Die Bildung der Kupfererze im mittelsudetischen Rotliegenden

Ohne Zusammenfassung     

Stormwater harvesting in ephemeral streams: how to bypass clogging and unsaturated layers

To cope with water scarcity in drylands, stormwater is often collected in surface basins and subsequently stored in shallow aquifers via infiltration. These stormwater harvesting systems are often accompanied by high evaporation rates and hygiene problems. This is commonly a consequence of low infiltration rates, which are caused by clogging layers that form on top of the soil profile and the presence of a thick vadose zone. The present study aims to develop a conceptual solution to increase groundwater recharge rates in stormwater harvesting systems. The efficiency of vadose-zone wells and infiltration trenches is tested using analytical equations, numerical models, and sensitivity analyses. Dams built in the channel of ephemeral streams (wadis) are selected as a study case to construct the numerical simulations. The modelling demonstrated that vadose-zone wells and infiltration trenches contribute to effective bypassing of the clogging layer. By implementing these solutions, recharge begins 2250–8100% faster than via infiltration from the bed surface of the wadi reservoir. The sensitivity analysis showed that the recharge rates are especially responsive to well length and trench depth. In terms of recharge quantity, the well had the best performance; it can infiltrate up to 1642% more water than the reservoir, and between 336 and 825% more than the trench. Moreover, the well can yield the highest cumulative recharge per dollar and high recharge rates when there are limitations to the available area. The methods investigated here significantly increased recharge rates, providing practical solutions to enhance aquifer water storage in drylands.

     

Die Lagerungsverhältnisse der Altvulkanite

Zusammenfassung Es werden die Lagerungsverhältnisse der altvulkanischen Bildungen erörtert: Die fördertreue Lagerung der Tuffe und die teils kongruente, teils überschneidende, teils fördertreue Lagerung der Intrusivgruppen. Die Lagerung derselben beruht auf dem jeweiligen Verhältnis von Senkung und Hebung. Im Gegensatz dazu ist die inverse Lagerung der Scheiben innerhalb einer Intrusivgruppe bei stationärer Lage des Gebirges auf das zunehmende spezifische Gewicht der Schmelzen zurückzuführen. Diese Lagerung steht im Widerspruch zur Förderfolge. Dieser Befund bestätigt die Intrusivnatur der vorquartären Laven.Die Graben- und Kammerbasalte werden auf den Abriß eines Grabenkeils infolge der Horizontalen Dehnung und auf eine progressive Kammerbildung zurückgeführt. Sie gibt einen Hinweis auf den Raumgewinn nach unten. Es folgen Erörterungen über die Lagerungsbeziehungen der Intrusivkörper zu den Sedimenten und Tuffen. Am Schluß wird auf die methodische Anwendung der erkannten Gesetzmäßigkeiten hingewiesen. Im Anhang folgt eine Stellungnahme zu den bei der Diskussion vorgebrachten Einwänden.

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Pyroclasts are deposited in accordance with their eruption. Intrusives are found in congruent, overlapping, or in eruption-accordant positions, consequent to tectonic rise and subsidence. In stable areas the reversed succession within the volcanic complex follows an increased specific weight of the magma. Reversed successions of volcanic series corroborate the intrusive origin of the prequaternary lavas. The graben and chamber basalts depend on wedge-shaped graben subsidence, and on progressive formation of chambers.

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Résumé On examine ici les aspects des stratifications des formations volcaniques anciennes, en particulier la stratification des tuffs et celle des roches intrusives. La stratification de ces dernières est due aux diverses formes d'affaisement et de soulèvement. En contraste avec cela, la disposition inverse des plaques à l'intérieur d'un groupe de roches intrusives dans une position stationnaire de la montagne doit s'expliquer par l'accroissement du poids spécifique du magma. Cette disposition se trouve en opposition avec l'ordre d'arrivée. Cette constation permet de confirmer la nature intrusive de «laves» préquaternaires. Les basaltes des fossés et les basaltes des salles ont attribués à un graben par suite de l'extension horizontale et à une formation progressive de salles. Celle-ci apporte une indication sur le gain d'espace réalisé vers le bas.A la fin on attire l'attention sur les aspects de la stratification des corps intrusifs par rapport aux sédiments et aux tuffs ainsi que sur l'application méthodique deces résultats. Dans l'appendice suit une prise de position par rapport aux objections formulées en cours de discussion.

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Investigation of the elevation of saltwater wedge due to subsurface dams

Subsurface dams are rather effective and used for the prevention of saltwater intrusion in coastal regions around the world. We carried out the laboratory experiments to investigate the elevation of saltwater wedge after the construction of subsurface dams. The elevation of saltwater wedge refers to the upward movement of the downstream saltwater wedge because the subsurface dams obstruct the regional groundwater flow and reduce the freshwater discharge. Consequently, the saltwater wedge cannot further extend in the longitudinal direction but rises in the vertical profile resulting in significant downstream aquifer salinization. In order to quantitatively address this issue, field-scale numerical simulations were conducted to explore the influence of various dam heights, distances, and hydraulic gradients on the elevation of saltwater wedge. Our investigation shows that the upward movement of the saltwater wedge and its areal extension in the vertical domain of the downstream aquifer become more severe with a higher dam and performed a great dependence on the freshwater discharge. Furthermore, the increase of the hydraulic gradient and the dam distance from the sea boundary leads to a more pronounced wedge elevation. This phenomenon comes from the variation of the freshwater discharge due to the modification of dam height, location, and hydraulic gradient. Large freshwater discharge can generate greater repulsive force to restrain the elevation of saltwater wedge. These conclusions provide theoretical references for the behaviour of the freshwater–seawater interface after the construction of subsurface dams and help optimize the design strategy to better utilize the coastal groundwater resources.     

3rd International Energy Forum in Hamburg,Germany, 22–23 November 1990

Reports

3rd International Energy Forum in Hamburg, Germany, 22–23 November 1990Meeting of leading experts to discuss the role of the Energy Industries in the Europe of the Future     

Intrusiver und extrusiver Peridoditmagmatismus im alpinotypen Bereich

Zusammenfassung Der Widerspruch, welcher sich aus der hohen Schmelztemperatur ultrabasischer Magmen und der geringen Kontaktmetamorphose ergibt, ist allgemein weder durch den kühlen Kristallbrei noch durch die tektonische Einschuppung von Bruchstücken der Peridoditschale lösbar. Die Platznahme der Ultrabasite erfolgte teils tief intrusiv, teils seicht intrusiv im Bereich der Geosynklinalböden, teils submarin extrusiv. Sedimentogene Serpentine sind sehr selten. Das Alter der Serpentine im alpinmediteranen Raum reicht vom Altpaläozoikum bis in die oberste Kreide.     

Salt transport on islands in the Okavango Delta: Numerical investigations

This study uses a numerical model to investigate the groundwater flow and salt transport mechanisms below islands in the Okavango Delta. Continuous evapotranspiration on the islands results in accumulation of solutes and the formation of a saline boundary layer, which may eventually become unstable. A novel Lagrangian method is employed in this study and compared to other numerical methods. The numerical results support the geophysical observations of density fingering on Thata Island. However, the process is slow and it takes some hundreds of years until density fingering is triggered. The results are sensitive to changes of the hydraulic gradient and the evapotranspiration rate. Small changes may lead to different plume developments. Results further demonstrate that density effects may be entirely overridden by lateral flow on islands embedded in a sufficiently high regional hydraulic gradient.     

Holocene climate evolution of the Ugii Nuur basin,Mongolia

In order to evaluate the Holocene palaeoenvironmental evolution of the Ugii Nuur basin, central Mongolia, investigations on chemical and mineralogical properties of lacustrine sediments were carried out on a 630 cm sediment core from lake Ugii Nuur. The interpretation of the record is based on a principal component analysis （PCA） of the elemental composition of the samples. The results show that lacustrine deposition started at 10.6 kyr BP. Low lake level conditions were identified during the Early Holocene （10.6-7.9 kyr BP）. The Mid Holocene （7.9-4.2 kyr BP） was characterized by generally higher lake levels and thus higher moisture supply, but it experienced strong climatic fluctuations. Arid conditions prevailed from 4.2-2.8 kyr BP and were followed by a stable, more humid phase until today.