Effect of the Dead Sea–Red Sea canal modelling on the prediction of the Dead Sea conditions

A project to link the Dead Sea to the Red Sea via a canal is undergoing extensive study. In previous works, a generalized mathematical model describing the state of the Dead Sea and a simulation model to implement it have been developed. The model is extended to include the proposed canal project and investigates two alternative modelling canal scenarios: (1) introducing the canal water inflow into the bottom layer or (2) the top layer of the sea. The predicted general effects of the canal are the restoration of the water level of the sea to pre‐1970s level; an increase in the total evaporation rate and a decrease in the top layer salinity. Implementing scenario 1, the model predicts that: the water level of the Dead Sea will exceed the desired level design value and therefore shorter filling time can be used; seasonal stratification will persist; total evaporation rate will increase Modestly; there will a small decrease in the salinity of the top layer but a substantial decrease in the salinity of the bottom layer, which will hurt industries severely; there will be a continuation of seasonal crystallization of aragonite and gypsum. Implementing scenario 2 the model predicts that: the water level of the Dead Sea will be maintained at the desired level design value; stratification will be re‐established, with the formation of a permanent two‐layer system; there will be a substantial increase in the total evaporation rate; the salinity of the top layer will decrease significantly but there will be continuous slower salinity increase in the bottom layer; the crystallization of aragonite will cease, but seasonal gypsum crystallization can be expected to continue as soon as the filling period ends and the canal shifts into normal operation. Copyright © 2003 John Wiley & Sons, Ltd.     

Prediction of the Dead Sea dynamic behaviour with the Dead Sea–Red Sea Canal

A project to link the Dead Sea (DS) to the Red Sea (RS) via a canal is undergoing extensive study. In a previous work, a generalised mathematical model describing the behaviour of the Dead Sea has been developed. Here, the model is extended to include the proposed canal project with a desalination plant. The general effects of a DS–RS Canal predicted by the model were the formation of a permanent two-layer system thus re-establishing stratification conditions, an increase in the evaporation rate due to a decrease in the top layer salinity, the cease in aragonite precipitation, and the re-occurrence of seasonal gypsum precipitation after the filling period depending on the filling regime applied.     

Long‐term prediction of the water level and salinity in the Dead Sea

The long‐term water level variations of the Dead Sea (DS) were assessed using a previously developed simulation model. The model establishes the condition of the DS by evaluating a series of ordinary differential equations describing mass balances on the water and major chemical species. The DS was modelled as a two‐layer system. The model was modified using up‐to‐date inflow data and recent hypsometric graphs to derive the volume–area–level relationships. Three scenarios were studied: continuation of current conditions; a cessation in industrial activity when the DS water level drops to a certain level; and a simplified weather change scenario. The model predicted that the DS will not dry up, but its level will continue to drop with a decelerating rate with no equilibrium level in 500 years. Changing climate would accelerate the level drop. In the 500 year period, after an initial increase, the DS salinity drops. The opposite behaviour is noted in the evaporation rate, which increases after an initial decrease. Ceasing industrial pumping would eventually restore the DS to its normal level, but with changed conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

The water balance of the Dead Sea: an integrated approach

The Dead Sea is the lowest spot on Earth. It is a closed saline lake located in the middle of the Jordan Rift Valley between Lake Tiberias and the Red Sea. Its major tributaries are the Jordan River itself and the Dead Sea side wadis. The Dead Sea has a unique ecosystem and its water has curative, industrial and recreational significance. The level of the Dead Sea has been continuously falling since the early 1930s at an average rate of 0·7 m per year. The water level, as of February 1998, is about 410·9 m below mean sea level. In this paper, a water balance model is developed for the Dead Sea by considering different hydrological components of this water balance, including precipitation, runoff, evaporation and groundwater flow. This model is calibrated based on historical levels of the Dead Sea. Different scenarios are investigated, including the proposed Dead Sea–Red Sea Canal. This project is supposed to halt the shrinking of the Dead Sea and restore it to pre‐1950 levels in the next century. Copyright © 2000 John Wiley & Sons, Ltd.     

Discharge estimation of submarine springs in the Dead Sea based on velocity or density measurements in proximity to the water surface

The Dead Sea is a closed lake, the water level of which is lowering at an alarming rate of about 1 m/year. Factors difficult to determine in its water balance are evaporation and groundwater inflow, some of which emanate as submarine groundwater discharge. A vertical buoyant jet generated by the difference in densities between the groundwater and the Dead Sea brine forms at submarine spring outlets. To characterize this flow field and to determine its volumetric discharge, a system was developed to measure the velocity and density of the ascending submarine groundwater across the center of the stream along several horizontal sections and equidistant depths while divers sampled the spring. This was also undertaken on an artificial submarine spring with a known discharge to determine the quality of the measurements and the accuracy of the method. The underwater widening of the flow is linear and independent of the volumetric spring discharge. The temperature of the Dead Sea brine at lower layers primarily determines the temperature of the surface of the upwelling, produced above the jet flow, as the origin of the main mass of water in the submarine jet flow is Dead Sea brine. Based on the measurements, a model is presented to evaluate the distribution of velocity and solute density in the flow field of an emanating buoyant jet. This model allows the calculation of the volumetric submarine discharge, merely requiring either the maximum flow velocity or the minimal density at a given depth.     

Changes in the Dead Sea Level and their Impacts on the Surrounding Groundwater Bodies

In this paper the reaction of the salt‐/freshwater interface due to the changes in the Dead Sea level are elaborated at in details by using the inflows into the Dead Sea, the outflows due to evaporation losses and artificial discharges, and the hydrographic registrations of the Dead Sea level. The analyses show that the interface seaward migration resulted in a groundwater discharge of around 423 Mio m³ per meter drop in the level of the Dead Sea in the period 1994–1998 and of around 525 Mio m³/m in the period 1930–1937. The additional amount of groundwater joining the Dead Sea due to the interface seaward migration was 51 Mio m³ per one square kilometer of shrinkage in the area of the Dead Sea in the period 1930–1937 and 91 Mio m³/km² in the period 1994–1998. The riparian states of the Dead Sea are nowadays loosing 370 Mio m³/a of freshwater to the Dead Sea through the interface readjustment mechanisms as a result of their over exploitation of waters which formerly fed the Dead Sea.     

Estimation of evaporation from the Dead Sea

A project to link the Dead Sea to the Red Sea via a canal is undergoing extensive study. As part of this study, a method to estimate evaporation from the Dead Sea is required as it is a hypersaline lake in which standard methods cannot be applied. Two methods based on Penman and Dalton formulae were examined. The method derived here is a modified Penman model that estimates the evaporation as a function of salinity, humidity, air temperature and wind speed. Other parameters such as water temperature are included implicitly in the model. The results obtained were verified as satisfactory agreement was achieved by comparison with previous measurements. A short‐cut relationship to estimate evaporation as a function of salinity only was also derived. Copyright © 1999 John Wiley & Sons, Ltd.     

Does the Actual Drop in Dead Sea Level Reflect the Development of Water Sources Within its Drainage Basin?

As a part of Jordan’s efforts to quantify the effect of the Dead Sea level decline on the precious groundwater resources of the surrounding aquifers, the authors analyzed the historic or predevelopment inflows and outflows of the Dead Sea basin and the resulting water balance which included precipitation, evaporation, surface‐ and groundwaters. The predevelopment situation was taken as the point of departure for the sake of this study. Furthermore, the present situation was analyzed in an attempt to quantify the groundwater inflows into the Dead Sea as a result of drop in the Dead Sea level. The groundwater component and the corresponding saltwater/freshwater interface were taken as the variables to balance the levels of the sea that would have been reached without the contribution of the uncontrolled groundwater inflows as a result of the salt/freshwater interface seaward migration. The present day water balance that includes all the water diversion projects from all riparians indicates serious declines in the Dead Sea level. The effects of the present day level declines on the fresh groundwater/saltwater interface indicate that considerable amounts of groundwater are driven into the Sea as a result of the seaward migration of the freshwater/saline water interface.     

Studying Long-term Variations in the Caspian Sea with the Use of the Theory of Stochastic Differential Equations

Nonlinear mechanisms of long-term variations in the Caspian Sea level are described. It is shown that with account taken of the dependence of the evaporation depth from the Volga basin surface on soil moisture content and the dependence of the evaporation depth from the sea surface on its level, we obtain a fundamentally new (chaotic) oscillation mechanism with several attraction levels. The stochastic differential equations describing the water budget of the sea basin and the sea proper and the respective solutions of the Fokker–Planck–Kolmogorov equation are shown to have stationary bimodal density of the level probability. The random process, characterizing the sea level variations at a nonlinear dependence between the evaporation rate and the level is found to be non-Gaussian. Noise-induced transitions, caused by nonlinear evaporation processes are described. A new nonlinear stochastic theory describing the Caspian Sea level variations and based on predicted physical effects is suggested.     

Barium and radium in the Dead Sea

We have measured Ba in Dead Sea samples collected before and after the 1979 overturn, and²²⁶Ra in nine samples collected after the overturn. Before this overturn, Ba and the²²⁶Ra data measured by Chung and Craig [4] show that a distinct two-layer structure existed, with higher concentrations in the upper layer. After the overturn, both elements were uniformly distributed in the water column. The inventories of Ba and Ra calculated from these data are the same for the periods before and after the overturn. If the inventories were constant during the last meromictic phase then the input rate must be balanced by the removal rate, and a mass balance model can be constructed to estimate physical parameters based on known or deduced sources and sinks. The sources include inputs from the Jordan River, springs around the Dead Sea, and submerged springs or seepages, etc. The sinks include coprecipitation with aragonite, gypsum, precipitation of barite, coprecipitation of Ra with barite, particulate scavenging, and radioactive decay for Ra. Our data include measurements of Ba and²²⁶Ra in gypsum, aragonite and halite from the Dead Sea, as well as in some of the inflowing rivers and springs.The inclusion of particulate scavenging as a sink is a major element of the model. We find that, without inclusion of a Ba scavenging term in the deep water, the lake volume at the previous overturn as calculated from the Ba data would be unrealistically high in comparison with historical records. The inclusion of particulate scavenging for Ra in the model reduces the calculated duration of the last meromictic phase significantly.Our model excludes internal mixing between the upper and lower water masses. With this restriction, various sets of model parameters were calculated as a function of theRa/Ba scavenging rate ratio. If the ratio is one, the calculated age of the last meromictic phase is about a hundred years. A substantial increase in the Ra input rate is required to balance the removal rate by particulate scavenging as well as decay. If the ratio is zero, i.e. no particulate scavenging for Ra, the age is about 260 years, as obtained by Stiller and Chung [2].     

Tritium in the Dead Sea

Tritium data in the Dead Sea for the period 1960–1979 are given. Tritium levels have increased until 1965 in the upper layers of the Dead Sea reaching a level of 170 TU, in response to the atmospheric buildup of tritium from thermonuclear testing. The levels have been decreasing ever since, both because of rapidly declining atmospheric concentrations of tritium and because of mixing of the surface layers with tritium deficient, deeper water masses. The depth of penetration of the tracer delineated the depth of meromictic stratification and successfully monitored the deepening of the pycnocline, until the overturn in 1979 homogenised the entire tritium profile. Modelling the changing tritium inventory over this period showed the predominance of the direct exchange across the air/sea interface, both in the buildup of tritium in the lake and also in its subsequent removal from it. The good fit between calculated and measured tritium inventories confirmed the evaporation estimate of 1.46 m/yr (the mean value for the period) with a precision unattained by other methods.     

Water balance estimation under the challenge of data scarcity in a hyperarid to Mediterranean region

Water budget analyses are important for the evaluation of the water resources in semiarid and arid regions. The lack of observed data is the major obstacle for hydrological modelling in arid regions. The aim of this study is the analysis and calculation of the natural water resources of the Western Dead Sea subsurface catchment, one which is highly sensitive to rainfall resulting in highly variable temporal and spatial groundwater recharge. We focus on the subsurface catchment and subsequently apply the findings to a large‐scale groundwater flow model to estimate the groundwater discharge to the Dead Sea. We apply a semidistributed hydrological model (J2000g), originally developed for the Mediterranean, to the hyperarid region of the Western Dead Sea catchment, where runoff data and meteorological records are sparsely available. The challenge is to simulate the water budget, where the localized nature of extreme rainstorms together with sparse runoff data results in few observed runoff and recharge events. To overcome the scarcity of climate input data, we enhance the database with mean monthly rainfall data. The rainfall data of 2 satellites are shown to be unsuitable to fill the missing rainfall data due to underrepresentation of the steep hydrological gradient and temporal resolution. Hydrological models need to be calibrated against measured values; hence, the absence of adequate data can be problematic. Therefore, our calibration approach is based on a nested strategy of diverse observations. We calculate a direct surface runoff of the Western Dead Sea surface area (1,801 km²) of 3.4 mm/a and an average recharge (36.7 mm/a) for the 3,816 km² subsurface drainage basin of the Cretaceous aquifer system.     

The Interface Configuration of the Fresh‐/Dead Sea Water – Theory and Measurements

The high‐density Dead Sea water (1.235 g/cm³) forms a special interface configuration with the fresh groundwater resources of its surrounding aquifers. The fresh groundwater column beneath its surroundings is around one tenth of its length compared to oceanic water. This fact alone indicates the vulnerability of the fresh groundwater resources to the impacts of changes in the Dead Sea level and to saltwater migration. Ghyben‐Herzberg and Glover equations were used to calculate the volumes of water in coastal aquifers which were replaced by freshwater due to the interface seaward migration as a result of the drop in the level of the Dead Sea. For that purpose, the dynamic equation of Glover approach has been integrated to accommodate that type of interface readjustment. The calculated amounts of freshwater which substituted salt Dead Sea water due to the migration of interface are 3.21 · 10¹¹ m³, from a Dead Sea level of –392 m to τ411 m below sea level. The average porosity of coastal aquifers was calculated to range from 2.8 to 2.94%. Geoelectric sounding measurements showed that areas underlying the coastal aquifers formerly occupied by the Dead Sea water are gradually becoming flushed and occupied by freshwater. The latter is becoming salinized due to the residuals of Dead Sea water in the aquifer matrix, the present salinity of which is lower than that of the Dead Sea water. At the same time salt dissolution from the Lisan Marl formation is causing collapses along the shorelines in the form of sinkholes, tens of meters in diameter and depth.     

南海蒸发和净淡水通量的季节和年际变化

以19年（1988～2006年）的SSM/I（Special Sensor Microwave/ Imager）卫星观测为基础,计算了南海的逐月海面蒸发量,并结合SSM/I的降雨观测,得到了南海的逐月净淡水通量,并分析其季节和年际变化.研究结果表明：南海的蒸发量年变化基本呈双峰型结构,降雨和净淡水通量呈单峰型结构.1988～2001年,南海的蒸发量呈上升趋势,增长速率为1 mm/yr;2001～2006年,以1.9 mm/yr的速率减少.南海的降雨量和净淡水通量与Nino3指数成负相关,相关系数为-0.62和-0.58.在1997～1998厄尔尼诺暖事件期间,降雨量和净淡水通量均显著下降,且以其为界,降雨量在此之前以1.3 mm/yr的速率增长,净淡水通量升降趋势不明显;而在此之后,降雨以8.5 mm/yr的速率下降,净淡水通量的下降速率为7.5 mm/yr.     

The Sinai subplate and tectonic evolution of the northern Red Sea region

Although the precise boundaries and kinematics of the Sinai subplate are still doubtful, it has a significant role in the tectonic evolution of the northern Red Sea region. On the basis of earthquake distribution, the Sinai region can be considered as a subplate partially separated from the African plate by the Suez rift. The relative motion between Africa, Sinai and Arabia is the main source generating the present-day earthquake activity in the Gulf of Suez and the Gulf of Aqaba regions.According to geological observations, the southern segment of the Dead Sea fault system can be characterized by a left-lateral displacement of about 107km since the Middle Miocene, in contrast to the northern segment where only 25 to 35km offset can be inferred. We think that along the southern segment the total displacement was 72km until the late Miocene (10Ma). The earthquake activity is strongly reduced along the northern segment of the Dead Sea fault segment. Therefore, we suggest that the northern part (Yammouneh fault) evolves through initial cracking of the crust due to build-up of stress since the Pliocene time (5Ma) and propagates northward into Lebanon and Syria. This last 5 million years is the period when the southern and northern segments became linked and formed a single fault system with a new displacement of 35km.According to the proposed model the predicted opening pole of the Red Sea is near 34.0oN, 22.0oE with an angle of total rotation of 3.4o since the early miocene, providing a 0.82cm/a opening rate in the northern Red Sea. We suggest that the Dead Sea strike-slip fault was active since Middle Miocene time (15Ma) with a slip rate of 0.72cm/a to provide a total displacement of about 107km. This strike slip motion occured about an Euler pole near 33.0oN, 21.0oE with a rotation angle of about 3.0o. It can be inferred from the proximity of the pole and angle of rotations for the Red Sea and Dead Sea fault that more than 85% of the motion has been accommodated on the Gulf of Aqaba and the Dead Sea fault and less than 15% in the Gulf of Suez.This model predicts a normal extensional motion in the Gulf of Suez with a minor left-lateral strike-slip component. We expect the pole of this motion to be at 31.0oN, 29.0oE, offshore of Alamein city about 320 km west of the Nile Delta. The rate of motion through the last 15Ma (Middle Miocene) is about 0.1 cm/a and the angle of rotation is 0.9o. During this period the total opening of the Suez rift is 15 km while the rest of the motion (45 km) occured mainly through the first phase of the development before the Middle Miocene.     

Surge modelling in the eastern Irish Sea: present and future storm impact

It is believed that, in the future, the intensity and frequency of extreme coastal flooding events may increase as a result of climate change. The Natural Environment Research Council (NERC) Flood Risk from Extreme Events (FREE) project, Coastal Flooding by Extreme Events and EU FP7 Morphological Impacts and Coastal Risks Induced by Extreme Storm Events project are investigating the flood risks in the eastern Irish Sea, an area that includes most of England’s coastal types. Using a previously modelled and validated historical extreme surge event, in November 1977, we now investigate the changes in peak surge as a result of possible future climate conditions. In order to simulate the surge, we have set up a one-way nested approach, using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System 3D baroclinic model, from a domain covering the whole NW European continental shelf, through to a 1.85 km Irish Sea model; both areas are forced by tides, atmospheric pressure and winds. We use this modelling system to investigate the impact of enhanced wind velocities and increased sea levels on the peak surge elevation and residual current pattern. The results show that sea level rise has greater potential to increase surge levels than increased wind speeds.     

The influence of the bottom cold water on the seasonal variability of the Tsushima warm current

Previous studies have concluded that the volume transport and surface current velocity of the Tsushima Warm Current are at a maximum between summer and autumn and at a minimum between winter and spring. Each study has obtained these results indirectly, using the sea level difference across the Tsushima-Korea Strait or dynamic calculation. Numerical experiments are performed to estimate the seasonal variability in the sea level difference caused by the Bottom Cold Water (BCW), which intrudes from the Sea of Japan along the Korean coast in the bottom layer. These experiments basically treat the baroclinic adjustment problem of the BCW in a rectangular cross section perpendicular to the axis (northeast-southwest direction) of the Tsushima-Korea Strait. It is a five-layer model for summer and a two-layer model for winter. The initial conditions and parameters in models are chosen so as to match the calculated velocity-density fields with the observed velocity-density fields [Isobe A., S. Tawara, A. Kaneko and M. Kawano (1994) Continental Shelf Research, 14, 23–35.]. Consequently, the experiments prove that the observed seasonal variability in the sea level difference across the Tsushima-Korea Strait largely contains the baroclinic motion caused by the BCW. It should be noted that the position of the BCW also plays an important role in producing a considerable seasonal variation of the sea level difference. It is critical to remove the baroclinic contribution from the observed sea level differences across the Tsushima-Korea Strait in order to estimate the seasonal variation in the volume transport of the Tsushima Warm Current.     

Seismicity of the Sinai subplate region:kinematicimplications

The seismic activity of the Sinai subplate region on the basis of both historical (2200B.C.–1900 A.D.) and recent (1900–1995) earthquake catalogs have been evaluated.Moderateand large earthquakes occurred mainly at the subplate boundaries, Dead Sea Fault (DSF) systemin the east, Cyprean arc in the north, and Suez rift in the southwest.Along the Dead Sea Fault system the activity concentrated at the southern andcentralsegments. The earthquake distribution appears to have a tendency to cluster in time andspace.The swarms (February, 1983; April, 1990; August, 1993 and November, 1995) in the GulfofAqaba indicate that the southern segment of the Dead Sea Fault system is the mostseismogenicthrough the last two decades. North of the Dead Sea depression the seismic activitytends to haveoccurred with NW trend to extend under the Levantine Sea. Although the northernsegment ofthe Dead Sea Fault system is well defined from geological, geophysical and historicalearthquakeactivity recent seismic activity is practically absent especially north of Latitude 34°N.In the eastern Mediterranean the seismicity is much higher in the area of the Hellenicarcthan in the Cyprean arc. Moreover, the activity occurs in a wide belt suggesting that theplateboundary is a deformation zone instead of a single line.The seismic activity in the Gulf of Suez is scattered and does not have any distincttrend.However, three active zones are delineated. At the mouth of the gulf most of activityisconcentrated where the Sinai triple junction (Africa, Arabia, Sinai) is situated. The centralpartand the northern part of the gulf include the adjacent area as far as the river Nile. Actually,theactivity is markedly decreased from south to north.Although there is no seismological evidence that the Suez rift continues into theeasternMediterranean, the activity in the Gulf of Suez region cannot be ignored.The parameters of magnitude-frequency relation (a, b) indicate thatthelevel of earthquake activity in the Sinai subplate region is generally moderate. Moreover,theenergy release curve shows a regular trend and reflects occasional high activity. © 1999ElsevierScience Ltd. All rights reserved.     

The distribution of deuterium and O in dry soils : 1. Theory

A mathematical model is developed describing the shape of H₂¹⁸O and HDO depth profiles which result from evaporation of water from dry soil under quasi-steady state conditions. Typically, isotope concentrations rise from a minimum at the soil surface to a maximum a short distance beneath the surface, and then decrease approximately exponentially to constant concentrations at depth. The model predicts that for isothermal conditions, the slope of the relationship between ¹⁸O and deuterium δ-values of samples of the soil water will be 30% lower for a dry soil than for a wet soil evaporating under the same conditions. It is concluded that low slopes should be indicative of soil water or groundwater recharged under arid or semi-arid conditions. Using the shape of the ¹⁸O and deuterium profiles, three independent methods for estimating evaporation for dry soils are developed. When water loss occurs by both transpiration and evaporation, the slope of the ¹⁸O-D relationship should be slightly lower than that for a site where water loss occurs by evaporation alone.     

Snow cover and runoff modelling in a high mountain catchment with scarce data: effects of temperature and precipitation parameters

Snowmelt is an important source of runoff in high mountain catchments. Snowmelt modelling for alpine regions remains challenging with scarce gauges. This study simulates the snowmelt in the Karuxung River catchment in the south Tibetan Plateau using an altitude zone based temperature‐index model, calibrates the snow cover area and runoff simulation during 2003–2005 and validates the model performance via snow cover area and runoff simulation in 2006. In the snowmelt and runoff modelling, temperature and precipitation are the two most important inputs. Relevant parameters, such as critical snow fall temperature, temperature lapse rate and precipitation gradient, determine the form and amount of precipitation and distribution of temperature and precipitation in hydrological modelling of the sparsely gauged catchment. Sensitivity analyses show that accurate estimation of these parameters would greatly help in improving the snowmelt simulation accuracy, better describing the snow‐hydrological behaviours and dealing with the data scarcity at higher elevations. Specifically, correlation between the critical snow fall temperature and relative humidity and seasonal patterns of both the temperature lapse rate and the precipitation gradient should be considered in the modelling studies when precipitation form is not logged and meteorological observations are only available at low elevation. More accurate simulation of runoff involving snowmelt, glacier melt and rainfall runoff will improve our understanding of hydrological processes and help assess runoff impacts from a changing climate in high mountain catchments. Copyright © 2013 John Wiley & Sons, Ltd.