ALBERT

Beschreibung: Despite being the main drinking water resource for over 5 million people, the water balance of the Eastern Mountain Aquifer system on the western side of the Dead Sea is poorly understood. The regional aquifer consists of fractured and karstified limestone – aquifers of Cretaceous age, and it can be separated into a Cenomanian aquifer (upper aquifer) and Albian aquifer (lower aquifer). Both aquifers are exposed along the mountain ridge around Jerusalem, which is the main recharge area. From here, the recharged groundwater flows in a highly karstified aquifer system towards the east and discharges in springs in the lower Jordan Valley and Dead Sea region. We investigated the Eastern Mountain Aquifer system for groundwater flow, groundwater age and potential mixtures, and groundwater recharge. We combined 36Cl ∕ Cl, tritium, and the anthropogenic gases SF6, CFC-12 (chlorofluorocarbon) and CFC-11, while using CFC-113 as “dating” tracers to estimate the young water components inside the Eastern Mountain Aquifer system. By application of lumped parameter models, we verified young groundwater components from the last 10 to 30 years and an admixture of a groundwater component older than about 70 years. Concentrations of nitrate, simazine (pesticide), acesulfame K (ACE-K; artificial sweetener) and naproxen (NAP; drug) in the groundwater were further indications of infiltration during the last 30 years. The combination of multiple environmental tracers and lumped parameter modelling helped to understand the groundwater age distribution and to estimate recharge despite scarce data in this very complex hydrogeological setting. Our groundwater recharge rates support groundwater management of this politically difficult area and can be used to inform and calibrate ongoing groundwater flow models.

Beschreibung: The conjoint discussion of tectonic features, correlations of element concentrations, δ18O, δD, and 87Sr/86Sr of groundwater leads to new insight into sources of groundwater, their flow patterns, and salinization in the Yarmouk Basin. The sources of groundwater are precipitation infiltrating into basaltic rock or limestone aquifers. Leaching of relic brines and dissolution of gypsum and calcite from the limestone host rocks generate enhanced salinity in groundwater in different degrees. High U(VI) suggests leaching of U from phosphorite-rich Upper Cretaceous B2 formation. Both very low U(VI) and specific rare earth element including yttrium (REY) distribution patterns indicate interaction with ferric oxyhydroxides formed during weathering of widespread alkali olivine basalts in the catchment area. REY patterns of groundwater generated in basaltic aquifers are modified by interaction with underlying limestones. Repeated sampling over 18 years revealed that the flow paths towards certain wells of groundwater varied as documented by changes in concentrations of dissolved species and REY patterns and U(VI) contents. In the Yarmouk Gorge, groundwater with basaltic REY patterns but high U(VI) and low Sr2+ and intermediate sulfate concentrations mainly ascends in artesian wells tapping a buried flower structure fault system crossing the trend of the gorge.

Beschreibung: Despite being the main drinking water resource for over five million people, the water balance of the Eastern Mountain Aquifer system on the western side of the Dead Sea is poorly understood. The regional aquifer consists of fractured and karstified limestone – aquifers of Cretaceous age and can be separated in Cenomanian aquifer (upper aquifer) and Albian aquifer (lower aquifer). Both aquifers are exposed along the mountain ridge around Jerusalem, which is the main recharge area. From here, the recharged groundwater flows in a highly karstified aquifer system towards the east, to discharge in springs in the Lower Jordan Valley and Dead Sea region. We investigated the Eastern Mountain Aquifer system on groundwater flow, groundwater age and potential mixtures, and groundwater recharge. We combined 36Cl/Cl, tritium and the anthropogenic gases SF6, CFC-12 and CFC-11, CFC-113 as dating tracers to estimate the young water components inside the Eastern Mountain Aquifer system. By application of lumped parameter models, we verified young groundwater components from the last 10 to 30 years and an admixture of a groundwater component older than about 70 years. Concentrations of nitrate, Simazine® (Pesticide), Acesulfame K® (artificial sweetener) and Naproxen® (drug) in the groundwater were further indications of infiltration during the last 30 years. The combination of multiple environmental tracers and lumped parameter modelling helped to understand the groundwater age distribution and to estimate recharge despite scarce data in this very complex hydrogeological setting. Our groundwater recharge rates support groundwater management of this politically difficult area and can be used to inform and calibrate ongoing groundwater flow models.

Beschreibung: Enclosed topographic depressions are characteristic of karst landscapes on Earth. The developmental relationship between depression types, such as sinkholes (dolines) and uvalas, has been the subject of debate, mainly because the long developmental timescales in classical limestone karst settings impede direct observation. Here we characterize the morphometric properties and spatio-temporal development of ∼1150 sinkholes and five uvalas formed from ∼1980 to 2017 in an evaporite karst setting along the eastern coast of the hypersaline Dead Sea (at Ghor Al-Haditha, Jordan). The development of sinkhole populations and individual uvalas is intertwined in terms of onset, evolution and cessation. The sinkholes commonly develop in clusters, within which they may coalesce to form compound or nested sinkholes. In general, however, the uvalas are not defined by coalescence of sinkholes. Although each uvala usually encloses several clusters of sinkholes, it develops as a larger-scale, gentler and structurally distinct depression. The location of new sinkholes and uvalas shows a marked shoreline-parallel migration with time, followed by a marked shoreline-perpendicular (i.e. seaward) growth with time. These observations are consistent with theoretical predictions of karstification controlled by a laterally migrating interface between saturated and undersaturated groundwater, as induced by the 35 m fall in the Dead Sea water level since 1967. More generally, our observations indicate that uvalas and the sinkhole populations within them, although morphometrically distinct, can develop near-synchronously by subsidence in response to subsurface erosion.

Beschreibung: The fall of hydrological base-level is long established as a driver of geomorphological change in both fluvial and karst systems, but few natural occurrences occur on timescales suitable for direct observation. Here we document the spatiotemporal development of fluvial and karstic landforms along the eastern coast of the hypersaline Dead Sea (at Ghor al-Haditha, Jordan) during a 50-year period of regional base-level decline from 1967 to 2017. Combining remote sensing data with close-range photogrammetric surveys, we show that the 35 m base-level fall has caused shoreline retreat of up to 2.5 km, and resulted in: (1) incision of new meandering or straight/braided stream channels and (2) formation of 〉 1100 sinkholes and several salt-karst uvalas. Both alluvial incision and karst-related subsidence represent significant hazards to local infrastructure. The development of groundwater-fed meandering stream channels is in places interlinked with that of the sinkholes and uvalas. Moreover, active areas of channel incision and sinkhole development both migrate seaward in time, broadly in tandem with shoreline retreat. Regarding theoretical effects of base-level fall, our observations show some deviations from those predicted for channel geometry, but are remarkably consistent with those for groundwater-related salt karstification. Our results present, for the first time in the Dead Sea region, the dual response of surface and subsurface hydrological systems to base level drop as indicated by fluvial and karst geomorphological analysis.

Beschreibung: Recent studies investigating groundwater parameters e.g. heads, chemical composition and heat transfer, argued that groundwater flow paths in the Lower Yarmouk Gorge area are controlled by geological features such as faults or dikes (Goretzki et al., 2016; Magri et al., 2016; Roded et al., 2013; Siebert et al., 2014). However, the nature of such features as well as their exact locations were previously unknown. In the present manuscript, we propose a new fault pattern in the Lower Yarmouk Gorge area constructed by compiling and revising geological and geophysical data from the study area including borehole information, geological maps cross-sections and seismic data from southern Golan Heights and northern Ajloun Mountain. The presented pattern is composed of strike-slip and thrust faults, which are associated with the Dead Sea Transform system and with the Kinnarot pull-apart basin. Compressional and tensional structures developed in different places forming a series of fault-blocks probably causing a non-uniform spatial hydraulic connection between them. This study provides a coarse fault block model and improved structural constraints that serve as fundamental input for future hydrogeological modelling.

Beschreibung: Submarine groundwater discharge (SGD) is highly variable in spatial and temporal terms due to interplay of several terrestrial and marine processes. While discrete in-situ measurements provide a continuous temporal scale to investigate underlying processes and thus accounts for temporal heterogeneity, remotely sensed thermal infrared radiation sheds light on the spatial heterogeneity as it provides a continuous spatial scale. Here we report results of the combination of both, the continuous spatial and temporal scales, using the ability of an Unmanned Aerial Vehicle to hover above a predefined location and the continuous recording of thermal radiation of a coastal area at the Dead Sea (Israel). With a flight altitude of 65m above the water surface resulting in a spatial resolution of 13cm and a thermal camera (FLIRTau2) which measures the upwelling long-wave infrared radiation at 4Hz resolution we are able to generate a time sequence of thermal radiation images which allows us to analyse spatiotemporal SGD dynamics. In turn, we are able to enhance focused SGD spots otherwise being camouflaged by strong lateral flow dynamics that may not be observed on single thermal radiation images. Plus, we show the spatiotemporal behavior of a SGD induced thermal radiation pattern to vary in size and over time by up to 55% for focused SGDs and by up to 600% for diffuse SGDs due to different underlying flow dynamics. These flow dynamics even display a short-term periodicity in the order of 20 to 78s for diffuse SGD which we attribute to an interplay of conduit maturity/geometry and wave setup.

Beschreibung: Submarine groundwater discharge (SGD) is highly variable in spatial and temporal terms due to the interplay of several terrestrial and marine processes. While discrete in situ measurements may provide a continuous temporal scale to investigate underlying processes and thus account for temporal heterogeneity, remotely sensed thermal infrared radiation sheds light on the spatial heterogeneity as it provides a continuous spatial scale. Here we report results of the combination of both the continuous spatial and temporal scales, using the ability of an unmanned aerial vehicle (UAV) to hover above a predefined location, and the continuous recording of thermal radiation of a coastal area at the Dead Sea (Israel). With a flight altitude of 65 m above the water surface resulting in a spatial resolution of 13 cm and a thermal camera (FLIR Tau2) that measures the upwelling long-wave infrared radiation at 4 Hz resolution, we are able to generate a time series of thermal radiation images that allows us to analyse spatio-temporal SGD dynamics. In turn, focused SGD spots, otherwise camouflaged by strong lateral flow dynamics, are revealed that may not be observed on single thermal radiation images. The spatio-temporal behaviour of an SGD-induced thermal radiation pattern varies in size and over time by up to 155 % for focused SGDs and by up to 600 % for diffuse SGDs due to different underlying flow dynamics. These flow dynamics even display a short-term periodicity of the order of 20 to 78 s for diffuse SGD, which we attribute to an interplay between conduit maturity–geometry and wave set-up.

Beschreibung: Recent studies investigating groundwater parameters, e.g., heads, chemical composition, and heat transfer, argued that groundwater flow paths in the Lower Yarmouk Gorge (LYG) area are controlled by geological features such as faults or dikes. However, the nature of such features, as well as their exact locations, were so far unknown. In the present paper, we propose a new fault pattern in the LYG area by compiling and revising geological and geophysical data from the study area, including borehole information, geological map cross sections, and seismic data from the southern Golan Heights and northern Ajloun mountains. The presented pattern is composed of strike–slip and thrust faults, which are associated with the Dead Sea transform system and with the Kinnarot pull-apart basin. Compressional and tensional structures developed in different places, forming a series of fault blocks probably causing a non-uniform spatial hydraulic connection between them. This study provides a coarse fault-block model and improved structural constraints that serve as fundamental input for future hydrogeological modeling which is a suggested solution for an enigmatic hydrological situation concerning three riparian states (Syria, Jordan, and Israel) in a water-scarce region. In areas of water scarcity and transboundary water resources, transient 3-D flow simulations of the resource are the most appropriate solution to understand reservoir behavior. This is an important tool for the development of management strategies. However, those models must be based on realistic geometry, including structural features. The study at the LYG is intended to show the importance of such kinds of structural investigations for providing the necessary database in geologically stressed areas without sufficient data. Furthermore, during the hydrogeological investigation, a mismatch with results of pull-apart basin rim fault evolution studies was discovered. We argue that this mismatch may result from the settings at the eastern rim of the basin as the en-echelon changes from pull-apart basins (Dead Sea, Kinnarot, Hula) to a push-up ridge (Hermon).