Erosion pattern of artificial gravel deposits

Sediment replenishment with artificial gravel deposits is an option to compensate for sediment deficits in rivers and to improve their ecological conditions. Predicting and quantifying the erosion rate of an artificial gravel deposit is important to successfully perform river restoration projects. Laboratory experiments have been done to investigate the influence of various parameters on the erosion pattern of artificial gravel deposits. In the present paper the effects of deposit geometry, bulk density, grain size distribution, and hydraulic load on the erosion process are described. The temporal evolution of the deposit geometry and the corresponding mean erosion rates were studied. The mean erosion rate increases with deposit height, deposit width, and decreasing grain size. Furthermore, no significant impact of the bulk density was observed. Equations to predict the mean erosion rate are proposed. This investigation helps to determine the design frequency of gravel dumping and deposit volumes for restoration projects.     

Long‐range terrestrial laser scanning for geomorphological change detection in alpine terrain – handling uncertainties

Long‐range terrestrial laser scanning (TLS) is an emerging method for the monitoring of alpine slopes in the vicinity of infrastructure. Nevertheless, deformation monitoring of alpine natural terrain is difficult and becomes even more challenging with larger scan distances. In this study we present approaches for the handling of spatially variable measurement uncertainties in the context of geomorphological change detection using multi‐temporal data sets. A robust distance measurement is developed, which deals with surface roughness and areas of lower point densities. The level of detection (LOD), i.e. the threshold distinguishing between real surface change and data noise, is based on a confidence interval considering the spatial variability of TLS errors caused by large laser footprints, low incidence angles and surface roughness. Spatially variable positional uncertainties are modelled for each point according to its range and the object geometry hit. The local point cloud roughness is estimated in the distance calculation process from the variance of least‐squares fitted planes. Distance calculation and LOD assessment are applied in two study areas in the Eastern Alps (Austria) using multi‐temporal laser scanning data sets of slopes surrounding reservoir lakes. At Finstertal, two TLS point clouds of high alpine terrain and scanned from ranges between 300 and 1800 m are compared. At Gepatsch, the comparison is done between an airborne laser scanning (ALS) and a TLS point cloud of a vegetated mountain slope scanned from ranges between 600 and 3600 m. Although these data sets feature different conditions regarding the scan setup and the surface conditions, the presented approach makes it possible to reliably analyse the geomorphological activity. This includes the automatic detection of rock glacier movement, rockfall and debris slides, even in areas where a difference in vegetation cover could be observed. Copyright © 2016 John Wiley & Sons, Ltd.     

Stable Sulfur Isotopic Evidence for Historical Changes of Sulfur Cycling in Estuarine Sediments from Northern Florida

Data on abundance and isotopic composition of porewater and sedimentary sulfur species are reported for relatively uncontaminated and highly contaminated fine-grained anoxic sediments of St. Andrew Bay, Florida. A strong contrast in amount and composition of sedimentary organic matter at the two sites allows a comparative study of the historical effects of increased organic loading on sulfur cycling and sulfur isotopic fractionation. In the contaminated sediments, an increase in organic loading caused increased sedimentary carbon/sulfur ratios and resulted in higher rates of bacterial sulfate reduction, but a lower efficiency of sulfide oxidation. These differences are well reflected in the isotopic composition of dissolved sulfate, sulfide, and sedimentary pyrite. Concentration and isotopic profiles of dissolved sulfate, organic carbon, and total sulfur suggest that the anaerobic decomposition of organic matter is most active in the upper 8cm but proceeds at very slow rates below this depth. The rapid formation of more than 90% of pyrite in the uppermost 2 cm which corresponds to about 3 years of sediment deposition allows the use of pyrite isotopic composition for tracing changing diagenetic conditions. Sediment profiles of the sulfur isotopic composition of pyrite reflect present-day higher rates of bacterial sulfate reduction and lower rates of sulfide oxidation, and record a profound change in the diagenetic cycling of sulfur in the contaminated sediments coincident with urban and industrial development of the St. Andrew Bay area.     

Nickel und Kobalt in Gesteinen des Nördlinger Ries

Zusammenfassung Von Glasbomben aus dem Suevit und kristallinen Gesteinen verschiedener Auswurfbreccien des Rieskraters wurden die Nickel- und Kobaltgehalte bestimmt. Die Gläser enthalten 10,0–51,5 ppm Ni (Mittel von 70 Analysen: 30,1 ppmNi) und 4,8–15,8 ppm Co (Mittel von 50 Analysen: 12,1 ppm Co). Die höchsten Nickel- und Kobaltgehalte finden sich in den nicht rekristallisierten und chemisch unveränderten Bomben des Typ I. Die kristallinen Gesteine des Grundgebirges enthalten 2,5–140 ppm Ni (22 Analysen) und 2,2–29,8 ppm Co (22 Analysen).Die Kobaltgehalte der nicht rekristallisierten Gläser sind ziemlich einheitlich (10,7–15,8 ppm) und ebenso hoch wie diejenigen der kristallinen Gesteine ähnlicher Gehalte an MgO, MgO+FeO+Fe₂O₃ und SiO₂. Die Nickelgehalte der nicht rekristallisierten Gläser dagegen streuen inhomogen über einen größeren Bereich (30,0–51,5 ppm). Sie sind im Mittel höher als die der kristallinen Gesteine mit ähnlichen Gehalten an MgO, MgO+FeO+Fe₂O₃ und SiO₂. Der maximale Unterschied beträgt 25 ppm Ni.

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Ni and Co in rocks from the Nördlinger Ries

Ni and Co have been determined in glass bombs from the suevite and crystalline rocks from different breccia outcrops in the Ries crater. The glasses contain 10.0–51.5 ppm Ni (average of 70 analyses: 30.1 ppm Ni) and 4.8–15.8 ppm Co (average of 50 analyses: 12.1 ppm Co). Highest contents of Ni and Co are to be found in non-recrystallized and chemically unchanged bombs of type I. Crystalline rocks from the basement contain 2.5–140 ppm Ni (22 analyses) and 2.2–29.8 ppm Co (22 analyses).The Co-contents of non-recrystallized glasses are rather uniform (10.7–15.8 ppm) and as high as those of crystalline rocks of similar content of MgO, MgO+FeO+Fe₂O₃ and SiO₂. The Ni-contents of non-recrystallized glasses are inhomogeneously scattered over a larger range (30.0–51.5 ppm). On the average, they are higher than those of crystalline rocks with similar contents of MgO, MgO+FeO+Fe₂O₃ and SiO₂. The maximum difference is 25 ppm Ni.

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Herr Prof. W. von Engelhardt veranlaßte die Bearbeitung dieses interessanten Themas und nahm am Fortgang der Untersuchungen regen Anteil. Herr Dr. D. Stöffler stellte freundlicherweise Probenmaterial zur Verfügung und Herr Dr. H. Puchelt war mir bei analytischen Fragen behilflich. Ihnen allen danke ich für die Förderung dieser Arbeit.     

Die Ausbreitung hochfrequenter Hertzscher Felder in Kalilagerstätten

Zusammenfassung 1) Die Versuche fanden in den Gruben Hannovers, des Werragebietes und des Südharzes statt. 2) Die Untersuchungen erstreckten sich über das ganze praktisch in Betracht kommende Wellenband, angefangen von den Meterwellen bis in den 1000 Meter-Bereich. 3) Im Zuge der Untersuchungen konnten die bisher gr?ssten, unter Tag überhaupt erzielten Reichweiten erreicht werden. Die gr?sste Reichweite wurde zwischen zwei Hannoverischen Gruben erzielt und betrug bei 14 Kilometer. 4) Frequenz und geologische Faktoren sind stets von Einfluss. 5) Die Versuche zeigen, dass unter Kalilagerst?tten Funkmutungsverfahren nach dem Reflexions- und Refraktionsprinzip für gr?ssere Aufschlussteufen m?glich sind. 6) Die Versuche haben alle Voraussetzungen des Grubenfunks so weit gekl?rt, dass dessen praktischer Einführung nichts im Wege steht.

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Summary The purpose of the experiments described in this paper was to investigate the conditions of propagation of a transmitter situated below the surface of the ground. This problem is of interest to both radio engineers and geophysicists. By determination of the extinction and reflection areas of electrical discontinuity may be located. The experiments were carried out in German potassic salt mines. Rocks of potassic salts are known as very bad conductors. Therefore the extinction is but very little. In this area ranges up to 14 kilometres were reached. This is the greatest range obtained up to now under the surface of the ground. The investigations were carried out with different wave lengths from 10 up to 2000 metres. The influence of geological discontinuities, alkaline deposits and disturbed areas was always very great. The author mentions that the above ranges could certainly still be considerably increased by application of all technical means available at present.