Spatial multi-criteria analysis for selecting potential sites for aquifer recharge via harvesting and infiltration of surface runoff in north Jordan

In (semi-)arid regions, available water resources are scarce and groundwater resources are often overused. Therefore, the option to increase available water resources by managed aquifer recharge (MAR) via infiltration of captured surface runoff was investigated for two basins in northern Jordan. This study evaluated the general suitability of catchments to generate sufficient runoff and tried to identify promising sites to harvest and infiltrate the runoff into the aquifer for later recovery. Large sets of available data were used to create regional thematic maps, which were then combined to constraint maps using Boolean logic and to create suitability maps using weighted linear combination. This approach might serve as a blueprint which could be adapted and applied to similar regions. The evaluation showed that non-committed source water availability is the most restricting factor for successful water harvesting in regions with <200 mm/a rainfall. Experiences with existing structures showed that sediment loads of runoff are high. Therefore, the effectiveness of any existing MAR scheme will decrease rapidly to the point where it results in an overall negative impact due to increased evaporation if maintenance is not undertaken. It is recommended to improve system operation and maintenance, as well as monitoring, in order to achieve a better and constant effectiveness of the infiltration activities.     

Density-dependent dispersion in heterogeneous porous media Part I: A numerical study

In this paper, we describe carefully conducted numerical experiments, in which a dense salt solution vertically displaces fresh water in a stable manner. The two-dimensional porous media are weakly heterogeneous at a small scale. The purpose of these simulations, conducted for a range of density differences, is to obtain accurate concentration profiles that can be used to validate nonlinear models for high-concentration-gradient dispersion. In this part we focus on convergence of the computations, in numerical and statistical sense, to ensure that the uncertainty in the results is small enough.Concentration variances are computed, which give estimates of the uncertainty in local concentration values. These local variations decrease with increasing density contrast. For tracer transport, obtained longitudinal dispersivities are in accordance with analytical findings. In the case of high-density contrasts, stabilizing gravity forces counteract the growth of dispersive fingers, decreasing the effective width of the transition zone. For small log-permeability variances, the decrease of the apparent dispersivity that is found is in agreement with laboratory results for homogeneous columns.     

A numerical integration of a two-level quasi-geostrophic model with variable Rossby parameter

Summary Circulation patterns were obtained from a two-level quasi-geostrophic model, in which the Rossby parameter varied with latitude. The initial basic state was characterized by a constant zonal flow at both reference level. The results we re compared with the pattern obtained in a series of experiments with a similar model, in which the Rossby parameter was assumed to be constant. the initial zonal flow in these experiments was assumed in one case to be constant with latitude, in the second casse to have a symmetrical jet centered on the central latitude, and in the thrid case to have its maximum in the southern half of the region. the results of the experiment with a variable Rossby parameter have the closest resemblance to the patterns observed in the real atmospehre. In particular, during the mature stages of the run, the distribution of the zonallyaveraged eddytransport of momentum corresponded quite well to patterns actually observed in the atmosphere.

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Zusammenfassung Aus einem quasi-geostrophischen Modell mit breitenabhängigem rossby-Parameter wurden Zirkulationsformen errechnet. Der Anfangszustand war durc eine konstante zonale Strömung in zwei Niveaus charakteriseirt. Die Resultate wurden mit Zirkulationen verglichen, die in einer Reihe von Experimenten mit einem ähnlichen Modell, in dem aber der Rossby-Parameter konstant angenommen war, erhalten worden waren. In einemk dieser Fälle wurde angenommen, daß die ursprüngliche zonale Strömung breitenunabhängig war, in einem anderen fall wurde angenommen, daß die Strömung in einem symmetrischen Jetstream über eine mittleren Breite konzentriert war, und in einem dritten Fall wurden angenommen, daß die zonale Strömung ihr Maximum in der südlichen Hälfte des Bereiches hatte. Die Resultate des Experiments mit dem veränderlichen Rossby-Parameter haben die meiste Ähnlichkeit mit Zirkulationsformen in der wirklichen Atmosphäre. Insbesondere paßt die Verteilung des zonal gemittelten Momentumtransports in den Reifestadien des Versuchs gut zu den tatsächlich in der Atmosphäre beobachteten Zirkulationsformen.

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Résumé On a calculé les formes de circulation découlant d'un modèle quasigéostrophique dont le paramètres de Rossby dépendaient de la latitude. L'état initial en était caractérisé par un courant zonal constant aux deux niveaux. Lels résultats ont été comparés à ceux d'une série d'essais effectués avec un modèle semblable, mais dans lequel les paramètres de Rossby restaient constants. Dans un de ces cas, on a admis que la circulation zonale initiale ne dépendait pas de la latitude. Dans un deuxième, on a simulé un jet symétriquement à une latitude moyenne. Dans un troisième enfin, on a placè le maximum de la circulation zonale dans la moitié sud de l'espace étudié. Les résultats obtenus en partant des essais basés sur un paramètre de Rossby variable sont les plus semblables aux formes de circulation observées réellement dans l'atmosphère. En particulier, la répartition du transport turbulent de la quantité de mouvement — moyenne zonale calculée au stade de maturité de l'essai — est très voisine des formes de circulation observées réellement dans l'atmosphère.

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With 9 Figures

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The research reported in this document has been sponsored by the Air Force Cambridge Research Laboratories under Grant AF EOAR 63-108 through the European Office of Aerospace Reasearch (OAR), United States Air Force.     

Kleinraummeteorologische Studien im Federseegebiet in Strahlungsnächten

Zusammenfassung Die vorliegende Studie befaßt sich mit den meteorologischen Vorgängen in einer extrem stabil aufgebauten Kaltluft, wie sie sich in Strahlungsnächten in einem abgeschlossenen Becken mit ebener, horizontaler Talsohle von einigen Kilometern Ausdehnung und im wesentlichen einheitlichem Untergrund einer Moorlandschaft herausbildet.Untersucht wird in erster Linie das Eigenleben der so abgeschlossenen Luftmasse. Dabei zeigt sich, daß der Zustand eines ruhenden Kaltluftsees zumeist erst im Endstadium des nächtlichen Prozesses näherungsweise erreicht wird. Während des größten Teiles der Nacht kommen vielmehr überraschend lebhafte und weitreichende angenähert horizontale Bewegungen leicht zustande, die sich im thermischen Gefüge wie in der Windstruktur kundtun und in dem Verhalten der Nebel- und Dunstfelder sichtbar werden. Unter der Wirkung von Schwerkraft, Druckgefälle und Reibung entstehen einfache Gleitvorgänge, Schaukelbewegungen, fortschreitende Wellen und Seiches, die in einzelnen Beispielen beschrieben werden. Ähnlich wie in der Großraummeteorologie bilden sich durch das quantenhafte Verhalten der Energieumsätze Luftkörperindividuen, deren Deformation hier einfacheren Gesetzen folgt. Trotz ihrer sehr verschiedenen Größenordnung von einigen Dekametern bis zu mehreren Kilometern Ausdehnung bei geringer vertikaler Mächtigkeit zeigen sie auf ihrer Vorderseite einheitlich die Form des vonW. Schmidt in Modellversuchen gefundenen Böenkopfes.Der Einfluß höherer Luftschichten auf die stabilisierte Bodenkaltluft äußert sich in aufgeprägten Wellen und Frendlufteinschüben. Das Beispiel eines nächtlichen Wärmeeinbruchs aus der Höhe wird eingehend beschrieben.

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Summary The present study deals with the meteorological processes in an extremely stable cold air, formed in clear nights in a confined basin with a plane, horizontal basis extended for some kilometres, and with an essentially uniform ground in a fen-country.In the first place the proper life of the so limited air is studied. It becomes evident, that the state of a resting lake of cold air generally is approximately reached but in the final phase of the night-time process. Moreover, for the greater part of the night surprising active and extended movements of nearly horizontal course easily occur, becoming evident in the structure of wind and temperature stratification and also visible in the behaviour of fog and haze fields. Produced by gravitation, pressure gradient and friction, simple gliding and swinging motions, proceeding waves and seiches result which are described in single examples. Corresponding to the large scale meteorology individual air bodies form by the quantum-like behaviour of energy transformations. Their deformation in this case however, takes course according to simpler laws. In spite of their much various magnitude of the dimensions of some decametres up to several kilometres, while being of small vertical extension they show in their fore part in all cases the shape of a Böenkopf as found byW. Schmidt by model experiments.The influence of upper atmospheric layers on the stable cold air near the ground manifests itself by impressed waves and by influxes of heterogeneous air. An example of a nocturnal invasion of warm air from aloft is described in detail.

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Résumé Cette étude traite des processus météorologiques dans un air froid d'une stratification extrêmement stable, qui se développent pendant des nuits claires dans un bassin fermé, ayant une base plane et horizontale, d'une étendue de quelques km, et recouverte par le sol essentiellement homogène d'une région marécageuse.C'est surtout la «vie propre» de cette masse d'air limitée qui est étudiée. Il se trouve que, le plus souvent, l'état d'un «lac immobile d'air froid» n'est atteint approximativement qu'à la fin du processus nocturne. Pendant la plus grande partie de la nuit, se produisent au contraire facilement des mouvements presque horizontaux étonnamment actifs et étendus, qui se manifestent dans la structure thermique et du vent, et qui deviennent visibles par le comportement des couches de brouillard et de brume. De simples processus de glissement, des oscillations, des ondes progressives et des seiches se forment sous l'influence de la gravitation, du gradient de pression et du frottement; ils sont décrits par des exemples particuliers. Comme cela se produit dans la météorologie à grande échelle, il se forme des corps atmosphériques individuels à la suite du comportement en quanta des transformations d'énergie. Leur déformation a lieu cependant selon des lois plus simples. En dépit de leur étendue très variable allant de quelques decamètres à plusieurs km, et leur épaisseur peu considérable, ils montrent tous à leur partie antérieure la forme d'un «Böenkopf», pareil à celui queW. Schmidt a trouvé à la suite de ses expériences qu'il fit avec des modèles.L'influence des couches supérieures de l'atmosphère sur l'air froid stable au sol se manifeste par l'impression d'ondes et par des apports d'air étranger. On décrit ensuite en détail une invasion nocturne d'air chaud depuis les couches supérieures.

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Mit 13 Textabbildungen.

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Herrn Prof. Dr.W. Peppler, zum 70. Geburtstag.     

Fe-Ni and Mn-Cr isotopic systems in sulfides from unequilibrated enstatite chondrites

In situ measurements of ⁶⁰Fe-⁶⁰Ni and ⁵³Mn-⁵³Cr isotopic systems with an ion microprobe have been carried out for sulfide assemblages from unequilibrated enstatite chondrites (UECs). Evidence for the initial presence of ⁶⁰Fe has been observed in nine sulfide inclusions from three UECs: ALHA77295, MAC88136, and Qingzhen. The inferred initial (⁶⁰Fe/⁵⁶Fe) [(⁶⁰Fe/⁵⁶Fe)₀] ratios show a large variation range, from ∼2 × 10⁻⁷ to ∼2 × 10⁻⁶. The sulfide inclusions with high Fe/Ni ratios yield (⁶⁰Fe/⁵⁶Fe)₀ ratios of ∼(2-7) × 10⁻⁷, similar to most of the (⁶⁰Fe/⁵⁶Fe)₀ values of troilite and pyroxene observed in unequilibrated ordinary chondrites (UOCs). Inclusions with high inferred (⁶⁰Fe/⁵⁶Fe)₀ ratios (∼1-2 × 10⁻⁶) have low Fe/Ni ratios and the magnitude of the ⁶⁰Ni excesses is similar in two MAC88136 assemblages in spite of a difference of a factor of two in their Fe/Ni ratios. The inferred high (⁶⁰Fe/⁵⁶Fe)₀ ratios were probably the result of Fe-Ni re-distribution in the sulfides during later alteration processes.The ⁵³Mn-⁵³Cr system was measured in five of the sulfide assemblages that were examined for their ⁶⁰Fe-⁶⁰Ni systematics. The ⁵³Mn-⁵³Cr isochrons yielded variable initial (⁵³Mn/⁵⁵Mn) [(⁵³Mn/⁵⁵Mn)₀] ratios from ∼(2-7) × 10⁻⁷. There is no obvious correlation between the (⁶⁰Fe/⁵⁶Fe)₀ and (⁵³Mn/⁵⁵Mn)₀ ratios. The variable ⁵³Mn-⁵³Cr isochrons probably also indicate later disturbance to the isotopic systems in these sulfides. Even though no chronological information can be extracted from the ⁶⁰Fe-⁶⁰Ni and ⁵³Mn-⁵³Cr systems in these UEC sulfides, our results indicate that ⁶⁰Fe was present in the enstatite chondrite formation region of the early Solar System.     

Snow accumulation distribution inferred from time‐lapse photography and simple modelling

The spatial and temporal distribution of snow accumulation is complex and significantly influences the hydrological characteristics of mountain catchments. Many snow redistribution processes, such as avalanching, slushflow or wind drift, are controlled by topography, but their modelling remains challenging. In situ measurements of snow accumulation are laborious and generally have a coarse spatial or temporal resolution. In this respect, time‐lapse photography shows itself as a powerful tool for collecting information at relatively low cost and without the need for direct field access. In this paper, the snow accumulation distribution of an Alpine catchment is inferred by adjusting a simple snow accumulation model combined with a temperature index melt model to match the modelled melt‐out pattern evolution to the pattern monitored during an ablation season through terrestrial oblique photography. The comparison of the resulting end‐of‐winter snow water equivalent distribution with direct measurements shows that the achieved accuracy is comparable with that obtained with an inverse distance interpolation of the point measurements. On average over the ablation season, the observed melt‐out pattern can be reproduced correctly in 93% of the area visible from the fixed camera. The relations between inferred snow accumulation distribution and topographic variables indicate large scatter. However, a significant correlation with local slope is found and terrain curvature is detected as a factor limiting the maximal snow accumulation. Copyright © 2010 John Wiley & Sons, Ltd.     

Titanium isotopic compositions of well‐characterized silicon carbide grains from Orgueil (CI): Implications for s‐process nucleosynthesis

Abstract— We have measured the titanium isotopic compositions of 23 silicon carbide grains from the Orgueil (CI) carbonaceous chondrites for which isotopic compositions of silicon, carbon, and nitrogen and aluminum‐magnesium systematics had been measured previously. Using the 16 most‐precise measurements, we estimate the relative contributions of stellar nucleosynthesis during the asymptotic giant branch (AGB) phase and the initial compositions of the parent stars to the compositions of the grains. To do this, we compare our data to the results of several published stellar models that employ different values for some important parameters. Our analysis confirms that s‐process synthesis during the AGB phase only slightly modified the titanium compositions in the envelopes of the stars where mainstream silicon carbide grains formed, as it did for silicon. Our analysis suggests that the parent stars of the >1 μm silicon carbide grains that we measured were generally somewhat more massive than the Sun (2–3 M_⊙) and had metallicities similar to or slightly higher than solar. Here we differ slightly from results of previous studies, which indicated masses at the lower end of the range 1.5–3 M_⊙ and metallicities near solar. We also conclude that models using a standard ¹³C pocket, which produces a good match for the main component of s‐process elements in the solar system, overestimate the contribution of the ¹³C pocket to s‐process nucleosynthesis of titanium found in silicon carbide grains. Although previous studies have suggested that the solar system has a significantly different titanium isotopic composition than the parent stars of silicon carbide grains, we find no compelling evidence that the Sun falls off of the array defined by those stars. We also conclude that the Sun does lie on the low‐metallicity end of the silicon and titanium arrays defined by mainstream silicon carbide grains.     

RAGLAND,AN LL3.4 CHONDRITE FIND FROM NEW MEXICO

The Ragland, New Mexico chondrite was found in 1978, and consists of a single stone of 12.16 kg that broke into three pieces. The stone is moderately weathered and has a pronounced chondritic texture. Bulk composition favors an LL classification, and modal analysis and oxygen isotopic composition are consistent with this. The thermoluminescence sensitivity of 0.056 ± 0.020 normalized to Dhajala, compositional variability of olivine (mean Fa 18.3, σ = 10.1) and low-Ca pyroxene (mean Fs 14.6, σ = 6.7), and Ca concentrations in olivine indicate metamorphic subtype 3.4 ± 0.1. The isotopically heavy oxygen composition, which is characteristic of subtypes 3.0–3.1, may be a primary characteristic and not a result of weathering. Low concentrations of radiogenic ⁴⁰Ar and planetary ³⁶Ar suggest noble gas loss.     

Ammonium in aqueous fluids to 600 °C, 1.3 GPa: A spectroscopic study on the effects on fluid properties, silica solubility, and K-feldspar to muscovite reactions

The behavior of ammonium, NH₄⁺, in aqueous systems was studied based on Raman spectroscopic experiments to 600 °C and about 1.3 GPa. Spectra obtained at ambient conditions revealed a strong reduction of the dynamic three-dimensional network of water with addition of ammonium chloride, particularly at small solute concentrations. The differential scattering cross section of the ν₁-NH₄⁺ Raman band in these solutions was found to be similar to that of salammoniac.The Raman band of silica monomers at ∼780 cm⁻¹ was present in all spectra of the fluid at high temperatures in hydrothermal diamond-anvil cell experiments with H₂O ± NH₄Cl and quartz or the assemblage quartz + kyanite + K-feldspar ± muscovite/tobelite. However, these spectra indicated that dissolved silica is less polymerized in ammonium chloride solutions than in comparable experiments with water. Quantification based on the normalized integrated intensity of the H₄SiO₄⁰ band showed that the silica solubility in experiments with H₂O + NH₄Cl was significantly lower than that in equimolal NaCl solutions. This suggests that ammonium causes a stronger decrease in the activity of water in chloridic solutions than sodium.The Raman spectra of the fluid also showed that a significant fraction of ammonium was converted to ammonia, NH₃, in all experiments at temperatures above 300 °C. This indicates a shift towards acidic conditions for experiments without a buffering mineral assemblage. The estimated pH of the fluid was ∼2 at 600 °C, 0.26 GPa, 6.6 m initial NH₄Cl, based on the ratio of the integrated ν₁-NH₃ and ν₁-NH₄⁺ intensities and the HCl⁰ dissociation constant. The NH₃/NH₄⁺ ratio increased with temperature and decreased with pressure. This implies that more ammonium should be retained in K-bearing minerals coexisting with chloridic fluids upon high-P low-T metamorphism. At 500 °C, 0.73 GPa, ammonium partitions preferentially into the fluid, as constrained from infrared spectroscopy on the muscovite and from mass balance.The conversion of K-feldspar to muscovite proceeded much faster in experiments with NH₄Cl solutions than in comparable experiments with water. This is interpreted as being caused by enhancement of the rate-limiting alumina solubility, suggesting complexation of Al with NH₄. Nucleation and growth of mica at the expense of K-feldspar and NH₄⁺/K⁺ exchange between fluid and K-feldspar occurred simultaneously, but incorporation of NH₄⁺ into K-feldspar was distinctly faster than K-feldspar consumption.