Eliyahu Rosenthal

Assessment of transmission losses and groundwater recharge from runoff events in a wadi under shortage of data on lateral inflow, Negev, Israel

A hydrological–lithostratigraphical model was developed for assessment of transmission losses and groundwater recharge from runoff events in arid water courses where hydrological and meteorological records are incomplete. Water balance equations were established for reaches between hydrometric stations. Because rainfall and tributary flow data are scarce, lateral inflow, which is an essential component of the water balance equation, could not be estimated directly. The solution was obtained by developing a method which includes a hydrological–lithostratigraphical analogy. This is based on the following assumptions: (a) runoff resulting from a given rainfall event is related to the watershed surface lithology; (b) for a given event, the spatial distribution of runoff reflects the distribution of rainfall: and (c) transmission losses are uniquely related to the total inflow to the reach. The latter relationship, called the loss function, and the water balance equation comprise a model which simultaneously assesses lateral inflow and transmission losses for runoff events recorded at the terminal stations. The model was applied to three reaches of the arid Nahal Tsin in Israel. In this case study, the transmission losses were of the same order of magnitude as the flow at the major hydrometric stations. The losses were subdivided into channel moistening, which subsequently evaporates, and deep percolation, which recharges groundwater. For large runoff events, evaporation was substantially smaller than the losses. The mean annual recharge of groundwater from runoff events in the Tsin watershed was 4·1×106 m3, while the mean annual flow volume at the major stations ranged from 0·6 to 1·5×106 m3. Once in 100 years, the annual recharge may be seven times higher than the mean annual value, but the recharge during most years is very small. Copyright

Rare earths and yttrium hydrostratigraphy along the Lake Kinneret–Dead Sea–Arava transform fault, Israel and adjoining territories

Rare earth elements and Y (REY) have been analysed in 49 groundwaters from localities in the areas of Lake Kinneret and the Jordan and Arava Valleys. These waters originate from various aquifers and the REY abundances are expected to be controlled by the aquifer rocks. The REY pattern allow one to distinguish interaction of waters with basalts, basalt-limestone interaction zones (silicified limestones), limestones from the Judea and Avdat Groups (Upper Cretaceous and Eocene, respectively), and sandstones of the Lower Cretaceous Kurnub Group. Groundwater from the Quaternary alluvial fill (Dead Sea Group) are either controlled by Judea Group limestone or Kurnub Group sandstone. The REY patterns show characteristic features for each group. In hydrogeological systems, the rocks of natural replenishment areas are usually not the same as rock units from which the waters are collected. This becomes evident by comparing the lithostratigraphic groups from which the waters were collected and the hydrochemical grouping according to REY patterns with their characteristic trends and anomalies. In many cases, there is a correspondence between the lithostratigraphic and the hydrochemical grouping; in other cases, the 2 groupings disagree. This disagreement proves inter-aquifer flow of groundwater. In some cases, the geologically derived aquifers rocks of origin, differ from those indicated by REY patterns. Thus, applying the REY grouping, new fundamental information for hydrological models can be given and sources of salinisation can be elucidated.

The chemical evolution of Kurnub Group paleowater in the Sinai-Negev province : a mass balance approach

Abstract The chemical evolution of the Kurnub Group paleowater was studied starting from rainwater in recharge areas of the Sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer. This was achieved by investigating the chemical composition of groundwater, ionic ratios, degrees of saturation with common mineral species, normative analysis of dissolved salts and by modeling of rock/water interaction and mixing processes occurring along groundwater flow paths. The initial groundwater composition used is from the Nakhel well in Sinai. It evolves from desert rainwater percolating through typical Kurnub Group lithology in Sinai. This rainwater dissolves mainly gypsum, halite and dolomite together with smaller amounts of marine aerosol and K-feldspar. At the same time it precipitates calcite, SiO 2 , smectite and degasses CO 2 . Between the area of Nakhel and the northern Negev the chemistry of Kurnub Group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas, small amounts of feldspars and of dolomite cement in sandstones eroded from the Arabo-Nubian igneous massif of Sinai and organic degradation-derived CO 2 . Concomitantly, there is precipitation of calcite, smectite, SiO 2 and probably analcime characteristic of sediments in continental closed basins. North of the Negev, the Kurnub Group fluids are diluted and altered by mixing with Judea Group aquifer groundwaters. On the E there is mixing with residual brines from the water body ancestral to the Dead Sea, prior to discharge into the Arava valley. Rock/water interaction indicated by NETPATH and PHREEQC modeling is in agreement with lithology and facies changes previously observed in the Kurnub Group sequence.

Epigenetic dolomitization and iron mineralization along faults and their possible relation to the paleohydrology of southern Israel

Abstract Iron mineralization occurs in carbonate rocks of the Cretaceous Judea Group in northern Sinai and the Negev. This mineralization, along with strong enrichment of trace metals, fills fissures and veins. The mineralization is not directly emplaced into the Judea Group limestones but rather within epigenetic dolomites or ankerites which postdate the country rocks. The epigenetic phenomena are narrowly restricted to regional tectonic lineaments. The association of mineralization phenomena with tectonic zones of high permeability suggests that fluid transfer between two distinctly different geochemical environments was the main mineral emplacing agent. Epigenetic dolomitization initially resulted from upflow of old Mg-rich brines along the fault face. During later stages, the residual CaCl 2 brines flowing through the underlying Paleozoic-Mesozoic clastic rocks accumulated Fe and trace metals by leaching of volcanic intrusions. The introduction, via faulting, of these pressurized, acidic, low Eh, metal-bearing brines into the overlying aerated and alkaline carbonate surroundings led to precipitation of Fe which in turn scavenged the trace metals. The Mg-rich brines developed during the Cambrian-Lower Cretaceous mostly continental time-interval. The episodic expulsion of pressurized dolomitizing and metal-bearing brines was related to various stages of tectonic and igneous activity occuring during the Early Miocene-Pleistocene.

The effect of hydraulic anisotropies on intensely exploited groundwater resources: the numerical evaluation of a hydrothermal transboundary aquifer system in the Middle East

Previous investigations postulate the presence of a zone of high hydraulic anisotropy parallel to the principle axis of the Lower Yarmouk Gorge (LYG) in the Middle East. Driven by mixed convection, heated fresh groundwaters ascend within the gorge from confined Cretaceous units through artesian wells and Hammat Gader springs. Two-dimensional transient numerical simulations of coupled fluid flow and heat transport processes are used to investigate the impact of (1) a zone of hydraulic anisotropy and (2) abstraction on hydraulic heads and temperature profiles in the shallow aquifers. The models successfully reproduce hydraulic head distribution pre- and post-groundwater abstraction; dominance of conductive and advective heat transport processes is also shown. The models further support the existence of a structural feature along the principle axis of the gorge, which hydraulically connects groundwaters in both flanks, while cross flow of groundwaters is prevented. That implies a subsurface anisotropic zone, which lets the gorge act as a complex conduit-barrier system where adjacent N–S and S–N flow-fields confluence and get drained towards the Jordan Rift. The present numerical investigations support the hypothesis that, most likely, structural features that represent physical anisotropies control the hydrothermal system of the LYG. Furthermore, the study provides an example of numerical investigation of a complex transboundary aquifer system, with emphasis on existent anisotropies, structural ambivalence and restricted field accessibility.RésuméDe précédentes recherches postulent la présence d’une zone d’importante anisotropie hydraulique parallèle à l’axe principal des gorges du Yarmouk inférieur (LYG) dans le Moyen-Orient. Mues par une convection mixte, les eaux douces souterraines chaudes montent dans les gorges à partir des unités crétacées captives, par les puits artésiens et les sources de Hammat Gader. Des simulations numériques transitoires bidimensionnelles des procédés couplés de flux de fluide et de transport de la chaleur sont employées pour étudier l’impact (1) d’une zone d’anisotropie hydraulique et (2) des prélèvements sur les charges hydrauliques et les profils de température dans les aquifères peu profonds. Les modèles reproduisent avec succès la distribution des charges hydrauliques avant et après les prélèvements d’eaux souterraines; la dominance des procédés de conduction et d’advection dans le transport de la chaleur est. également montrée. De plus, les modèles soutiennent l’idée de l’existence d’un dispositif structural le long de l’axe principal des gorges, qui relie hydrauliquement les eaux souterraines des deux flancs, tandis l’écoulement transverse des eaux souterraines est. empêché. Cela suppose une zone anisotrope souterraine, qui laisse les gorges agir en tant que système complexe de conduit-barrière où les champs d’écoulements adjacents N–S et S–N confluent et sont drainés par le rift jordanien. Les investigations numériques actuelles soutiennent l’hypothèse que, le plus probablement, les éléments structuraux qui représentent des anisotropies physiques commandent le système hydrothermal du LYG. En outre, l’étude fournit un exemple de recherche numérique sur un système aquifère transfrontalier complexe, en mettant l’accent sur les anisotropies existantes, l’ambivalence structurale et une accessibilité restreinte au terrain.ResumenLas investigaciones previas postulan la presencia de una zona de alta anisotropía hidráulica paralela al eje principal de Lower Yarmouk Gorge (LYG) en el Medio Oriente. Impulsado por la convección mixta, las aguas subterráneas dulces calientes ascienden dentro de la garganta desde unidades confinadas del Cretácico a través de pozos artesianos y manantiales de Hammat Gader. Se utilizan simulaciones numéricas bidimensionales transitorias de procesos acoplados de flujo de fluidos y transporte de calor para investigar el impacto de (1) una zona de anisotropía hidráulica y (2) captación sobre cargas hidráulicas y perfiles de temperatura en los acuíferos poco profundos. Los modelos reproducen con éxito la distribución de la carga hidráulica antes y después de la extracción del agua subterránea; también se muestra el dominio de los procesos de transporte de calor conductivo y advectivo. Los modelos respaldan además la existencia de una característica estructural a lo largo del eje principal de la garganta, que conecta hidráulicamente las aguas subterráneas en ambos flancos, mientras que se evita el flujo cruzado de las aguas subterráneas. Eso implica una zona anisotrópica en el subsuelo, que permite que la garganta actúe como un complejo sistema de barrera de conductos donde confluyen los campos de flujo adyacentes N–S y S–N y se drenan hacia el Jordan Rift. Las investigaciones numéricas actuales respaldan la hipótesis de que, muy probablemente, las características estructurales que representan anisotropías físicas controlan el sistema hidrotermal del LYG. Además, el estudio proporciona un ejemplo de investigación numérica de un complejo sistema acuífero transfronterizo, con énfasis en las anisotropías existentes, la ambivalencia estructural y la accesibilidad restringida al campo.摘要在中东,过去的研究假定存在着一个平行于Yarmouk峡谷下游主轴的高度水力各向异性带。受到混合对流的驱使,加热的地下淡水通过自流井和Hammat Gader泉群从承压白垩纪单元向外涌出,其水位在峡谷内抬升。采用耦合液体流和热传送过程二维瞬时数值模拟调查了(1)水力各向异性带和(2)抽水对浅层含水层水头和温度剖面的影响。模型成功地再现了抽水前后的水头分布;还显示出传导和平流热传输过程转主导地位。模型进一步支持沿峡谷的主轴存在着一个构造特征,在地下水交叉水流受到阻碍时,这个构造特征就会水力上连接两岸的地下水。这意味着在地表以下存在着一个各向异性带,这个各向异性带能够使峡谷担当一个复杂的通道屏障系统,在这里毗邻的N–S 和 S–N流场汇合,并且向约旦裂谷排水。目前的数值调查结果支持这一假设,即很可能代表物理各向异性的构造特征控制着Yarmouk峡谷下游水热系统。此外,研究还为复杂的跨边界含水层系统的数值调查,尤其是侧重现有的各向异性、构造上各种情况并存以及抵达野外场地受限的数值调查提供了样板。ResumoInvestigações anteriores postulam a presença de uma zona de elevada anisotropia hidráulica paralela ao eixo principal do Baixo Desfiladeiro de Yarmouk (BDY), no oriente médio. Conduzidas por convecção mista, as águas subterrâneas aquecidas ascendem dentro do desfiladeiro de Unidades Cretáceas através de poços artesianos e nas nascentes de Hammat Gader. Simulações numéricas de transiente bidimensional de processos de fluxo de fluidos e transporte de calor acoplados são utilizados para investigar os impactos de (1) uma zona de anisotropia hidráulica e (2) explotação nas alturas piezométricas e perfis de temperatura em aquíferos rasos. Os modelos reproduzem com sucesso a distribuição da altura piezométrica pré e pós a explotação; é mostrada também a dominância de processos condutivos e convectivos de transporte de calor. Os modelos suportam ainda a existência de uma feição estrutural ao longo do eixo principal do desfiladeiro, com águas subterrâneas hidraulicamente conectadas em ambos os flancos, enquanto o fluxo cruzado de águas subterrâneas é impedido. Isso implica numa zona anisotrópica subsuperficial, o que permite que o desfiladeiro atue como um complexo sistema conduto-barreira, onde ocorre confluência de fluxos N–S e S–N adjacentes e são drenados para a Fenda do Jordão. A investigação numérica presente apoia a hipótese de que, muito provavelmente, feições estruturais que representam anisotropias físicas controlam o sistema hidrotermal do BDY. Além disso, o estudo fornece um exemplo de investigação numérica de um complexo sistema aquífero transfronteiriço, com ênfase nas anisotropias existentes, ambivalência estrutural e de restrita acessibilidade.