areas of sea level may have different patterns of anti-hypertensive drugs. Such a relation has never been reported in Jordan. Study objectives: the current study investigated how the sea level will impact the prevalence of hypertension in these areas, and how will affect the pharmacological properties of such a population. Methodology: a cross-sectional study design was involved to collect data from study participants. A total of 1000 participants were randomly selected from the two study areas. 500 participants from each. Participants were matched for age and gender. Blood pressure were measured for all participants. Blood samples were withdrawn to investigate the level of angiotensin II. Data was collected through organizing a working excel sheet and was further analyzed through using SPSS version 20. Data was presented as means, standard deviations, frequencies and percentages. The relationships between variables were examined using independent T-test. Significance was measured at an alpha < 0.05. Study findings: the main findings of the present study were that the mean of SBP is significantly higher in the Dead Sea (122.42±10.53 mmHg) than the Sea level area (118.07±11.64 mmHg), (p=0.001). Another significant variable was MBP which its mean was 91.64 ± 8.90 mmHg in the Dead Sea and 89.84 ± 8.72 mm Hg. The difference in the mean was statistically significant (p=0.001). The level of angiotensin II was 8.84 ± 4.65pg/ml in the Dead Sea area and 11.21± 6.05pg/ml in the area of the Sea level. The difference in the mean of the two study areas was not statistically significant (p>0.05). Conclusions: although the level of angiotensin II was not significantly varied between the study areas, but its trend was to be higher in the Sea level area. It was surprised to have higher levels of SBP and MBP in the Dead Sea rather than the Seal level area. It can be implied that the therapeutic options of hypertensive drugs follow different patterns independent of angiotensin II pathways.

Salt dissolution and sinkhole formation: Results of laboratory experiments

The accepted mechanism for the formation of thousands of sinkholes along the coast of the Dead Sea suggests that their primary cause is dissolution of a salt layer by groundwater undersaturated with respect to halite. This is related to the drop in the Dead Sea level, which caused a corresponding drop of the freshwater-saltwater interface, resulting in fresher groundwater replacing the brines that were in contact with the salt layer. In this study we used physical laboratory experiments to examine the validity of this mechanism by reproducing the full dynamic natural process and to examine the impact of different hydrogeological characteristics on this process. The experimental results show surface subsidence and sinkhole formation. The stratigraphic configurations of the aquifer, together with the mechanical properties of the salt layer, determine the dynamic patterns of the sinkhole formation (instantaneous versus gradual formation). Laboratory experiments were also used to study the potential impact of future stratification in the Dead Sea, if and when the “Red Sea-Dead Sea Canal” project is carried out, and the Dead Sea level remains stable. The results show that the dissolution rates are slower by 1 order of magnitude in comparison with a nonstratified saltwater body, and therefore, the processes of salt dissolution and sinkhole formation will be relatively restrained under these conditions.

Dead Sea Levels during the Bronze and Iron Ages

The history of lake-level changes at the Dead Sea during the Holocene was determined mainly by radiocarbon dating of terrestrial organic debris. This article reviews the various studies that have been devoted over the past 2 decades to defining the Dead Sea levels during the Bronze and Iron Ages (≃5.5 to 2.5 ka cal BP) and adds new data and interpretation. In particular, we focus on research efforts devoted to refining the chronology of the sedimentary sequence in the Ze'elim Gully, a key site of paleoclimate investigation in the European Research Council project titled Reconstructing Ancient Israel. The Bronze and Iron Ages are characterized by significant changes in human culture, reflected in archaeological records in which sharp settlement oscillations over relatively short periods of time are evident. During the Early Bronze, Intermediate Bronze, Middle Bronze, and Late Bronze Ages, the Dead Sea saw significant level fluctuations, reaching in the Middle Bronze an elevation of ≃370 m below mean sea level (bmsl), and declining in the Late Bronze to below 414 m bmsl. At the end of the Late Bronze Age and upon the transition to the Iron Age, the lake recovered slightly and rose to ≃408 m bmsl. This recovery reflected the resumption of freshwater activity in the Judean Hills, which was likely accompanied by more favorable hydrological-environmental conditions that seem to have facilitated the wave of Iron Age settlement in the region.

Closing the (widening) gap between natural water resources and water needs in the Jordan River Basin: a long-term perspective

The supply of renewable natural water available in a sustainable fashion in the Jordan River Basin, comprising Israel, Jordan and the Palestinian Authority, will soon drop below 100 m3/person/year. Drawing on recent technological progress and policy innovations, a comprehensive policy to address the region's water problems in the long run is offered. The policy has a dual goal: to satisfy the needs of a growing population (domestic, irrigation and industry) and to preserve important environmental amenities, including restoration of the Lower Jordan River and stabilization of the Dead Sea level. The gap between natural water supplies and the basic needs of the growing population will be closed by conservation and desalination; at the same time, all domestic water will be recycled and will be available for reuse in irrigation and environmental restoration. Over time the supply of recycled water that should be allocated for environmental restoration (accounting for the compensation of irrigators) will suffice to partially restore the Lower Jordan River and contribute to the stabilization of the Dead Sea. The analysis is relevant in a wide range of real-world situations, where satisfying the basic needs of a growing population and preserving environmental amenities become critical.

Dead Sea pollen record and history of human activity in the Judean Highlands (Israel) from the Intermediate Bronze into the Iron Ages (∼2500–500 BCE)

A detailed pollen record for the time interval of ∼2500–500 BCE, which covers the time period of the Intermediate Bronze Age (Early Bronze Age IV) into the Iron Ages in the Levant, is presented. The study was conducted in the Ze’elim Gully, which drains the southern Judean Highlands into the Dead Sea. During the Bronze and Iron Ages, the Judean Highlands exhibited dramatic settlement fluctuations. To better understand these oscillations, high-resolution fossil pollen data were combined with a recent pollen data set, lithological features, radiocarbon dating and palaeohydrological information derived from the Dead Sea levels. Due to the occurrence of hiatuses in this fluvial environment, we used a composite profile which was based on two palynological-sedimentological profiles. This integrated information enabled us to reconstruct in great detail for the first time the environmental conditions in relation to the picture derived from archaeological field-work in the Judean Highlands. Evidence for drier climate conditions at the end of the Late Bronze Age may account for the dramatic changes in the settlement pattern which include the destruction of a large number of urban centres and shrinkage of other major sites, not only in the Judean Highlands but in the entire southern Levant. This arid phase may have been one of the reasons for the collapse of eastern Mediterranean civilizations in the mid-thirteenth and twelfth centuries BCE. The improved conditions in the Judean highlands during the Iron Age I (evident by the increasing percentages of both Mediterranean elements and agricultural taxa, e.g. olive and cereals) enabled the recovery of settlement activity, which is the backdrop for the rise of ancient Israel.

Possible connection between large volcanic eruptions and level rise episodes in the Dead Sea Basin

The June 1991 Pinatubo volcanic eruption perturbed the atmosphere, triggering short-term worldwide changes in surface and lower troposphere temperatures, precipitation, and runoff. The following winter was anomalously wet in the Levant, with a ∼2-m increase in the Dead Sea level that created a distinct morphological terrace along the lake's shore. Given the global radiative and chemical effects of volcanogenic aerosols on climatic systems, we tested the hypothesis that the 1991–92 winter shore terrace is a modern analogue to the linkage between past volcanic eruptions and a sequence of shore terraces on the cliffs around the Dead Sea Basin (DSB). Sixteen shore terraces, detected using airborne laser scanning data, were interpreted as indicating short-term level rises due to episodes of enhanced precipitation and runoff during the dramatic drop in Lake Lisan's (palaeo-Dead Sea) level at the end of the Last Glacial Maximum. The terraces were compared with a dated time series of volcanogenic sulfate from the GISP2 ice core, and similar numbers of sulfate concentration peaks and shore terraces were found. Furthermore, a significant correlation was found between SO4 concentration peaks and the heights of the terraces. This correlation may indicate a link between the explosivity of past eruptions, the magnitude of stratospheric injection, and their impact on the northern hemisphere water balance. The record of such short-term climato-hydrological effects is made possible by the dramatic desiccation of Lake Lisan. Detailed records of such events, albeit rare because of their vulnerability and short longevity, provide an important demonstration of global climatic teleconnections.

Impacts of abrupt climate changes in the Levant from Last Glacial Dead Sea levels

A new, detailed lake level curve for Lake Lisan (the Last Glacial Dead Sea) reveals a high frequency of abrupt fluctuations during Marine Isotope Stage 3 (MIS3) compared to the relatively high stand characterizing MIS2, and the significantly lower Holocene lake. The lake level fluctuations reflect the hydrological conditions in the large watershed of the lake, which in turn reflects the hydro-climatic conditions in the central Levant region. The new curve shows that the fluctuations coincide on millennial timescales with temperature variations recorded in Greenland. Four patterns of correlation are observed through the last ice age: (1) maximum lake elevations were reached during MIS2, the coldest interval; (2) abrupt lake level drops to the lowest elevations coincided with the occurrence of Heinrich (H) events; (3) the lake returned to higher-stand conditions along with warming in Greenland that followed H-events; (4) significant lake level fluctuations coincided with virtually every Greenland stadial–interstadial cycle.Over glacial–interglacial time-scales, Northern Hemisphere glacial cooling induces extreme wetness in the Levant, with high lake levels reaching ∼160 m below mean sea level (mbmsl), approximately 240 m above typical Holocene levels of ∼400 mbmsl. These orbital time-scale shifts are driven by expansions of the European ice sheet, which deflect westerly storm tracks southward to the Eastern Mediterranean, resulting in increased sea-air temperature gradients that invoke increased cyclogenesis, and enhanced moisture delivery to the Levant. The millennial-scale lake level drops associated with Greenland stadials are most extreme during Heinrich stadials and reflect abrupt cooling of the Eastern Mediterranean atmosphere and sea-surface, which weaken the cyclogenic rain engine and cause extreme Levant droughts. During the recovery from the effect of Heinrich stadials, the regional climate configuration resumed typical glacial conditions, with enhanced Levant precipitation and a rise in Lake Lisan levels. Similar cyclicity in the transfer of moisture to the Levant affected lake levels during all of the non-Heinrich stadial–interstadial cycles.

Localisation and temporal variability of groundwater discharge into the Dead Sea using thermal satellite data

The semi-arid region of the Dead Sea heavily relies on groundwater resources. This dependence is exacerbated by both population growth and agricultural activities and demands a sustainable groundwater management. Yet, information on groundwater discharge as one main component for a sustainable management varies significantly in this area. Moreover, discharge locations, volume and temporal variability are still only partly known. A multi-temporal thermal satellite approach is applied to localise and semi-quantitatively assess groundwater discharge along the entire coastline. The authors use 100 Landsat ETM + band 6.2 data, spanning the years between 2000 and 2011. In the first instance, raw data are transformed to sea surface temperature (SST). To account for groundwater intermittency and to provide a seasonally independent data set ∆T (maximum SST range) per-pixel within biennial periods is calculated subsequently. Groundwater affected areas (GAA) are characterised by ∆T 10 °C. This allows the exact identification of 37 discharge locations (clusters) along the entire Dead Sea coast, which spatially correspond to available in situ discharge observations. Tracking the GAA extents as a direct indicator of groundwater discharge volume over time reveals (1) a temporal variability correspondence between GAA extents and recharge amounts, (2) the reported rigid ratios of discharge volumes between different spring areas not to be valid for all years considering the total discharge, (3) a certain variability in discharge locations as a consequence of the Dead Sea level drop, and finally (4) the assumed flushing effect of old Dead Sea brines from the sedimentary body to have occurred at least during the two series of 2000–2001 and 2010–2011.

3D Imaging of Dead Sea Area Using Weighted Multipath Summation: A Case Study

The formation of sinkholes along the Dead Sea is caused by the rapid decline of the Dead Sea level, as a possible result of human extensive activity. According to one of the geological models, the sinkholes in several sites are clustered along a narrow coastal strip developing along lineaments representing faults in NNW direction. In order to understand the relationship between a developing sinkhole and its tectonic environment, a high-resolution (HR) three-dimensional (3D) seismic reflection survey was carried out at the western shoreline of the Dead Sea. A recently developed 3D imaging approach was applied to this 3D dataset. Imaging of subsurface is performed by a spatial summation of seismic waves along time surfaces using recently proposed multipath summation with proper weights. The multipath summation is performed by stacking the target waves along all possible time surfaces having a common apex at the given point. This approach does not require any explicit information on parameters since the involved multipath summation is performed for all possible parameters values within a wide specified range. The results from processed 3D time volume show subhorizontal coherent reflectors at approximate depth of 50–80 m which incline on closer location to the exposed sinkhole and suggest a possible linkage between revealed fault and the sinkholes.

The decline of the early Neolithic population center of 'Ain Ghazal and corresponding earth-surface processes, Jordan Rift Valley

'Ain Ghazal is among the earliest large population centers known in the Middle East. A total of four major stratigraphic cultural units have been identified: 1) The oldest Middle Pre-Pottery Neolithic B (MPPNB) unit (10.2 to 9.5cal ka BP) clearly corresponds with the early Holocene maximum Dead Sea levels. 2) The second unit consists of Late Pre-Pottery Neolithic B (LPPNB) in situ walls and hearths. 3) In the subsequent PPNC (8.9 to 8.6cal ka BP) the population density at the settlement drops dramatically, which corresponds with a significant drop in the Dead Sea level. 4) The 4th stratigraphic unit is characterized by the “Yarmoukian rubble layer”. Additionally, there is evidence for a previously unrecognized use of the site by Chalcolithic pastoralists. Sedimentological analyses reveal a constant increase in dust from a remote source during the entire human occupation period, which correlates well with the detectable drops in climatic humidity from the Dead Sea. As the major focus of this study, we can now rule out previous notions that the “Yarmoukian” rubble layer could have been produced by (catastrophic) slope-scale gravitational movements. To this point, it appears that the Neolithic mega-site was abandoned due to a climatic aridification.

Monitoring of Dead Sea water surface variation using multi-temporal satellite data and GIS

Remote sensing (RS) and geographic information systems (GIS) are very useful for environmental-related studies, particularly in the field of surface water studies such as monitoring of lakes. The Dead Sea is exposed to very high evaporating process with considerable scarcity of water sources, thus leading to a remarkable shrinkage in its water surface area. The lake suffers from dry out due to the negative balance of water cycle during the previous four decades. This paper discusses the application of RS, GIS, and Global Positioning System to estimate the lowering and the shrinkage of Dead Sea water surface over the period 1810–2005. A set of multi-temporal remote sensing images were collected and processed to show the lakes aerial extend shrinkage from 1973 up to 2004. Remote sensing data were used to extract spatial information and to compute the surface areas for Dead Sea for various years. The current study aims at estimating the fluctuation of Dead Sea level over the study period with special emphasis on the environmental impact assessment that includes the degradation level of the Dead Sea. The results indicated that there is a decrease of 20 m in the level of the Dead Sea that has occurred during the study period. Further, the results showed that the water surface area of the Dead Sea has shrunk from 934.26 km2 in 1973 to 640.62 km2 in 2004.

TEM study of the geoelectrical structure and groundwater salinity of the Nahal Hever sinkhole site, Dead Sea shore, Israel

Since the 1990s a large number of sinkholes have appeared in the Dead Sea (DS) coastal area. Sinkhole development was triggered by the lowering of the DS level. In the literature the relationship between the sinkholes and the DS level is explained by intrusion of relatively fresh water into the aquifer thereby dramatically accelerating the salt dissolution with creation of subsurface caverns, which in turn cause sinkholes. The main goal of our project was detection and localization of relatively fresh groundwater. During our study we used the transient electromagnetic method (TEM) to measure the electrical resistivity of the subsurface. As a test site we selected Nahal Hever South which is typical for the DS coast. Our results show that resistivity of the shallow subsurface reflects its vertical and lateral structure, e.g., its main hydrogeological elements explain the inter-relations between geology, hydrogeology, and sinkholes. The TEM method has allowed detailed differentiation of layers (clay, salt, etc.) in the subsurface based on their bulk resistivity. The 10 m-thick salt layer composed of idiomorphic crystals of halite deposited during the earlier Holocene period was extrapolated from borehole HS-2 through the study area. It was found that in Nahal Hever the typical value of the bulk resistivity of clay saturated with the DS brine varies between 0.2 and 0.3 Ωm, whereas saturated gravel and sandy sediments are characterized by resistivity between 0.4 and 0.6 Ωm. The high water salinity of the aquifer (enveloping the salt layer) expressed in terms of resistivity is also an important characterization of the sinkhole development mechanism. The electrical resistivity of the aquifer in the vicinity of the salt unit and its western border did not exceed 1 Ωm (in most cases aquifer resistivity was 0.2–0.6 Ωm) proving that, in accordance with existing criteria, the pores of the alluvial sediments are filled with highly mineralized DS brine. However, we suggest that the criterion of the aquifer resistivity responsible for the salt dissolution should be decreased from 1 Ωm to 0.6 Ωm corresponding to the chloride concentration of approximately 100 g/l (the chloride saturation condition reaches 224 g/l in the northern DS basin and 280 g/l in the southern one). Based on TEM results we can reliably conclude that in 2005, when most of sinkholes had appeared at the surface, salt was located within a very low resistivity environment inside sediments saturated with DS brine. Intrusion of relatively fresh groundwater into the aquifer through the 600 × 600 m2area affected by sinkholes has not been observed.

The Dead Sea sinkhole hazard: Geophysical assessment of salt dissolution and collapse

A geophysical approach is presented for analyzing processes of subsurface salt dissolution and associated sinkhole hazard along the Dead Sea. The implemented methods include Seismic Refraction (SRFR), Transient Electromagnetic Method (TEM), Electric Resistivity Tomography (ERT), and Ground Penetration Radar (GPR). The combination of these methods allows the delineation of the salt layer boundaries, estimating its porosity distribution, finding cavities within the salt layer, and identifying deformations in the overlying sediments. This approach is shown to be useful for anticipating the occurrence of specific sinkholes, as demonstrated on both shores of the Dead Sea. These sinkholes are observed mainly along the edge of a salt layer deposited during the latest Pleistocene, when Lake Lisan receded to later become the Dead Sea. This salt layer is dissolved by aggressive water flowing from adjacent and underlying aquifers which drain to the Dead Sea. Sinkhole formation is accelerating today due to the rapid fall of the Dead Sea levels during the last 30years, caused by anthropogenic use of its water.

Raising the Dead without a Red Sea-Dead Sea project? Hydro-economics and governance

Abstract. Seven decades of extractions have dramatically reduced Jordan River flows, lowered the Dead Sea level, opened sink holes, and caused other environmental problems. The fix Jordan, Israel, and the Palestinians propose would build an expensive multipurpose conveyance project from the Red Sea to the Dead Sea that would also generate hydropower and desalinate water. This paper compares the Red-Dead project to alternatives that may also raise the Dead Sea level. Hydro-economic model results for the Jordan-Israel-Palestinian inter-tied water systems show two restoration alternatives are more economically viable than the proposed Red-Dead project. Many decentralized new supply, wastewater reuse, conveyance, conservation, and leak reduction projects and programs in each country can together increase economic benefits and reliably deliver up to 900 MCM yr−1 to the Dead Sea. Similarly, a smaller Red-Dead project that only generates hydropower can deliver large flows to the Dead Sea when the sale price of generated electricity is sufficiently high. However, for all restoration options, net benefits fall and water scarcity rises as flows to the Dead Sea increase. This finding suggests (i) each country has no individual incentive to return water to the Dead Sea, and (ii) outside institutions that seek to raise the Dead must also offer countries direct incentives to deliver water to the Sea besides building the countries new infrastructure.

Response of the Mediterranean and Dead Sea coastal aquifers to sea level variations

The present study examines the response of groundwater systems to expected changes in the Mediterranean Sea (rise of <1cm/yr) and Dead Sea levels (decline of ∼1 m/yr). A fast response is observed in the Dead Sea coastal aquifer, exhibited both in the drop of the water levels and in the location of the fresh‐saline water interface. No such effect is yet observed in the Mediterranean coastal aquifer, as expected. Numerical simulations, using the FeFlow software, show that the effect of global sea level rise depends on the coastal topography next to the shoreline. A slope of 2.5‰ is expected to yield a shift of the interface by 400 m, after a rise of 1m (∼100 years), whereas a vertical slope will yield no shift. Reduced recharge due to climate change or overexploitation of groundwater also enhances the inland shift of the interface.

North Atlantic influence on 19th–20th century rainfall in the Dead Sea watershed, teleconnections with the Sahel, and implication for Holocene climate fluctuations

The importance of understanding processes that govern the hydroclimate of the Mediterranean Basin is highlighted by the projected significant drying of the region in response to the increase in greenhouse gas concentrations. Here we study the long-term hydroclimatic variability of the central Levant region, situated in the eastern boundary of the Basin, as reveled by instrumental observations and the Holocene record of Dead Sea level variations. Observations of 19th and 20th century precipitation in the Dead Sea watershed region display a multidecadal, anti-phase relationship to North Atlantic (NAtl) sea surface temperature (SST) variability, such that when the NAtl is relatively cold, Jerusalem experiences higher than normal precipitation and vice versa. This association is underlined by a negative correlation to precipitation in the sub-Saharan Sahel and a positive correlation to precipitation in western North America, areas that are also affected by multidecadal NAtl SST variability. These observations are consistent with a broad range of Holocene hydroclimatic fluctuations from the epochal, to the millennial and centennial time scales, as displayed by the Dead Sea lake level, by lake levels in the Sahel, and by direct and indirect proxy indicators of NAtl SSTs. On the epochal time scale, the gradual cooling of NAtl SSTs throughout the Holocene in response to precession-driven reduction of summer insolation is associated with previously well-studied wet-to-dry transition in the Sahel and with a general increase in Dead Sea lake levels from low stands after the Younger Dryas to higher stands in the mid- to late-Holocene. On the millennial and centennial time scales there is also evidence for an anti-phase relationship between Holocene variations in the Dead Sea and Sahelian lake levels and with proxy indicators of NAtl SSTs. However the records are punctuated by abrupt lake-level drops, which appear to be in-phase and which occur during previously documented abrupt major cooling events in the Northern Hemisphere. We propose that the mechanisms by which NAtl SSTs affect precipitation in the central Levant is related to the tendency for high (low) pressure anomalies to persist over the eastern North Atlantic/Western Mediterranean region when the Basin is cold (warm). This, in turn, affects the likelihood of cold air outbreaks and cyclogenesis in the Eastern Mediterranean and, consequently, rainfall in the central Levant region. Depending on its phase, this natural mechanism can alleviate or exacerbate the anthropogenic impact on the regions’ hydroclimatic future.

Comparative community genomics in the Dead Sea: an increasingly extreme environment

Owing to the extreme salinity ( approximately 10 times saltier than the oceans), near toxic magnesium levels (approximately 2.0 M Mg(2+)), the dominance of divalent cations, acidic pH (6.0) and high-absorbed radiation flux rates, the Dead Sea represents a unique and harsh ecosystem. Measures of microbial presence (microscopy, pigments and lipids) indicate that during rare bloom events after exceptionally rainy seasons, the microbial communities can reach high densities. However, most of the time, when the Dead Sea level is declining and halite is precipitating from the water column, it is difficult to reliably measure the presence of microorganisms and their activities. Although a number of halophilic Archaea have been previously isolated from the Dead Sea, polar lipid analyses of biomass collected during Dead Sea blooms suggested that these isolates were not the major components of the microbial community of these blooms. In this study, in an effort to characterize the perennial microbial community of the Dead Sea and compare it with bloom assemblages, we performed metagenomic analyses of concentrated biomass from hundreds of liters of brine and of microbial material from the last massive Dead Sea bloom. The difference between the two conditions was reflected in community composition and diversity, in which the bloom was different and less diverse from the residual brine population. The distributional patterns of microbial genes suggested Dead Sea community trends in mono- and divalent cation metabolisms as well as in transposable elements. This may indicate possible mechanisms and pathways enabling these microbes to survive in such a harsh environment.

Long-term monitoring of the Dead Sea level and brine physico-chemical parameters “from 1987 to 2008”

The Dead Sea brine quality was assessed in order to provide scientific basis for researchers' needs. Four times a month, brine samples were collected from the Arab Potash Company (APC) point of intake and analyzed for physico-chemical parameters in the laboratory over 22 years, and Dead Sea surface temperature and level were measured during each sampling. The mean density values for the collected samples during the last 22 years ranged from 1.2040 g/cm 3 in 1992 to 1.2393 g/cm 3 in 2007, with an average value of 1.2376 g/cm 3. The brine salinity values ranged from 293.6 in 1992 to 339.3 g/l in 2008 with an average value of 337.73 g/l. The ionic dominance observed was Cl − > Mg ++ > Na + > Ca ++ > K +. The results showed that diluting the Dead Sea brine affects both magnesium and sodium chlorides significantly because of their high solubilities in fresh water and their large reserves.

The effect of base level changes and geological structures on the location of the groundwater divide, as exhibited in the hydrological system between the Dead Sea and the Mediterranean Sea

Summary The effects of base (sea or lake) level changes on the location and elevation of the groundwater divide were examined in the hydrological system between the Mediterranean Sea and the Dead Sea. Steady-state simulations were conducted with a 1-D analytical model and transient conditions were simulated using FEFLOW groundwater modeling software. Two hydrological scenarios were simulated: (a) a transition to a new steady-state, following the expected drop of 150 m of the Dead Sea level; and (b) the time of the precursor of the Dead Sea (Lisan Lake), some 20,000 years ago, when the lake level was about 250 m above the present-day Dead Sea level and the Mediterranean Sea level was 120 m below its present one. The results of the simulations show that the Dead Sea level drop has led to a progressive decline in the groundwater level up to several kilometers inland from the shoreline. The hydraulic gradient increases, and thus the discharge to the lake also increases at the expense of the storage, and also due to a small enlargement of the recharge zone by a ∼600 m shift of the divide. Broadly, the subsurface hydrological system is compartmentalized into several sections, separated by low permeability fold structures bounding the mountainous uplands. Most of the groundwater recharge occurs in the uplands. Given this geometry and the available water level measurements, analytical and numerical modeling results show that only changes in the Dead Sea level and recharge rate result in dramatic changes for the scenarios examined. Limited by the low permeability folds, the effects of the Dead Sea level on the groundwater level are most pronounced in the vicinity of the Judea Desert lowland. The folds also greatly limit migration of the groundwater divide associated with changes in the Dead Sea level. Transient simulations show a peak increase of ∼30% in the Dead Sea groundwater flux in ∼75 years, resulting from drainage of lowland aquifers. After more than 500 years the groundwater flux is expected to return to values no more than 4% higher than at the beginning of the simulation. This small net increase is consistent with the small shift in the groundwater divide.

Extreme rates of channel incision and shape evolution in response to a continuous, rapid base-level fall, the Dead Sea, Israel

In nature, opportunities are limited for recording the response to a rapid ongoing base-level fall and for examining its effects on channel evolution during the process. Following a dramatic base-level fall, the natural laboratory area of the Dead Sea offers such an opportunity. Classical shape evolution models of incised channels describe the response to an "impulse" type base-level drop after it became stabilized. The Dead Sea delineates during its continuous level drop a different mode of adjustment from those previously conceptualized. We have recorded the entrenchment rates of channels and their transient shape evolution “at a station” in real time, i.e., during the ongoing base-level fall. This study represents the first attempt to apply integrated time series of high resolution DEMs, change detection maps, Differential Global Position System measurements, and field methods to monitor vertical and horizontal entrenchment rates, as well as the evolution of the cross-sectional shape of channels in response to a continuous and rapidly lowering base level. Mean vertical entrenchment rates are very high, 0.4–0.8 m/y, and widening rates are even higher (2.1–24 m/y). Elevation-change detection maps demonstrate along banks a patchy pattern of channel entrenchment, indicating the initial widening stage. The incised channels have a trapezoidal, gorge-like, cross-sectional form, i.e., they have developed beyond the initial stage of net vertical incision. However, neither advanced channel widening nor development of an inner floodplain has been observed. We conclude that widening is yet ineffective in damping the vertical adjustment. The continuous and rapid lowering of the Dead Sea level entraps the drainage systems in the vertical incision mode, preventing the evolutionary progression toward a wide, graded, and stable geometry which has been conceptualized in existing models.