H. Hötzl

Sedimentary and structural evolution of the northwest Arabian Red Sea margin

Abstract An investigation of the northwestern margin of the Arabian peninsula (Midyan region) provides new insights into the two-stage development of the Red Sea graben system: the early Red Sea-Suez stage and the later Red Sea-Aqaba stage. The early stage is characterized by the passive subsidence of a continental graben since the Early Oligocene. After a period of enhanced subsidence of the basin in the Early Miocene this stage ended at the Langhian/Serra valian boundary (14 Ma). The later stage was initiated by a release of stresses by strike-slip movement along the newly formed Aqaba-Levant transform. Creation of the new plate boundary was accompanied by stagnation of extension in the Gulf of Suez branch of the early rift stage. Strike-slip motion on the Aqaba-Levant structure is younger than 14 Ma and is recorded by the post-Langhian compressional structures in the area of the Midyan peninsula, which developed by transpression along the curved path of a left-lateral strike-slip fault.

Low-angle detachment origin for the Red Sea Rift System

Abstract The tectonic and magmatic history of the Jizan coastal plain (Tihama Asir, southwest Arabia) suggests a two-stage evolution. A first stage of extension began during the Oligocene and ended with uplift of the Arabian graben shoulder which began about 14 Ma ago. It was followed by a period of approximately 10 Ma characterized by magmatic and tectonic quiescence. A second stage of extension began roughly contemporaneously with the onset of seafloor spreading in the southern Red Sea some 4–5 Ma ago and is still active today. The geometry of faulting in the Jizan area supports a Wernicke model of simple shear for the development of the southern Red Sea. Regional asymmetries of the Red Sea area, such as the distribution of volcanism, the marginal topography and asymmetries in the geophysical signatures are consistent with such a model. Available seismic profiles allow a rough estimate for β-values of the Arabian Red Sea margin and were used to simulate subsidence history and heat flow of the Red Sea for “classical” two-layer stretching models. Neither finite uniform nor finite non-uniform stretching models can account for observed subsidence and heat flow data. Thus, two model scenarios of whole-lithosphere normal simple-shear are presented for the geological history of the southwestern Arabian margin of the Red Sea. These models are limited because of the Serravallian rearrangement in the kinematics of the Red Sea.

An experimental study of miscible displacements in porous media with variation of fluid density and viscosity

The effect of fluid density and viscosity on dispersion in miscible displacements in porous media is examined. Miscible displacement experiments with fluid pairs having density and viscosity differences are carried out in a Plexiglas column containing a homogeneous and isotropic sand pack. Tracer tests and tests of both stable and unstable miscible displacement are conducted using NaCl and glycerine solutions. Concentration breakthrough curves are measured through an electrical monitoring technique. Following the conventional convection–dispersion formulation, the dispersion coefficient is determined by performing a least squares fit to the measured concentration breakthrough curves. It is found that for stable displacements dispersion coefficients drop continually when density differences increase or when viscosity ratios of the displaced and displacing fluid decrease. In the unstable case the dispersion coefficients increase with both density and viscosity differences.

The sedimentary evolution of the Red Sea rift: a comparison of the northwest (Egyptian) and northeast (Saudi Arabian) margins

Abstract Comparison of the sedimentary sequences outcropping on opposite sides of the Red Sea, although based on relatively limited data, reveals many similarities. The Cretaceous and Paleogene, pre-rift series are very similar throughout the northwestern parts of the Red Sea and in the Gulf of Suez. Syn-rift sediments, both in Saudi Arabia and in Egypt may be readily subdivided into a basal, continental unit, a transgressive marine series, an evaporitic formation, and a final (Pliocene), mixed clastic-carbonate phase. These marked variations express a comparable geodynamic evolution on opposite sides of the rift. However, these similarities are modified by important differences which are partly chronological and concern the precocity of initial syn-rift sedimentation in the Midyan region of Saudi Arabia. There are also important lithological differences within each of the major units. The chronological and lithological differences may be due either to the diachronous evolution of the various segments of the basin, or to different environments of sedimentation whose localisation differed with respect to a common rift axis.

Climatic changes and water resources in the Middle East and North Africa

Global Climate Changes - Sources and Impacts on the Water Cycle.- Climate Change and Water Cycle - Some Lessons from the Geological Past.- Climate Change and the Water Cycle - Some Information Concerning Precipitation Trends.- Moroccan Climate in the Present and Future: Combined View from Observational Data and Regional Climate Scenarios.- Impact of Climate Change on Water Availability in.- Climatic Changes in Lebanon, Predicting Uncertain Precipitation Events - Do Climatic Cycles Exist?.- Impact of Climate Change on Water Resources.- Water Resources Management in the Middle East under Aspects of Climatic Changes.- Virtual Water Trade as an Adaptation Demand Management of Climate Change Impact on Water Resources in the Middle East.- The Impacts of Climate Change on Water Resources in Jordan.- Impact of Climate Change on Water Resources of Lebanon: Indications of Hydrological Droughts.- The Impact of Global Warming on the Water Resources of the Middle East: Past, Present, and Future.- Decadal Precipitation Variances and Reservoir Inflow in the Semi-Arid Upper Draa Basin (South- Eastern Morocco).- Management Options for a Sustainable Groundwater Use in the Middle Draa Oases under the Pressure of Climatic Changes.- Water Resources and Water Management.- A Decision Support System (DSS) for Water Resources Management, - Design and Results from a Pilot Study in Syria.- Management Strategies of Water Resources in the Arid Zone of South-Eastern Morocco.- The Role of Groundwater During Drought in Tunisia.- The Evolution of Groundwater Exploration Methods in the Moroccan Oases through History, and Managing Ecological Risk of their Present Pollution.- Investigating Unconsolidated Aquifers in an Arid Environment - A Case Study from the Lower Jordan Valley/Jordan.- Water Resources Protection Efforts in Jordan and their Contribution to a Sustainable Water Resources Management.- Model Investigations on the Groundwater System in Jordan - A Contribution to the Resources Management (National Water Master Plan).- Seawater Intrusion in Greater Beirut, Lebanon.- Long Term (1970 - 2001) Eco-Hydrological Processes in Lake Kinneret and its Watershed.- Transfer of the Concepts of the European Water Framework Directive to Arid and Semiarid Regions.- Seal Formation Effects on Soil Infiltration and Runoff in Arid and Semiarid Regions under Rainfall and Sprinkler Irrigation Conditions.- Restoring the Shrinking Dead Sea - The Environmental Imperative -.- Groundwater in the Shallow Aquifer of the Jericho Area, Jordan Valley - Noble Gas Evidence for Different Sources of Salinization.- The Interaction of Population Dynamics and Transformations in Water Supply Systems in the Jordan River Basin.

Mapping the vulnerability of groundwater to the contamination of four carbonate aquifers in Europe

The vulnerability of four European aquifers with different hydrogeological and climatic characteristics was evaluated using the COP method. The results obtained were statistically analyzed by determination coefficients to measure which factor has greater importance in the vulnerability index. Furthermore, a new parameter has been designed to measure the vulnerability for the whole of the aquifer. The results demonstrate that COP is a useful method to assess the vulnerability of the test sites under consideration. The results obtained are coherent with the conceptual model of each pilot aquifer and the available hydrogeological information (hydrographs, isotopic data, tracer tests). Fissured carbonate aquifers (diffuse flow systems) are less vulnerable than karst aquifers (conduit flow systems) and the vulnerability index is more positively correlated with the O factor (unsaturated zone protection capacity) in the first case. The karst aquifers are more vulnerable than fissured aquifers and they show a higher correlation between the C factor (karst features) and the vulnerability index. Climatic variation (precipitation for example) influences the final vulnerability index of the aquifers according to the weight in the index and the spatial distribution.

Large tectonic and lithospheric structures of the Red Sea region

Abstract Using new tectonic data regarding the timing and mechanical development of large fracture structures and a review of deep seismic data especially in relation to crustal thickness, a geodynamic evolutionary model for the Nubo-Arabian region is described. Combination of the data sets results in a 3-D picture of the crustal structure of the region and definition of problems regarding the geodynamic evolution of the Red Sea structure. Evidence from northwest Saudi Arabia, bordering the northern end of the Red Sea, suggests that rifting began around 32–30 Ma. During the Miocene, rifting intensified probably including significant lithospheric thinning. This first stage of development ended in the Middle Miocene, about 14 Ma, when the complete rift structure was about as wide as the present day Gulf of Suez. Between the Middle Miocene and the Upper Miocene/Pliocene boundary, about 10 ± 2 Ma, the Aqaba-Levant structure became active and thus the Gulf of Suez became essentially stagnant. Since this time about 70% of the total opening of the Red Sea has occurred, again probably including significant lithospheric thinning. This opening has been taken up totally by the movement along the Aqaba-Levant fault. Finally, about 5 Ma seafloor spreading began in the central axial trough of the Red Sea south of 21°N. A better knowledge of the thickness and nature of the present day Red Sea crust is still required so that the amount of opening of the Red Sea can be more accurately estimated.

Separation of groundwater-flow components in a karstified aquifer using environmental tracers

Abstract Groundwater discharges from the intensively karstified Taurus Mountains to the Mediterranean Sea, either along the contact zone between the mountains and the Travertine Plateau (the Kirkgozler Springs, 15 m3/s), or through the travertine (e.g. the Dudenbasi Spring, 18 m3/s) and underneath it (unnamed submarine springs, unknown discharges). In an attempt to identify the hydraulic connections between the various outlet points, groundwater was analyzed for stable and radioactive isotopes, CFCs and He. The upgradient springs, belonging to the Kirkgozler–Dudenbasi system, were proven to be a mixture of recent and older water on the basis of their low 14C values (12–22.4 pmc), their exceptionally high He content (429–991 μcc/kg) and 3He:4He (R:Ra) ratios (1.471–2.602) and their measurable 3H and CFC contents (1.9–5.9 TU and 0.84 to 3.27 pmoles/kg, respectively). The older component probably contains an even lower amount of modern C. However, the undersaturation of the mixture with respect to calcite, its high CO2 content (up to 83 mg/L) and its enriched 13C values (−2.2 to −4.1‰) suggest intensive water/rock interactions, which would contribute 14C-devoid bicarbonates to the solution. Downgradient springs discharging along the Mediterranean coast contain groundwater contributions from higher altitudes, as evidenced by their depleted δ18O and δD composition with respect to the local precipitation; however, a larger portion of the recent water component could be contributed from direct precipitation on the travertine. This larger component is reflected in the increased 3H (3.4 to 8.4 TU) and 14C (32.7–63.6 pmc) contents, atmospheric He (43–82 pmoles/kg), R:Ra values (1.006–1.198) and CFC contamination of the water.

Origin of the Danube-Aach system

The Swabian Alb formed by an Upper Jurassic carbonate sequence is the most extensive karst area of Germany. The western part is crossed by the upper Danube River. It represents an old, mainly Pliocene, drainage system that is now restricted by the young Rhine system. The low base level of the upper Rhine graben causes a strong headward erosion. Since the Upper Pliocene, the Danube has lost more than 90% of its headwaters. The underground Danube-Aach karst system of the western Alb represents the last capture of the Rhine, leading periodically to a complete loss of water in the upper Danube. The seepage of this water, together with the huge karst catchment area, supplies the strong discharge of the Aach Spring, forming the largest spring of Germany with an average discharge of 8.5 m3 s−1.

Sources and processes affecting the spatio-temporal distribution of pharmaceuticals and X-ray contrast media in the water resources of the Lower Jordan Valley, Jordan

The closed basin of the Lower Jordan Valley with the Dead Sea as final sink features high evapotranspiration rates and almost complete reuse of treated wastewater for irrigation farming. This study focuses on the water transfer schemes and the presence, spreading, and potential accumulation of pharmaceutical residues in the local water resources based on findings of a five-year monitoring program. Overall 16 pharmaceuticals and 9 iodinated X-ray contrast media were monitored in groundwater, surface water, and treated wastewater. A total of 95 samples were taken to cover all geographical settings and flow paths from origin (wastewater) to target (groundwater). Nine substances were detected in groundwater, with concentrations ranging between 11 ng/L and 33,000 ng/L. Sometimes, detection rates were higher than in comparable studies: Diatrizoic acid 75%, iopamidol 42%, iopromide 19%, iomeprol 11%, carbamazepine and iohexol 8%, ibuprofen 6%, and fenofibrate and iothalamic acid 3%. Concentrations in groundwater generally increase from north to south depending on the application of treated wastewater for irrigation. Almost all substances occurred most frequently and with highest concentrations in treated wastewater, followed by surface water and groundwater. As exception, diatrizoic acid was found more frequently in groundwater than in treated wastewater, with concentrations being similar. This indicates the persistence of diatrizoic acid with long residence times in local groundwater systems, but may also reflect changing prescription patterns, which would be in accordance with increasing iopamidol findings and surveys at local hospitals. Trend analyses confirm this finding and indicate a high probability of increasing iopamidol concentrations, while other substances did not reveal any trends. However, no proof of evaporative enrichment could be found. The high spatial and temporal variability of the concentrations measured calls for further systematic studies to assess the long-term evolution of organic trace substances in this reuse setting.