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  • Wiley  (9)
  • Nature Publishing Group  (3)
  • Seismological Society of America  (2)
  • Nature Publishing Group (NPG)
  • 1
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    Spatial variability in specific discharge and streamwater chemistry during low flows: results from snapshot sampling campaigns in eleven Swiss catchments (2019)
    Wiley
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    Publikationsdatum: 2019
    Beschreibung: Abstract Catchments consist of distinct landforms that affect the storage and release of subsurface water. Certain landforms may be the main contributors to streamflow during extended dry periods and these may vary for different catchments in a given region. We present a unique dataset from snapshot field campaigns during low‐flow conditions in eleven catchments across Switzerland to illustrate this. The catchments differed in size (10 to 110 km2), varied from predominantly agricultural lowlands to Alpine areas, and covered a range of physical characteristics. During each snapshot campaign, we jointly measured streamflow and collected water samples for the analysis of major ions and stable water isotopes. For every sampling location (basin), we determined several landscape characteristics from national geo‐datasets, including drainage area, elevation, slope, flowpath length, dominant land use, and geological and geomorphological characteristics, such as the lithology and fraction of Quaternary deposits. The results demonstrate very large spatial variability in specific low‐flow discharge and water chemistry: neighboring sampling locations could differ significantly in their specific discharge, isotopic composition and ion concentrations, indicating that different sources contribute to streamflow during extended dry periods. However, none of the landscape characteristics that we analyzed could explain the spatial variability in specific discharge or stream water chemistry in multiple catchments. This suggests that local features determine the spatial differences in discharge and water chemistry during low‐flow conditions and that this variability cannot be assessed a priori from available geodata and statistical relations to landscape characteristics. The results furthermore suggest that measurements at the catchment outlet during low‐flow conditions do not reflect the heterogeneity of the different source areas in the catchment that contribute to streamflow.
    Print ISSN: 0885-6087
    Digitale ISSN: 1099-1085
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley
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  • 2
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    A probabilistic sediment cascade model of sediment transfer in the Illgraben (2014)
    Wiley
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    Publikationsdatum: 2014-01-23
    Beschreibung: We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snow melt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000-2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 3
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    Jack oliver (1923-2011) (2011)
    Nature Publishing Group (NPG)
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    Publikationsdatum: 2011-02-11
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Molnar, Peter -- England -- Nature. 2011 Feb 10;470(7333):176. doi: 10.1038/470176a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geological Sciences at the University of Colorado in Boulder, Colorado 80309, USA. peter.molnar@colorado.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21307924" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von Nature Publishing Group (NPG)
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  • 4
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    Kinematics of the Pamir and Hindu Kush regions from GPS geodesy (2013)
    Wiley
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    Publikationsdatum: 2013-04-12
    Beschreibung: [1]  GPS velocities measured in the Pamir and surrounding regions show a total of ~30 mm/yrof northward relative motion between stable Pakistan and Eurasia. The convergence budget is partitioned into10–15 mm/yr of localized shortening across theTrans-Alai Thrust, which bounds the Pamir on the north, consistent with southward subduction of intact lithosphere. Another 10–15 mm/yr of shortening is distributed across the Chitral Himalaya and Hindu Kush, suggesting that Hindu Kush seismicity might be related to northward subduction of Indian lithosphere. Modest shortening at 〈5 mm/yr occurs north of the Trans-Alai Thrust, across the South Tien Shan and between the Ferghana Valley and Eurasia. Negligible north–south shortening occurs within the high Pamir, but as much as5 mm/yr, and perhaps 10 mm/yr, of east–west extension occurs within this region. This extension is matched by a comparable amount of east–west shortening in the Tajik Depression.The localization of shortening to the margins of the Pamir combined with observations of distributed internal extension implies that theeast-west vertically averaged, horizontal compressive normal stress is smaller than the north–south compressive stress.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 5
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    Erosional power in the Swiss Alps: characterization of slope failure in the Illgraben (2012)
    Wiley
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    Publikationsdatum: 2012-04-22
    Beschreibung: ABSTRACT Landslides and rockfalls are key geomorphic processes in mountain basins. Their quantification and characterization are critical for understanding the processes of slope failure and their contributions to erosion and landscape evolution. We used digital photogrammetry to produce a multi-temporal record of erosion (1963 – 2005) of a rock slope at the head of the Illgraben, a very active catchment prone to debris flows in Switzerland. Slope failures affect 70% of the study slope and erode the slope at an average rate of 0.39 ± 0.03 m yr¯¹. The analysis of individual slope failures yielded an inventory of ~2500 failures ranging over 6 orders of magnitude in volume, despite the small slope area and short study period. The slope failures form a characteristic magnitude-frequency distribution with a rollover and a power-law tail between ~200 m³ and 1.6x10⁶ m³ with an exponent of 1.65. Slope failure volume scales with area as a power law with an exponent of 1.1. Both values are low for studies of bedrock landslides and rockfall and result from the highly fractured and weathered state of the quartzitic bedrock. Our data suggest that the magnitude-frequency distribution is the result of two separate slope failure processes. Type (1) failures are frequent, small slides and slumps within the weathered layer of highly fractured rock and loose sediment, and make up the rollover. Type (2) failures are less frequent and larger rockslides and rockfalls within the internal bedded and fractured slope along pre-determined potential failure surfaces, and make up the power-law tail. Rockslides and rockfalls of high magnitude and relatively low frequency make up 99% of the total failure volume and are thus responsible for the high erosion rate. They are also significant in the context of landscape evolution as they occur on slopes above 45° and limit the relief of the slope. Copyright © 2012 John Wiley & Sons, Ltd.
    Print ISSN: 0197-9337
    Digitale ISSN: 1096-9837
    Thema: Geographie , Geologie und Paläontologie
    Publiziert von Wiley
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  • 6
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    Combined Flow Abstraction and Climate Change Impacts on an Aggrading Alpine River (2017)
    Wiley
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    Publikationsdatum: 2017-12-29
    Beschreibung: Recent climatic warming and associated glacial retreat may have a large impact on sediment release and transfer in Alpine river basins. Concurrently, the sediment transport capacity of many European Alpine streams is affected by hydropower exploitation, notably where flow is abstracted but the sediment supply downstream is maintained. Here, we investigate the combined effects of climate change and flow abstraction on morphodynamics and sediment transfer in the Borgne River, Switzerland. From photogrammetrically derived historical Digital Elevation Models (DEMs) we find considerable net aggradation of the braided river bed (up to 5 meters) since the onset of flow abstraction in 1963. Reaches responded through bed level steepening which was strongest in the upper most reach. Widespread aggradation however did not commence until the onset of glacier retreat in the late 1980s and the dry and warm years of the early 1990s. Upstream flow intake data shows that this aggradation coincided with an increase in sediment supply, although aggradation accounts for no more than 25% of supplied material. The remainder was transferred through the studied reaches. Estimations of bed load transport capacity indicate that flow abstraction reduces transport capacity by 1-2 orders of magnitude. Whilst residual transport rates vary with morphological evolution, they are in the same order of magnitude as the sediment supply rates, which is why significant transport remains. However, the reduction in transport capacity makes the system more sensitive to short-term (annual) changes in climate-driven hydrological variability and climate-induced changes in intake management and sediment delivery rates.
    Print ISSN: 0043-1397
    Digitale ISSN: 1944-7973
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 7
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    Ecomorphodynamics of rivers with converging boundaries (2014)
    Wiley
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    Publikationsdatum: 2014-06-17
    Beschreibung: ABSTRACT Many rivers worldwide show converging sections where a characteristic limiting front for vegetation establishment on gravel bars is observed. An important conceptual model was advanced by Gurnell and Petts (2006), who demonstrated that for the convergent section of the Tagliamento River, the downstream front of vegetation establishment can be explained by unit stream power. We introduce a theoretical framework based on 1-D ecomorphodynamic equations modified to account for the biological dynamics of vegetation. We obtain the first analytical result explaining the position and river width where vegetation density is expected to vanish in relation to a characteristic streamflow magnitude and both hydraulic and biologic parameters. We apply our model to a controlled experiment within a convergent flume channel with growing seedlings perturbed by periodic floods. For a range of timescales where hydrological and biological processes interact, we observe the formation of a front in the convergent section beyond which vegetation cannot survive, the location of which is explained by flow magnitude. This experiment confirms that the timescales of the involved processes and the unit stream power determine the existence and the position of the front within convergent river reaches, respectively. Copyright © 2014 John Wiley & Sons, Ltd.
    Print ISSN: 0197-9337
    Digitale ISSN: 1096-9837
    Thema: Geographie , Geologie und Paläontologie
    Publiziert von Wiley
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  • 8
    Digitale Medien
    Digitale Medien
    Preliminary conclusions of the Royal Society and Academia Sinica 1985 geotraverse of Tibet (1986)
    [s.l.] : Nature Publishing Group
    Nature 323 (1986), S. 501-507 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The 1985 Chinese/British expedition to the Tibetan Plateau attempted to solve the question of the origin of the very thick crustal rocks in this region. Continuing northwards movement of the Indian plate over the past 38 Myr has given rise to severe folding and thrust faulting, causing crustal ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/323501a0
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  • 9
    Digitale Medien
    Digitale Medien
    Plate Tectonics of the Red Sea and East Africa (1970)
    [s.l.] : Nature Publishing Group
    Nature 226 (1970), S. 243-248 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The relative motion between the plates on each side of the East African Rift Valley can be obtained from the opening of the Red Sea and the Gulf of Aden. The calculated direction of relative motion agrees well with fault plane solutions for earthquakes north of the ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/226243a0
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  • 10
    Digitale Medien
    Digitale Medien
    Relatively recent construction of the Tien Shan inferred from GPS measurements of present-day crustal deformation rates (1996)
    [s.l.] : Nature Publishing Group
    Nature 384 (1996), S. 450-453 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The Tien Shan, some 2,500km long and 300-500 km wide, forms a typical intracontinental mountain belt, far from either the locus of collision between continents or a subduction zone (Fig. 1), although it is a consequence of the collision between India and the rest of Eurasia. Within the belt, thrust ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/384450a0
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