WorldWideScience

Sample records for periglacial slope deposits

  1. Periglacial microclimate in low-altitude scree slopes supports relict biodiversity

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Zacharda, M.; Němcová, L.; Šmilauer, P.; Nekola, J. C.

    2012-01-01

    Roč. 46, 35-36 (2012), s. 2145-2157 ISSN 0022-2933 Institutional research plan: CEZ:AV0Z50070508 Keywords : periglacial microclimate * habitat islands * arthropods Subject RIV: EH - Ecology, Behaviour Impact factor: 0.778, year: 2012

  2. Factors influencing periglacial fluvial morphology in the northern European Russian tundra and taiga

    NARCIS (Netherlands)

    Huisink, M.; de Moor, J.J.W.; Kasse, C.; Virtanen, T.

    2002-01-01

    The influence of geology, discharge regime, slope, vegetation type, vegetation density and permafrost conditions on periglacial channel morphology has been investigated in the Usa catchment (northern European Russia). Rivers are dominated by meandering or anabranching plan forms and rarely show

  3. Geochemical prospecting techniques for ore deposits in periglacial regions

    International Nuclear Information System (INIS)

    Pitul'ko, V.M.

    1977-01-01

    Necessity and prospects of the implementation of geochemical methods of search in periglacial regions are discussed. The behaviour of chemical elements under the conditions of oxide and sulphate cryogenic topographies whose development has common regularities is analyzed. According to the specificity of migration the observed elements have been divided into four groups: active, mobile, low-mobile and inert migrants. Uranium which is present in ores in the form of pitchblende in oxide zones of the oxidation is actively redistributed. In zones of the oxidation of rare metal metasomatites connected with alkalic ultrabasic rocks only that part of U is mobile which being released from pyrochlore forms the regenerated uranium black and the partial enrichment of the iron gossan. Th like other elements of the 4-th group in all oxidation zones is observed to accumulate in minerals - concentrators: thorite, pyrochlore and so on. A diagram is plotted which characterizes the migration of elements whithin aureole landscapes as well as in automonous and dependent topographies of ore-free areas. The complex nature of secondary aureoles displays the most complete anomalous spectrum of elements - indicators of mineralization. The table of the most typical elements - indicators of the secondary scattering of some endogenic deposits of the cryolitic zone is given

  4. Seasonal frost conditions in different periglacial landforms in the Eastern Pyrenees from 2003 to 2015

    Science.gov (United States)

    Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Oliva, Marc; Gómez-Ortiz, Antonio

    2016-04-01

    Glaciers shaped the headwaters and valley floors in the Eastern Pyrenees during the Last Glaciation at elevations above 2100-2200 m. Since the deglaciation of these areas, periglacial processes have generated a wide range of periglacial landforms, such as rock glaciers, patterned ground and debris slopes. The role of soil temperatures is decisive for the degree of activity of periglacial processes: cryoturbation, solifluction, frost weathering, etc. Nowadays, periglacial processes in the Eastern Pyrenees are driven by a seasonal frozen layer extending 5-7 months. In general, at 2100 m the seasonal frost reaches 20 cm depth, while at 2700 m reaches 50 cm depth. However, soil temperatures, and thus, periglacial processes are strongly controlled by the large interannual variability of the snow cover. With the purpose of understanding the rhythm and intensity of soil freezing/thawing in 2003 we set up several monitoring sites along a vertical transect from the valley floors (1100 m) to the high plateaus (2700 m) across the southern slope of the Puigpedrós massif (2914 m), in the Eastern Pyrenees. The monitoring of soil temperatures has been conducted from 2003 to 2015 in different periglacial landforms using UTL and Hobo loggers. These loggers were installed at depths of 5, 20 and 50 cm at five sites: Calmquerdós (2730 m), Malniu (2230 m), La Feixa (2150 m), Meranges (1600 m) and Das (1097 m). Air temperatures used as reference come from two automatic stations of the Catalan Meteorological Survey in Malniu and Das, and with two loggers installed in La Feixa and Meranges. No permafrost regime was detected in none of the sites. Data shows evidence of the control of snow cover on the depth of the frozen layer and on the number of freeze-thaw cycles. Air temperatures at 2000-2200 m show a mean of 150 freeze-thaw cycles per year. In La Feixa, with very thin snow cover, only 67 cycles are recorded at 5 cm depth and 5 cycles at 50 cm depth. In Malniu, located at a higher

  5. The impact of periglacial cover beds on runoff generation in a small spring catchment, Ore Mountains

    Science.gov (United States)

    Heller, Katja; Hübner, Rico; Kleber, Arno

    2010-05-01

    The knowledge of hillslope processes is essential to improve pollutant research and flood prediction. Relic periglacial covers are widespread on slopes of the central European low mountain ranges. Cover beds are assumed to be an important control factor for subcutaneous water flow paths. Periglacial cover beds originated by solifluction, kryoturbation and accumulation of loess during Pleistocene times. Differences in bulk density, sediment type, as well as structure and rate of coarse clasts in the layers result in vertical disparity in hydraulic conductivity (anisotropy), leading to interflow. This hypothesis has been testing in an ongoing study in a small spring catchment (6 ha) in the eastern Ore Mountains, south-eastern Germany, since November 2007. The study area is underlain by gneiss and is formed as a slope hollow. The cover beds consist of a 3-layer complex with upper layer, intermediate layer and basal layer. Soil water tension within the layers is measured with 76 recording tensiometers. Electrical resistivity tomography was used to monitor the spatial dispersal of soil moisture. Results of hydrometrical measurements and of electrical resistivity surveys will be described and new findings on slope water dynamics will be presented.

  6. Hidden Ice Worlds - Pleistocene glacigenic deposits in Essex, England. Application of the novel systematic approach to thin-section description.

    Science.gov (United States)

    Leszczynska, Karolina; Boreham, Julie; Boreham, Steve

    2013-04-01

    In the 'Hidden Ice Worlds' research project a novel systematic approach for thin-section description (Leszczynska et al., 2011) is applied to analyse the internal structure of 8 m thick periglacially disturbed sequence from the Royal Oak Pit - a small disused quarry in East Anglia, Essex, east of Chelmsford, near Danbury. Danbury Hill is situated on the south-eastern margin of the Elsterian (Anglian) till sheet. This area was glaciated only once, during the Pleistocene, Elsterian (Anglian) glaciation (480-420 ka BP), however two local ice-sheet margin fluctuations are envisaged (inter alia Turner, 1970 and others). The stratigraphical sequence of the Royal Oak Pit comprises: massive gravel, arranged in sheets, overlain by fine silty-clay and silty-sand with ripple marks and planar cross beds, overlain by a 50 cm thick unit of massive gravel gradually changing into periglacially disturbed silty-clayey-gravel with the bottom 50 cm of fine laminated silty clay. This sequence is situated on the lee side of Danbury Hill, at over 50 m OD. This is an atypical location for the periglacially disturbed deposits of such a substantial thickness (up to 8 m), which usually occur in the lower areas. The deposits at this site were investigated at a macro-scale using field-section logging, ground penetrating radar survey, clast lithology, clay mineralogy analysis and loss-on-ignition and at a micro-scale using thin-section analysis. There are two main aims of the project presented: • To describe the genesis and to discern the main processes associated with the formation of the unusually thick periglacially disturbed unit at the Danbury Hill slope and • To test the novel, tree-based, systematic approach as a guiding tool for thin for thin-section description of Quaternary deposits (Leszczynska et al., 2011). The results of the micromorphological analyses of the deposits from the Royal Oak Pit allow a new hypothesis for the origin of the sequence to be put forward. The main

  7. High mountain soils and periglacial features at the Torres del Paine, National Park Torres del Paine, Chile.

    Science.gov (United States)

    Senra, Eduardo; Schaefer, Carlos; Simas, Felipe; Gjorup, Davi

    2015-04-01

    The Torres del Paine National Park (TPNP) is located on the southern limit of the Andean Southern Ice Field, part of the Magallanes and Antartica Chilena region, in the province of Ultima Esperanza. The TPNP has a very heterogeneous climate due to orographic influence and wet air masses from the Pacific. The geology is basically Cretaceous metasedimentary rocks and Miocene granitic plutons and batholiths. We studied the main soils and geoenvironments of Mt Ferrier mountain and its surroundings, based on soils , landforms and vegetation aspects. The geoenvironmental stratification was based on the combined variation and integration of pedo-litho-geomorphological features with the vegetation. WE used detailed geological maps, a DEM and slope maps and WorlView II satellite images. Fifteen soils profiles were sampled and classified according to Soil Taxonomy (2010) at all genovironments, ranging from 50 m a.s.l to the at high plateau just below the permanent snowline, under periglacial conditions (~1004m asl). Three soil temperature and moisture monitoring sites were set, allowing for 24 consecutive months (2011 to 2013). Seven geoenvironments were identified with distinct soil and landform characteristics, all with a similar geological substrate. The landform and vegetation have a strong connection with the landscape dynamic, controlling erosional and depositional processes, resulting from glacier advances and retreats in the Late Quaternary. Wind blown materials is widespread, in the form of loess material, accumulating in the higher parts of the landscape. On the other hand, accumulation of organic matter in the water-saturated depressions is common in all altitudes. Generally the soils are acidic and dystrophic, with little exceptions. The following geoenvironments were identified: Periglacial Tundra, Loess slopes, Talus and scarpmentd, Fluvio-glacial terraces, Fluvio-lacustrine plains, Moraines and Paleodunes. The regional pedology show the occurrence of five soil

  8. Plant Functional Traits Are More Consistent Than Plant Species on Periglacial Patterned Ground in the Rocky Mountains of Montana

    Science.gov (United States)

    Apple, M. E.; Ricketts, M. K.; Gallagher, J. H. R.

    2017-12-01

    Periglacial patterned ground exists as stripes and hexagons near glaciers and snowfields, some of which are former glaciers. The patterns are accentuated by profound differences in plant cover between the sloping surfaces, generally perceived as green, and the flat treads, generally perceived as brown but which are not devoid of plant life. On four sites in the Rocky Mountains of Montana we detected strong similarities in plant functional traits on the sloping surfaces of striped and hexagonal periglacial patterned ground. On Mt. Keokirk in the Pioneer Mountains, Kinnickinnick, Arctostaphylos uva-ursi, dominates narrow green stripes. On Goat Flat in the Pintler Mountains, Mountain Avens, Dryas octopetala, dominates the side walls of hexagonally patterned ground and narrow green stripes. At Glacier National Park, D. octopetala and the Arctic Willow, Salix arctica, co-dominate the green risers of widely-spaced striped periglacial patterned system at Siyeh Pass, while D. octopetala, S. arctica, and the Mountain Heather, Phyllodoce glanduliflora, co-dominate the green risers of the widely-spaced stripes of Piegan Pass. All four of these dictotyledonous angiosperm species are adventitiously-rooted dwarf shrubs with simple leaves. Of these, P. glanduliflora, A. uva-ursi and D. octopetala are evergreen. D. octopetala is symbiotic with N-fixing Frankia sp. All are mycorrhizal, although D. octopetala and S. arctica are ectomycorrhizal and P. glanduliflora and A. uva-ursi have ericaceous mycorrhizae. In contrast, dwarf shrubs are scarce on flat treads and within hexagons, which are chiefly inhabited by herbaceous, taprooted or rhizomatous, VAM angiosperms. As the green stripes and hexagon walls have greater plant cover, they likely have greater organic material due to leaf buildup and root turnover, anchor themselves and the soil with adventitious roots, their clonality suggests long lives, and N-fixing influences N dynamics of the periglacial patterned ground.

  9. Constraining Depositional Slope From Sedimentary Structures in Sandy Braided Streams

    Science.gov (United States)

    Lynds, R. M.; Mohrig, D.; Heller, P. L.

    2003-12-01

    Determination of paleoslopes in ancient fluvial systems has potentially broad application to quantitatively constraining the history of tectonics and paleoclimate in continental sequences. Our method for calculating paleoslopes for sandy braided streams is based upon a simple physical model that establishes depositional skin-frictional shear stresses from assemblages of sedimentary structures and their associated grain size distributions. The addition of a skin-frictional shear stress, with a geometrically determined form-drag shear stress results in a total boundary shear stress which is directly related to water-surface slope averaged over an appropriate spatial scale. In order to apply this model to ancient fluvial systems, it is necessary to measure the following: coarsest suspended sediment size, finest grain size carried in bed load, flow depth, dune height, and dune length. In the rock record, suspended load and bed load can be accurately assessed by well-preserved suspended load deposits ("low-energy" ripples) and bed load deposits (dune foresets). This model predicts an average slope for the North Loup River near Taylor, Nebraska (modern case study) of 2.7 x 10-3. The measured reach-averaged water surface slope for the same reach of the river is 1.37 x 10-3. We suggest that it is possible to calculate the depositional slope of a sandy fluvial system by a factor of approximately two. Additionally, preliminary application of this model to the Lower Jurassic Kayenta Formation throughout the Colorado Plateau provides a promising and consistent evaluation of paleoslope in an ancient and well-preserved, sandy braided stream deposit.

  10. Modelling the Long-term Periglacial Imprint on Mountain Landscapes

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou

    Studies of periglacial processes usually focus on small-scale, isolated phenomena, leaving less explored questions of how such processes shape vast areas of Earth’s surface. Here we use numerical surface process modelling to better understand how periglacial processes drive large-scale, long-term...

  11. UAV-based detection and spatial analyses of periglacial landforms on Demay Point (King George Island, South Shetland Islands, Antarctica)

    Science.gov (United States)

    Dąbski, Maciej; Zmarz, Anna; Pabjanek, Piotr; Korczak-Abshire, Małgorzata; Karsznia, Izabela; Chwedorzewska, Katarzyna J.

    2017-08-01

    High-resolution aerial images allow detailed analyses of periglacial landforms, which is of particular importance in light of climate change and resulting changes in active layer thickness. The aim of this study is to show possibilities of using UAV-based photography to perform spatial analysis of periglacial landforms on the Demay Point peninsula, King George Island, and hence to supplement previous geomorphological studies of the South Shetland Islands. Photogrammetric flights were performed using a PW-ZOOM fixed-winged unmanned aircraft vehicle. Digital elevation models (DEM) and maps of slope and contour lines were prepared in ESRI ArcGIS 10.3 with the Spatial Analyst extension, and three-dimensional visualizations in ESRI ArcScene 10.3 software. Careful interpretation of orthophoto and DEM, allowed us to vectorize polygons of landforms, such as (i) solifluction landforms (solifluction sheets, tongues, and lobes); (ii) scarps, taluses, and a protalus rampart; (iii) patterned ground (hummocks, sorted circles, stripes, nets and labyrinths, and nonsorted nets and stripes); (iv) coastal landforms (cliffs and beaches); (v) landslides and mud flows; and (vi) stone fields and bedrock outcrops. We conclude that geomorphological studies based on commonly accessible aerial and satellite images can underestimate the spatial extent of periglacial landforms and result in incomplete inventories. The PW-ZOOM UAV is well suited to gather detailed geomorphological data and can be used in spatial analysis of periglacial landforms in the Western Antarctic Peninsula region.

  12. Facies-controlled reservoir properties in ramp-fan and slope-apron deposits, Miocene Puente Formation, Los Angeles basin

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, K.T.; Geving, R.L.; Suchecki, R.K.

    1989-03-01

    The Miocene Puente Formation in outcrops of the eastern Los Angeles basin is interpreted as a succession of slope-apron and ramp-fan deposits that accumulated in a prism-rise wedge. The principal depositional components of this dominantly base-of-slope and ramp system are ramp-fan channels and lobes, and slope-channel and slope-apron channel/interchannel deposits. Facies-specific textural, compositional, and diagenetic attributes observed in thin section assist in the classification of depositional facies. Specifically, occurrence of carbonate cement, clay mineralogy, and abundance of organic material vary as a function of component facies architecture of the depositional system. Slope and ramp-fan channel-fill sandstones are characterized by pervasive carbonate cements, including poikilotopic and fine-grained calcite, fine-grained and baroque dolomite, and minor siderite. Diagenetic clays predate carbonate cements, and dolomite predates coarser, void-filling calcite. Ramp-fan lobe and interchannel deposits are carbonate free but are rich in detrital clay and organic matter. Diagenetic clays include mixed-layer illite/smectite and kaolinite. Sediments deposited in slope-apron channel fill are virtually cement free except for small amounts of authigenic illite/smectite. Slope-apron interchannel deposits are characterized by high content of organic matter and clay-rich matrix. Potential reservoir characteristics, such as grain size, sorting, and abundance of depositional clay matrix, are related to the primary sedimentary properties of depositional architectural components in the ramp-fan and slope-apron system. Additional diagenetic modifications, without consideration of compaction, were controlled by precipitation reactions associated with fluid flow along pathways related to the depositional architectural framework.

  13. Geomorphological processes in Britain in a periglacial age

    International Nuclear Information System (INIS)

    Pitty, A.F.

    1988-12-01

    Significant changes in geomorphological processes can be anticipated over the timescales relevant to the Safety Assessments being formulated by United Kingdom Nirex Ltd. The opening sections of this Report emphasise the intrinsic uncertainties concerning the study and interpretation of periglacial phenomena, both in their present-day setting, and as presumed relict features in the British Isles. A section illustrates how emphases have veered and varied in this area of study. An implication, with particular reference to the British Isles, is that the study of periglacial phenomena is, itself, subject to significant short-term changes. The Report reviews the climate of a periglacial environment, emphasising the difficulties involved in translations from present-day analogue areas, which often have intrinsic differences, when compared with the British Isles. The significance of frost penetration, microclimate and snow cover is explained. (Author)

  14. Morfología periglacial del volcán Llullaillaco (Chile/Argentina

    Directory of Open Access Journals (Sweden)

    Schroder, H.

    2000-12-01

    Full Text Available The periglacial processes in the High Andes and resulting periglacial phenomena are presented here by example of Mt. Llullaillaco, at 24°43’ S and 68°32’W, on the frontier between Argentina and Chile. The landforming processes reflect the recent and present extremely arid climate as well as the different age of the volcanics. The range of periglacial landforms, the vertical distribution and association that are described here, result from the interactions of climate and bedrocks. The upper periglacial limits are the highest of the world. The identified phenomena allow to differentiate between the subandine (below 4,100 m, subandine/andine (4,100-4,300 m, andine (4,300-4,700 m, lower periglacial (4,700-5,800 m, medium periglacial (5,800-6,300 m and upper periglacial (6,300-6,739 m altitudinal zones. Due to the extreme aridity glaciers cannot form today. Their absence therefore is not due to insufficiently low temperatures, but to lack of humidity.

    [de]
    Die periglaziale Oberflachenformung und der sich daraus ergebende periglaziale Formenschatz werden im Bereich der Hochanden am Beispiel des Llullaillaco bei 24°43' s.Br. und 68°32' w.L. nuf der Grenze zwischen Argentinien und Chile vorgestellt. Die Formungsprozesse spiegeln das subrezent und rezent extrem trockene Klima sowie das unterschiedliche Alter der Vulkanite ivider. Aus den neigungsdifferenzierten Wechselbeziehungen mit Klima und Gestein ergeben sich eine Vielzahl von Periglazialformen, deren hohenwiirtige Verteilung und Vergesellschaftung beschrieben werden. Die periglazialen Hohengrenzen sind die hochsten unserer Erde. Entsprechend dem ausgegliederten Formenschatz konnte zwischen subandiner (unter 4100 m, subandiner/andiner (4100-4300 m, andiner (4300-4700 m, unterer periglazialer (4700-5800 m, mittlerer periglazialer (5800-6300 m und obérer periglazialer Stufe (6300-6739 m unterschieden werden. Die extreme Trockenheit filhrt dazu, dass sich rezent keine Gletscher

  15. Introduction to the special issue: permafrost and periglacial research from coasts to mountains

    Science.gov (United States)

    Schrott, Lothar; Humlum, Ole

    2017-09-01

    This special issue of Geomorphology includes eleven papers dealing with permafrost and periglacial research from coasts to mountains. The compilation represents a selection from 47 presentations (oral and posters) given at the 4th European Conference on Permafrost - IPA Regional Conference (EUCOP4, June 2014) in the session ;Periglacial Geomorphology;. Geomorphology as a leading journal for our discipline is particularly suitable to publish advances in permafrost and periglacial research with a focus on geomorphic processes. Since 1989 Geomorphology has published 121 special issues and two special issues are explicitly dedicated to permafrost and periglacial research, however, only with a focus on research in Antarctica. In this special issue we present papers from the Canadian Beaufort Sea, Alaska, Spitzbergen, central western Poland, the European Alps, the eastern Sudetes, the southern Carpathians, Nepal, and Antarctica.

  16. Habitable periglacial landscapes in martian mid-latitudes

    Science.gov (United States)

    Ulrich, M.; Wagner, D.; Hauber, E.; de Vera, J.-P.; Schirrmeister, L.

    2012-05-01

    Subsurface permafrost environments on Mars are considered to be zones where extant life could have survived. For the identification of possible habitats it is important to understand periglacial landscape evolution and related subsurface and environmental conditions. Many landforms that are interpreted to be related to ground ice are located in the martian mid-latitudinal belts. This paper summarizes the insights gained from studies of terrestrial analogs to permafrost landforms on Mars. The potential habitability of martian mid-latitude periglacial landscapes is exemplarily deduced for one such landscape, that of Utopia Planitia, by a review and discussion of environmental conditions influencing periglacial landscape evolution. Based on recent calculations of the astronomical forcing of climate changes, specific climate periods are identified within the last 10 Ma when thaw processes and liquid water were probably important for the development of permafrost geomorphology. No periods could be identified within the last 4 Ma which met the suggested threshold criteria for liquid water and habitable conditions. Implications of past and present environmental conditions such as temperature variations, ground-ice conditions, and liquid water activity are discussed with respect to the potential survival of highly-specialized microorganisms known from terrestrial permafrost. We conclude that possible habitable subsurface niches might have been developed in close relation to specific permafrost landform morphology on Mars. These would have probably been dominated by lithoautotrophic microorganisms (i.e. methanogenic archaea).

  17. Volcanic terrain and the possible periglacial formation of "excess ice" at the mid-latitudes of Utopia Planitia, Mars

    Science.gov (United States)

    Soare, R. J.; Horgan, B.; Conway, S. J.; Souness, C.; El-Maarry, M. R.

    2015-08-01

    At the mid-latitudes of Utopia Planitia (UP), Mars, a suite of spatially-associated landforms exhibit geomorphological traits that, on Earth, would be consistent with periglacial processes and the possible freeze-thaw cycling of water. The suite comprises small-sized polygonally-patterned ground, polygon-junction and -margin pits, and scalloped, rimless depressions. Typically, the landforms incise a dark-toned terrain that is thought to be ice-rich. Here, we investigate the dark-toned terrain by using high resolution images from the HiRISE as well as near-infrared spectral-data from the OMEGA and CRISM. The terrain displays erosional characteristics consistent with a sedimentary nature and near-infrared spectra characterised by a blue slope similar to that of weathered basaltic-tephra. We also describe volcanic terrain that is dark-toned and periglacially-modified in the Kamchatka mountain-range of eastern Russia. The terrain is characterised by weathered tephra inter-bedded with snow, ice-wedge polygons and near-surface excess ice. The excess ice forms in the pore space of the tephra as the result of snow-melt infiltration and, subsequently, in-situ freezing. Based on this possible analogue, we construct a three-stage mechanism that explains the possible ice-enrichment of a broad expanse of dark-toned terrain at the mid-latitudes of UP: (1) the dark-toned terrain accumulates and forms via the regional deposition of sediments sourced from explosive volcanism; (2) the volcanic sediments are blanketed by atmospherically-precipitated (H2O) snow, ice or an admixture of the two, either concurrent with the volcanic-events or between discrete events; and, (3) under the influence of high obliquity or explosive volcanism, boundary conditions tolerant of thaw evolve and this, in turn, permits the migration, cycling and eventual formation of excess ice in the volcanic sediments. Over time, and through episodic iterations of this scenario, excess ice forms to decametres of

  18. Hydraulic experimental investigation on spatial distribution and formation process of tsunami deposit on a slope

    Science.gov (United States)

    Harada, K.; Takahashi, T.; Yamamoto, A.; Sakuraba, M.; Nojima, K.

    2017-12-01

    An important aim of the study of tsunami deposits is to estimate the characteristics of past tsunamis from the tsunami deposits found locally. Based on the tsunami characteristics estimated from tsunami deposit, it is possible to examine tsunami risk assessment in coastal areas. It is considered that tsunami deposits are formed based on the dynamic correlation between tsunami's hydraulic values, sediment particle size, topography, etc. However, it is currently not enough to evaluate the characteristics of tsunamis from tsunami deposits. This is considered to be one of the reasons that the understanding of the formation process of tsunami deposits is not sufficiently understood. In this study, we analyze the measurement results of hydraulic experiment (Yamamoto et al., 2016) and focus on the formation process and distribution of tsunami deposits. Hydraulic experiment was conducted with two-dimensional water channel with a slope. Tsunami was inputted as a bore wave flow. The moving floor section was installed as a seabed slope connecting to shoreline and grain size distribution was set some cases. The water level was measured using ultrasonic displacement gauges, and the flow velocity was measured using propeller current meters and an electromagnetic current meter. The water level and flow velocity was measured at some points. The distribution of tsunami deposit was measured from shoreline to run-up limit on the slope. Yamamoto et al. (2016) reported the measurement results on the distribution of tsunami deposit with wave height and sand grain size. Therefore, in this study, hydraulic analysis of tsunami sediment formation process was examined based on the measurement data. Time series fluctuation of hydraulic parameters such as Froude number, Shields number, Rouse number etc. was calculated to understand on the formation process of tsunami deposit. In the front part of the tsunami, the flow velocity take strong flow from shoreline to around the middle of slope. From

  19. Periglacial processes incorporated into a long-term landscape evolution model

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, D.L.; Knudsen, Mads Faurschou

    Little is known about the long-term influence of periglacial processes on landscape evolution in cold areas, even though the efficiency of frost cracking on the breakdown of rocks has been documented by observations and experiments. Cold-room laboratory experiments show that a continuous water...... supply and sustained sub- zero temperatures are essential to develop fractures in porous rocks (e.g. Murton, 2006), but the cracking efficiency for harder rock types under natural conditions is less clear. However, based on experimental results for porous rocks, Hales and Roering (2007) proposed a model...... by their model and the elevation of scree deposits in the Southern Alps, New Zealand. This result suggests a link between frost-cracking efficiency and long-term landscape evolution and thus merits further investigations. Anderson et al. (2012) expanded this early model by including the effects of latent heat...

  20. A nomogram for interpreting slope stability of fine-grained deposits in modern and ancient-marine environments.

    Science.gov (United States)

    Booth, J.S.; Sangrey, D.A.; Fugate, J.K.

    1985-01-01

    This nomogram was designed to aid in interpreting the causes of mass movement in modern and ancient settings, to provide a basis for evaluating and predicting slope stability under given conditions and to further the understanding of the relationships among the several key factors that control slope stability. Design of the nomogram is based on effective stress and combines consolidation theory as applicable to depositional environments with the infinite-slope model of slope-stability analysis. If infinite-slope conditions are assumed to exist, the effective overburden stress can be used to derive a factor of safety against static slope failure by using the angle of internal friction and the slope angle. -from Authors

  1. A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins

    Science.gov (United States)

    Goodfellow, Bradley W.

    2012-12-01

    A review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation. If present, this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated. These blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm, Neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the Quaternary. Based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields, other regoliths in periglacial settings, and regoliths from non-periglacial settings, a fingerprint of chemical weathering in periglacial landscapes was identified. A mobile regolith origin under, at least seasonal, periglacial conditions is indicated where clay(%) ≤ 0.5*silt(%) + 8 across a sample batch. This contrasts with a mobile regolith origin under non-periglacial conditions, which is indicated where clay(%) ≥ 0.5*silt(%) - 6 across a sample batch with clay(%) ≥ 0.5*silt(%) + 8 in at least one sample. A range of secondary minerals, which frequently includes interstratified minerals and indicates high local variability in leaching conditions, is also commonly present in regoliths exposed to periglacial conditions during their formation. Clay/silt ratios display a threshold response to temperature, related to the freezing point of water, but there is little response to precipitation or regolith residence time. Lithology controls clay and silt abundances, which increase from felsic, through intermediate, to mafic compositions, but does not control clay/silt ratios. Use of a sedigraph or Coulter Counter to determine regolith granulometry systematically indicates lower clay abundances and intra-site variability than use of a pipette or hydrometer. In contrast to clay/silt ratios, secondary

  2. Depositional turbidity currents in diapiric minibasins on the continental slope: Formulation and theory

    OpenAIRE

    Toniolo, Horacio; Lamb, Michael; Parker, Gary

    2006-01-01

    The northern continental slope of the Gulf of Mexico is riddled with numerous subsiding diapiric minibasins bounded by ridges, many but not all of which are connected by channels created by turbidity currents. The region is economically relevant in that many of these diapiric minibasins constitute focal points for the deposition of sand. Some of these sandy deposits in turn serve as excellent reservoirs for hydrocarbons. A better understanding of the "fill and spill" process by which minibasi...

  3. Study of southern CHAONAN sag lower continental slope basin deposition character in Northern South China Sea

    Science.gov (United States)

    Tang, Y.

    2009-12-01

    Northern South China Sea Margin locates in Eurasian plate,Indian-Australia plate,Pacific Plates.The South China Sea had underwent a complicated tectonic evolution in Cenozoic.During rifting,the continental shelf and slope forms a series of Cenozoic sedimentary basins,including Qiongdongnan basin,Pearl River Mouth basin,Taixinan basin.These basins fill in thick Cenozoic fluviolacustrine facies,transitional facies,marine facies,abyssal facies sediment,recording the evolution history of South China Sea Margin rifting and ocean basin extending.The studies of tectonics and deposition of depression in the Southern Chaonan Sag of lower continental slope in the Norther South China Sea were dealt with,based on the sequence stratigraphy and depositional facies interpretation of seismic profiles acquired by cruises of“China and Germany Joint Study on Marine Geosciences in the South China Sea”and“The formation,evolution and key issues of important resources in China marginal sea",and combining with ODP 1148 cole and LW33-1-1 well.The free-air gravity anomaly of the break up of the continental and ocean appears comparatively low negative anomaly traps which extended in EW,it is the reflection of passive margin gravitational effect.Bouguer gravity anomaly is comparatively low which is gradient zone extended NE-SW.Magnetic anomaly lies in Magnetic Quiet Zone at the Northern Continental Margin of the South China Sea.The Cenozoic sediments of lower continental slope in Southern Chaonan Sag can be divided into five stratum interface:SB5.5,SB10.5,SB16.5,SB23.8 and Hg,their ages are of Pliocene-Quaternary,late Miocene,middle Miocene,early Miocene,paleogene.The tectonic evolution of low continental slope depressions can be divided into rifting,rifting-depression transitional and depression stages,while their depositional environments change from river to shallow marine and abyssa1,which results in different topography in different stages.The topographic evolvement in the study

  4. The periglacial engine of mountain erosion – Part 1: Rates of frost cracking and frost creep

    Directory of Open Access Journals (Sweden)

    J. L. Andersen

    2015-10-01

    Full Text Available With accelerating climate cooling in the late Cenozoic, glacial and periglacial erosion became more widespread on the surface of the Earth. The resultant shift in erosion patterns significantly changed the large-scale morphology of many mountain ranges worldwide. Whereas the glacial fingerprint is easily distinguished by its characteristic fjords and U-shaped valleys, the periglacial fingerprint is more subtle but potentially prevails in some mid- to high-latitude landscapes. Previous models have advocated a frost-driven control on debris production at steep headwalls and glacial valley sides. Here we investigate the important role that periglacial processes also play in less steep parts of mountain landscapes. Understanding the influences of frost-driven processes in low-relief areas requires a focus on the consequences of an accreting soil mantle, which characterises such surfaces. We present a new model that quantifies two key physical processes: frost cracking and frost creep, as a function of both temperature and sediment thickness. Our results yield new insights into how climate and sediment transport properties combine to scale the intensity of periglacial processes. The thickness of the soil mantle strongly modulates the relation between climate and the intensity of mechanical weathering and sediment flux. Our results also point to an offset between the conditions that promote frost cracking and those that promote frost creep, indicating that a stable climate can provide optimal conditions for only one of those processes at a time. Finally, quantifying these relations also opens up the possibility of including periglacial processes in large-scale, long-term landscape evolution models, as demonstrated in a companion paper.

  5. Geomorphic features as indicators of climatic fluctuations in a periglacial environment, northern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Nyberg, R; Lindh, L [Lund Univ. (SE). Dept. of Physical Geography

    1990-01-01

    Goemorphic responses to climatic fluctuations in the periglacial mountain environment of northern Sweden, especially the Abisko mountains, are discussed. Although the frequency and magnitude of rapid mass movements are related to climatic conditions, the depositional patterns of the processes and the variable availability of source material complicate their use as climatic indicators. Possibly, debris flows and slushflows were frequent during the Little Ice Age, according to lichenometric dating of old deposits. Field observations suggest a fairly high frequency also during the last few decades. Boulder pavements, moraine-like ridges and glacial striae in front of major snowfields indicate these were previously larger and in some cases active as small glaciers perhaps in the cold beginning of the 1900's. During the warm 1920-30's snowpatches and glaciers, as well as permafrost mounds were affected by a general degeneration. Climatic inferences made from the mentioned features are still very crude. Tentatively, it is suggested that they are presently beginning to respond to the cooling trend affecting northern Scandinavia since about 1940. The anticipated impact of a greenhouse warming of the atmosphere has thus so far not been noticeable in this high latitude area. (authors).

  6. Grèzes litées and their genesis: the site of Enscherange in the Rhenish-Ardennes Massif as a case study

    Directory of Open Access Journals (Sweden)

    Nyssen, Jan

    2016-03-01

    Full Text Available The freeze-thaw cycles in periglacial areas during the Quaternary glacials increased frost weathering, leading to a disintegration of rock formations. Transported downslope, clasts allowed in some areas the formation of stratified slope deposits known as “grèzes litées”. This study reviews the existing theories and investigates the grèzes litées deposits of Enscherange and Rodershausen in Luxembourg. This process was reinforced by the lithostructural control of the parent material expressed by the dip of schistosity (66° and its orientation parallel to the main slopes in the area. This gave opportunities to activate the frost-weathering process on top of the ridge where the parent material outcropped. As the stratified slope deposits have a dip of 23° and as there is no significant lateral variation in rock fragment size, slope processes that involve only gravity are excluded and transportation in solifluction lobes with significant slopewash and sorting processes is hypothesized. The Enscherange formation, the biggest known outcrop of grèzes litées in north-western Europe, shows evidence of clear layering over the whole profile depth. A palaeolandscape reconstruction shows that ridges must have been tens of metres higher than presently. The investigation of the matrix composition shows Laacher See tephra in the overlying periglacial cover bed with infiltrations of the minerals in the reworked upper layer of the grèzes litées deposit. Chronostratigraphic approaches using the underlying cryoturbation zone and Laacher See heavy minerals in the overlying topsoil place the formation of grèzes litées deposits in the Late Pleistocene.

  7. Large-scale Mass Transport Deposits in the Valencia Basin (Western Mediterranean): slope instability induced by rapid sea-level drawdown?

    Science.gov (United States)

    Cameselle, Alejandra L.; Urgeles, Roger; Llopart, Jaume

    2014-05-01

    The Messinian Salinity Crisis (MSC) strongly affected the physiography of the Mediterranean margins at the end of the Miocene. The sharp sea-level fall gave a new configuration to the Mediterranean basin and created dramatic morphological and sedimentological changes: margins have been largely eroded whereas the deep basins accumulated thick evaporitic and detrital units. Amongst these detrital units, there are evidences on seismic reflection data for major large-scale slope failure of the Mediterranean continental margins. About 2700 km of seismic reflection profiles in the southwestern part of the Valencia Basin (Western Mediterranean) have enabled us the detailed mapping of distinctive Messinian erosional surfaces, evaporites and deep detrital deposits. The detrital deposits occur in a distinct unit that is made of chaotic, roughly-bedded or transparent seismic bodies, which have been mainly mapped in the basin domain. Locally, the seismic unit shows discontinuous high-amplitude reflections and/or an imbricate internal structure. This unit is interpreted to be formed by a series of Mass Transport Deposits (MTDs). Rapid drawdown has long been recognized as one of the most severe loadings conditions that a slope can be subjected to. Several large historical slope failures have been documented to occur due to rapid drawdown in dams, riverbanks and slopes. During drawdown, the stabilizing effect of the water on the upstream face is lost, but the pore-water pressures within the slope may remain high. The dissipation of these pore pressures in the slope is controlled by the permeability and the storage characteristics of the slope sediments. We hypothesize that the MTDs observed in our data formed under similar conditions and represent a large-scale equivalent of this phenomenon. Therefore, these MTDs can be used to put some constraints on the duration of the drawdown phase of the MSC. We have performed a series of slope stability analysis under rapid Messinian sea

  8. Possible pingos and a periglacial landscape in northwest Utopia Planitia

    Science.gov (United States)

    Soare, R.J.; Burr, D.M.; Wan, Bun Tseung J.-M.

    2005-01-01

    Hydrostatic (closed-system) pingos are small, elongate to circular, ice-cored mounds that are perennial features of some periglacial landscapes. The growth and development of hydrostatic pingos is contingent upon the presence of surface water, freezing processes and of deep, continuous, ice-cemented permafrost. Other cold-climate landforms such as small-sized, polygonal patterned ground also may occur in the areas where pingos are found. On Mars, landscapes comprising small, elongate to circular mounds and other possible periglacial features have been identified in various areas, including Utopia Planitia, where water is thought to have played an important role in landscape evolution. Despite the importance of the martian mounds as possible markers of water, most accounts of them in the planetary science literature have been brief and/or based upon Viking imagery. We use a high-resolution Mars Orbiter Camera image (EO300299) and superposed Mars Orbiter Laser Altimeter data tracks to describe and characterise a crater-floor landscape in northwest Utopia Planitia (64.8?? N/292.7?? W). The landscape comprises an assemblage of landforms that is consistent with the past presence of water and of periglacial processes. This geomorphological assemblage may have formed as recently as the last episode of high obliquity. A similar assemblage of landforms is found in the Tuktoyaktuk peninsula of northern Canada and other terrestrial cold-climate landscapes. We point to the similarity of the two assemblages and suggest that the small, roughly circular mounds on the floor of the impact crater in northwest Utopia Planitia are hydrostatic pingos. Like the hydrostatic pingos of the Tuktoyaktuk peninsula, the origin of the crater-floor mounds could be tied to the loss of ponded, local water, permafrost aggradation and the evolution of a sub-surface ice core. ?? 2004 Elsevier Inc. All rights reserved.

  9. Cryogenic Cave Pearls In the Periglacial Zones of Ice Caves

    Czech Academy of Sciences Publication Activity Database

    Žák, Karel; Orvošová, M.; Filippi, Michal; Vlček, M.; Onac, B. P.; Persoiu, A.; Rohovec, Jan; Světlík, Ivo

    2013-01-01

    Roč. 83, č. 2 (2013), s. 207-220 ISSN 1527-1404 R&D Projects: GA ČR GAP210/10/1760 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 ; RVO:61389005 Keywords : caves * cryogenic caves * ice caves * periglacial zones Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.943, year: 2013

  10. 3D modeling of surface quarries and deposits of mined materials and the monitoring of slopes

    Directory of Open Access Journals (Sweden)

    Ivan Maňas

    2007-06-01

    Full Text Available The application of computer technology by simulating opencast mining and deposits of raw materials. The mathematic principles of three-dimensional probabilistic models of raw materials deposits and a familiarization with the user interface software GEOLOGICKY MODEL. The principles of the simulation of opencast mines, generation intersections with models of raw materials deposits, computation of mining materials with the quality scaling,and the design of advanced mining with the software BANSKY MODEL.The monitoring the potential of dynamic movements’ of unstable slopes with the automatic total station and a following interpretation in general time intervals by means of the software MONITORING.

  11. Fundamental changes of granular flows dynamics, deposition and erosion processes at high slope angles: insights from laboratory experiments.

    Science.gov (United States)

    Farin, Maxime; Mangeney, Anne; Roche, Olivier

    2014-05-01

    Geophysical granular flows commonly interact with their substrate in various ways depending on the mechanical properties of the underlying material. Granular substrates, resulting from deposition of earlier flows or various geological events, are often eroded by avalanches [see Hungr and Evans, 2004 for review]. The entrainment of underlying debris by the flow is suspected to affect flow dynamics because qualitative and quantitative field observations suggest that it can increase the flow velocity and deposit extent, depending on the geological setting and flow type [Sovilla et al., 2006; Iverson et al., 2011]. Direct measurement of material entrainment in nature, however, is very difficult. We conducted laboratory experiments on granular column collapse over an inclined channel with and without an erodible bed of granular material. The controlling parameters were the channel slope angle, the granular column volume and its aspect ratio (i.e. height over length), the inclination of the column with respect to the channel base, the channel width, and the thickness and compaction of the erodible bed. For slope angles below a critical value θc, between 10° and 16°, the runout distance rf is proportional to the initial column height h0 and is unaffected by the presence of an erodible bed. On steeper slopes, the flow dynamics change fundamentally since a last phase of slow propagation develops at the end of the flow front deceleration, and prolongates significantly the flow duration. This phase has similar characteristics that steady, uniform flows. The slow propagation phase lasts longer for increasing slope angle, column volume, column inclination with respect to the slope, and channel width, and for decreasing column aspect ratio. It is however independent of the maximum front velocity and, on an erodible bed, of the maximum depth of excavation within the bed. Both on rigid and erodible beds, the increase of the slow propagation phase duration has a crucial effect

  12. Slope and basinal deposits adjacent to isolated carbonate platforms in the Indian Ocean: Sedimentology, geomorphology, and a new 1.2 Ma record of highstand shedding

    Science.gov (United States)

    Counts, J. W.; Jorry, S.; Jouet, G.

    2017-12-01

    Newly analyzed bathymetric, seismic, and core data from carbonate-topped seamounts in the Mozambique Channel reveals a variety of depositional processes and products operating on platform slopes and adjacent basins. Mass transport complexes (including turbidites and debrites), leveed channel systems with basin-floor fans, and contourites are imaged in high resolution in both seafloor maps and cross-section, and show both differences and similarities compared with platform slopes in the Bahamas and elsewhere. In some, though not all, platforms, increased sedimentation can be observed on the leeward margins, and slope rugosity may be asymmetric with respect to prevailing wind direction. Deposition is also controlled by glacial-interglacial cycles; cores taken from the lower slopes (3000+ m water depth) of carbonate platforms reveal a causative relationship between sea level and aragonite export to the deep ocean. δ18O isotopes from planktonic and benthic foraminifera of two 27-meter cores, reveal a high-resolution, continuous depositional record of carbonate sediment dating back to 1.2 Ma. Sea level rise, as determined by correlation with the LR04 benthic stack, is coincident with increased aragonite flux from platform tops. Gravity flow deposits are also affected by platform flooding—the frequency of turbidite/debrite deposits on pinnacle slopes increases during highstand, although such deposits are also present during glacial episodes. The results reported here are the first record of highstand shedding in the southern Indian Ocean, and provide the longest Quaternary sediment record to date in the region, including the Mid-Brunhes transition (MIS 11) that serves as an analog for the current climate conditions. In addition, this is the first study to describe sedimentation on the slopes of these platforms, providing an important point of comparison that has the potential to influence source-to-sink carbonate facies models.

  13. Fundamental change of granular flows dynamics, deposition and erosion processes at sufficiently high slope angles: insights from laboratory experiments

    Science.gov (United States)

    Farin, M.; Mangeney, A.; Roche, O.

    2013-12-01

    Geophysical granular flows commonly interact with their substrate in various ways depending on the mechanical properties of the underlying material. Granular substrates, resulting from deposition of earlier flows or various geological events, are often eroded by avalanches [see Hungr and Evans, 2004 for review]. The entrainment of underlying debris by the flow is suspected to affect flow dynamics because qualitative and quantitative field observations suggest that it can increase the flow velocity and deposit extent, depending on the geological setting and flow type [Sovilla et al., 2006; Iverson et al., 2011]. Direct measurement of material entrainment in nature, however, is very difficult. We conducted laboratory experiments on granular column collapse over an inclined channel with and without an erodible bed of granular material. The controlling parameters were the channel slope angle, the granular column volume and its aspect ratio (i.e. height over length), the inclination of the column with respect to the channel base, the channel width, and the thickness and compaction of the erodible bed. For slope angles below a critical value θc, between 10° and 16°, the runout distance rf is proportional to the initial column height h0 and is unaffected by the presence of an erodible bed. On slopes greater than θc, the flow dynamics change fundamentally since a last phase of slow propagation develops at the end of the flow front deceleration, and prolongates significantly the flow duration. This phase has similar characteristics that steady, uniform flows. The slow propagation phase lasts longer for increasing column volume, column inclination with respect to the slope, and channel width, and for decreasing column aspect ratio. It is however independent of the maximum front velocity and, on an erodible bed, of the maximum depth of excavation within the bed. Both on rigid and erodible beds, the increase of the slow propagation phase duration has a crucial effect on

  14. A 5000km2 data set along western Great Bahama Bank illustrates the dynamics of carbonate slope deposition

    Science.gov (United States)

    Schnyder, Jara S. D.; Jo, Andrew; Eberli, Gregor P.; Betzler, Christian; Lindhorst, Sebastian; Schiebel, Linda; Hebbeln, Dierk; Wintersteller, Paul; Mulder, Thierry; Principaud, Melanie

    2014-05-01

    An approximately 5000km2 hydroacoustic and seismic data set provides the high-resolution bathymetry map of along the western slope of Great Bahama Bank, the world's largest isolated carbonate platform. This large data set in combination with core and sediment samples, provides and unprecedented insight into the variability of carbonate slope morphology and the processes affecting the platform margin and the slope. This complete dataset documents how the interplay of platform derived sedimentation, distribution by ocean currents, and local slope and margin failure produce a slope-parallel facies distribution that is not governed by downslope gradients. Platform-derived sediments produce a basinward thinning sediment wedge that is modified by currents that change directions and strength depending on water depth and location. As a result, winnowing and deposition change with water depth and distance from the margin. Morphological features like the plunge pool and migrating antidunes are the result of currents flowing from the banktop, while the ocean currents produce contourites and drifts. These continuous processes are punctuated by submarine slope failures of various sizes. The largest of these slope failures produce several hundred of km2 of mass transport complexes and could generate tsunamis. Closer to the Cuban fold and thrust belt, large margin collapses pose an equal threat for tsunami generation. However, the debris from margin and slope failure is the foundation for a teeming community of cold-water corals.

  15. Slope-apron deposition in an ordovician arc-related setting: The Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina

    Science.gov (United States)

    Mangano, M.G.; Buatois, L.A.

    1997-01-01

    The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform. The coincidence of a thick Arenig-Llanvirn sedimentary succession and volcanic-plutonic arc rocks suggests an extensional or transtensional arc setting, and is consistent with evidence of an extensional regime within the volcanic arc in the northern Puna region. The studied stratigraphic sections consist of volcanic rocks and six sedimentary facies. The facies can be clustered into four facies associations. Association 1, composed of facies A (laminated siltstones and mudstones) and B (massive mudstones and siltstones), is interpreted to have accumulated from silty-muddy high-and low-density turbidity currents and highly fluid, silty debris flows, with subsequent reworking by bottom currents, and to a lesser extent, hemipelagic suspension in an open-slope setting. Facies association 2 is dominated by facies C (current-rippled siltstones) strata. These deposits are interpreted to record overbank sedimentation from fine-grained turbidity currents. Facies E (matrix-supported volcanic breccias) interbedded with andesitic lava units comprises facies association 3. Deposition was contemporaneous with subaqueous volcanic activity, and accumulated from cohesive debris flows in a coarse-grained wedge at the base of slope. Facies association 4 is typified by facies D (vitric fine-grained sandstones and siltstones) and F (channelized and graded volcanic conglomerates and breccias) deposits. These strata commonly display thinning-and fining-upward trends, indicating sedimentation from highly-concentrated volcaniclastic turbidity currents in a channelized system. The general characteristics of these deposits of fresh

  16. Possible slow periglacial mass wasting at the Southern Hemisphere on Mars.

    Science.gov (United States)

    Johnsson, Andreas; Reiss, Dennis; Hauber, Ernst; Hiesinger, Harald

    2014-05-01

    Small-scale lobate landforms which are strikingly similar to terrestrial solifluction lobes are cataloged at the Southern Hemisphere on Mars. Terrestrial periglacial solifluction lobes are formed by frost creep, a combination of repeated frost heave and thaw consolidation, and gelifluction (visco-plastic deformation of near saturated soil) in the active layer on top of the permafrost table (e.g., Matsuoka, 2001). All publically available HiRISE images between latitudes 40°S and 80°S on Mars are being used in this study. Compared to previous studies of small-scale lobes in the northern mid and high latitudes (e.g., Gallagher et al., 2011; Johnsson et al., 2012; Barrett et al., 2013), these landforms also occur, in most cases, in close spatial proximity to fluvial gullies and polygonal terrain. This study aims to investigate whether the southern small-scale lobes differ from the northern counterparts in terms of morphology and distribution. Furthermore, spatio-temporal relationships to landforms with ground-ice affinity, such as gullies and polygonal terrain, are investigated. Solifluction-like small-scale lobes have been studied in detail at the northern hemisphere on Mars (Gallagher et al., 2011), where they are widely distributed at high latitudes between 59°N and 80°N (Johnsson et al., 2012). Small-scale lobes are proposed to represent freeze-thaw activity late in Martian climate history (Gallagher et al., 2011; Balme and Gallagher, 2011; Johnsson et al, 2012; Balme et al., 2013). Small-scale lobes differ from permafrost creep (i.e. rock glaciers) in having low fronts, decimeters to less than impact crater slopes fewer lobes have been observed so far in this study. The project is on-going and more work is required to firmly establish their distribution and their association to gullies and polygonal terrain. Though landforms indicative of freeze-thaw activity may be rare on flat terrain on Mars, there is growing evidence that freeze-thaw conditions may have

  17. Mars: Periglacial Morphology and Implications for Future Landing Sites

    Science.gov (United States)

    Heldmann, Jennifer L.; Schurmeier, Lauren; McKay, Christopher; Davila, Alfonso; Stoker, Carol; Marinova, Margarita; Wilhelm, Mary Beth

    2015-01-01

    At the Mars Phoenix landing site and in much of the Martian northern plains, there is ice-cemented ground beneath a layer of dry permafrost. Unlike most permafrost on Earth, though, this ice is not liquid at any time of year. However, in past epochs at higher obliquity the surface conditions during summer may have resulted in warmer conditions and possible melting. This situation indicates that the ice-cemented ground in the north polar plains is likely to be a candidate for the most recently habitable place on Mars as near-surface ice likely provided adequate water activity approximately 5 Myr ago. The high elevation Dry Valleys of Antarctica provide the best analog on Earth of Martian ground ice. These locations are the only places on Earth where ice-cemented ground is found beneath dry permafrost. The Dry Valleys are a hyper-arid polar desert environment and in locations above 1500 m elevation, such as University Valley, air temperatures do not exceed 0 C. Thus, similarly to Mars, liquid water is largely absent here and instead the hydrologic cycle is dominated by frozen ice and vapor phase processes such as sublimation. These conditions make the high elevation Dry Valleys a key Mars analog location where periglacial processes and geomorphic features can be studied in situ. This talk will focus on studies of University Valley as a Mars analog for periglacial morphology and ice stability. We will review a landing site selection study encompassing this information gleaned from the Antarctic terrestrial analog studies plus Mars spacecraft data analysis to identify candidate landing sites for a future mission to search for life on Mars.

  18. Electrical imaging and self-potential surveys to study the geological setting of the quaternary slope deposits in the Agri high valley (Southern Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Giano, S I; Schiattarella, M [Basilicata Univ., Potenza (Italy). Centro di Geodinamica; Lapenna, V; Piscitelli, S [Consiglio Nazionale delle Ricerche, Tito, PZ (Italy). Ist. di Metodologie Avanzate di Analisi Ambientale

    2000-04-01

    The paper presents the results of a geophysical survey carried out to outline the structural modelling of quarternary slope deposits in the northern part of Agri high valley (Basilicata region, Italy). Quaternary folding and brittle deformations of the subaerial slope deposits have been studied combining electrical imaging and self-potential surveys with geological structural analysis. This integrated approach indicates that the area underwent both transpressional and transtensional tectonics during Pleistocene times as testified by the existence of a push up structure in the basement buried by deformed Quaternary breccias. On this basis, the valley appears to be a more complex structure than a simple extensional graben, as traditionally assumed in the literature.

  19. Surface morphology of fans in the high-Arctic periglacial environment of Svalbard : Controls and processes

    NARCIS (Netherlands)

    De Haas, Tjalling|info:eu-repo/dai/nl/374023190; Kleinhans, Maarten G.|info:eu-repo/dai/nl/217675123; Carbonneau, Patrice E.; Rubensdotter, Lena; Hauber, Ernst

    2015-01-01

    Fan-shaped landforms occur in all climatic regions on Earth. They have been extensively studied in many of these regions, but there are few studies on fans in periglacial, Arctic and Antarctic regions. Fans in such regions are exposed to many site-specific environmental conditions in addition to

  20. Evaluation of Wax Deposition and Its Control During Production of Alaska North Slope Oils

    Energy Technology Data Exchange (ETDEWEB)

    Tao Zhu; Jack A. Walker; J. Liang

    2008-12-31

    Due to increasing oil demand, oil companies are moving into arctic environments and deep-water areas for oil production. In these regions of lower temperatures, wax deposits begin to form when the temperature in the wellbore falls below wax appearance temperature (WAT). This condition leads to reduced production rates and larger pressure drops. Wax problems in production wells are very costly due to production down time for removal of wax. Therefore, it is necessary to develop a solution to wax deposition. In order to develop a solution to wax deposition, it is essential to characterize the crude oil and study phase behavior properties. The main objective of this project was to characterize Alaskan North Slope crude oil and study the phase behavior, which was further used to develop a dynamic wax deposition model. This report summarizes the results of the various experimental studies. The subtasks completed during this study include measurement of density, molecular weight, viscosity, pour point, wax appearance temperature, wax content, rate of wax deposition using cold finger, compositional characterization of crude oil and wax obtained from wax content, gas-oil ratio, and phase behavior experiments including constant composition expansion and differential liberation. Also, included in this report is the development of a thermodynamic model to predict wax precipitation. From the experimental study of wax appearance temperature, it was found that wax can start to precipitate at temperatures as high as 40.6 C. The WAT obtained from cross-polar microscopy and viscometry was compared, and it was discovered that WAT from viscometry is overestimated. From the pour point experiment it was found that crude oil can cease to flow at a temperature of 12 C. From the experimental results of wax content, it is evident that the wax content in Alaskan North Slope crude oil can be as high as 28.57%. The highest gas-oil ratio for a live oil sample was observed to be 619.26 SCF

  1. Sandy aeolian deposits and environments and their relation to climate during the Last Glacial Maximum and Lateglacial in northwest and central Europe

    NARCIS (Netherlands)

    Kasse, C.

    2002-01-01

    Periglacial aeolian sand sheets and dunes of the last glacial cover extensive areas of northwest and central Europe. Four sedimentary facies have been described that could be related to fluvio-aeolian and cryogenic processes, moisture content of the depositional surface and surface morphology.

  2. True Volumes of Slope Failure Estimated From a Quaternary Mass-Transport Deposit in the Northern South China Sea

    Science.gov (United States)

    Sun, Qiliang; Alves, Tiago M.; Lu, Xiangyang; Chen, Chuanxu; Xie, Xinong

    2018-03-01

    Submarine slope failure can mobilize large amounts of seafloor sediment, as shown in varied offshore locations around the world. Submarine landslide volumes are usually estimated by mapping their tops and bases on seismic data. However, two essential components of the total volume of failed sediments are overlooked in most estimates: (a) the volume of subseismic turbidites generated during slope failure and (b) the volume of shear compaction occurring during the emplacement of failed sediment. In this study, the true volume of a large submarine landslide in the northern South China Sea is estimated using seismic, multibeam bathymetry and Ocean Drilling Program/Integrated Ocean Drilling Program well data. The submarine landslide was evacuated on the continental slope and deposited in an ocean basin connected to the slope through a narrow moat. This particular character of the sea floor provides an opportunity to estimate the amount of strata remobilized by slope instability. The imaged volume of the studied landslide is 1035 ± 64 km3, 406 ± 28 km3 on the slope and 629 ± 36 km3 in the ocean basin. The volume of subseismic turbidites is 86 km3 (median value), and the volume of shear compaction is 100 km3, which are 8.6% and 9.7% of the landslide volume imaged on seismic data, respectively. This study highlights that the original volume of the failed sediments is significantly larger than that estimated using seismic and bathymetric data. Volume loss related to the generation of landslide-related turbidites and shear compaction must be considered when estimating the total volume of failed strata in the submarine realm.

  3. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden)); Zugec, Nada (Bergab, Goeteborg (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties

  4. The GRASP project - a multidisciplinary study of hydrology and biogeochemistry in a periglacial catchment area

    Science.gov (United States)

    Johansson, Emma; Lindborg, Tobias

    2017-04-01

    The Arctic region is sensitive to global warming, and permafrost thaw and release of old carbon are examples of processes that may have a positive feedback effect to the global climate system. Quantification and assumptions on future change are often based on model predictions. Such models require cross-disciplinary data of high quality that often is lacking. Biogeochemical processes in the landscape are highly influenced by the hydrology, which in turn is intimately related to permafrost processes. Thus, a multidisciplinary approach is needed when collecting data and setting up field experiments aiming at increase the understanding of these processes. Here we summarize and present data collected in the GRASP, Greenland Analogue Surface Project. GRASP is a catchment-scale field study of the periglacial area in the Kangerlussuaq region, West Greenland, focusing on hydrological and biogeochemical processes in the landscape. The site investigations were initiated in 2010 and have since then resulted in three separate data sets published in ESSD (Earth system and Science Data) each one focusing on i) meteorological data and hydrology, ii) biogeochemistry and iii) geometries of sediments and the active layer. The three data-sets, which are freely available via the PANGAEA data base, enable conceptual and coupled numerical modeling of hydrological and biogeochemical processes. An important strength with the GRASP data is that all data is collected within the same, relatively small, catchment area. This implies that measurements are more easily linked to the right source area or process. Despite the small catchment area it includes the major units of the periglacial hydrological system; a lake, a talik, a supra- and subpermafrost aquifer and, consequently, biogeochemical processes in each of these units may be studied. The new data from GRASP is both used with the aim to increase the knowledge of present day periglacial hydrology and biogeochemistry but also in order to

  5. Western Slope Colorado

    International Nuclear Information System (INIS)

    Epis, R.C.; Callender, J.F.

    1981-01-01

    A conference on the geology and geologic resources of the Western Slope of western Colorado and eastern Utah is presented. Fourteen papers from the conference have been abstracted and indexed for the Department of Energy's Energy Data Base. These papers covered such topics as uranium resources, oil shale deposits, coal resources, oil and gas resources, and geothermal resources of the area

  6. Modelling Periglacial Processes on Low-Relief High-Elevation Surfaces

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Knudsen, Mads Faurschou; Egholm, D.L.

    history in many regions of the world. The glacial buzzsaw concept suggests that intense glacial erosion focused at the equilibrium-line altitude (ELA) leads to a concentration in surface area close to the ELA. However, even in predominantly glacial landscapes, such as the Scandinavian Mountains, the high...... as a function of mean annual air temperature and sediment thickness. This allows us to incorporate periglacial processes into a long-term landscape evolution model where surface elevation, sediment thickness, and climate evolve over time. With this model we are able to explore the slow feedbacks between...... evolution model can be used for obtaining more insight into the conditions needed for formation of low-relief surfaces at high elevation. Anderson, R. S. Modeling the tor-dotted crests, bedrock edges, and parabolic profiles of high alpine surfaces of the Wind River Range, Wyoming. Geomorphology, 46, 35...

  7. Relict Forms of a Disappeared Mountain. The Periglacial Deposits in Asinara Island-Sardinia, Italy

    Directory of Open Access Journals (Sweden)

    Sergio GINESU

    2014-10-01

    Full Text Available Asinara Island is located in northwestern Sardinia (Italy and only recently has been divested as a maximum-security prison and returned to nature protection as a National Park with Marine Protected Area along the coastal perimeter. Geologically, the island is formed by a Paleozoic basement in transition between the metamorphic rocks and the Pre-Hercynian granitic batholith of Sardinia. New surveys carried out to reconstruct the recent evolution of the landscape have shown a lot of deposits formed by large blocks of granitoid and anphibolitic rocks representing a favorable situation to produce this material formation in terms of differential erosion in periglaciar environment. Similar morphologies are possible to observe in many places in Sardinia continental hard rocks as effect of the conditions of refreezing periods ("glacial". These deposits are commonly known as " block streams " or " block fields " and reported for the first time in Italy in 1990 in the central area of the island of Sardinia, about 500 meters above sea level. Their presence in Sardinia is always documented in a range of altitudes not less than 350-400 meters and, in this case for the first time they have been identified in close proximity to the coastline. In addition, some of these deposits cover the thalwegs present on the granite rocks in the central portion of the island. The most interesting cases are represented by the deposits located on the northwestern side, near the lighthouse of Punta Scorno. The widespread presence of these deposits suggests significant areal erosion of the island terrain; they probably accumulated during the colder episodes that have characterized the Middle and Upper Pleistocene of the entire western Mediterranean. These testify the existence of an energy relief higher than the present one and a coastline located about 25 kilometers from the current position, however, documented by the block stream of Cala Arena, the first deposit located for

  8. SKB studies of the periglacial environment - report from field studies in Kangerlussuaq, Greenland 2008 and 2010

    International Nuclear Information System (INIS)

    Clarhaell, Anders

    2011-03-01

    In order to reduce uncertainties in safety assessments of the planned repository of spent nuclear fuel, SKB identified the need to increase the understanding of glacial and periglacial environments. In collaboration with Posiva OY (Finland) and NWMO (Canada), SKB started the Greenland Analogue Project (GAP) in order to study the effect of climate cooling and glaciation on repository safety. GAP chose an area northeast of Kangerlussuaq, West Greenland, to be studied as a present-day analogue of a future glacial environment in both Scandinavia and Canada. The GAP, planned to run from 2009 until 2012, conducts in situ investigations of some of the parameters and processes needed to achieve a realistic understanding of how an ice sheet may impact a deep repository. In addition, the GAP will provide measurements, observations and data that may significantly improve safety assessments and risk analyses of glaciation scenarios /SKB 2011/. Issues regarding the periglacial surface environment are not included in GAP's primary focus, which has led SKB to initiate parallel activities in the same area. This new project is named The Greenland Analogue Surface Project (GRASP), and will conduct conceptual and numerical modelling of ecosystems, hydrology and near surface hydrogeology. Choosing the same investigation area for the two projects will facilitate common usage of base-line data and logistics in the field. Information from the GRASP will be applied for a better understanding of ecological and hydrological processes in a future periglacial environment in Forsmark. Annual and long-term dynamics of the permafrost are of special interest, as well as the impact of taliks on the transport of matter from the bedrock up towards the surface. This report primarily describes findings from the field season of 2010, but does also report on field work conducted by SKB in 2008. The report provides some background information on the area, describes preliminary results and set-up for

  9. SKB studies of the periglacial environment - report from field studies in Kangerlussuaq, Greenland 2008 and 2010

    Energy Technology Data Exchange (ETDEWEB)

    Clarhaell, Anders

    2011-03-15

    In order to reduce uncertainties in safety assessments of the planned repository of spent nuclear fuel, SKB identified the need to increase the understanding of glacial and periglacial environments. In collaboration with Posiva OY (Finland) and NWMO (Canada), SKB started the Greenland Analogue Project (GAP) in order to study the effect of climate cooling and glaciation on repository safety. GAP chose an area northeast of Kangerlussuaq, West Greenland, to be studied as a present-day analogue of a future glacial environment in both Scandinavia and Canada. The GAP, planned to run from 2009 until 2012, conducts in situ investigations of some of the parameters and processes needed to achieve a realistic understanding of how an ice sheet may impact a deep repository. In addition, the GAP will provide measurements, observations and data that may significantly improve safety assessments and risk analyses of glaciation scenarios /SKB 2011/. Issues regarding the periglacial surface environment are not included in GAP's primary focus, which has led SKB to initiate parallel activities in the same area. This new project is named The Greenland Analogue Surface Project (GRASP), and will conduct conceptual and numerical modelling of ecosystems, hydrology and near surface hydrogeology. Choosing the same investigation area for the two projects will facilitate common usage of base-line data and logistics in the field. Information from the GRASP will be applied for a better understanding of ecological and hydrological processes in a future periglacial environment in Forsmark. Annual and long-term dynamics of the permafrost are of special interest, as well as the impact of taliks on the transport of matter from the bedrock up towards the surface. This report primarily describes findings from the field season of 2010, but does also report on field work conducted by SKB in 2008. The report provides some background information on the area, describes preliminary results and set-up for

  10. [Characteristics of Soil Respiration along Eroded Sloping Land with Different SOC Background on the Hilly Loess Plateau].

    Science.gov (United States)

    Chen, Gai; Xu, Ming-xiang; Zhang, Ya-feng; Wang, Chao-hua; Fan, Hui-min; Wang, Shan-shan

    2015-09-01

    This study aimed to characterize soil respiration along eroded sloping land at erosion and deposition area under different soil organic carbon(SOC) levels, and linked the relationship between soil respiration and soil temperature, soil moisture, SOC and slope position. Experiments were carried out in the plots of S type slopes include five different soil organic carbon levels in the Loess Hilly Region. The S type slopes were divided into control area at the top of the slope, erosion area at the middle of the slope and deposition area at the toe of the slope. We found that soil temperature had a greater impact on soil respiration in the deposition area, whereas soil moisture had a greater impact on soil respiration in the erosion area compared among control area, erosion area and deposition area. In addition, SOC was the most important factor affecting soil respiration, which can explain soil respiration variation 54. 72%, followed by soil moisture, slope position and soil temperature, which explain soil respiration variation 18. 86% , 16. 13% and 10. 29%, respectively. Soil respiration response to erosion showed obvious on-site and off-site effects along the eroded sloping land. Soil respiration in the erosion area was reduced by 21. 14% compared with control area, and soil respiration in the deposition area was increased by 21. 93% compared with control area. Erosion effect on source and sink of carbon emission was correlated with SOC content of the eroded sloping land. When SOC content was higher than 6. 82 g.kg-1, the slope. erosion tended to be a carbon sequestration process, and when SOC content was lower than 3.03 g.kg-1, the slope erosion tended to be a process of the carbon emission source. The model could reflect the relationship between soil respiration and independent variables of soil organic carbon content, soil temperature and moisture.

  11. Seismic analysis of clinoform depositional sequences and shelf-margin trajectories in Lower Cretaceous (Albian) strata, Alaska North Slope

    Science.gov (United States)

    Houseknecht, D.W.; Bird, K.J.; Schenk, C.J.

    2009-01-01

    Lower Cretaceous strata beneath the Alaska North Slope include clinoform depositional sequences that filled the western Colville foreland basin and overstepped the Beaufort rift shoulder. Analysis of Albian clinoform sequences with two-dimensional (2D) seismic data resulted in the recognition of seismic facies inferred to represent lowstand, transgressive and highstand systems tracts. These are stacked to produce shelf-margin trajectories that appear in low-resolution seismic data to alternate between aggradational and progradational. Higher-resolution seismic data reveal shelf-margin trajectories that are more complex, particularly in net-aggradational areas, where three patterns commonly are observed: (1) a negative (downward) step across the sequence boundary followed by mostly aggradation in the lowstand systems tract (LST), (2) a positive (upward) step across the sequence boundary followed by mostly progradation in the LST and (3) an upward backstep across a mass-failure d??collement. These different shelf-margin trajectories are interpreted as (1) fall of relative sea level below the shelf edge, (2) fall of relative sea level to above the shelf edge and (3) mass-failure removal of shelf-margin sediment. Lowstand shelf margins mapped using these criteria are oriented north-south in the foreland basin, indicating longitudinal filling from west to east. The shelf margins turn westward in the north, where the clinoform depositional system overstepped the rift shoulder, and turn eastward in the south, suggesting progradation of depositional systems from the ancestral Brooks Range into the foredeep. Lowstand shelf-margin orientations are consistently perpendicular to clinoform-foreset-dip directions. Although the Albian clinoform sequences of the Alaska North Slope are generally similar in stratal geometry to clinoform sequences elsewhere, they are significantly thicker. Clinoform-sequence thickness ranges from 600-1000 m in the north to 1700-2000 m in the south

  12. Geometry and significance of stacked gullies on the northern California slope

    Science.gov (United States)

    Field, M.E.; Gardner, J.V.; Prior, D.B.

    1999-01-01

    Recent geophysical surveys off northern California reveal patterns of gullies on the sea floor and preserved within continental-slope deposits that represent both erosional and aggradational processes. These surveys, conducted as part of the STRATAFORM project, combined multibeam bathymetry and backscatter with high-resolution seismic profiles. These data provide a new basis for evaluating gully morphology, distribution, and their significance to slope sedimentation and evolution. The continental margin off northern California exhibits an upper slope that has undergone both progradation and aggradation. The slope surface, which dips at sea floor. These erosional gullies locally truncate individual reflectors, have small depositional levees, and exhibit greater relief than do overlying gullies exposed on the sea floor. The older subsurface gullies document a period of widespread, but minor, erosion and downslope transport, presumably from a large, proximal sediment source. The cycles of downcutting and gully excavation are a minor part of the stratigraphic section, and are likely related to the combined influence of lower sea levels and higher sediment yields. During aggradation of the slope depositional sequences, sediment was draped over the gully features, producing sediment layers that mimic the underlying gully form. Consequently, gully morphology and geometries were preserved and migrated upwards with time. The processes that produce aggraded gully drape also resulted in laterally continuous strata and were most likely related to a period when the sediment source was dispersed from a more distal (10s of km) source, such as during present conditions. The draped sequences also contain a few new gullies, which indicates that gullies can be initiated at all or most stages of slope growth.

  13. Periglacial fires and trees in a continental setting of Central Canada, Upper Pleistocene.

    Science.gov (United States)

    Bélanger, N; Carcaillet, C; Padbury, G A; Harvey-Schafer, A N; Van Rees, K J C

    2014-03-01

    Fire is a key factor controlling global vegetation patterns and carbon cycling. It mostly occurs under warm periods during which fuel builds up with sufficient moisture, whereas such conditions stimulate fire ignition and spread. Biomass burning increased globally with warming periods since the last glacial era. Data confirming periglacial fires during glacial periods are very sparse because such climates are likely too cold to favour fires. Here, tree occurrence and fires during the Upper Pleistocene glacial periods in Central Canada are inferred from botanical identification and calibrated radiocarbon dates of charcoal fragments. Charcoal fragments were archived in sandy dunes of central Saskatchewan and were dated >50000-26600 cal BP. Fragments were mostly gymnosperms. Parallels between radiocarbon dates and GISP2-δ¹⁸O records deciphered relationships between fire and climate. Fires occurred either hundreds to thousands of years after Dansgaard-Oeschger (DO) interstadial warming events (i.e., the time needed to build enough fuel for fire ignition and spread) or at the onset of the DO event. The chronological uncertainties result from the dated material not precisely matching the fires and from the low residual ¹⁴C associated with old sample material. Dominance of high-pressure systems and low effective moisture during post-DO coolings likely triggered flammable periglacial ecosystems, while lower moisture and the relative abundance of fuel overshadowed lower temperatures for fire spread. Laurentide ice sheet (LIS) limits during DO events are difficult to assess in Central Canada due to sparse radiocarbon dates. Our radiocarbon data set constrains the extent of LIS. Central Saskatchewan was not covered by LIS throughout the Upper Pleistocene and was not a continental desert. Instead, our results suggest long-lasting periods where fluctuations of the northern tree limits and fires after interstadials occurred persistently. © 2014 John Wiley & Sons Ltd.

  14. The periglacial engine of mountain erosion – Part 1: Rates of frost cracking and frost creep

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou

    2015-01-01

    present a new model that quantifies two key physical processes: frost cracking and frost creep, as a function of both temperature and sediment thickness. Our results yield new insights into how climate and sediment transport properties combine to scale the intensity of periglacial processes. The thickness...... of the soil mantle strongly modulates the relation between climate and the intensity of mechanical weathering and sediment flux. Our results also point to an offset between the conditions that promote frost cracking and those that promote frost creep, indicating that a stable climate can provide optimal...

  15. Cryophenomena in the Cold Desert of Atacama

    Science.gov (United States)

    Buchroithner, Dr.; Trombotto, Dr.

    2012-04-01

    The study area of the Valle de Barrancas Blancas in the High Atacama Andes of Chile (68°39' W, 27°02' S), a kind of Patagonian "bajo sin salida", shows well preserved landforms resulting from a combination of slope, eolian, lacustrine/litoral, fluvial, glacial and periglacial regimes. They permit the reconstruction of geomorphological processes within this isolated catchment of approximately 160 km2. The mean annual air temperature varies between -2 and -4 °C and the precipitation is approximately 150 mm/a. Snowfall is frequent but the snow is quickly sublimated, redeposited and/or covered by cryosediments, i.e. mainly pumice pebbles. Water bodies present icings, even in summer. Regarding its climatic conditions the study area represents an extremely cold desertic region. Extremophile microfauna was also found. The area displays both in situ mountain permafrost and creeping permafrost. The active layer is 30 to 45 cm thick. It is a periglacial macro-environment where interdependent processes, and not only cryogenic processes but also erosion and eolian deposition and the action of fluvial washout mainly caused by precipitation, accumulation, retransportation/redeposition and melting of snow, play an important role. The cryogenic geomorphology of the Valle de Barrancas Blancas is varied and contains microforms such as patterned ground and microforms caused by cryoturbation, as well as mesoforms like rockglaciers and cryoplanation surfaces. Slopes are strongly affected by gelifluction. New cryoforms in South America and in the Southern Hemisphere like the Atacama Pingo (Pingo atacamensis) and Permafrosted Dunes ("Dunas heladas") were found. Intense niveo-eolian processes participate in the erosion of preexisting landforms, in the formation of subterraneous ice layers, and the retransportation/redeposition of snow and sediments. Studies of this periglacial environment are crucial for the understanding of Tundrean paleoenvironments and Martian conditions.

  16. Slope failures and timing of turbidity flows north of Puerto Rico

    Science.gov (United States)

    ten Brink, Uri S.; Chaytor, Jason D.

    2014-01-01

    The submerged carbonate platform north of Puerto Rico terminates in a high (3,000–4,000 m) and in places steep (>45°) slope characterized by numerous landslide scarps including two 30–50 km-wide amphitheater-shaped features. The origin of the steep platform edge and the amphitheaters has been attributed to: (1) catastrophic failure, or (2) localized failures and progressive erosion. Determining which of the two mechanisms has shaped the platform edge is critically important in understanding landslide-generated tsunami hazards in the region. Multibeam bathymetry, seismic reflection profiles, and a suite sediment cores from the Puerto Rico Trench and the slope between the trench and the platform edge were used to test these two hypotheses. Deposits within trench axis and at the base of the slope are predominantly composed of sandy carbonate turbidites and pelagic sediment with inter-fingering of chaotic debris units. Regionally-correlated turbidites within the upper 10 m of the trench sediments were dated between ∼25 and 22 kyrs and ∼18–19 kyrs for the penultimate and most recent events, respectively. Deposits on the slope are laterally discontinuous and vary from thin layers of fragmented carbonate platform material to thick pelagic layers. Large debris blocks or lobes are absent within the near-surface deposits at the trench axis and the base of slope basins. Progressive small-scale scalloping and self-erosion of the carbonate platform and underlying stratigraphy appears to be the most likely mechanism for recent development of the amphitheaters. These smaller scale failures may lead to the generation of tsunamis with local, rather than regional, impact.

  17. Periglacial morphogenesis in the Paris basin: insight from geophysical survey and consequences for the fate of soil pollution

    Science.gov (United States)

    Thiry, Médard; van Oort, Folkert; Thiesson, Julien; Van Vliet-Lanoe, Brigitte

    2013-09-01

    Geophysical survey by Automatic Resistivity Profiling (ARP©) system of the Pierrelaye-Bessancourt area revealed remarkable conductive polygon patterns of 20- to 30-m diameter detected between 0.5- and 1.7-m depth. Trenches dug down to the limestone substrate allowed detailing of the pedological and lithological units that compose such polygonal features. The patterns are formed by greenish glauconite and carbonated sand hollows where clay-rich pedological horizons bend downward, forming narrow tongs extending up to 2- to 3-m depth. Such structures were interpreted as a buried polygonal ice-wedge network (thermokarst depressions). Geometrical relationships between the lithological units and consecutive erosional surfaces allowed the identification of successive landscape events and a landscape chronology. The sequence started during the Saalian glaciation with (1) the development of patterned grounds by thermokarstic cryoturbation; (2) the consecutive deflation/erosion during post-permafrost aridity; (3) the loess and eolian sand deposits; (4) the weathering of the former deposits with development of pedogenic horizons during the Eemian interglacial; (5) the recurrent cryoturbation and thermal cracking leading to infolding of the pedogenic horizons during the Pleniglacial optimum (Weichselian); and finally (5) the erosion that levelled the periglacial microreliefs, most probably during the last glacial stage (Weichselian), leading to the modern landscape. In this agricultural area, urban waste water has been spread for more than 100 years by flooding irrigation for food crop production and has led to high levels of metal pollution in the surface horizons of the soils. The polygonal cryogenic structures have major impacts on soil hydrology and dispersion/distribution of heavy metals toward the geological substrate. Such structures are essential to consider when conceiving proposals for future soil management of this polluted area.

  18. Effects of slope on the formation of dunes in dilute, turbulent pyroclastic currents: May 18th, 1980 Mt. St. Helens eruption

    Science.gov (United States)

    Bendana, Sylvana; Brand, Brittany D.; Self, Stephen

    2014-05-01

    The flanks of Mt St Helens volcano (MSH) are draped with thin, cross-stratified and stratified pyroclastic density current (PDC) deposits. These are known as the proximal bedded deposits produced during the May 18th, 1980 eruption of MSH. While the concentrated portions of the afternoon PDCs followed deep topographic drainages down the steep flanks of the volcano, the dilute overriding cloud partially decoupled to develop fully dilute, turbulent PDCs on the flanks of the volcano (Beeson, D.L. 1988. Proximal Flank Facies of the May 18, 1980 Ignimbrite: Mt. St. Helens, Washington.). The deposits along the flank thus vary greatly from those found in the pumice plain, which are generally thick, massive, poorly-sorted, block-rich deposits associated with the more concentrated portions of the flow (Brand et al, accepted. Dynamics of pyroclastic density currents: Conditions that promote substrate erosion and self-channelization - Mount St Helens, Washington (USA). JVGR). We explore the influence of topography on the formation of these dilute currents and influence of slope on the currents transport and depositional mechanisms. The deposits on steeper slopes (>15°) are fines depleted relative to the proximal bedded deposits on shallower slopes (<15°). Bedform amplitude and wavelength increase with increasing slope, as does the occurrence of regressive dunes. Increasing slope causes an increase in flow velocity and thus an increase in flow turbulence. The fines depleted deposits suggest that fine ash elutriation is more efficient in flows with stronger turbulence. The longer wavelength and amplitudes suggest that bedform morphology is directly related to flow velocity, an important finding since the controls on bedform wavelength and amplitude in density stratified flows remains poorly constrained. The occurrence of regressive dunes, often interpreted as high flow-regime bedforms, on steeper slopes relative to progressive dunes on shallower slopes further attests to the

  19. Biodiversity impact of the aeolian periglacial geomorphologic evolution of the Fontainebleau Massif (France)

    Science.gov (United States)

    Thiry, M.; Liron, M. N.

    2009-04-01

    erosion of the sand beneath the bordering sandstone benches, resulting in overhangs. These structures are the most common in the western district of the Fontainebleau Massif. Ponds develop on the tightly silicified and impermeable sandstone pans that form the "platières". There are permanent ponds and temporary wet zones, formed of interconnected or isolated depressions. The origin of these ponds has to be questioned with regard to the landscape shaping. Their origin is directly bound to the hollowing of uncemented, sandy zones, within the sandstone pans forming the "platières". Erosion by runoff cannot be considered; the only way to hollow them out is by deflation processes. No direct dating of the Quaternary dune and loess deposits of the Fontainebleau Massif exists. Nevertheless, dating of paleopodzols interlayered between drift sands, pond deposits and bones within congelifracts allow relating these periglacial features with the end of the last glacial period. For now, there is no dating to assess what belongs to older glacial periods. Distribution of the aeolian patterns The Fontainebleau Massif displays noteworthy morphological diversities in the various districts of the forest. Some of these differentiations result from geological features, but most of them are related to erosion processes, and among them deflation processes leaved different imprints in the western and eastern districts of the Fontainebleau Massif. The topography played an important role controlling the aeolian processes. Deflation was important in the westerly upwind district. In the westerly front face, aeolian erosion was activated by turbulences around the topographic obstacles. The reliefs funneled the winds and gave rise to swirls that hollow the blowouts. This area displays the sharpest and more chiseled landforms of the massif. Moreover, the sandstone scarps at the edge of the "platières" are high and uncovered, with frequent overhangs. The collapsed sandstone blocks of the "chaos" are

  20. Landform Degradation and Slope Processes on Io: The Galileo View

    Science.gov (United States)

    Moore, Jeffrey M.; Sullivan, Robert J.; Chuang, Frank C.; Head, James W., III; McEwen, Alfred S.; Milazzo, Moses P.; Nixon, Brian E.; Pappalardo, Robert T.; Schenk, Paul M.; Turtle, Elizabeth P.; hide

    2001-01-01

    The Galileo mission has revealed remarkable evidence of mass movement and landform degradation on Io. We recognize four major slope types observed on a number of intermediate resolution (250 m/pixel) images and several additional textures on very high resolution (10 m/pixel) images. Slopes and scarps on Io often show evidence of erosion, seen in the simplest form as alcove-carving slumps and slides at all scales. Many of the mass movement deposits on Io are probably mostly the consequence of block release and brittle slope failure. Sputtering plays no significant role. Sapping as envisioned by McCauley et al. remains viable. We speculate that alcove-lined canyons seen in one observation and lobed deposits seen along the bases of scarps in several locations may reflect the plastic deformation and 'glacial' flow of interstitial volatiles (e.g., SO2) heated by locally high geothermal energy to mobilize the volatile. The appearance of some slopes and near-slope surface textures seen in very high resolution images is consistent with erosion from sublimation-degradation. However, a suitable volatile (e.g., H2S) that can sublimate fast enough to alter Io's youthful surface has not been identified. Disaggregation from chemical decomposition of solid S2O and other polysulfur oxides may conceivably operate on Io. This mechanism could degrade landforms in a manner that resembles degradation from sublimation, and at a rate that can compete with resurfacing.

  1. Geomorphology and Sediment Stability of a Segment of the U.S. Continental Slope off New Jersey.

    Science.gov (United States)

    Robb, J M; Hampson, J C; Twichell, D C

    1981-02-27

    The morphology of complex deposits of Pleistocene sediments covering the upper continental slope between Lindenkohl Canyon and South Toms Canyon results from both depositional and erosional processes. Small slump or slide features were detected primarily on the flanks of canyons or valleys and were observed to occur only within Pleistocene-aged sediments. Eocene to Miocene sediments are exposed over much of the mid- and lower slope in this area.

  2. Relationships between contourite deposition, climate and slope instability: new insights from the Demerara Plateau (French Guyana)

    Science.gov (United States)

    Tallobre, C.; Bassetti, M. A.; Loncke, L.; Giresse, P.; Bayon, G.; Buscail, R.

    2015-12-01

    A Contourite Depositional System (CDS) has been described at the Demerara Plateau (DP) based on seismic investigations, but little is known about the mechanisms of associated sediment deposition and its interaction with past deep ocean circulation patterns (e.g. bottom current velocity) and bottom morphology related to ancient event of slope instability. The new seismic and bathymetric data recently acquired allow describing in details the CDS on the DP. Erosional and syn-sedimentary features on the seafloor (comet tail, « longitudinal waves », contourite drifts and moats) have been observed, helping to constrain the sedimentary processes at the origin of the CDS construction. Also, the recovery and multi-proxy analysis of sediment cores allows the characterization of sedimentary environments and possible relation with climate forcing. These sediment cores are characterized by the presence of several beds rich in glauconite grains. Glauconite can form at the sediment/water interface by winnowing effect that prevent sediment deposition and increase the residence time at the seafloor. Under strong winnowing conditions, glauconite grains can develop at several stages of maturity. We observed that the residence time and hence the maturity of glauconite is reflected by the color changes (light to dark green), the presence of crack on grains, the formation of (secondary) glauconite lamellae and decrease of grain porosity. A chronological framework (based on radiocarbon dates and δ18O variations) of contourite sequences at the studied location indicates correlation with grain-size parameters (sortable silt) and allows one to further constrain their dynamics through time. The combination of these proxies allows us to estimate and understand the evolution and the impact of the bottom current on sedimentation on the DP during the last 80 ky. These results show the potentiality of the glauconite study to estimate the relative variation of bottom current velocity at margins.

  3. Geological hazards investigation - relative slope stability map

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Suk; Kim, Won Young; Yu, Il Hyon; Kim, Kyeong Su; Lee, Sa Ro; Choi, Young Sup [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1997-12-01

    The Republic of Korea is a mountainous country; the mountains occupy about three quarters of her land area, an increasing urban development being taken place along the mountainside. For the reason, planners as well as developers and others must realize that some of the urban areas may be threaten by geologic hazards such as landslides and accelerated soil and rock creeps. For the purpose of environmental land-use planning, a mapping project on relative slope-stability was established in 1996. The selected area encompasses about 5,900 km{sup 2} including the topographic maps of Ulsan, Yongchon, Kyongju, Pulguksa, and Kampo, all at a scale of 1:50,000. Many disturbed and undisturbed soil samples, which were collected from the ares of the landslides and unstable slopes, were tested for their physical properties and shear strength. They were classified as GC, SP, SC, SM, SP-SM, SC-SM, CL, ML, and MH according to the Unified Soil Classification System, their liquid limit and plasticity index ranging from 25.3% to as high as 81.3% and from 4.1% to 41.5%, respectively. X-ray analysis revealed that many of the soils contained a certain amount of montmorillonite. Based on the available information as well as both field and laboratory investigation, it was found out that the most common types of slope failures in the study area were both debris and mud flows induced by the heavy rainfalls during the period of rainy season; the flows mostly occurred in the colluvial deposits at the middle and foot of mountains. Thus the deposits generally appear to be the most unstable slope forming materials in the study area. Produced for the study area were six different maps consisting of slope classification map, soil classification map, lineament density map, landslide distribution map, zonal map of rainfall, and geology map, most of them being stored as data base. Using the first four maps and GIS, two sheets of relative slope-stability maps were constructed, each at a scale of 1

  4. Topography and stratigraphy of Martian polar layered deposits

    Science.gov (United States)

    Blasius, K. R.; Cutts, J. A.; Howard, A. D.

    1982-01-01

    The first samples of high resolution Viking Orbiter topographic and stratigraphic data for the layered polar deposits of Mars are presented, showing that these deposits are with respect to both slopes and angular relief similar to those in the south. It is also demonstrated that, in conjunction with stereophotogrammetry, photoclinometry holds promise as a tool for detailed layered deposit studies. The spring season photography, which lends itself to photoclinometric analysis, covers the entire area of the north polar deposits. Detailed tests of layered terrain evolution hypotheses will be made, upon refinement of the data by comparison with stereo data. A more promising refining technique will make use of averaging perpendicular to selected sections to enhance SNR. Local reliefs of 200-800 m, and slopes of 1-8 deg, lead to initial calculations of average layer thickness which yields results of 14-46 m, linearly correlated with slope.

  5. Influence of Waves and Tides on Upper Slope Turbidity Currents and their Deposits: An Outcrop and Laboratory Study

    Science.gov (United States)

    Daniller-Varghese, M. S.; Smith, E.; Mohrig, D. C.; Goudge, T. A.; Hassenruck-Gudipati, H. J.; Koo, W. M.; Mason, J.; Swartz, J. M.; Kim, J.

    2017-12-01

    Research on interactions of turbidity currents with waves and tides highlight both their importance and complexity. The Elkton Siltstone at Cape Arago, Oregon, USA, preserves rhythmically bedded deposits that we interpret as the product of tidally modified hyperpycnal flows under the influence of water-surface waves. Evidence for the interpretation of tidal influence is taken from couplet thickness measurements consistent with semidiurnal tides arranged into monthly cycles. These deposits were likely sourced from suspended-sediment laden river plumes; thinner, finer-grained beds represent deposition during flood tide, and thicker, coarser-grained beds represent deposition during ebb tide. Sedimentary structures within the rhythmites change from proximal to distal sections, but both sections preserve combined-flow bedforms within the beds, implying wave influence. Our paleo-topographic reconstruction has the proximal section located immediately down-dip of the shelf slope-break and the distal section located 1.5km further offshore in 125m greater water depth. We present experimental results from wave-influenced turbidity currents calling into question the interpretation that combined-flow bedforms necessarily require deposition at or above paleo-wave base. Turbidity currents composed of quartz silt and very fine sand were released into a 10m long, 1.2m deep tank. Currents ran down a 9-degree ramp with a motor driven wave-maker positioned at the distal end of the tank. The currents interacted with the wave field as they travelled downslope into deeper water. While oscillatory velocities measured within the wave-influenced turbidity currents decreased with distance downslope, the maximum oscillatory velocities measured in the combined-flow currents at depth were five to six times larger than those measured under a wave field without turbidity currents. These results suggest that combined-flow turbidity currents can transmit oscillating-flow signals beneath the

  6. Hydrological modelling of a slope covered with shallow pyroclastic deposits from field monitoring data

    Directory of Open Access Journals (Sweden)

    R. Greco

    2013-10-01

    Full Text Available A one-dimensional hydrological model of a slope covered with pyroclastic materials is proposed. The soil cover is constituted by layers of loose volcanic ashes and pumices, with a total thickness between 1.8 m and 2.5 m, lying upon a fractured limestone bedrock. The mean inclination of the slope is around 40°, slightly larger than the friction angle of the ashes. Thus, the equilibrium of the slope, significantly affected by the cohesive contribution exerted by soil suction in unsaturated conditions, may be altered by rainfall infiltration. The model assumes a single homogeneous soil layer occupying the entire depth of the cover, and takes into account seasonally variable canopy interception of precipitation and root water uptake by vegetation, mainly constituted by deciduous chestnut woods with a dense underbrush growing during late spring and summer. The bottom boundary condition links water potential at the soil–bedrock interface with the fluctuations of the water table of the aquifer located in the fractured limestone, which is conceptually modelled as a linear reservoir. Most of the model parameters have been assigned according to literature indications or from experimental data. Soil suction and water content data measured between 1 January 2011 and 20 July 2011 at a monitoring station installed along the slope allowed the remaining parameters to be identified. The calibrated model, which reproduced very closely the data of the calibration set, has been applied to the simulation of the hydrological response of the slope to the hourly precipitation record of 1999, when a large flow-like landslide was triggered close to the monitored location. The simulation results show that the lowest soil suction ever attained occurred just at the time the landslide was triggered, indicating that the model is capable of predicting slope failure conditions.

  7. The Q-Slope Method for Rock Slope Engineering

    Science.gov (United States)

    Bar, Neil; Barton, Nick

    2017-12-01

    Q-slope is an empirical rock slope engineering method for assessing the stability of excavated rock slopes in the field. Intended for use in reinforcement-free road or railway cuttings or in opencast mines, Q-slope allows geotechnical engineers to make potential adjustments to slope angles as rock mass conditions become apparent during construction. Through case studies across Asia, Australia, Central America, and Europe, a simple correlation between Q-slope and long-term stable slopes was established. Q-slope is designed such that it suggests stable, maintenance-free bench-face slope angles of, for instance, 40°-45°, 60°-65°, and 80°-85° with respective Q-slope values of approximately 0.1, 1.0, and 10. Q-slope was developed by supplementing the Q-system which has been extensively used for characterizing rock exposures, drill-core, and tunnels under construction for the last 40 years. The Q' parameters (RQD, J n, J a, and J r) remain unchanged in Q-slope. However, a new method for applying J r/ J a ratios to both sides of potential wedges is used, with relative orientation weightings for each side. The term J w, which is now termed J wice, takes into account long-term exposure to various climatic and environmental conditions such as intense erosive rainfall and ice-wedging effects. Slope-relevant SRF categories for slope surface conditions, stress-strength ratios, and major discontinuities such as faults, weakness zones, or joint swarms have also been incorporated. This paper discusses the applicability of the Q-slope method to slopes ranging from less than 5 m to more than 250 m in height in both civil and mining engineering projects.

  8. Seasonal inorganic nitrogen release in alpine lakes on the Colorado western slope

    Science.gov (United States)

    Inyan, B.I.; Williams, M.W.; Tonnessen, K.; Turk, J.T.; Campbell, D.H.

    1998-01-01

    In the Rocky Mountains, the association of increases in acidic deposition with increased atmospheric loading of sulfate and direct changes in surface water chemistry has been well established. The importance, though, of increased nitrogen (N) deposition in the episodic acidification of alpine lakes and N saturation in alpine ecosystems is only beginning to be documented. In alpine areas of the Colorado Front Range, modest loadings of N in deposition have been associated with leakage of N to surface waters. On the Colorado western slope, however, no leakage of N to surface waters has been reported. A 1995 study that included early season under-ice water samples that were not available in earlier studies showed that there is, in fact, N leakage to surface waters in some western slope basins. Under-ice nitrate (NO3-) concentrations were as high as 10.5 ??q L-1, and only decreased to detection limits in September. Landscape type appears to be important in leakage of N to surface waters, which is associated with basins having steep slopes, thin soils, and large amounts of exposed bedrock. NO3- leakage compounds the existing sensitivity to episodic acidification from low acid neutralizing capacity (ANC), which is less than 40 ??eq L-1 in those basins.

  9. Observations of periglacial landforms in Utopia Planitia with the High Resolution Imaging Science Experiment (HiRISE)

    Science.gov (United States)

    Lefort, A.; Russell, P.S.; Thomas, N.; McEwen, A.S.; Dundas, C.M.; Kirk, R.L.

    2009-01-01

    The region of western Utopia Planitia (80-105 degreesE, 40-55 degrees N) displays several types of landforms similar to Earth periglacial features, including scallop-shaped depressions and networks of polygonal terrains. The scalloped depressions have been proposed to originate from thermokarstic processes such as sublimation and/or melting of near-surface ground ice. Using HiRISE imagery, we characterize these depressions and several associated, distinct polygon networks in unprecedented morphologic and topographic detail and investigate support for an ice-based degradation process. The scalloped depressions and interior polygons and ridges are found to evolve together, mainly influenced by sublimation, local proximity of ground ice to the surface, and obliquity variations.

  10. Electrical resistivity tomography (ERT surveys on glacial deposits in Romanian Carpathians

    Directory of Open Access Journals (Sweden)

    Andrei ZAMOSTEANU

    2014-11-01

    Full Text Available The study presents preliminary results regarding the use of electrical resistivity surveys in the assessment of the internal structure of the glacial deposits from the Romanian Carpathians.ERT is a geophysical method used to quantify changes in electrical resistivity of the ground towards passing electric current across an array of electrodes and simultaneous measurement of the induced potential gradient. Using specific software the measurements are further processed and correlated with the topography in order to obtain bedrock resistivity features. Therefore, the method is useful to evaluate the characteristics of geological strata and is widely used for mapping shallow subsurface geological structures. In the mountain regions ERT studies have been applied in different glacial and periglacial geomorphological studies - for permafrost detection (in Romanian Carpathians - Urdea et. al., 2008; Vespremeanu-Stroe et al., 2012, slope deformation analysis, the assessment of slip surface depths, sediment thickness, groundwater levels etc. One of the most commonly 2-D array used is the Wenner electrode configuration, which is moderately sensitive to both horizontal and vertical ground structures.Due to their elevations and Pleistocene’s climatic conditions, the Romanian Carpathians have been partially affected by Quaternary glaciations. The glaciers descended to about 1050-1200 m a.s.l. (Urdea and Reurther, 2009 in the Transylvanian Alps and Rodna Mountains (Eastern Carpathians carving a large number of U-shaped valleys and glacial cirques (Mîndrescu, 2006 and forming accumulations of unconsolidated glacial debris (moraines. Our study areas are two sites located in the northern (Rodna Mts. and southern (Iezer Păpuşa Mts. part of the mountain range.

  11. Turbid Flows and Their Deposits on Slopes with Minibasins : A Modelling Approach

    NARCIS (Netherlands)

    Wang, X.

    2015-01-01

    Passive continental margins display a great diversity of seafloor bathymetries induced by gravity driven extensional faulting and compressional folding, as well as diapiric movements of salt or mud. In many diapirically controlled settings, slope bathymetries are complicated and characterized by

  12. Dip-slope and Dip-slope Failures in Taiwan - a Review

    Science.gov (United States)

    Lee, C.

    2011-12-01

    Taiwan is famous for dip-slope and dip-slope slides. Dip-slopes exist at many places in the fold-and-thrust belt of Taiwan. Under active cutting of stream channels and man-made excavations, a dip-slope may become unstable and susceptible for mass sliding. Daylight of a bedding parallel clay seam is the most dangerous type for dip-slope sliding. Buckling or shear-off features may also happen at toe of a long dip-slope. Besides, a dip-slope is also dangerous for shallow debris slides, if the slope angle is between 25 to 45 degrees and the debris (colluvium or slope wash) is thick (>1m). These unstable slopes may slide during a triggering event, earthquake or typhoon storm; or even slide without a triggering event, like the 2010 Tapu case. Initial buckling feature had been found in the dip-slope of the Feitsui arch dam abutment after detailed explorations. Shear-off feature have also been found in dip-slope located in right bank of the Nahua reservoir after field investigation and drilling. The Chiufengerhshan slide may also be shear-off type. On the other hand, the Tapu, the Tsaoling slides and others are of direct slide type. The Neihoo Bishan slide is a shallow debris slide on dip-slope. All these cases demonstrate the four different types of dip-slope slide. The hazard of a dip-slope should be investigated to cover these possible types of failure. The existence of bedding parallel clay seams is critical for the stability of a dip-slope, either for direct slide or buckling or shear-off type of failure, and is a hot point during investigation. Because, the stability of a dip-slope is changing with time, therefore, detailed explorations to including weathering and erosion rates are also very necessary to ensure the long-term stability of a dip-slope.

  13. Records of continental slope sediment flow morphodynamic responses to gradient and active faulting from integrated AUV and ROV data, offshore Palos Verdes, southern California Borderland

    Science.gov (United States)

    Maier, Katherine L.; Brothers, Daniel; Paull, Charles K.; McGann, Mary; Caress, David W.; Conrad, James E.

    2016-01-01

    Variations in seabed gradient are widely acknowledged to influence deep-water deposition, but are often difficult to measure in sufficient detail from both modern and ancient examples. On the continental slope offshore Los Angeles, California, autonomous underwater vehicle, remotely operated vehicle, and shipboard methods were used to collect a dense grid of high-resolution multibeam bathymetry, chirp sub-bottom profiles, and targeted sediment core samples that demonstrate the influence of seafloor gradient on sediment accumulation, depositional environment, grain size of deposits, and seafloor morphology. In this setting, restraining and releasing bends along the active right-lateral Palos Verdes Fault create and maintain variations in seafloor gradient. Holocene down-slope flows appear to have been generated by slope failure, primarily on the uppermost slope (~ 100–200 m water depth). Turbidity currents created a low relief (water depositional systems. These results help to bridge gaps in scale between existing deep-sea and experimental datasets and may provide constraints for future numerical modeling studies.

  14. Factors influencing chloride deposition in a coastal hilly area and application to chloride deposition mapping

    Directory of Open Access Journals (Sweden)

    H. Guan

    2010-05-01

    Full Text Available Chloride is commonly used as an environmental tracer for studying water flow and solute transport in the environment. It is especially useful for estimating groundwater recharge based on the commonly used chloride mass balance (CMB method. Strong spatial variability in chloride deposition in coastal areas is one difficulty encountered in appropriately applying the method. A high-resolution bulk chloride deposition map in the coastal region is thus needed. The aim of this study is to construct a chloride deposition map in the Mount Lofty Ranges (MLR, a coastal hilly area of approximately 9000 km2 spatial extent in South Australia. We examined geographic (related to coastal distance, orographic, and atmospheric factors that may influence chloride deposition, using partial correlation and regression analyses. The results indicate that coastal distance, elevation, as well as terrain aspect and slope, appear to be significant factors controlling chloride deposition in the study area. Coastal distance accounts for 70% of spatial variability in bulk chloride deposition, with elevation, terrain aspect and slope an additional 15%. The results are incorporated into a de-trended residual kriging model (ASOADeK to produce a 1 km×1 km resolution bulk chloride deposition and concentration maps. The average uncertainty of the deposition map is about 20–30% in the western MLR, and 40–50% in the eastern MLR. The maps will form a useful basis for examining catchment chloride balance for the CMB application in the study area.

  15. Source and depositional processes of coarse-grained limestone event beds in Frasnian slope deposits (Kostomłoty-Mogiłki quarry, Holy Cross Mountains, Poland)

    Science.gov (United States)

    Vierek, Aleksandra

    2010-10-01

    The Kostomłoty-Mogiłki succession is situated in the Kostomłoty transitional zone between the shallow-water Kielce stromatoporoid-coral platform and the deeper Łysogóry basin. In the Kostomłoty-Mogiłki quarry, the upper part of the Szydłówek Beds and Kostomłoty Beds are exposed. The Middle-Upper Frasnian Kostomłoty Beds are composed of shales, micritic and nodular limestones with abundant intercalations of detrital limestones. The dark shales and the micritic and nodular limestones record background sedimentation. The interbedded laminated and detrital limestones reflect high-energy deposition (= event beds). These event beds comprise laminated calcisiltites, fine-grained calcarenites, coarse-grained grain-supported calcirudites fabrics, and matrix-supported calcirudites. The material of these event beds was supplied by both erosion of the carbonate-platform margin and cannibalistic erosion of penecontemporaneous detrital limestones building the slope of this platform. Storms and the tectonic activity were likely the main causes of erosion. Combined and gravity flows were the transporting mechanisms involved in the reworking and redeposition.

  16. Overpressure, Flow Focusing, Compaction and Slope Stability on the continental slope: Insights from IODP Expedition 308

    Science.gov (United States)

    Flemings, P. B.

    2010-12-01

    Integrated Ocean Drilling Program Expepedition 308 used direct measurements of pore pressure, analysis of hydromechanical properties, and geological analysis to illuminate how sedimentation, flow focusing, overpressure, and slope stability couple beneath the seafloor on the deepwater continental slope in the Gulf of Mexico. We used pore pressure penetrometers to measure severe overpressures (60% of the difference between lithostatic stress and hydrostatic pressure) that extend from the seafloor for 100’s of meters. We ran uniaxial consolidation experiments on whole core and found that although permeability is relatively high near the seafloor, the sediments are highly compressible. As a result, the coefficient of consolidation (the hydraulic diffusivity) is remarkably constant over a large range of effective stresses. This behavior accounts for the high overpressure that begins near the seafloor and extends to depth. Forward modeling suggests that flow is driven laterally along a permeable unit called the Blue Unit. Calculations suggest that soon after deposition, lateral flow lowered the effective stress and triggered the submarine landslides that we observe. Later in the evolution of this system, overpressure may have pre-conditioned the slope to failure by earthquakes. Results from IODP Expedition 308 illustrate how pore pressure and sedimentation control the large-scale form of continental margins, how submarine landslides form, and provide strategies for designing stable drilling programs.

  17. WHISPERS Project on the easternmost slope of the Ross Sea (Antarctica): preliminary results.

    Science.gov (United States)

    Olivo, E.; De Santis, L.; Bergamasco, A.; Colleoni, F.; Gales, J. A.; Florindo-Lopez, C.; Kim, S.; Kovacevic, V.; Rebesco, M.

    2017-12-01

    The advance and retreat of the West Antarctic Ice Sheet from the outer continental shelf and the oceanic circulation are the main causes of the depositional processes on the Ross Sea continental slope, at present time and during the most of the Cenozoic. Currently the Antarctic Bottom Water formation is directly linked to the relatively warm Circumpolar Deep Water that, encroaching the continental shelf, mixes with the colder Ross Sea Bottom Water. Detailed multibeam and geological surveys useful to locate and characterize peculiar morphological structures on the bottom are essential to study how the glacial and oceanographic processes interact with the seabed sediments. In the framework of the PNRA-WHISPERS project (XXXIIth Italian Antarctic expedition - January/March 2017), new multibeam bathymetric, sub-bottom chirp, were acquired from the easternmost margin of the Ross Sea, on the southeastern side of the Hayes Bank, usually covered by sea ice. We observed on the upper slope erosional features (incised gullies of likely glacial meltwater origin). A broad scar in the upper slope is characterized by an elongated SSW-NNE ridge (10 km long, 850-1200 m water depth, 2 km wide), that may be a remnants of previous glacial or debris flow deposits, eroded by meltwater outwash discharge at the beginning of grounding ice retreat and by RSBW cascading along the slope, as documented by Expandable Bathy-Thermograph and Acoustic Depth Current Profile data. Sub-bottom chirp profiles crossing this ridge show a very low amplitude reflective sea bed, supporting the hypothesis of its soft sediment nature, in good agreement with a very low acoustic velocity obtained by multichannel seismic data reprocessing. The occurrence of internal stratification on 2D multichannel seismic profiles would discount a gas-fluids related mud volcano origin. No sediment cores were collected, due to bad sea conditions and limited ship time, further data collection would be needed to fully understand

  18. Paleomagnetism and rock magnetism from sediments along a continental shelf-to-slope transect in the NW Barents Sea: Implications for geomagnetic and depositional changes during the past 15 thousand years

    Science.gov (United States)

    Caricchi, C.; Lucchi, R. G.; Sagnotti, L.; Macrì, P.; Morigi, C.; Melis, R.; Caffau, M.; Rebesco, M.; Hanebuth, T. J. J.

    2018-01-01

    Paleomagnetic and rock magnetic data were measured on glaciomarine silty-clay successions along an E-W sediment-core transect across the continental shelf and slope of the Kveithola paleo-ice stream system (south of Svalbard, north-western Barents Sea), representing a stratigraphic interval spanning the last deglaciation and the Holocene. The records indicate that magnetite is the main magnetic mineral and that magnetic minerals are distinctly less abundant on the shelf than at the continental slope. The paleomagnetic properties allow for the reconstruction of a well-defined characteristic remanent magnetization (ChRM) throughout the sedimentary successions. The stratigraphic trends of rock magnetic and paleomagnetic parameters are used for a shelf-slope core correlation and sediment facies analysis is applied for depositional processes reconstruction. The new paleomagnetic records compare to the PSV and RPI variation predicted for the core sites by a simulation using the global geomagnetic field variation models SHA.DIF.14k and CALS7K.2 and closest PSV and RPI regional stack curves. The elaborated dataset, corroborated by available 14C ages, provides a fundamental chronological framework to constrain the coupling of shelf-slope sedimentary processes and environmental changes in the NW Barents Sea region during and after deglaciation.

  19. Transport and transfer rates in the waters of the continental shelf and slope: SEEP

    International Nuclear Information System (INIS)

    Biscaye, P.E.; Anderson, R.F.

    1993-01-01

    The overall Shelf Edge Exchange Processes (SEEP) Program, which began in 1980 or 1981, had as its goal the testing of a hypothesis with respect to the fate of particulate matter formed in and introduced into the waters of the continental shelf adjacent to the northern east coast of the US, i.e., the MAB. The original hypothesis was that a large proportion of the particles in general, and of the particulate organic carbon (POC) in particular, was exported from the shelf, across the shelf/slope break and front, into the waters of, and, to some degree, deposited in the sediments of the continental slope. This hypothesis was based on budgets of organic carbon and lead-210 that did not account for a large proportion of those species in the waters or sediments of the shelf, and on a carbon-rich band of sediments centered on the slope at ∼1,000 m water depth. The results of the first SEEP experiment, south of New England and Long Island (SEEP-1) suggested, but did not prove, that there was only a relatively small proportion of the carbon which was exported from the shelf to the slope. The objective of the second experiment -- SEEP-2 -- done under the subject grant, was to tighten the experiment in terms of the kinds of data collected, and to focus it more on the shelf and only the upper slope, where shelf-derived particles were thought to be deposited

  20. Sea-level related resedimentation processes on the northern slope of Little Bahama Bank (Middle Pleistocene to Holocene)

    DEFF Research Database (Denmark)

    Lantzsch, H.; Roth, S.; Reijmer, J.J.G.

    2007-01-01

    -slope depositional environment. The sediment composition indicates sea-level related deposition processes for the past 375000 years (marine isotope stages 1 to 11). The sediments consist of: (i) periplatform ooze (fine-grained particles of shallow-water and pelagic origin) with moderate variations in carbonate...

  1. Slope movements

    International Nuclear Information System (INIS)

    Wagner, P.

    2009-01-01

    On this poster some reasons of slope movements on the territory of the Slovak Republic are presented. Slope movements induced deterioration of land and forests, endangering of towns villages, and communications as well as hydro-engineering structures. Methods of preventing and stabilisation of slope movements are presented.

  2. Fault slip versus slope deformations: Experience from paleoseismic trenches in the region with low slip-rate faults and strong Pleistocene periglacial mass wasting (Bohemian Massif)

    Czech Academy of Sciences Publication Activity Database

    Špaček, P.; Valenta, Jan; Tábořík, Petr; Ambrož, V.; Urban, M.; Štěpančíková, Petra

    2017-01-01

    Roč. 451, 7 SEP (2017), s. 56-73 ISSN 1040-6182 R&D Projects: GA ČR GAP210/12/0573; GA MŠk(CZ) LM2015079; GA MŠk 7AMB13AT023 Institutional support: RVO:67985891 Keywords : Active faulting * Paleoseismology * Slope deformation * Solifluction * Colluvium * Quaternary * Bohemian massif Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.199, year: 2016

  3. Characterising weak layers that accommodate submarine landslides on the Northwest African continental slope

    Science.gov (United States)

    Urlaub, M.; Krastel, S.; Geersen, J.; Schwenk, T.

    2017-12-01

    Numerous studies invoke weak layers to explain the occurrence of large submarine landslides (>100 km³), in particular those on very gentle slopes (translational, such that failure takes place along bedding-parallel surfaces at different stratigraphic depths. This suggests that failure occurs along weak layers, which are deposited repeatedly over time. Using high resolution seismic reflection data we trace several failure surfaces of the Cap Blanc Slide complex offshore Northwest Africa to ODP-Site 658. Core-seismic integration shows that the failure surfaces coincide with diatom oozes that are topped by clay. Along Northwest Africa diatom-rich sediments are typically deposited at the end of glacial periods. In the seismic data these oozes show up as distinct high amplitude reflectors due to their characteristic low densities. Similar high-amplitude reflectors embedded into low-reflective seismic units are commonly observed in shallow sediments (<100 m below seafloor) along the entire Northwest African continental slope. The failure surfaces of at least three large landslides coincide with such reflectors. As the most recent Pleistocene glacial periods likely influenced sediment deposition along the entire Northwest African margin in a similar manner we hypothesize that diatom oozes play a critical role for the generation of submarine landslides off Northwest Africa as well as globally within subtropical regions. An initiative to drill the Northwest African continental slope with IODP is ongoing, within which this hypothesis shall be tested.

  4. Glacial and periglacial environment monitoring in Aosta Valley - Northwestern Italian Alps

    Science.gov (United States)

    Motta, Elena; Cremonese, Edoardo; Morra di Cella, Umberto; Pogliotti, Paolo; Vagliasindi, Marco

    2010-05-01

    Aosta Valley is a small alpine region of about 3.300 km2 located in the NW Italy, on the southern side of the Alps and surrounded by the highest Alpine peaks such as Mont Blanc (4810m), Mont Rose (4634m) and Cervino (4478m), More than 50% of the territory has an elevation above 2000 metres asl. High mountain, glacial and periglacial environments cover a significant part of the territory. As the cryosphere is strongly sensitive to climate change, global warming effects are particularly evident in this alpine region, and they often affect environment and social and economic life, thus representing a key issue for politicians and people working and living in the valley. Among these effects, some of the most important are the decrease of water storage due to glaciers retreat and the increasing natural hazards as a consequence of rapid environmental dynamics. Hence the importance of monitoring glacial and periglacial environment, in order to quantify effects of climate change, to detect new dynamics and to manage consequences on the environment and the social life. In Aosta Valley the understanding of these phenomena is carried out by means of several actions, both at a regional scale and on specific representative sites. A multi-temporal analysis of aerial photographs, orthophotos and satellite imagery allows to detect glaciers evolution trend at a regional scale. All this information is collected in a Regional Glacier inventory, according to the World Glaciers Inventory standard and recommendations. Analysis of the information collected in the Inventory show that the total area presently covered by glaciers is about 135 km2; area changes occurred in the past has been about -44.3 km2, and -17 km2. between 1975 and 2005. Glacier inventory also gathers - for each of the about 200 glaciers - morphological data, information about events and photos both historical and present. Glacier mass balance (the difference resulting from the mass gained by the glacier through the

  5. Numerical modelling of hydrologically-driven slope instability by means of porous media mechanics

    Science.gov (United States)

    Kakogiannou, Evanthia; Sanavia, Lorenzo; Lora, Marco; Schrefler, Bernhard

    2015-04-01

    Heavy rainfall can trigger slope failure which generally involves shallow soil deposit of different grading and origin usually in a state of partial saturation. In this case of slope instability, the behaviour of the soil slope is closely related not only to the distribution of pore-water pressure but also to the stress state during rainfall infiltration involving both mechanical and hydrological processes. In order to understand better these physical key processes, in this research work, the modelling of rainfall induced slope failure is considered as a coupled variably saturated hydro-mechanical problem. Therefore, the geometrically linear finite element code Comes-Geo for non-isothermal elasto-plastic multiphase solid porous materials is used, as developed by B.A. Schrefler and his co-workers. In this context, a detailed numerical analysis of an experimental slope stability test due to rainfall infiltration is presented. The main goals of this work are to understand the triggering mechanisms during the progressive failure, the effect of using different constitutive models of the mechanical soil behavior on the numerical results and the use of the second order work criterion on the detection of slope instability.

  6. Numerical Modelling of Seismic Slope Stability

    Science.gov (United States)

    Bourdeau, Céline; Havenith, Hans-Balder; Fleurisson, Jean-Alain; Grandjean, Gilles

    Earthquake ground-motions recorded worldwide have shown that many morphological and geological structures (topography, sedimentary basin) are prone to amplify the seismic shaking (San Fernando, 1971 [Davis and West 1973] Irpinia, 1980 [Del Pezzo et al. 1983]). This phenomenon, called site effects, was again recently observed in El Salvador when, on the 13th of January 2001, the country was struck by a M = 7.6 earthquake. Indeed, while horizontal accelerations on a rock site at Berlin, 80 km from the epicentre, did not exceed 0.23 g, they reached 0.6 g at Armenia, 110 km from the epicentre. Armenia is located on a small hill underlaid by a few meters thick pyroclastic deposits. Both the local topography and the presence of surface layers are likely to have caused the observed amplification effects, which are supposed to have contributed to the triggering of some of the hundreds of landslides related to this seismic event (Murphy et al. 2002). In order to better characterize the way site effects may influence the triggering of landslides along slopes, 2D numerical elastic and elasto-plastic models were developed. Various geometrical, geological and seismic conditions were analysed and the dynamic behaviour of the slope under these con- ditions was studied in terms of creation and location of a sliding surface. Preliminary results suggest that the size of modelled slope failures is dependent on site effects.

  7. Deposition of eroded soil on terraced croplands in Minchet catchment, Ethiopian Highlands

    Directory of Open Access Journals (Sweden)

    Alemtsehay Subhatu

    2017-09-01

    Full Text Available In the Ethiopian Highlands, soil and water conservation practices are of utmost importance to conserve eroded soil and combat soil loss. This study provides detailed results on on-site sediment deposition and net soil loss in terraced croplands in a catchment in the sub-humid Ethiopian Highlands. Sediment deposition was measured on horse bean and maize fields during the crop growing seasons of 2014 and 2015. Measurements took place on observation plots on terraced cropland with varying spacing between terraces and varying slope gradients. Net soil loss, in this case the amount leaving the terraced cropland, was calculated by modelling the Universal Soil Loss Equation (USLE for the whole observation field and subtracting the measured sediment deposition. The study result showed about 8–11 t ha−1 sediment was deposited in the deposition zone of the terraced cropland, with greater sediment deposition on terraces with narrow spacing and steeper slope gradients. Sediment deposition was highest in July and August, and relatively low in September. Annual soil loss ranged from 32 to 37 t ha−1 in the terraced cropland of the study area. From the total soil loss in the crop growing season, about 54–74% sediment was deposited on the deposition zone of terraced crop fields. Implementation of soil and water conservation with narrow spacing, especially on the steep slopes of the sub-humid Ethiopian Highlands or other similar area, are thus highly recommended as they enable conservation of the eroded soil in the cropland.

  8. Cyclic settlement behavior of strip footings resting on reinforced layered sand slope

    Directory of Open Access Journals (Sweden)

    Mostafa A. El Sawwaf

    2012-10-01

    Full Text Available The paper presents a study of the behavior of model strip footings supported on a loose sandy slope and subjected to both monotonic and cyclic loads. The effects of the partial replacement of a compacted sand layer and the inclusion of geosynthetic reinforcement were investigated. Different combinations of the initial monotonic loads and the amplitude of cyclic loads were chosen to simulate structures in which loads change cyclically such as machine foundations. The affecting factors including the location of footing relative to the slope crest, the frequency of the cyclic load and the number of load cycles were studied. The cumulative cyclic settlement of the model footing supported on a loose sandy slope, un-reinforced and reinforced replaced sand deposits overlying the loose slope were obtained and compared. Test results indicate that the inclusion of soil reinforcement in the replaced sand not only significantly increases the stability of the sandy slope itself but also decreases much both the monotonic and cumulative cyclic settlements leading to an economic design of the footings. However, the efficiency of the sand–geogrid systems depends on the properties of the cyclic load and the location of the footing relative to the slope crest. Based on the test results, the variation of cumulative settlements with different parameters is presented and discussed.

  9. Characteristics of the Paleozoic slope break system and its control on stratigraphic-lithologic traps: An example from the Tarim Basin, western China

    Directory of Open Access Journals (Sweden)

    Hao Liu

    2015-07-01

    Full Text Available Based on comprehensive analyses of seismic and log data, this study indicates that mainly four widespread angular to minor angular unconformities (Tg8, Tg51, Tg5 and Tg3 were formed during the Paleozoic. Through the interpretation of structural unconformities, calculation of eroded thickness, correction of palaeo-water depth and compaction and compilation of the Early Paleozoic structural maps, the Early Paleozoic slope break belt (geomorphologic unit of the Tarim Basin is subdivided into uplift area, subaqueous uplift area, rift slope break belt, flexure slope break belt (slope belt, depression area and deep basin area. Palaeogeomorphology of the Cambrian-Early Ordovician was approximately in EW trend within which three tectonic units including the Tabei Palaeo-uplift, the northern Depressional Belt and the southern Palaeo-uplift developed respectively and are grouped into two slope break systems namely as the Tabei Palaeo-uplift and the southern Palaeo-uplift. These tectonic units obviously control the deposition of isolated platform, open platform, restricted platform and deep basin. Influenced by extrusion in the Mid-Late Ordovician, the southern and northern subaqueous uplifts gradually elevated and then were eroded. Resultantly two slope break systems developed, namely as the northern and central Palaeo-uplifts which obviously controlled the deposition of provenance area, isolated platform, mixed continental shelf, slope and basin facies. The intensive extrusion of the Mid-Late Ordovician leads to significant tectonic deformation of the Tarim Basin: large area of uplifting and erosion and development of EW trending anticline and syncline. Deposition of shore, tidal flat, delta, shallow marine clastics and deep marine facies is obviously controlled by the Tabei, the southern and the Tadong Palaeo-uplifts. Slope break systems control development of stratigraphic unconformity and thus truncation and onlap unconformity zones become favorable

  10. The Influence of Slope Breaks on Lava Flow Surface Disruption

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Stephen M.; Fagents, Sarah A.; Wright, Robert

    2014-01-01

    Changes in the underlying slope of a lava flow impart a significant fraction of rotational energy beyond the slope break. The eddies, circulation and vortices caused by this rotational energy can disrupt the flow surface, having a significant impact on heat loss and thus the distance the flow can travel. A basic mechanics model is used to compute the rotational energy caused by a slope change. The gain in rotational energy is deposited into an eddy of radius R whose energy is dissipated as it travels downstream. A model of eddy friction with the ambient lava is used to compute the time-rate of energy dissipation. The key parameter of the dissipation rate is shown to be rho R(sup 2/)mu, where ? is the lava density and mu is the viscosity, which can vary by orders of magnitude for different flows. The potential spatial disruption of the lava flow surface is investigated by introducing steady-state models for the main flow beyond the steepening slope break. One model applies to slow-moving flows with both gravity and pressure as the driving forces. The other model applies to fast-moving, low-viscosity, turbulent flows. These models provide the flow velocity that establishes the downstream transport distance of disrupting eddies before they dissipate. The potential influence of slope breaks is discussed in connection with field studies of lava flows from the 1801 Hualalai and 1823 Keaiwa Kilauea, Hawaii, and 2004 Etna eruptions.

  11. Surficial geology and geomorphology of Potter County, Pennsylvania

    Science.gov (United States)

    Denny, C.S.

    1956-01-01

    striated pebbles and is only locally marked by a terminal moraine or by a distinct change in the surficial deposits. The drift border is relatively straight and crosses the Genesee quadrangle in a northwesterly direction with little regard for the major topographic features, thus suggesting that the Wisconsin ice sheet had a relatively straight and steep front. Over most of the unglaciated part of Potter County, the bedrock is concealed beneath rubble that probably was formed during the Iowan or Tazewell substage, almost contemporaneously with the adjacent drift. In general, the rubble is thickest and most extensive within about 10 miles of the drift border, becoming thinner and less continuous farther away. The apparent parallelism between a belt of thick periglacial deposits and the drift border suggests that the deposits result from climatic factors in operation while the Wisconsin ice sheet was nearby. Ancient soil structures or patterned ground occur at, or near, the surface of both the periglacial deposits and the adjacent drift. These ancient soil structures are so similar to modern forms in arctic or alpine environments that they are considered to be the result of vigorous frost action. Many of the structures are believed to be a result of down-slope movement of debris by solifluction, facilitated by a frozen subsoil as much as 10 feet deep. Perennially frozen ground may have been present, but this is not a prerequisite. The periglacial deposits underlie long smooth slopes that extend from ridge crest to valley bottom. Flood plains are absent near the headwaters of many streams, the valley walls forming a V-shaped profile. While frost action was in progress, forests probably were restricted to flood plains, lower slopes, and scattered upland areas. Large parts of the upland were bare or partly covered by tundra vegetation; elsewhere, there were scattered trees but no dense forest. 1 2 SURFICIAL GEOLOGY AND GEOMORPHOLOGY OF POTTER COUNTY, PENNSYLVANIA Recent

  12. Spatial distribution level of land erosion disposition based on the analysis of slope on Central Lematang sub basin

    Science.gov (United States)

    Putranto, Dinar Dwi Anugerah; Sarino, Yuono, Agus Lestari

    2017-11-01

    Soil erosion is a natural process that is influenced by the magnitude of rainfall intensity, land cover, slope, soil type and soil processing system. However, it is often accelerated by human activities, such as improper cultivation of agricultural land, clearing of forest land for mining activities, and changes in topographic area due to use for other purposes such as pile materials, mined pits and so on. The Central Lematang sub-basin is part of the Lematang sub basin, at the Musi River Region Unit, South Sumatra Province, in Indonesia, which has a topographic shape with varying types of slope and altitude. The critical condition of Central Lematang sub basin has been at an alarming rate, as more than 47.5% of topographic and land use changes are dominated by coal mining activities and forest encroachment by communities. The method used in predicting erosion is by USPED (Unit Stream Power Erosion and Disposition). This is because the USPED [1] method can predict not only sediment transport but also the value of peeling (detachment) and sediment deposition. From slope analysis result, it is found that the highest erosion potential value is found on slope (8-15%) and the sediment is carried on a steep slope (15-25%). Meanwhile, the high sediment deposition area is found in the waters of 5.226 tons / ha / year, the steeper area of 2.12 tons / ha / year.

  13. Assessment of Slope Stability of Various Cut Slopes with Effects of Weathering by Using Slope Stability Probability Classification (SSPC)

    Science.gov (United States)

    Ersöz, Timur; Topal, Tamer

    2017-04-01

    Rocks containing pore spaces, fractures, joints, bedding planes and faults are prone to weathering due to temperature differences, wetting-drying, chemistry of solutions absorbed, and other physical and chemical agents. Especially cut slopes are very sensitive to weathering activities because of disturbed rock mass and topographical condition by excavation. During and right after an excavation process of a cut slope, weathering and erosion may act on this newly exposed rock material. These acting on the material may degrade and change its properties and the stability of the cut slope in its engineering lifetime. In this study, the effect of physical and chemical weathering agents on shear strength parameters of the rocks are investigated in order to observe the differences between weathered and unweathered rocks. Also, slope stability assessment of cut slopes affected by these weathering agents which may disturb the parameters like strength, cohesion, internal friction angle, unit weight, water absorption and porosity are studied. In order to compare the condition of the rock materials and analyze the slope stability, the parameters of weathered and fresh rock materials are found with in-situ tests such as Schmidt hammer and laboratory tests like uniaxial compressive strength, point load and direct shear. Moreover, slake durability and methylene blue tests are applied to investigate the response of the rock to weathering and presence of clays in rock materials, respectively. In addition to these studies, both rock strength parameters and any kind of failure mechanism are determined by probabilistic approach with the help of SSPC system. With these observations, the performances of the weathered and fresh zones of the cut slopes are evaluated and 2-D slope stability analysis are modeled with further recommendations for the cut slopes. Keywords: 2-D Modeling, Rock Strength, Slope Stability, SSPC, Weathering

  14. Late-stage development of the Bryant Canyon turbidite pathway on the Louisiana continental slope

    Science.gov (United States)

    Twichell, David C.; Nelson, Hans; Damuth, John E.

    2000-01-01

    GLORIA sidescan imagery, multibeam bathymetry, seismic profiles, and piston cores (3–5 m penetration) reveal the near-surface geology of the Bryant Canyon turbidite pathway on the continental margin of Louisiana. This pathway extends from the continental shelf edge, across the continental slope, to a deep-sea fan on the continental rise. The pathway is narrow (thalweg no longer has a continuous down-slope gradient. Some mini-basin floors along the pathway are now more than 500 m deeper than their basin’s spill point. We propose a 6-stage conceptual model to explain our observations for the evolution of a mini-basin along this turbidite pathway. In this model, an active channel feeds sand to a mini-basin (Stabe B). Once the mini-basin is filled, the sand deposit is entrenched by a bypass channel (Stage C). When the turbidite system shuts off, salt migration oversteepens the mini-basin walls (Stage D) which collapse and create a layer of mass-transport deposits on the mini-basin floor (Stage E). The depositional succession is capped by a layer of highstand hemipelagic drape (Stage F). The Bryant Canyon turbidite pathway provides a recent example of a large turbidite pathway in the Gulf of Mexico that crosses an area of active salt tectonics thus providing a conceptual model for older systems in similar settings. In Bryant Canyon, thick turbidite sands presumably are found in mini-basins however, they are sealed by thick, fine-grained, mass-transport deposits which terminate mini-basin turbidite deposition cycles. The importance of mass-transport deposits in basins along this turbidite pathway is in startling contrast to the Trinity-Brazos pathway whose shallow subsurface expression is virtually free of mass-transport deposits and has undergone minimal deformation by salt movement.

  15. North Slope (Wahluke Slope) expedited response action cleanup plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi{sup 2} (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives.

  16. North Slope (Wahluke Slope) expedited response action cleanup plan

    International Nuclear Information System (INIS)

    1994-02-01

    The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi 2 (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives

  17. Large quaternary landslides in the central appalachian valley and ridge province near Petersburg, West Virginia

    Science.gov (United States)

    Southworth, C. Scott

    1988-01-01

    Geological mapping and photointerpretation of side-looking airborne radar images and color-infrared aerial photographs reveal two large Quaternary landslides in the Valley and Ridge province of the central Appalachians near Petersburg, W. Va. The Elkhorn Mountain rock avalanche occurs on the thrust-faulted northwestern flank of the Elkhorn Mountain anticlinorium. A minimum of 7 ?? 106 m3 of quartzite colluvium was transported more than 3 km from a 91 m high escarpment of Silurian Tuscarora Quartzite. The extensively vegetated deposit may owe, in part, its transport and weathering to periglacial conditions during the Pleistocene. In contrast, the Gap Mountain rock block slide is a single allochthonous block that is 1.2 km long, 0.6 km wide, and at least 60 m thick. The 43 ?? 106 m3 block is composed of limestone of the Helderberg Group and the Oriskany Sanstone of Early Devonian age. Planar detachment probably occurred along a dissolution bedding plane near the Shriver Chert and the Oriskany Sandstone contact. Failure probably was initiated by downcutting of the South Branch Potomac River during the Pleistocene. Landslides of this magnitude suggest accelerated erosion during periglacial climates in the Pleistocene. The recognition of these large slope failures may provide evidence of paleoclimatic conditions and, thereby, increase our understanding of the geomorphologic development of the Valley and Ridge province. ?? 1988.

  18. Testing OSL failures against a regional glaciation chronology from southern Scandinavia

    DEFF Research Database (Denmark)

    Houmark-Nielsen, Michael

    2008-01-01

    Middle Weichselian periglacial strata and Last Glacial Maximum (LGM) ice proximal deposits showing pre-LGM ages. Suggestions are given as to how the depositional environment may influence the dating results. Even though independent dating anchors the marine Cyprina clay and last interglacial peat bogs...

  19. Geochemical Identification of Windblown Dust Deposits in the Upper Permian Brushy Canyon Formation, Southern New Mexico

    Science.gov (United States)

    Tice, M. M.; Motanated, K.; Weiss, R.

    2009-12-01

    Windblown dust is a potentially important but difficult-to-quantify source of siliciclastics for sedimentary basins worldwide. Positively identifying windblown deposits requires distinguishing them from other low density suspension transport deposits. For instance, laminated very fine grained sandstones and siltstones of the Upper Permian Brushy Canyon Formation have been variously interpreted as 1) the deposits of slow-moving, low-density turbidity currents, 2) distal overbank deposits of turbidity currents, 3) the deposits of turbulent suspensions transported across a pycnocline (interflows), and 4) windblown dust. This facies forms the bulk of Brushy Canyon Formation slope deposits, so understanding its origin is critical to understanding the evolution of the basin as a whole. We use a geochemical mapping technique (x-ray fluorescence microscopy) to show that these rocks are up to two times enriched in very fine sand sized zircon and rutile grains relative to Bouma A divisions of interbedded turbidites, suggesting substantial turbulence during transport. However, in contrast with the A divisions, the laminated sandstones and siltstones never show evidence of scour or amalgamation, implying that flow turbulence did not interact with underlying beds. Moreover, proximal loess deposits are often characterized by elevated Zr/Al2O3. These observations are most consistent with windblown interpretations for Brushy Canyon Formation slope sediments, and suggest that evolution of this early deepwater slope system was controlled largely by short-distance aeolian transport of very fine sand and silt from the coast. Heavy mineral incorporation into Brushy Canyon Formation slope deposits as reflected in laminae-scale bulk Zr and Ti abundances may preserve a long-term record of local wind intensity during the Upper Permian.

  20. Sedimentary dynamics and high-frequency sequence stratigraphy of the southwestern slope of Great Bahama Bank

    Science.gov (United States)

    Wunsch, Marco; Betzler, Christian; Eberli, Gregor P.; Lindhorst, Sebastian; Lüdmann, Thomas; Reijmer, John J. G.

    2018-01-01

    New geophysical data from the leeward slope of Great Bahama Bank show how contour currents shape the slope and induce re-sedimentation processes. Along slope segments with high current control, drift migration and current winnowing at the toe of slope form a deep moat. Here, the slope progradation is inhibited by large channel incisions and the accumulation of large mass transport complexes, triggered by current winnowing. In areas where the slope is bathed by weaker currents, the accumulation of mass transport complexes and channel incision is rather controlled by the position of the sea level. Large slope failures were triggered during the Mid-Pleistocene transition and Mid-Brunhes event, both periods characterized by changes in the cyclicity or the amplitude of sea-level fluctuations. Within the seismic stratigraphic framework of third order sequences, four sequences of higher order were identified in the succession of the upper Pleistocene. These higher order sequences also show clear differences in function of the slope exposure to contour currents. Two stochastic models emphasize the role of the contour currents and slope morphology in the facies distribution in the upper Pleistocene sequences. In areas of high current influence the interplay of erosional and depositional processes form a complex facies pattern with downslope and along strike facies alterations. In zones with lower current influence, major facies alternations occur predominately in downslope direction, and a layer-cake pattern characterizes the along strike direction. Therefore, this study highlights that contour currents are an underestimated driver for the sediment distribution and architecture of carbonate slopes.

  1. Model slope infiltration experiments for shallow landslides early warning

    Science.gov (United States)

    Damiano, E.; Greco, R.; Guida, A.; Olivares, L.; Picarelli, L.

    2009-04-01

    Occurrence of fast landslides has become more and more dangerous during the last decades, due to the increased density of settlements, industrial plants and infrastructures. Such problem is particularly worrying in Campania (Southern Italy), where the fast population growth led a diffuse building activity without planning: indeed, recent flowslides caused hundreds of victims and heavy damages to buildings, roads and other infrastructures. Large mountainous areas in Campania are mantled by loose pyroclastic granular soils up to a depth of a few meters from top soil surface. These soils have usually a grain size that falls in the domain of silty sands, including pumice interbeds (gravelly sands), with saturated hydraulic conductivities up to the order of 10-1 cm/min. Such deposits often cover steep slopes, which stability is guaranteed by the apparent cohesion due to suction under unsaturated conditions, that are the most common conditions for these slopes [Olivares and Picarelli, 2001]. Whereas rainfall infiltration causes soil to approach saturation, suction vanishes and slope failure may occur. Besides soil physical properties, landslide triggering is influenced by several factors, such as rainfall intensity, soil initial moisture and suction, slope inclination, boundary conditions. Whereas slope failure occurs with soil close to being saturated, landslide may develop in form of fast and destructive flowslide. Calibration of reliable mathematical models of such a complex phenomenon requires availability of experimental observations of the major variables of interest, such as soil moisture and suction, soil deformation and displacements, pore water pressure, during the entire process of infiltration until slope failure. Due to the sudden trigger and extremely rapid propagation of such type of landslides, such data sets are rarely available for natural slopes where flowslides occurred. As a consequence landslide risk assessment and early warning in Campania rely on

  2. Calcareous nannofossil biostratigraphy and geochronology of Neogene trench-slope cover sediments in the south Boso Peninsula, central Japan: Implications for the development of a shallow accretionary complex

    Science.gov (United States)

    Chiyonobu, Shun; Yamamoto, Yuzuru; Saito, Saneatsu

    2017-07-01

    The geological structure and calcareous nannofossil biostratigraphy of the Middle to Late Miocene trench-slope succession in the southern Boso Peninsula, central Japan, were examined to obtain chronological constraints on the accretion and formation of the trench-slope architecture. As a result, trench-slope cover sediments (Kinone and Amatsu Formations) are clearly distinguishable from the Early Miocene Hota accretionary complex (Hota Group). The Hota accretionary complex was deposited below the carbonate compensation depth (CCD) and was affected by intense shearing, forming an east-west trending and south-verging fold and thrust belt. In contrast, the trench-slope cover sediments basically have a homoclinal dip, except at the northern rim where they are bounded by fault contact. They contain many species of calcareous nannofossils and foraminifers, which are indicative of their depositional environment above the CCD, and they show shallowing-upward sedimentary structures. Biostratigraphy revealed that the depositional age of the trench-slope sediments is ca. 15-5.5 Ma, suggesting that there is an approximately 2 myr hiatus beween the Miura Group and the underlying accretionary prism. Based on these results, the age of accretion of the Hota Group is inferred to be between ca. 17-15 Ma, and the group is covered by trench-slope sediments overlain on it after ca. 15 Ma. The timing of accretion and the age of the trench-slope basin tend to be younger southward of the Boso Peninsula. The accretionary system of the Boso Peninsula apparently developed in two stages, in the Middle Miocene and in the Late Miocene to Pliocene.

  3. Editorial: Introduction to the Special Issue ;Slope Tectonics: Inherited Structures, Morphology of Deformation and Catastrophic Failure;

    Science.gov (United States)

    Hermanns, R. L.; Oppikofer, T.; Jaboyedoff, M.; Clague, J. J.; Scarascia-Mugnozza, G.

    2017-07-01

    The "Conference on Slope Tectonics" has become an international scientific meeting point to present and discuss a variety of topics related to slope deformation and the deposits of related failures. The first conference took place on February 15-16, 2008 at University of Lausanne (Switzerland). It was followed by a second conference on September 6-10, 2011, in Austria (organized by the Geological Survey of Austria) and a third on September 8-12, 2014, in Norway (organized by the Geological Survey of Norway). The two later events included field trips. It has become a tradition that selected papers from these conference are published - papers from the first conference were published by the Geological Society as Special Publication 351 (Jaboyedoff, 2011), and those from the second conference were published in a special issue of Tectonophysics (Baron and Jaboyedoff, 2013). This special issue of Geomorphology is a collection of papers presented at the Norwegian Conference on Slope Tectonics. This collection of papers focuses on the role of tectonics in gravitationally induced rock-slope instabilities. The slopes either deform over long periods as deep-seated gravitational slope deformation (DSGSD) or more rapidly as rockslides or rock avalanches. The reconstruction of slope deformation is an integral part of the studies captured in this special issue.

  4. Carbonate Channel-Levee Systems Influenced by Mass-Transport Deposition, Browse Basin, Australia

    Science.gov (United States)

    Dunlap, D.; Janson, X.; Sanchez-Phelps, C.; Covault, J. A.

    2017-12-01

    Submarine channels are primary conduits for clastic sediment transport to deep-water basins, thereby controlling the location of marine depocenters and sediment bypass. The evolution and depositional character of submarine channels have broad implications to sediment dispersal, sediment quality, and hydrocarbon exploration potential. Siliciclastic channel systems have been extensively studied in modern environments, seismic and outcrop; however, carbonate channel-levee deposits have only recently been explored. Here we utilize newly released high-resolution (90 Hz) seismic-reflection data from the Australian Browse Basin to document the influence of mass-transport complex (MTC) deposition on the stratigraphic architecture of carbonate channel-levee systems. The 2014 vintage seismic survey is 2500 km2 and hosts numerous large Miocene-age carbonate channel-levee complexes basinward of the shelf edge. Regional horizons and individual channel forms were mapped. Channels range from 200-300 m wide and are bounded by high-relief levee-overbank wedges (>100 ms TWTT). These channels extend across the survey area >70 km. The leveed-channels were sourced from middle and late Miocene slope gullies linked to platform carbonates. Slope-attached and locally derived MTC's are evident throughout the Miocene section likely related to periods of basin inversion and shelf-edge gully incision. We interpret that regionally extensive (>1000 km2) slope-attached MTC's can shut down a channel-levee system and trigger the initiation of a new system, whereas more locally derived (wasting and turbidity currents, which informs depositional models of carbonate slope systems and calls for re-evaluation of the controls on stratigraphic patterns in mixed siliciclastic-carbonate deep-water basins.

  5. 16 determination of posterior tibia slope and slope deterioration

    African Journals Online (AJOL)

    normal slope and mechanical axis of the knee (7). The slope is reported to deepen in osteoarthritis; meaning increased articular surface contact and increased tibial translation (8). Total knee replacement aims to restore the mechanical axis of the natural knee joint. This axis will be changed by an altered PTS; yet after.

  6. Slope Estimation from ICESat/GLAS

    Directory of Open Access Journals (Sweden)

    Craig Mahoney

    2014-10-01

    Full Text Available We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM. The technique is applied to large footprint waveforms (\\(\\sim\\ mean diameter from the Ice, Cloud and Land Elevation Satellite (ICESat Geoscience Laser Altimeter System (GLAS to produce a slope dataset of near-global coverage at \\(0.5^{\\circ} \\times 0.5^{\\circ}\\ resolution. ISM slope estimates are compared against high resolution airborne LiDAR slope measurements for nine sites across three continents. ISM slope estimates compare better with the aircraft data (R\\(^{2}=0.87\\ and RMSE\\(=5.16^{\\circ}\\ than the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM inferred slopes (R\\(^{2}=0.71\\ and RMSE\\(=8.69^{\\circ}\\ ISM slope estimates are concurrent with GLAS waveforms and can be used to correct biophysical parameters, such as tree height and biomass. They can also be fused with other DEMs, such as SRTM, to improve slope estimates.

  7. Preliminary Slope Stability Study Using Slope/ W

    International Nuclear Information System (INIS)

    Nazran Harun; Mohd Abd Wahab Yusof; Kamarudin Samuding; Mohd Muzamil Mohd Hashim; Nurul Fairuz Diyana Bahrudin

    2014-01-01

    Analyzing the stability of earth structures is the oldest type of numerical analysis in geotechnical engineering. Limit equilibrium types of analyses for assessing the stability of earth slopes have been in use in geotechnical engineering for many decades. Modern limit equilibrium software is making it possible to handle ever-increasing complexity within an analysis. It is being considered as the potential method in dealing with complex stratigraphy, highly irregular pore-water pressure conditions, various linear and nonlinear shear strength models and almost any kind of slip surface shape. It allows rapid decision making by providing an early indication of the potential suitability of sites based on slope stability analysis. Hence, a preliminary slope stability study has been developed to improve the capacity of Malaysian Nuclear Agency (Nuclear Malaysia) in assessing potential sites for Borehole Disposal for Disused Sealed Radioactive Sources. The results showed that geometry of cross section A-A ' , B-B ' , C-C ' and D-D ' achieved the factor of safety not less than 1.4 and these are deemed acceptable. (author)

  8. Cold-climate slope deposits and landscape modifications of the Mid-Atlantic Coastal Plain, Eastern USA

    Science.gov (United States)

    Newell, Wayne L.; Dejong, B.D.

    2011-01-01

    The effects of Pleistocene cold-climate geomorphology are distributed across the weathered and eroded Mid-Atlantic Coastal Plain uplands from the Wisconsinan terminal moraine south to Tidewater Virginia. Cold-climate deposits and landscape modifications are superimposed on antecedent landscapes of old, weathered Neogene upland gravels and Pleistocene marine terraces that had been built during warm periods and sea-level highstands. In New Jersey, sequences of surficial deposits define a long history of repeating climate change events. To the south across the Delmarva Peninsula and southern Maryland, most antecedent topography has been obscured by Late Pleistocene surficial deposits. These are spatially variable and are collectively described as a cold-climate alloformation. The cold-climate alloformation includes time-transgressive details of climate deterioration from at least marine isotope stage (MIS) 4 through the end of MIS 2. Some deposits and landforms within the alloformation may be as young as the Younger Dryas. Southwards along the trend of the Potomac River, these deposits and their climatic affinities become diffused. In Virginia, a continuum of erosion and surficial deposits appears to be the product of ‘normal’ temperate, climate-forced processes. The cold-climate alloformation and more temperate deposits in Virginia are being partly covered by Holocene alluvium and bay mud.

  9. Stratigraphy and Facies of Cretaceous Schrader Bluff and Prince Creek Formations in Colville River Bluffs, North Slope, Alaska

    Science.gov (United States)

    Flores, Romeo M.; Myers, Mark D.; Houseknecht, David W.; Stricker, Gary D.; Brizzolara, Donald W.; Ryherd, Timothy J.; Takahashi, Kenneth I.

    2007-01-01

    Stratigraphic and sedimentologic studies of facies of the Upper Cretaceous rocks along the Colville River Bluffs in the west-central North Slope of Alaska identified barrier shoreface deposits consisting of vertically stacked, coarsening-upward parasequences in the Schrader Bluff Formation. This vertical stack of parasequence deposits represents progradational sequences that were affected by shoaling and deepening cycles caused by fluctuations of sea level. Further, the vertical stack may have served to stabilize accumulation of voluminous coal deposits in the Prince Creek Formation, which formed braided, high-sinuosity meandering, anastomosed, and low-sinuosity meandering fluvial channels and related flood plain deposits. The erosional contact at the top of the uppermost coarsening-upward sequence, however, suggests a significant drop of base level (relative sea level) that permitted a semiregional subaerial unconformity to develop at the contact between the Schrader Bluff and Prince Creek Formations. This drop of relative sea level may have been followed by a relative sea-level rise to accommodate coal deposition directly above the unconformity. This rise was followed by a second drop of relative sea level, with formation of incised valley topography as much as 75 ft deep and an equivalent surface of a major marine erosion or mass wasting, or both, either of which can be traced from the Colville River Bluffs basinward to the subsurface in the west-central North Slope. The Prince Creek fluvial deposits represent late Campanian to late Maastrichtian depositional environments that were affected by these base level changes influenced by tectonism, basin subsidence, and sea-level fluctuations.

  10. Assessment and mapping of slope stability based on slope units: A ...

    Indian Academy of Sciences (India)

    Shallow landslide; infinite slope stability equation; return period precipitation; assessment; slope unit. ... 2010), logistic regression ... model to assess the hazard of shallow landslides ..... grating a fuzzy k-means classification and a Bayesian.

  11. Spectro-Morphologic Analysis of Pyroclastic Deposits on Mercury

    Science.gov (United States)

    Doressoundiram, A.; Besse, S.; Hersérant, W.

    2014-12-01

    Observations of the MESSENGER spacecraft in orbit around Mercury have shown that volcanism is a very important process that has shaped the surface of the planet. Kerber et al. [2011,2014] have identified 200 pyroclastic deposits candidates based on color ratio and morphology images. Goudge et al. [2014] used the visible portion of the MASCS spectrometer to do further analysis on the spectral nature of the deposits. The authors have shown that the deposits have specific UV properties probably caused by Oxygen-Metal charges transfer, and a correlation between the slope of the UV-downturn and the age of the surrounding terrains. In this study, we use the full range of the MASCS spectrometer (300-1400nm) to characterize the spectral properties of the pyroclastic deposits. Moreover, additional observations have been obtained since the last publications, and this allows specific studies of previously non-imaged deposits. This study shows that the visible slope of the deposits is changing as a function of distance from the vent, as seen on the Moon for pyroclastic deposits and their mafic absorption bands [Besse et al, 2013]. This is consistent with a decrease of thickness of the deposits that are mixed with background material. Surprisingly, the UV-downturn parameter proposed by Goudge et al. [2014] does not change as the distance to the vent increase. Eventually, the near infrared portion does not appear to have absorption bands in the range 900nm-1200nm, consistent with the very low iron abundance of the surface of Mercury. This could also be due to the lower signal to noise ratio of the near infrared portion of the MASCS instrument, and further analysis are needed to confirm these results. The use of visible images from the MDIS camera has revealed that some of the pyroclastic deposits candidates are certainly correlated with hollows.

  12. Correlation between vegetation pattern and microtopography in periglacial areas of the Central Alps

    Directory of Open Access Journals (Sweden)

    Gerdol, Renato

    1990-06-01

    Full Text Available The distributional patterns of plant species were analyzed within periglacial microforms belonging to the collective groups of patterned grounds and sorted stripes In the Ortles-Cevedale group (Lombardy, Italy. The edges of primitive polygons are practically free of vegetation, whilst the central areas are colonized by pioneer plants of detritic slopes. This is clearly correlated with a low degree of sediment sorting. The morphological evolution of the forms proceeds at a faster rate at the edge of polygons than in the central areas. Vegetation, on the other hand, colonizes the coarse debris at the polygons’ edges slowly but colonizes the fine material in the central areas actively. The centre of the most evolved polygons is covered by a carpet of Salix herbacea. Age determinations of Salix shoots are not useful for dating purposes, but provide Information about the local microclimate.

    [es] Se han analizado los modelos de distribución de especies vegetales en microformas periglaciares pertenecientes al tipo de suelos estructurales en el Ortles-Cevedale (Lombardía, Italia. Los límites de los polígonos de piedras están prácticamente libres de vegetación, mientras las áreas centrales están colonizadas por plantas pioneras de laderas pedregosas. La evolución morfológica actúa a mayor velocidad en el borde de los polígonos que en las áreas centrales. Por otro lado, la vegetación coloniza lentamente los bordes de los polígonos, y más activamente las zonas centrales. El centro de la mayoría de los polígonos está cubierto por un manto de Salix herbacea. La determinación de la edad de los vástagos de Salix no ha sido un método útil a efectos cronológicos, pero proporciona información sobre el microclima local.
    [fr] On étude les modèles de distribution d'espèces végétaux dans microformes périglaciaires appartenants au type de sols structurales dans l'Ortles-Cevedale (Lombardie

  13. Infiltration on sloping terrain and its role on runoff generation and slope stability

    Science.gov (United States)

    Loáiciga, Hugo A.; Johnson, J. Michael

    2018-06-01

    A modified Green-and-Ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application. This paper's theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations (pdes) governing infiltration and runoff. These pdes are solved by employing an explicit finite-difference numerical method that yields the infiltration, the infiltration rate, the depth to the wetting front, the rate of runoff, and the depth of runoff everywhere on the slope during external wetting. Data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration, soil hydraulic characteristics and antecedent moisture, and the slope's hydraulic and geometric characteristics. The presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding. This paper's theory also develops the 1D pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration. Three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain.

  14. A benthic carbon budget for the continental slope off Cape Hatteras, N.C.

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, C.J.; Blair, N.E.; DeMaster, D.J.; Jahnke, R.A.; Martens, C.S.

    1999-01-31

    The continental slope off Cape Hatteras, N.C. from approximately 36{degree} 00 minutes N to 35{degree} 20 minutes N is a region of relatively rapid sediment accumulation, organic matter deposition and subsequent remineralization. The measured fluxes are the highest reported for the slope off the eastern US Sediment accumulation rates range from 40 to 140 cm ky{sup -1}. Organic carbon deposition rates range from 3.5 to 7.4 moles C m{sup -2} yr{sup -1}. The areal coverage of this ''depocenter'' is probably controlled by interactions between physical oceanographic processes and the rugged topography of the seafloor. The organic matter deposited on the seafloor is primarily marine in origin and a mix of old and fresh particles. 73-93% of the depositing detritus is rapidly oxidized near the sediment/water interface. The controls on subsurface remineralization appear to be a complex function of the relative amount of metabolizable carbon delivered to the seabed both now and in the distant past (>=500ybp) and the extent of seabed irrigation. The age of DIC and CH{sub 4} produced within the seabed indicates that relatively young, reactive carbon is advected below the sediment surface and fuels subsurface remineralization. The stable isotopic composition of DIC produced within the seabed indicates the selective degradation of {sup 13}C-enriched fractions of the organic matter. The metabolizable fraction has a carbon isotopic signature of approx. -18{per_thousand};, while the organic matter that survives degradation and is buried has a d{sup 13}C closer to -20{per_thousand}.

  15. IMPROVED LARGE-SCALE SLOPE ANALYSIS ON MARS BASED ON CORRELATION OF SLOPES DERIVED WITH DIFFERENT BASELINES

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2017-07-01

    Full Text Available The surface slopes of planetary bodies are important factors for exploration missions, such as landing site selection and rover manoeuvre. Generally, high-resolution digital elevation models (DEMs such as those generated from the HiRISE images on Mars are preferred to generate detailed slopes with a better fidelity of terrain features. Unfortunately, high-resolution datasets normally only cover small area and are not always available. While lower resolution datasets, such as MOLA, provide global coverage of the Martian surface. Slopes generated from the low-resolution DEM will be based on a large baseline and be smoothed from the real situation. In order to carry out slope analysis at large scale on Martian surface based low-resolution data such as MOLA data, while alleviating the smoothness problem of slopes due to its low resolution, this paper presents an amplifying function of slopes derived from low-resolution DEMs based on the relationships between DEM resolutions and slopes. First, slope maps are derived from the HiRISE DEM (meter-level resolution DEM generated from HiRISE images and a series of down-sampled HiRISE DEMs. The latter are used to simulate low-resolution DEMs. Then the high-resolution slope map is down- sampled to the same resolution with the slope map from the lower-resolution DEMs. Thus, a comparison can be conducted pixel-wise. For each pixel on the slope map derived from the lower-resolution DEM, it can reach the same value with the down-sampled HiRISE slope by multiplying an amplifying factor. Seven sets of HiRISE images with representative terrain types are used for correlation analysis. It shows that the relationship between the amplifying factors and the original MOLA slopes can be described by the exponential function. Verifications using other datasets show that after applying the proposed amplifying function, the updated slope maps give better representations of slopes on Martian surface compared with the original

  16. Polar layered deposits on Mars: Inner structure and relation to the climate record

    Science.gov (United States)

    Kreslavsky, M.; Head, J.

    Martian polar layered deposits (PLD) have long been thought to contain a record of the past climate. Roles of deposition, ablation and flow in PLD are a subject of discussion and controversy. Understanding of these roles is critical for reading the climate record. We show that simple mechanism including latitude-dependent deposition and ablation, albedo feedback and role of slopes explains many essential features of the PLD. We consider the present-day PLD is a result of a history of H2O ice deposition and sublimation during some recent period of the geological history. The deposition - ablation balance is a function of latitude. Typically, net deposition occurs in the polar area inside some boundary latitude of zero balance, and net ablation occurs outside. This dividing latitude shifts back and forth due to climate change caused by (1) the change of the spin/orbit parameters ("astronomical forcing"), (2) availability of the water vapor source at lower latitudes (tropical mountain glaciers, high-latitude icy mantles, the opposite polar cap, groundwater discharge events), (3) internal climate instabilities. The outermost position of the ablation/deposition boundary was well outside the present margins of the PLD; in the opposite extremes, the area of the positive balance disappeared, and the whole polar cap underwent ablation. Through time such oscillations produced a dome-shaped stack of deposits with a possible thin layer of deposits outside the dome and with a number of unconformities inside. These unconformities will have an east-west oriented strike and a very shallow dip. There is a positive feedback between the deposition/ablation balance and albedo: high albedo favors deposition, and fresh deposits have high albedo. With this feedback, when the climate system goes through oscillations, the boundary latitude between positive and negative balance will stay for some periods of time at its outermost and innermost positions. This will result in steps in the

  17. Characterization of pyroclastic deposits and pre-eruptive soils following the 2008 eruption of Kasatochi Island Volcano, Alaska

    Science.gov (United States)

    Wang, B.; Michaelson, G.; Ping, C.-L.; Plumlee, G.; Hageman, P.

    2010-01-01

    The 78 August 2008 eruption of Kasatochi Island volcano blanketed the island in newly generated pyroclastic deposits and deposited ash into the ocean and onto nearby islands. Concentrations of water soluble Fe, Cu, and Zn determined from a 1:20 deionized water leachate of the ash were sufficient to provide short-term fertilization of the surface ocean. The 2008 pyroclastic deposits were thicker in concavities at bases of steeper slopes and thinner on steep slopes and ridge crests. By summer 2009, secondary erosion had exposed the pre-eruption soils along gulley walls and in gully bottoms on the southern and eastern slopes, respectively. Topographic and microtopographic position altered the depositional patterns of the pyroclastic flows and resulted in pre-eruption soils being buried by as little as 1 m of ash. The different erosion patterns gave rise to three surfaces on which future ecosystems will likely develop: largely pre-eruptive soils; fresh pyroclastic deposits influenced by shallowly buried, pre-eruptive soil; and thick (>1 m) pyroclastic deposits. As expected, the chemical composition differed between the pyroclastic deposits and the pre-eruptive soils. Pre-eruptive soils hold stocks of C and N important for establishing biota that are lacking in the fresh pyroclastic deposits. The pyroclastic deposits are a source for P and K but have negligible nutrient holding capacity, making these elements vulnerable to leaching loss. Consequently, the pre-eruption soils may also represent an important long-term P and K source. ?? 2010 Regents of the University of Colorado.

  18. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark

    International Nuclear Information System (INIS)

    Vidstrand, Patrik; Follin, Sven; Zugec, Nada

    2010-12-01

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions

  19. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden)); Zugec, Nada (Bergab, Stockholm (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions.

  20. Discussion on metallogenic prospect of sandstone-type uranium deposit in Yabulai basin

    International Nuclear Information System (INIS)

    Wang Lianshe; Li Xiangping

    2003-01-01

    Based on characteristics of initial basin type and tectonic reworking process, this article analyses the distribution features of depositional system and subsequent alteration of the target horizon of sandstone-type uranium deposits in Yabulai basin. Guided by prognostic criteria of sandstone-type uranium deposits, authors suggest that the post-depositional tectonic reworking in the basin was quite intense, and uranium metallogenic prospects are unfavorable. However, the Lower Cretaceous in the paleo-slope at the middle of the basin does show certain metallogenic prospects for sandstone-type uranium deposits

  1. Thermoluminescence dating of abyssal deposits in the north region of the South China Sea

    International Nuclear Information System (INIS)

    Peng Xiaoxian

    1988-01-01

    The ages of abyssal deposits have been studied by TL dating. The ages of the deposits from the wells Weima 1, 5 and 6 at the slope in the north of the South China Sea are 36,100 and 128 thousand years respectively

  2. Slippery Slope Arguments

    NARCIS (Netherlands)

    van der Burg, W.; Chadwick, R.F.

    1998-01-01

    Slippery slope arguments hold that one should not take some action (which in itself may be innocuous or even laudable) in order to prevent one from being dragged down a slope towards some clearly undesirable situation. Their typical purpose is to prevent changes in the status quo and, therefore,

  3. Hydraulic mechanism and time-dependent characteristics of loose gully deposits failure induced by rainfall

    Directory of Open Access Journals (Sweden)

    Yong Wu

    2015-12-01

    Full Text Available Failure of loose gully deposits under the effect of rainfall contributes to the potential risk of debris flow. In the past decades, researches on hydraulic mechanism and time-dependent characteristics of loose deposits failure are frequently reported, however adequate measures for reducing debris flow are not available practically. In this context, a time-dependent model was established to determine the changes of water table of loose deposits using hydraulic and topographic theories. In addition, the variation in water table with elapsed time was analyzed. The formulas for calculating hydrodynamic and hydrostatic pressures on each strip and block unit of deposit were proposed, and the slope stability and failure risk of the loose deposits were assessed based on the time-dependent hydraulic characteristics of established model. Finally, the failure mechanism of deposits based on infinite slope theory was illustrated, with an example, to calculate sliding force, anti-sliding force and residual sliding force applied to each slice. The results indicate that failure of gully deposits under the effect of rainfall is the result of continuously increasing hydraulic pressure and water table. The time-dependent characteristics of loose deposit failure are determined by the factors of hydraulic properties, drainage area of interest, rainfall pattern, rainfall duration and intensity.

  4. Effects of grapevine root density and reinforcement on slopes prone to shallow slope instability

    Science.gov (United States)

    Meisina, Claudia; Bordoni, Massimiliano; Bischetti, Gianbattista; Vercesi, Alberto; Chiaradia, Enrico; Cislaghi, Alessio; Valentino, Roberto; Bittelli, Marco; Vergani, Chiara; Chersich, Silvia; Giuseppina Persichillo, Maria; Comolli, Roberto

    2016-04-01

    Slope erosion and shallow slope instabilities are the major factors of soil losses in cultivated steep terrains. These phenomena also cause loss of organic matter and plants nutrients, together with the partial or total destruction of the structures, such as the row tillage pattern of the vineyards, which allow for the plants cultivation. Vegetation has long been used as an effective tool to decrease the susceptibility of a slope to erosion and to shallow landslides. In particular, the scientific research focused on the role played by the plant roots, because the belowground biomass has the major control on the potential development of soil erosion and of shallow failures. Instead, a comprehensive study that analyzes the effects of the roots of agricultural plants on both soil erosion and slope instability has not been carried out yet. This aspect should be fundamental where sloped terrains are cultivated with plants of great economical relevance, as grapevine. To contribute to fill this gap, in this study the features of root density in the soil profile have been analyzed in slopes cultivated with vineyards, located on a sample hilly area of Oltrepò Pavese (northern Italy). In this area, the viticulture is the most important branch of the local economy. Moreover, several events of rainfall-induced slope erosion and shallow landslides have occurred in this area in the last 6 years, causing several economical damages linked to the destruction of the vineyards and the loss of high productivity soils. Grapevine root distribution have been measured in different test-site slopes, representative of the main geological, geomorphological, pedological, landslides distribution, agricultural features, in order to identify particular patterns on root density that can influence the development of slope instabilities. Roots have been sampled in each test-site for characterizing their strength, in terms of the relation between root diameter and root force at rupture. Root

  5. Investigations of slope stability

    Energy Technology Data Exchange (ETDEWEB)

    Nonveiller, E.

    1979-01-01

    The dynamics of slope slides and parameters for calculating slope stability is discussed. Two types of slides are outlined: rotation slide and translation slide. Slide dynamics are analyzed according to A. Heim. A calculation example of a slide which occurred at Vajont, Yugoslavia is presented. Calculation results differ from those presented by Ciabatti. For investigation of slope stability the calculation methods of A.W. Bishop (1955), N. Morgenstern and M. Maksimovic are discussed. 12 references

  6. Effects of glaciological and hydro-meteorological conditions on the glacial danger in Zailiyskiy Alatau

    Directory of Open Access Journals (Sweden)

    A. R. Medeu

    2017-01-01

    Full Text Available A need to estimate a hazard of a mudflow stream appearance in the glacial-nival zone of the Northern slope of Zailiyskiy Alatau (Kasakhstan is now one of the really urgent problems. The objective of this study was to inves‑ tigate influence of glacial and hydrometeorological factors on the condition of snow-glacial zone of Zailiyskiy Alatau and find out a mudflow-forming role of the mudflow centers arising due to climate warming and degra‑ dation of glaciation: periglacial lakes, intramoraine channels and reservoirs, and also talik massifs of morainic deposits. We analyzed glacial processes in the Zailiysky Alatau over a long period using meteorological data of the Almaty weather station and its close correlations with data from weather stations in the mountains. The area of glaciations was found out to be reduced after the maximum of the Little Ice Age. A combined diagram of occurrence of the mudflow manifestations and factors causing them had been constructed on the basis of sta‑ tistical data on the landslide phenomena. Glacial mudflows were the most frequent in 1960–1990, and later on activity of them became weaker. We believe, that in the next 10–20 years, the glacial mudflow hazard in Zailiys‑ kiy Alatau can sharply decrease, but at the same time, a probability of occurrence of the rainfall mudflows can increase in the mountainous zone of the ridge due the increase of areas with melted moraine and slope deposits.

  7. Mapping basin-wide subaquatic slope failure susceptibility as a tool to assess regional seismic and tsunami hazards

    Science.gov (United States)

    Strasser, Michael; Hilbe, Michael; Anselmetti, Flavio S.

    2010-05-01

    With increasing awareness of oceanic geohazards, submarine landslides are gaining wide attention because of their catastrophic impacts on both offshore infrastructures (e.g. pipelines, cables and platforms) and coastal areas (e.g. landslide-induced tsunamis). They also are of great interest because they can be directly related to primary trigger mechanisms including earthquakes, rapid sedimentation, gas release, glacial and tidal loading, wave action, or clathrate dissociation, many of which represent potential geohazards themselves. In active tectonic environments, for instance, subaquatic landslide deposits can be used to make inferences regarding the hazard derived from seismic activity. Enormous scientific and economic efforts are thus being undertaken to better determine and quantify causes and effects of natural hazards related to subaquatic landslides. In order to achieve this fundamental goal, the detailed study of past events, the assessment of their recurrence intervals and the quantitative reconstruction of magnitudes and intensities of both causal and subsequent processes and impacts are key requirements. Here we present data and results from a study using fjord-type Lake Lucerne in central Switzerland as a "model ocean" to test a new concept for the assessment of regional seismic and tsunami hazard by basin-wide mapping of critical slope stability conditions for subaquatic landslide initiation. Previously acquired high-resolution bathymetry and reflection seismic data as well as sedimentological and in situ geotechnical data, provide a comprehensive data base to investigate subaquatic landslides and related geohazards. Available data are implemented into a basin-wide slope model. In a Geographic Information System (GIS)-framework, a pseudo-static limit equilibrium infinite slope stability equation is solved for each model point representing reconstructed slope conditions at different times in the past, during which earthquake-triggered landslides

  8. Metasomatic zoning at some stratiform rare metal deposits

    International Nuclear Information System (INIS)

    Altyntsev, Yu.V.; Bazhenov, M.I.; Bepeshov, G.V.; Komarnitskij, G.M.; Petrov, I.Ya.; Serykh, A.S.

    1985-01-01

    Metasomatic zoning of stratiform deposits of rare metals (Mo, Pb, As, V, Se, U, etc.) in intermontane depresions, deposited at the postorogenic stage of Paleozoic geosyncline region development, is considered. Geochemical and geophysical characteristics of metasomatic zoning in the case of sloping and steep rock deposition are given. It is established, that in rare metal deposits in variegated deposits of molassoid formation of Middle-Upper Paleozoic the external and internal zones of metasomatic alterations are distinctly separated. The external zone is presented by mineral association: quartz + -albile + -calcite + -epidote; the internal one - by hydromica + -chlorite + -analcite, laumontite + -hematite + -ankerite + -kaolinite. Geochemical zoning is manifested quite regularly at all the deposits and it is subjected to metasomatic zoning. Changes in physical properties of rocks reflect the metasomatic zoning. The character of metasomatic alterations of rocks, geochemical zoning of metasomatites at rare metal deposits in molassoid deposits and spatially contiguous deposits in volcanogenic complexes have common features. A supposition is made on polygenic ore formation in sedimentary rocks of the depressions

  9. Quaternary deposits and landscape evolution of the central Blue Ridge of Virginia

    Science.gov (United States)

    Eaton, L. Scott; Morgan, Benjamin A.; Kochel, R. Craig; Howard, Alan D.

    2003-01-01

    A catastrophic storm that struck the central Virginia Blue Ridge Mountains in June 1995 delivered over 775 mm (30.5 in) of rain in 16 h. The deluge triggered more than 1000 slope failures; and stream channels and debris fans were deeply incised, exposing the stratigraphy of earlier mass movement and fluvial deposits. The synthesis of data obtained from detailed pollen studies and 39 radiometrically dated surficial deposits in the Rapidan basin gives new insights into Quaternary climatic change and landscape evolution of the central Blue Ridge Mountains.The oldest depositional landforms in the study area are fluvial terraces. Their deposits have weathering characteristics similar to both early Pleistocene and late Tertiary terrace surfaces located near the Fall Zone of Virginia. Terraces of similar ages are also present in nearby basins and suggest regional incision of streams in the area since early Pleistocene–late Tertiary time. The oldest debris-flow deposits in the study area are much older than Wisconsinan glaciation as indicated by 2.5YR colors, thick argillic horizons, and fully disintegrated granitic cobbles. Radiocarbon dating indicates that debris flow activity since 25,000 YBP has recurred, on average, at least every 2500 years. The presence of stratified slope deposits, emplaced from 27,410 through 15,800 YBP, indicates hillslope stripping and reduced vegetation cover on upland slopes during the Wisconsinan glacial maximum.Regolith generated from mechanical weathering during the Pleistocene collected in low-order stream channels and was episodically delivered to the valley floor by debris flows. Debris fans prograded onto flood plains during the late Pleistocene but have been incised by Holocene stream entrenchment. The fan incision allows Holocene debris flows to largely bypass many of the higher elevation debris fan surfaces and deposit onto the topographically lower surfaces. These episodic, high-magnitude storm events are responsible for

  10. Nitrogen and Phosphorous Flow in Atlantic Forest Covered Watersheds on the Oceanic and Continental Slopes at Serra dos Órgãos mountain, Southeast of Brazil

    Science.gov (United States)

    Vidal, M. M.; De Souza, P.; De Mello, W. Z.; Damaceno, I.; Bourseau, L.; Rodrigues, R. D. A.; Mattos, B. B.

    2017-12-01

    Concentration of nutrients above natural levels are found even at remote or protected environments due to atmospheric transportation from biomass burning emissions, urban and industrial areas. This study evaluate N and P atmospheric deposition at the oceanic and continental slopes of Serra dos Órgãos mountain, which are influenced by the pollutants emission from the Metropolitan Region of Rio de Janeiro. Flux of dissolved forms of N and P were measured in three watersheds in headwaters of Piabanha basin, southeastern Brazil, to understand the dynamics of the biogeochemical processes of these elements, related to anthropic influences of atmospheric inputs and export via stream flow. Samples of bulk precipitation (weekly; n=47) and stream water (monthly; n=13) were collected along one year (Sept 2014 - Sept 2015). During that period the annual rainfall in the oceanic slope (2163 mm) was the double of the continental one. It is important to stress that the rainfall in the oceanic slope was 13 % and 28% in 2014/15, respectively, lower than the long term average. Atmospheric deposition of total dissolved nitrogen (TDN) on the oceanic and continental slopes were, respectively, 15 and 8.6 kg N ha-1 year-1. The TDN outputs by stream water were 5-7 times lower in oceanic slope and 28 times lower on the continental one. The relative contribution of dissolved organic nitrogen (DON; 65%-70%) was higher than the one of dissolved inorganic nitrogen (DIN; 30-35%) to TDN deposition. Atmospheric deposition of total dissolved phosphorus (TDP) in oceanic and continental slopes were 1.4 and 0.95 kg P ha-1 year-1. Dissolved Organic Phosphorus (DOP; 89-96%) was higher than the inorganic one (PO43-; 5-11%). TDP outputs were 2-4 times lower, regarding to atmospheric contribution. The contribution of DOP (73-77 %) was higher than DIP (23-27 %). Results show variations in quantities and forms of N and P species due to natural and anthropogenic processes which contribute to the cycling of

  11. Parameterization experiments performed via synthetic mass movements prototypes generated by 3D slope stability simulator

    Science.gov (United States)

    Colangelo, Antonio C.

    2010-05-01

    each cell in synthetic slope systems performed by relief unity emulator. The central methodological strategy is to locate the potential rupture surfaces (prs), main material discontinuities, like soil-regolith or regolith-rock transitions. Inner these "prs", we would to outline the effective potential rupture surfaces (eprs). This surface is a sub-set of the "prs" that presents safety factor less than unity (fwalls, the "slope stability simulator" generates a synthetic mass movement. The overlay material will slide until that a new equilibrium be attained at residual shear strength. These devices generate graphic 3D cinematic sequences of experiments in synthetic slope systems and numerical results about physical and morphological data about scars and deposits. Thus, we have a detailed geotechnical, morphological, topographic and morphometric description of these mass movements prototypes, for deal with effective mass movements found in the real environments.

  12. Topographic controls on pyroclastic density current dynamics: Insight from 18 May 1980 deposits at Mount St. Helens, Washington (USA)

    Science.gov (United States)

    Brand, Brittany D.; Bendaña, Sylvana; Self, Stephen; Pollock, Nicholas

    2016-07-01

    Our ability to interpret the deposits of pyroclastic density currents (PDCs) is critical for understanding the transport and depositional processes that control PDC dynamics. This paper focuses on the influence of slope on flow dynamics and criticality as recorded in PDC deposits from the 18 May 1980 eruption of Mt. St. Helens (USA). PDC deposits are found along the steep flanks (10°-30°) and across the pumice plain ( 5°) up to 8 km north of the volcano. Granulometry, componentry and descriptions of depositional characteristics (e.g., bedform morphology) are recorded with distance from source. The pumice plain deposits are primarily thick (3-12 m), massive and poorly-sorted, and represent deposition from a series of concentrated PDCs. By contrast, the steep flank deposits are stratified to cross-stratified, suggesting deposition from PDCs where turbulence strongly influenced transport and depositional processes. We propose that acceleration of the concentrated PDCs along the steep flanks resulted in thinning of the concentrated, basal region of the current(s). Enhanced entrainment of ambient air, and autofluidization from upward fluxes of air from substrate interstices and plunging breakers across rugged, irregular topography further inflated the currents to the point that the overriding turbulent region strongly influenced transport and depositional mechanisms. Acceleration in combination with partial confinement in slot canyons and high surface roughness would also increase basal shear stress, further promoting shear and traction transport in the basal region of the current. Conditions along the steep flank resulted in supercritical flow, as recorded by regressive bedforms, which gradually transitioned to subcritical flow downstream as the concentrated basal region thickness increased as a function of decreasing slope and flow energy. We also find that (1) PDCs were erosive into the underlying granular substrate along high slopes (> 25°) where currents were

  13. Soil slips and debris flows on terraced slopes

    Science.gov (United States)

    Crosta, G. B.; Dal Negro, P.; Frattini, P.

    Terraces cover large areas along the flanks of many alpine and prealpine valleys. Soil slips and soil slips-debris flows are recurrent phenomena along terraced slopes. These landslides cause damages to people, settlements and cultivations. This study investigates the processes related to the triggering of soil slip-debris flows in these settings, analysing those occurred in Valtellina (Central Alps, Italy) on November 2000 after heavy prolonged rainfalls. 260 landslides have been recognised, mostly along the northern valley flank. About 200 soil slips and slumps occurred in terraced areas and a third of them evolved into debris flows. Field work allowed to recognise the settings at soil slip-debris flow source areas. Landslides affected up to 2.5 m of glacial, fluvioglacial and anthropically reworked deposits overlying metamorphic basement. Laboratory and in situ tests allowed to characterise the geotechnical and hydraulic properties of the terrains involved in the initial failure. Several stratigraphic and hydrogeologic factors have been individuated as significant in determining instabilities on terraced slopes. They are the vertical changes of physical soil properties, the presence of buried hollows where groundwater convergence occurs, the rising up of perched groundwater tables, the overflow and lateral infiltration from superficial drainage network, the runoff concentration by means of pathways and the insufficient drainage of retaining walls.

  14. Assessment of risks of loose landslide deposits formed by the 2008 Wenchuan earthquake

    Science.gov (United States)

    Zhang, S.; Zhang, L. M.; Peng, M.; Zhang, L. L.; Zhao, H. F.; Chen, H. X.

    2012-05-01

    A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 × 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

  15. Slope of the Slope Derivative Surface used to characterize the complexity of the seafloor around St. John, USVI

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Slope of slope was calculated from the bathymetry surface for each raster cell by applying the ArcGIS Spatial Analyst 'Slope' Tool to a previously created slope...

  16. Constraining the sedimentology and stratigraphy of submarine intraslope lobe deposits using exhumed examples from the Karoo Basin, South Africa

    Science.gov (United States)

    Spychala, Y. T.; Hodgson, D. M.; Flint, S. S.; Mountney, N. P.

    2015-06-01

    Intraslope lobe deposits provide a process record of the infill of accommodation on submarine slopes and their recognition enables the accurate reconstruction of the stratigraphic evolution of submarine slope systems. Extensive exposures of discrete sand-prone packages in Units D/E and E, Fort Brown Formation, Karoo Basin, South Africa, permit analysis of the sedimentology and stacking patterns of three intraslope lobe complexes and their palaeogeographic reconstruction via bed-scale analysis and physical correlation of key stratal surfaces. The sand-prone packages comprise tabular, aggradationally to slightly compensationally stacked lobe deposits with constituent facies associations that can be attributed to lobe axis, lobe off-axis, lobe-fringe and distal lobe-fringe environments. Locally, intraslope lobe deposits are incised by low aspect ratio channels that mark basinward progradation of the deepwater system. The origin of accommodation on the slope for lobe deposition is interpreted to be due to differential compaction or healing of scars from mass wasting processes. The stacking patterns and sedimentary facies arrangement identified in this study are distinct from those of more commonly recognized basin-floor lobe deposits, thereby enabling the establishment of recognition criteria for intraslope lobe deposits in other less well exposed and studied fine-grained systems. Compared to basin floor lobes, intraslope lobes are smaller in volume, influenced by higher degrees of confinement, and tend to show aggradational stacking patterns.

  17. Geotechnical properties of ash deposits near Hilo, Hawaii

    Science.gov (United States)

    Wieczorek, G.F.; Jibson, R.W.; Wilson, R.C.; Buchanan-Banks, J. M.

    1982-01-01

    Two holes were hand augered and sampled in ash deposits near Hilo, Hawaii. Color, water content and sensitivity of the ash were measured in the field. The ash alternated between reddish brown and dark reddish brown in color and had water contents as high as 392%. A downhole vane shear device measured sensitivities as high as 6.9. A series of laboratory tests including grain size distribution, Atterberg limits, X-ray diffraction analysis, total carbon determination, vane shear, direct shear and triaxial tests were performed to determine the composition and geotechnical properties of the ash. The ash is very fine grained, highly plastic and composed mostly of gibbsite and amorphous material presumably allophane. The ash has a high angle of internal friction ranging from 40-43? and is classified as medium to very sensitive. A series of different ash layers was distinguished on the basis of plasticity and other geotechnical properties. Sensitivity may be due to a metastable fabric, cementation, leaching, high organic content, and thixotropy. The sensitivity of the volcanic ash deposits near Hilo is consistent with documented slope instability during earthquakes in Hawaii. The high angles of internal friction and cementation permit very steep slopes under static conditions. However, because of high sensitivity of the ash, these slopes are particularly susceptible to seismically-induced landsliding.

  18. Planning criteria for open pit mines under special consideration of slope stability and controlled blasting

    Energy Technology Data Exchange (ETDEWEB)

    Weise, H

    1986-04-01

    The criteria which influence the economics of a future surface mining operation are discussed; these include the size of the mine and the depth of the deposit. The methods of working are outlined - single bench, multiple bench - and choices of haulage equipment (trucks vs. conveyors) are discussed. For a mine using conveyors, the slope of the open pit will affect the operating cost. Pumps will be required to dewater the strata; it will be necessary to take steps to ensure slope stability. Bucket wheel excavators will be impeded by the presence of consolidated material, which may be best removed by shatter blasting. An example is given of the use of shatter blasting at the Neyveli lignite mine in Tamil Nadu, India. 5 references.

  19. Wave run-up on sandbag slopes

    Directory of Open Access Journals (Sweden)

    Thamnoon Rasmeemasmuang

    2014-03-01

    Full Text Available On occasions, sandbag revetments are temporarily applied to armour sandy beaches from erosion. Nevertheless, an empirical formula to determine the wave run -up height on sandbag slopes has not been available heretofore. In this study a wave run-up formula which considers the roughness of slope surfaces is proposed for the case of sandbag slopes. A series of laboratory experiments on the wave run -up on smooth slopes and sandbag slopes were conducted in a regular-wave flume, leading to the finding of empirical parameters for the formula. The proposed empirical formula is applicable to wave steepness ranging from 0.01 to 0.14 and to the thickness of placed sandbags relative to the wave height ranging from 0.17 to 3.0. The study shows that the wave run-up height computed by the formula for the sandbag slopes is 26-40% lower than that computed by the formula for the smooth slopes.

  20. Effect of cement injection on sandy soil slope stability, case study: slope in Petang district, Badung regency

    Science.gov (United States)

    Arya, I. W.; Wiraga, I. W.; GAG Suryanegara, I.

    2018-01-01

    Slope is a part of soil topography formed due to elevation difference from two soil surface. Landslides is frequently occur in natural slope, it is because shear force is greater than shear strength in the soil. There are some factor that influence slope stability such as: rain dissipation, vibration from earthquake, construction and crack in the soil. Slope instability can cause risk in human activity or even threaten human lives. Every years in rainy season, landslides always occur in Indonesia. In 2016, there was some landslide occurred in Bali. One of the most damaging is landslide in Petang district, Badung regency. This landslide caused main road closed entirely. In order to overcome and prevent landslide, a lot of method have been practiced and still looking for more sophisticated method for forecasting slope stability. One of the method to strengthen soil stability is filling the soil pores with some certain material. Cement is one of the material that can be used to fill the soil pores because when it is in liquid form, it can infiltrate into soil pores and fill the gap between soil particles. And after it dry, it can formed a bond with soil particle so that soil become stronger and the slope as well. In this study, it will use experimental method, slope model in laboratory to simulate a real slope behavior in the field. The first model is the slope without any addition of cement. This model will be become a benchmark for the other models. The second model is a slope with improved soil that injects the slope with cement. Injection of cement is done with varying interval distance of injection point is 5 cm and 10 cm. Each slope model will be given a load until the slope collapses. The slope model will also be analyzed with slope stability program. The test results on the improved slope models will be compared with unimproved slope. In the initial test will consist of 3 model. First model is soil without improvement or cement injection, second model is soil

  1. Constraining the sedimentology and stratigraphy of submarine intraslope lobe deposits using exhumed examples from the Karoo Basin, South Africa

    NARCIS (Netherlands)

    Spychala, Y. T.; Hodgson, D. M.; Flint, S. S.; Mountney, N. P.

    2015-01-01

    Intraslope lobe deposits provide a process record of the infill of accommodation on submarine slopes and their recognition enables the accurate reconstruction of the stratigraphic evolution of submarine slope systems. Extensive exposures of discrete sand-prone packages in Units D/E and E, Fort Brown

  2. The Role of Slope in the Fill and Spill Process of Linked Submarine Minibasins. Model Validation and Numerical Runs at Laboratory Scale.

    Science.gov (United States)

    Bastianon, E.; Viparelli, E.; Cantelli, A.; Imran, J.

    2015-12-01

    Primarily motivated by applications to hydrocarbon exploration, submarine minibasins have been widely studied during recent decades to understand the physical phenomenon that characterizes their fill process. Minibasins were identified in seismic records in the Gulf of Mexico, Angola, Trinidad and Tobago, Ireland, Nigeria and also in outcrops (e.g., Tres Pasos Formation, southern Chile). The filling of minibasis is generally described as the 'fill-and-spill' process, i.e. turbidity currents enter, are reflected on the minibasin flanks, pond and deposit suspended sediment. As the minibasin fills the turbidity current spills on the lowermost zone of the basin flank -spill point - and start filling the next basin downdip. Different versions of this simplified model were used to interpret field and laboratory data but it is still unclear how the minibasin size compared to the magnitude of the turbidity currents, the position of each basin in the system, and the slope of the minibasin system affects the characteristics of the deposit (e.g., geometry, grain size). Here, we conduct a numerical study to investigate how the 'fill-and-spill' model changes with increase in slopes of the minibasin system. First, we validate our numerical results against laboratory experiment performed on two linked minibasins located on a horizontal platform by comparing measured and simulated deposit geometries, suspended sediment concentration profiles and grain sizes. We then perform numerical simulations by increasing the minibasin system slope: deposit and flow characteristics are compared with the case of horizontal platform to identify how the depositional processes change. For the numerical study we used a three-dimensional numerical model of turbidity currents that solves the Reynolds-averaged Navier-Stokes equations for dilute suspensions. Turbulence is modeled by a buoyancy-modified k-ɛ closure. The numerical model has a deforming bottom boundary, to model the changes in the bed

  3. Recurring Slope Lineae (RSL) Observations Suggest Widespread Occurrence and Complex Behavior

    Science.gov (United States)

    Stillman, D. E.; Grimm, R. E.; Wagstaff, K.; Bue, B. D.; Michaels, T. I.

    2017-12-01

    RSL are described as narrow dark features that incrementally lengthen down steep slopes during warm seasons, fade in cold seasons, and recur annually. HiRISE observations from 5+ Mars years have allowed us to confirm 100 RSL sites and identify more than 600 candidate RSL sites. Detailed analysis of a few RSL sites has been performed using computer assisted analysis. RSL occur in low-albedo (dust-poor) regions with a latitude range of 42.2°N - 53.1°S. They are densely clustered throughout Valles Marineris (VM), in the light-toned layered deposits of Margaritifer and SW Arabia Terrae, Cerberus Fossae, and well-preserved impact craters in Chryse and Acidalia Planitae (CAP). RSL sites are also found at lower densities throughout the low-albedo highland terrains. RSL incrementally lengthen when their slopes are warm, thus the season at which RSL lengthen is dependent on latitude and slope orientation. While RSL occur on all slope orientation there is a large bias to W-facing and equatorial facing slopes. During the RSL activity season, RSL lengthening does not appear to be constant: (1) CAP RSL initially quickly lengthen and slow their lengthening rate by about an order of magnitude as temperatures increase, (2) many VM RSL sites possess RSL that fade at the same time that neighboring RSL on the same slope incrementally lengthen, and (3) some RSL sites in the southern mid-latitudes show at least two pulses of RSL activity - during the southern fall and summer RSL incrementally lengthen, fade, and then start incrementally lengthening again followed by fading as temperatures cool. The correlation of RSL activity to surface temperature, spectrally-derived hydrated salts, and quick fading all point to a wet formation mechanism. However, water sources remain problematic as water budgets suggest a much greater amount of water than could be trapped from the atmosphere. Additionally, some RSL occur in locations where subsurface discharge via an aquifer would be challenging

  4. Evidence for submarine landslides and continental slope erosion related to fault reactivation during the last glaciation offshore eastern Canada

    Science.gov (United States)

    Saint-Ange, F.; Campbell, C.; MacKillop, K.; Mosher, D. C.; Piper, D. J.; Roger, J.

    2012-12-01

    Many studies have proposed that reactivation of dormant faults during deglaciation is a source of neotectonic activity in glaciated regions, but few have demonstrated the relationship to submarine landslides. In this study, seabed morphology and shallow geology of the outer continental margin adjacent to the Charlie Gibbs Fracture Zone off Newfoundland, Canada was investigated for evidence of this relationship. The glacial history and morphology of the margin suggest that the entire continental shelf in the area, coincident with major continental crustal lineaments, was ice-covered during the Last glacial cycle, and transverse troughs delineate the paleo-icestream drainage patterns. A recent investigation of Notre Dame Trough revealed the existence of large sediment failures on the shelf. The current study investigates complex seafloor erosion and widespread mass transport deposition (MTD) on the continental slope seaward of Notre Dame Trough, using recently-acquired high resolution seismic reflection data and piston cores. The new data reveal that a trough mouth fan (TMF) is present on the slope seaward of Notre Dame Trough. The Notre Dame TMF is characterized by a succession of stacked debris flows, but does not show a lobate shape in plan view like other classic TMFs. Instead, the Notre Dame TMF has abruptly-truncated margins suggesting post-depositional failure and erosion of the fan deposits. Seismic reflection data show that the locations of the failures along the TMF margin are coincident with a set of shallow faults; however the current dataset does not image the deeper portion of the faults. On the upper slope immediately south of the TMF, a narrow and deeply incised canyon is located along-trend with the Notre Dame Trough. The location of this canyon appears to be controlled by a fault. Downslope from this canyon, along the southern margin of the TMF, a 25 km wide, flat-floored, U-shaped valley was eroded into a succession of stacked MTD-filled channels

  5. Stratigraphy and paleogeographic significance of a Late Pennsylvanian to Early Permian channeled slope sequence in the Darwin Basin, southern Darwin Hills, east-central California

    Science.gov (United States)

    Stevens, Calvin H.; Stone, Paul; Magginetti, Robert T.; Ritter, Scott M.

    2015-01-01

    The complex stratigraphy of late Paleozoic rocks in the southern Darwin Hills consists of regionally extensive Mississippian and Early to Middle Pennsylvanian rocks overlain by latest Pennsylvanian to Early Permian rocks, herein called the Darwin Hills sequence. Deposition of this latter sequence marked the beginning of the Darwin Basin. In Mississippian time, a carbonate platform prograded westward over slightly older slope deposits. In the Late Mississippian this platform was exposed to erosion and siliciclastic sediments were deposited. In Early to Middle Pennsylvanian time the area subsided, forming a west-facing ramp that was subjected to deformation and erosion in Middle or early Late Pennsylvanian time. Later this area was tilted westward and deep-water sediments were deposited on this slope. In latest Pennsylvanian to earliest Permian time, a major channel was cut through the older Pennsylvanian rocks and into the Upper Mississippian strata. This channel was gradually filled with increasingly finer grained, deep-water sediment as the area evolved into a basin floor by Early Permian (Sakmarian) time. Expansion of the Darwin Basin in Artinskian time led to a second phase of deposition represented by strata of the regionally extensive Darwin Canyon Formation. The geology in this small area thus documents tectonic events occurring during the early development of the Darwin Basin.

  6. Velocity-porosity relationships for slope apron and accreted sediments in the Nankai Trough Seismogenic Zone Experiment, Integrated Ocean Drilling Program Expedition 315 Site C0001

    Science.gov (United States)

    Hashimoto, Y.; Tobin, H. J.; Knuth, M.

    2010-12-01

    In this study, we focused on the porosity and compressional wave velocity of marine sediments to examine the physical properties of the slope apron and the accreted sediments. This approach allows us to identify characteristic variations between sediments being deposited onto the active prism and those deposited on the oceanic plate and then carried into the prism during subduction. For this purpose we conducted ultrasonic compressional wave velocity measurements on the obtained core samples with pore pressure control. Site C0001 in the Nankai Trough Seismogenic Zone Experiment transect of the Integrated Ocean Drilling Program is located in the hanging wall of the midslope megasplay thrust fault in the Nankai subduction zone offshore of the Kii peninsula (SW Japan), penetrating an unconformity at ˜200 m depth between slope apron sediments and the underlying accreted sediments. We used samples from Site C0001. Compressional wave velocity from laboratory measurements ranges from ˜1.6 to ˜2.0 km/s at hydrostatic pore pressure conditions estimated from sample depth. The compressional wave velocity-porosity relationship for the slope apron sediments shows a slope almost parallel to the slope for global empirical relationships. In contrast, the velocity-porosity relationship for the accreted sediments shows a slightly steeper slope than that of the slope apron sediments at 0.55 of porosity. This higher slope in the velocity-porosity relationship is found to be characteristic of the accreted sediments. Textural analysis was also conducted to examine the relationship between microstructural texture and acoustic properties. Images from micro-X-ray CT indicated a homogeneous and well-sorted distribution of small pores both in shallow and in deeper sections. Other mechanisms such as lithology, clay fraction, and abnormal fluid pressure were found to be insufficient to explain the higher velocity for accreted sediments. The higher slope in velocity-porosity relationship for

  7. Unravelling the depositional origins and diagenetic alteration of carbonate breccias

    Science.gov (United States)

    Madden, Robert H. C.; Wilson, Moyra E. J.; Mihaljević, Morana; Pandolfi, John M.; Welsh, Kevin

    2017-07-01

    and post-brecciation diagenesis. The diagenetic-, and to an extent depositional- and clast-characteristics of the Batu Gading deposits are diagnostic of breccia origins. The predominance of: early and pervasive stabilisation of calcitic components, pervasive compaction resulting in a fitted texture, and paucity of meteoric dissolution or cementation effects are collectively all indicators of slope deposition and lithification. These features are comparable with other regional and global examples of submarine slope breccias, and in particular those also from syntectonic settings (Wannier, 2009). The results of this study, along with regional analogues, suggest the potential for reworked carbonate debris in slope settings to be a viable way of investigating carbonate platform variability and their subsequent alteration in the absence of preserved platform top or margin deposits.

  8. Concentric Crater Fill in Utopia Planitia: Timing and Transitions Between Glacial and Periglacial Processes.

    Science.gov (United States)

    Levy, J.; Head, J.

    2008-09-01

    on steeply scalloped slopes. BTC surfaces are commonly found at the foot of crater wall interior slopes, and in topographic lows between BTsurfaced concentric ridges. BTC material is commonly draped on, and inter-fingered between, FBT mounds and HBT boundary walls at contacts between the two units, suggesting that BTC units superpose, and in places, embay BT units. FBT-covered hill surfaces are commonly ringed by HBT, which is in turn ringed by LC-BTC, and/or HCBTC. FBT-covered concentric ridges are commonly flanked by HBT in the lows between ridges, particularly in lows which also have exposures of LC- or HC-BTC polygons. Discussion Crater counts on BT material indicate an age of ~100 MY, consistent with counts on LDA [11]; crater counts on BTC units indicate an age of ~1 MY. This age difference suggests that BT and BTC are stratigraphically distinct units that were deposited at markedly different times. The small exposures of HBT and LC-BTC make distinguishing ages for these textures from ages of the more common FBT and HC-BTC surfaces impossible. However, the gradational contacts between each sub-texture, on both steep and gentle slopes, suggests that modification of two distinct units, rather than exposure of four radically different layers, accounts for the differences between sub-textures. On the basis of these observations, we propose the following formation sequence for BT and BTC units. BTC units are an atmospherically-emplaced, ice-rich deposit, temporally associated with recent latitude-dependent mantling events [12-14] containing sufficient dusty material to generate a surficial lag deposit during sublimation of near-surface ice [e.g., 15]. Thermal contraction cracking generates polygonal fractures, which initially enhance sublimation at polygon margins, generated HC-BTC polygons [15]. The lack of strongly lineated BTC polygons suggests that BTC deposits have not significantly flowed on ~1 MY timescales [e.g., 4, 16]. Infilling of polygonal fractures by

  9. Slope-scale dynamic states of rockfalls

    Science.gov (United States)

    Agliardi, F.; Crosta, G. B.

    2009-04-01

    Rockfalls are common earth surface phenomena characterised by complex dynamics at the slope scale, depending on local block kinematics and slope geometry. We investigated the nature of this slope-scale dynamics by parametric 3D numerical modelling of rockfalls over synthetic slopes with different inclination, roughness and spatial resolution. Simulations were performed through an original code specifically designed for rockfall modeling, incorporating kinematic and hybrid algorithms with different damping functions available to model local energy loss by impact and pure rolling. Modelling results in terms of average velocity profiles suggest that three dynamic regimes (i.e. decelerating, steady-state and accelerating), previously recognized in the literature through laboratory experiments on granular flows, can set up at the slope scale depending on slope average inclination and roughness. Sharp changes in rock fall kinematics, including motion type and lateral dispersion of trajectories, are associated to the transition among different regimes. Associated threshold conditions, portrayed in "phase diagrams" as slope-roughness critical lines, were analysed depending on block size, impact/rebound angles, velocity and energy, and model spatial resolution. Motion in regime B (i.e. steady state) is governed by a slope-scale "viscous friction" with average velocity linearly related to the sine of slope inclination. This suggest an analogy between rockfall motion in regime B and newtonian flow, whereas in regime C (i.e. accelerating) an analogy with a dilatant flow was observed. Thus, although local behavior of single falling blocks is well described by rigid body dynamics, the slope scale dynamics of rockfalls seem to statistically approach that of granular media. Possible outcomes of these findings include a discussion of the transition from rockfall to granular flow, the evaluation of the reliability of predictive models, and the implementation of criteria for a

  10. Mineralogical and geochemical study of contaminated soils on abandoned Sb deposits Dubrava and Poproc

    International Nuclear Information System (INIS)

    Klimko, T.; Jurkovic, L.

    2010-01-01

    In this paper we present initial results of mineralogical and geochemical study of secondary mineral phases, often with a high content of Sb and As, resulting from oxidation of sulphide minerals in the soil environment on two, now abandoned Sb deposits. Dubrava deposit is situated on the northern slopes of the Dumbier Low Tatras and Poproc deposit is located in the eastern part of Spis-Gemer Rudohorie. Both studied sites were in the past (second half of 20 th century) significant producers of antimony ore and Dubrava deposit belonged to medium-sized Sb deposits in the world.

  11. EFFECTS OF SLOPE SHAPES ON SOIL EROSION

    Directory of Open Access Journals (Sweden)

    Hüseyin ŞENSOY, Şahin PALTA

    2009-01-01

    Full Text Available Water is one of the most important erosive forces. A great number of factors also play a role in erosion process and slope characteristic is also one of them. The steepness and length of the slope are important factors for runoff and soil erosion. Another slope factor that has an effect on erosion is the shape of the slope. Generally, different erosion and runoff characteristics exist in different slopes which can be classified as uniform, concave, convex and complex shape. In this study, the effects of slope shape on erosion are stated and emphasized by taking similar researches into consideration.

  12. Rock slopes and reservoirs - lessons learned

    International Nuclear Information System (INIS)

    Moore, D.P.

    1999-01-01

    Lessons learned about slope stability in the course of four decades of monitoring, and in some cases stabilizing, slopes along British Columbia's hydroelectric reservoirs are discussed. The lessons are illustrated by short case histories of some of the more important slopes such as Little Chief Slide, Dutchman's Ridge, Downie Slide, Checkerboard Creek and Wahleach. Information derived from the monitoring and other investigations are compared with early interpretations of geology and slope performance. The comparison serves as an indicator of progress in slope stability determination and as a measure of the value of accumulated experience in terms of the potential consequences to safety and cost savings over the long life-span of hydroelectric projects.14 refs., 2 tabs., 15 figs

  13. Possible crater-based pingos, paleolakes and periglacial landscapes at the high latitudes of Utopia Planitia, Mars

    Science.gov (United States)

    Soare, R. J.; Conway, S. J.; Pearce, G. D.; Dohm, J. M.; Grindrod, P. M.

    2013-08-01

    Closed-system pingos (CSPs) are perennial ice-cored mounds that evolve in relatively deep and continuous permafrost. They occur where thermokarst lakes either have lost or are losing their water by drainage or evaporation and by means of freeze-thaw cycling, permafrost aggradation and pore-water migration. The presence of CSPs on Mars, particularly on late-Amazonian Epoch terrain at near-polar latitudes, would indicate: (1) the antecedent occurrence of ponded water at the mound-formation sites; (2) freeze-thaw cycling of this water; and (3) boundary-conditions of pressure and temperature at or above the triple point of water much more recently and further to the north than has been thought possible. In 2005 we studied two crater-floor landscapes in northern Utopia Planitia and used MOC narrow-angle images to describe mounds within these landscapes that shared a suite of geological characteristics with CSPs on Earth. Here, we show the results of a circum-global search for similar crater-floor landscapes at latitudes >˜55°N. The search incorporates all relevant MOC and HiRISE images released since 2005. In addition to the two periglacially suggestive crater-floor landscapes observed by us earlier, we have identified three other crater floors with similar landscapes. Interestingly, each of the five mound-bearing craters occur within a tight latitudinal-band (˜64-69°N); this could be a marker of periglacial landscape-modification on a regional scale. Just to the north of the crater-based pingo-like mounds Conway et al. have identified large (km-scale) crater-based perennial ice-domes. They propose that the ice domes develop when regional polar-winds transport and precipitate icy material onto the floor of their host craters. Under a slightly different obliquity-solution ice domes could have accumulated at the lower latitudes where the putative CSPs have been observed. Subsequently, were temperatures to have migrated close to or at 0 °C the ice domes could have

  14. How does slope form affect erosion in CATFLOW-SED?

    Science.gov (United States)

    Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

    2016-04-01

    Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

  15. Centrifuge model test of rock slope failure caused by seismic excitation. Plane failure of dip slope

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Kawai, Tadashi

    2008-01-01

    Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is essential to evaluate more accurately the possibilities of rock slope failure and the potential failure boundary, which are triggered by earthquake ground motions. The purpose of this study is to analyze dynamic failure characteristics of rock slopes by centrifuge model tests for verification and improvement of the analytical methods. We conducted a centrifuge model test using a dip slope model with discontinuities limitated by Teflon sheets. The centrifugal acceleration was 50G, and the acceleration amplitude of input sin waves increased gradually at every step. The test results were compared with safety factors of the stability analysis based on the limit equilibrium concept. Resultant conclusions are mainly as follows: (1) The slope model collapsed when it was excited by the sine wave of 400gal, which was converted to real field scale, (2) Artificial discontinuities were considerably concerned in the collapse, and the type of collapse was plane failure, (3) From response acceleration records observed at the slope model, we can say that tension cracks were generated near the top of the slope model during excitation, and that might be cause of the collapse, (4) By considering generation of the tension cracks in the stability analysis, correspondence of the analytical results and the experimental results improved. From the obtained results, we need to consider progressive failure in evaluating earthquake induced rock slope failure. (author)

  16. Post-depositional fracturing and subsidence of pumice flow deposits: Lascar Volcano, Chile.

    Science.gov (United States)

    Whelley, Patrick L; Jay, J; Calder, E S; Pritchard, M E; Cassidy, N J; Alcaraz, S; Pavez, A

    Unconsolidated pyroclastic flow deposits of the 1993 eruption of Lascar Volcano, Chile, have, with time, become increasingly dissected by a network of deeply penetrating fractures. The fracture network comprises orthogonal sets of decimeter-wide linear voids that form a pseudo-polygonal grid visible on the deposit surface. In this work, we combine shallow surface geophysical imaging tools with remote sensing observations and direct field measurements of the deposit to investigate these fractures and their underlying causal mechanisms. Based on ground penetrating radar images, the fractures are observed to have propagated to depths of up to 10 m. In addition, orbiting radar interferometry shows that deposit subsidence of up to 1 cm/year -1 occurred between 1993 and 1996 with continued subsidence occurring at a slower rate thereafter. In situ measurements show that 1 m below the surface, the 1993 deposits remain 5°C to 15°C hotter, 18 years after emplacement, than adjacent deposits. Based on the observed subsidence as well as estimated cooling rates, the fractures are inferred to be the combined result of deaeration, thermal contraction, and sedimentary compaction in the months to years following deposition. Significant environmental factors, including regional earthquakes in 1995 and 2007, accelerated settling at punctuated moments in time. The spatially variable fracture pattern relates to surface slope and lithofacies variations as well as substrate lithology. Similar fractures have been reported in other ignimbrites but are generally exposed only in cross section and are often attributed to formation by external forces. Here we suggest that such interpretations should be invoked with caution, and deformation including post-emplacement subsidence and fracturing of loosely packed ash-rich deposits in the months to years post-emplacement is a process inherent in the settling of pyroclastic material.

  17. Distal Ejecta from Lunar Impacts: Extensive Regions of Rocky Deposits

    Science.gov (United States)

    Bandfield, Joshua L.; Cahill, Joshua T. S.; Carter, Lynn M.; Neish, Catherine D.; Patterson, G. Wesley; Williams, Jean-Pierre; Paige, David A.

    2016-01-01

    Lunar Reconnaissance Orbiter (LRO) Diviner Radiometer, Mini-RF, and LRO Camera data were used to identify and characterize rocky lunar deposits that appear well separated from any potential source crater. Two regions are described: 1) A approximate 18,000 sq km area with elevated rock abundance and extensive melt ponds and veneers near the antipode of Tycho crater (167.5 deg E, 42.5 deg N). This region has been identified previously, using radar and aging data. 2) A much larger and more diffuse region, covering approximately 730,000 sq km, centered near 310 deg E, 35 deg S, containing elevated rock abundance and numerous granular flow deposits on crater walls. The rock distributions in both regions favor certain slope azimuths over others, indicating a directional component to the formation of these deposits. The spatial distribution of rocks is consistent with the arrival of ejecta from the west and northwest at low angles (approximately 10-30 deg) above the horizon in both regions. The derived age and slope orientations of the deposits indicate that the deposits likely originated as ejecta from the Tycho impact event. Despite their similar origin, the deposits in the two regions show significant differences in the datasets. The Tycho crater antipode deposit covers a smaller area, but the deposits are pervasive and appear to be dominated by impact melts. By contrast, the nearside deposits cover a much larger area and numerous granular flows were triggered. However, the features in this region are less prominent with no evidence for the presence of impact melts. The two regions appear to be surface expressions of a distant impact event that can modify surfaces across wide regions, resulting in a variety of surface morphologies. The Tycho impact event may only be the most recent manifestation of these processes, which likely have played a role in the development of the regolith throughout lunar history

  18. Structural characteristics of cohesive flow deposits, and a sedimentological approach on their flow mechanisms.

    Science.gov (United States)

    Tripsanas, E. K.; Bryant, W. R.; Prior, D. B.

    2003-04-01

    A large number of Jumbo Piston cores (up to 20 m long), acquired from the continental slope and rise of the Northwest Gulf of Mexico (Bryant Canyon area and eastern Sigsbee Escarpment), have recovered various mass-transport deposits. The main cause of slope instabilities over these areas is oversteepening of the slopes due to the seaward mobilization of the underlying allochthonous salt masses. Cohesive flow deposits were the most common recoveries in the sediment cores. Four types of cohesive flow deposits have been recognized: a) fluid debris flow, b) mud flow, c) mud-matrix dominated debris flow, and d) clast-dominated debris flow deposits. The first type is characterized by its relatively small thickness (less than 1 m), a mud matrix with small (less than 0.5 cm) and soft mud-clasts, and a faint layering. The mud-clasts reveal a normal grading and become more abundant towards the base of each layer. That reveals that their deposition resulted by several successive surges/pulses, developed in the main flow, than the sudden “freezing” of the whole flow. The main difference between mud flow and mud-matrix dominated debris flow deposits is the presence of small to large mud-clasts in the later. Both deposits consist of a chaotic mud-matrix, and a basal shear laminated zone, where the strongest shearing of the flow was exhibited. Convolute laminations, fault-like surfaces, thrust faults, and microfaults are interpreted as occurring during the “freezing” of the flows and/or by adjustments of the rested deposits. Clast-dominated debris flow deposits consist of three zones: a) an upper plug-zone, characterized by large interlocked clasts, b) a mid-zone, of higher reworked, inversely graded clasts, floating in a mud-matrix, and c) a lower shear laminated zone. The structure of the last three cohesive flow deposits indicate that they represent deposition of typical Bingham flows, consisting of an upper plug-zone in which the yield stress is not exceeded and an

  19. Simulating groundwater-peatland interactions in depression and slope peatlands in southern Quebec (Canada)

    Science.gov (United States)

    Larocque, M.; Quillet, A.; Paniconi, C.

    2013-12-01

    It is crucial to understand hydrogeological interactions between aquifers and peatlands in order to grasp the influence of aquifers in peatland water budgets, to understand the role of groundwater in the evolution or organic matter deposition, and to quantify how a peatland can sustain groundwater levels in a superficial aquifer. These questions have rarely been addressed in literature and there is currently no understanding of which process dominates aquifer-peatland exchanges in different geomorphological settings. The main purpose of the study was to use groundwater flow modeling to answer these questions in two contrasted geological contexts of southern Quebec (Canada). During a three-year study, six peatlands have been instrumented in the Becancour (Centre-du-Quebec) and Amos (Abitibi-Temiscamingue) regions of southern Quebec (Canada). At each site, either one or two transects of six piezometer nests (at 1.20 m depth in the organic deposits and in the mineral deposits below the peat) have been installed, for a total of twelve aquifer-peatland transects of approximately 500 m. The stratigraphy and geometry of the peatland-aquifer system, as well as the hydrodynamic properties of the organic and mineral deposits have been measured at all sites. Groundwater levels have been recorded from autumn 2010 to summer 2012. The Becancour peatlands have developed in depressions while the Amos peatlands have developed through the paludification of esker slopes. The maximum peat thickness measured in the Bécancour peatlands is 6.4 m while it is 4.5 m in the Amos region. In both regions, peatlands are fringed by sandy deposits that extend at least partly under the organic deposits. The thickness of these underlying deposits is not well defined, but available data suggests a metric scale thickness in areas close to the adjacent superficial aquifer. Field data is used to create 2D numerical models in Modflow to simulate flow between the shallow groundwater and the peatland on

  20. Tiltmeter Indicates Sense of Slope

    Science.gov (United States)

    Lonborg, J. O.

    1985-01-01

    Tiltmeter indicates sense and magnitude of slope used in locations where incline not visible to operator. Use of direct rather than alternating current greatly simplifies design of instrument capable of indicating sense of slope.

  1. Soil-landform-plant communities relationships of a periglacial landscape at Potter Peninsula, Maritime Antarctica

    Science.gov (United States)

    Poelking, E. L.; Schaefer, C. E. R.; Fernandes Filho, E. I.; de Andrade, A. M.; Spielmann, A. A.

    2014-08-01

    Integrated studies on the interplay between soils, periglacial geomorphology and plant communities are crucial for the understanding of climate change effects on terrestrial ecosystems of Maritime Antarctica, one of the most sensitive areas to global warming. Knowledge on physical environmental factors that influence plant communities can greatly benefit studies on monitoring climate change in Maritime Antarctica, where new ice-free areas are being constantly exposed, allowing plant growth and organic carbon inputs. The relationship between topography, plant communities and soils was investigated in Potter Peninsula, King George Island, Maritime Antarctica. We mapped the occurrence and distribution of plant communities and identified soil-landform-vegetation relationships. The vegetation map was obtained by classification of a Quickbird image, coupled with detailed landform and characterization of 18 soil profiles. The sub-formations were identified and classified, and we also determined the total elemental composition of lichens, mosses and grasses. Plant communities at Potter Peninsula occupy 23% of the ice-free area, at different landscape positions, showing decreasing diversity and biomass from the coastal zone to inland areas where sub-desert conditions prevail. There is a clear dependency between landform and vegetated soils. Soils with greater moisture or poorly drained, and acid to neutral pH, are favourable for mosses subformations. Saline, organic-matter rich ornithogenic soils of former penguin rookeries have greater biomass and diversity, with mixed associations of mosses and grasses, while stable felseenmeers and flat rocky cryoplanation surfaces are the preferred sites for Usnea and Himantormia lugubris lichens, at the highest surface. Lichens subformations cover the largest vegetated area, showing varying associations with mosses.

  2. Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk, Rishikesh, India

    Directory of Open Access Journals (Sweden)

    Tariq Siddique

    2015-10-01

    Full Text Available The road network in the Himalayan terrain, connecting remote areas either in the valleys or on the hill slopes, plays a pivotal role in socio-economic development of India. The planning, development and even maintenance of road and rail networks in such precarious terrains are always a challenging task because of complexities posed by topography, geological structures, varied lithology and neotectonics. Increasing population and construction of roads have led to destabilisation of slopes, thus leading to mass wasting and movement, further aggravation due to recent events of cloud bursts and unprecedented flash floods. Vulnerability analysis of slopes is an important component for the “Landslide Hazard Assessment” and “Slope Mass Characterisation” guide planners to predict and choose suitable ways for construction of roads and other engineering structures. The problem of landslides along the national highway-58 (NH-58 from Rishikesh to Devprayag is a common scene. The slopes along the NH-58 between Jonk and Rishikesh were investigated, which experienced very heavy traffic especially from March to August due to pilgrimage to Kedarnath shrine. On the basis of slope mass rating (SMR investigation, the area falls in stable class, and landslide susceptibility score (LSS values also indicate that the slopes under investigation fall in low to moderate vulnerability to landslide. More attentions should be paid to the slopes to achieve greater safe and economic benefits along the highway.

  3. Numerical computation of homogeneous slope stability.

    Science.gov (United States)

    Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong

    2015-01-01

    To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS).

  4. Linear chirped slope profile for spatial calibration in slope measuring deflectometry

    Energy Technology Data Exchange (ETDEWEB)

    Siewert, F., E-mail: frank.siewert@helmholtz-berlin.de; Zeschke, T. [Helmholtz Zentrum Berlin für Materialien und Energie, Institut für Nanometer Optik und Technologie, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Arnold, T.; Paetzelt, H. [Leibnitz Institut für Oberflächen Modifizierung Leipzig e.V., IOM, Permoserstr. 15, 04318 Leipzig (Germany); Yashchuk, V. V. [Lawerence Berkeley National Laboratory, Advanced Light Source, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2016-05-15

    Slope measuring deflectometry is commonly used by the X-ray optics community to measure the long-spatial-wavelength surface figure error of optical components dedicated to guide and focus X-rays under grazing incidence condition at synchrotron and free electron laser beamlines. The best performing instruments of this kind are capable of absolute accuracy on the level of 30-50 nrad. However, the exact bandwidth of the measurements, determined at the higher spatial frequencies by the instrument’s spatial resolution, or more generally by the instrument’s modulation transfer function (MTF) is hard to determine. An MTF calibration method based on application of a test surface with a one-dimensional (1D) chirped height profile of constant amplitude was suggested in the past. In this work, we propose a new approach to designing the test surfaces with a 2D-chirped topography, specially optimized for MTF characterization of slope measuring instruments. The design of the developed MTF test samples based on the proposed linear chirped slope profiles (LCSPs) is free of the major drawback of the 1D chirped height profiles, where in the slope domain, the amplitude strongly increases with the local spatial frequency of the profile. We provide the details of fabrication of the LCSP samples. The results of first application of the developed test samples to measure the spatial resolution of the BESSY-NOM at different experimental arrangements are also presented and discussed.

  5. Indoor radon in houses built on gravel and sand deposits in southern Finland

    Directory of Open Access Journals (Sweden)

    Hutri, K.-L.

    1993-06-01

    Full Text Available Studies by the Finnish Centre for Radiation and Nuclear Safety (STUK have shown that, in Finland, indoor radon concentrations are almost twice as high in houses built on sand or gravel as in houses built on other soil types. The aim of this study was to assess the radon risk on eskers, ice-marginal formations, and other gravel and sand deposits on the basis of factors that can be determined from geological maps. Altogether, 514 houses built on gravel and sand deposits were selected for the study from the indoor radon database of STUK. Several geological parameters were determined. Empirical statistical models were used to assess the significance of factors affecting indoor radon in glaciofluvial deposits and the sand-dominant littoral deposits occurring in association with them. A relationship was found between increased indoor radon concentrations and the location of a house on a steep-sided esker, in the southeastern rapakivi granite area and on the upper slope or top of an esker. The steepness of the slope also increased the radon concentration in houses on steep-sided eskers. The effect of the topographic features is due to subterranean air-flows. As estimated from the very sparse till sampling, the elevated uranium concentration increased the indoor radon concentration only in houses built on littoral deposits around eskers and ice-marginal formations.

  6. Tracking snowmelt in the subsurface: time-lapse electrical resistivity imaging on an alpine hill slope.

    Science.gov (United States)

    Thayer, D.; Parsekian, A.; Hyde, K.; Beverly, D.; Speckman, H. N.; Ewers, B. E.

    2015-12-01

    In the mountain West region the winter snowpack provides more than 70% of our annual water supply. Modeling and predicting the timing and magnitude of snowmelt-driven water yield is difficult due to the complexities of hydrologic systems that move meltwater from snow to rivers. Particular challenges are understanding the temporal and spatial domain of subsurface hydraulic processes at relevant scales, which range from points to catchments. Subsurface characterization often requires borehole instrumentation, which is expensive and extremely difficult to install in remote, rugged terrain. Advancements in non-invasive geophysical methods allow us to monitor changes in geophysical parameters over time and infer changes in hydraulic processes. In the No-Name experimental catchment in the Medicine Bow National Forest in Wyoming, we are conducting a multi-season, time-lapse electrical resistivity imaging survey on a sub-alpine hill slope. This south-facing, partially forested slope ranges from 5 degrees to 35 degrees in steepness and consists of a soil mantle covering buried glacial talus deposits of unknown depth. A permanent grid of down-slope and cross-slope electrode arrays is monitored up to four times a day. The arrays span the entire vertical distance of the slope, from an exposed bedrock ridge to a seasonal drainage below, and cover treed and non-treed areas. Geophysical measurements are augmented by temperature and moisture time-series instrumented below the surface in a contiguous 3 meter borehole. A time-series of multiple resistivity models each day from May to July shows the changing distribution of subsurface moisture during a seasonal drying sequence punctuated by isolated rain events. Spatial patterns of changing moisture indicate that soil and gravel in the top two meters drain into a saturated layer parallel to the slope which overlies less saturated material. These results suggest that water from snowmelt and rain events tends to move down-slope beneath

  7. Study on the response of unsaturated soil slope based on the effects of rainfall intensity and slope angle

    Science.gov (United States)

    Ismail, Mohd Ashraf Mohamad; Hamzah, Nur Hasliza

    2017-07-01

    Rainfall has been considered as the major cause of the slope failure. The mechanism leading to slope failures included the infiltration process, surface runoff, volumetric water content and pore-water pressure of the soil. This paper describes a study in which simulated rainfall events were used with 2-dimensional soil column to study the response of unsaturated soil behavior based on different slope angle. The 2-dimensional soil column is used in order to demonstrate the mechanism of the slope failure. These unsaturated soil were tested with four different slope (15°, 25°, 35° and 45°) and subjected to three different rainfall intensities (maximum, mean and minimum). The following key results were obtained: (1) the stability of unsaturated soil decrease as the rainwater infiltrates into the soil. Soil that initially in unsaturated state will start to reach saturated state when rainwater seeps into the soil. Infiltration of rainwater will reduce the matric suction in the soil. Matric suction acts in controlling soil shear strength. Reduction in matric suction affects the decrease in effective normal stress, which in turn diminishes the available shear strength to a point where equilibrium can no longer be sustained in the slope. (2) The infiltration rate of rainwater decreases while surface runoff increase when the soil nearly achieve saturated state. These situations cause the soil erosion and lead to slope failure. (3) The steepness of the soil is not a major factor but also contribute to slope failures. For steep slopes, rainwater that fall on the soil surface will become surface runoff within a short time compare to the water that infiltrate into the soil. While for gentle slopes, water that becomes surface runoff will move slowly and these increase the water that infiltrate into the soil.

  8. To what extent can intracrater layered deposits that lack clear sedimentary textures be used to infer depositional environments?

    Science.gov (United States)

    Cadieux, Sarah B.; Kah, Linda C.

    2015-03-01

    Craters within Arabia Terra, Mars, contain hundreds of meters of layered strata showing systematic alternation between slope- and cliff-forming units, suggesting either rhythmic deposition of distinct lithologies or similar lithologies that experienced differential cementation. On Earth, rhythmically deposited strata can be examined in terms of stratal packaging, wherein the interplay of tectonics, sediment deposition, and base level (i.e., the position above which sediment accumulation is expected to be temporary) result in changes in the amount of space available for sediment accumulation. These predictable patterns of sediment deposition can be used to infer changes in basin accommodation regardless of the mechanism of deposition (e.g. fluvial, lacustrine, or aeolian). Here, we analyze sedimentary deposits from three craters (Becquerel Crater, Danielson Crater, Crater A) in Arabia Terra. Each crater contains layered deposits that are clearly observed in orbital images. Although orbital images are insufficient to specifically determine the origin of sedimentary deposits, depositional couplets can be interpreted in terms of potential accommodation space available for deposition, and changes in the distribution of couplet thickness through stratigraphy can be interpreted in terms of changing base level and the production of new accommodation space. Differences in stratal packaging in these three craters suggest varying relationships between sedimentary influx, sedimentary base level, and concomitant changes in accommodation space. Previous groundwater upwelling models hypothesize that layered sedimentary deposits were deposited under warm climate conditions of early Mars. Here, we use observed stacking patterns to propose a model for deposition under cold climate conditions, wherein episodic melting of ground ice could raise local base level, stabilize sediment deposition, and result in differential cementation of accumulated strata. Such analysis demonstrates that

  9. Conduction mechanisms in thin atomic layer deposited Al2O3 layers

    International Nuclear Information System (INIS)

    Spahr, Holger; Montzka, Sebastian; Reinker, Johannes; Hirschberg, Felix; Kowalsky, Wolfgang; Johannes, Hans-Hermann

    2013-01-01

    Thin Al 2 O 3 layers of 2–135 nm thickness deposited by thermal atomic layer deposition at 80 °C were characterized regarding the current limiting mechanisms by increasing voltage ramp stress. By analyzing the j(U)-characteristics regarding ohmic injection, space charge limited current (SCLC), Schottky-emission, Fowler-Nordheim-tunneling, and Poole-Frenkel-emission, the limiting mechanisms were identified. This was performed by rearranging and plotting the data in a linear scale, such as Schottky-plot, Poole-Frenkel-plot, and Fowler-Nordheim-plot. Linear regression then was applied to the data to extract the values of relative permittivity from Schottky-plot slope and Poole-Frenkel-plot slope. From Fowler-Nordheim-plot slope, the Fowler-Nordheim-energy-barrier was extracted. Example measurements in addition to a statistical overview of the results of all investigated samples are provided. Linear regression was applied to the region of the data that matches the realistic values most. It is concluded that ohmic injection and therefore SCLC only occurs at thicknesses below 12 nm and that the Poole-Frenkel-effect is no significant current limiting process. The extracted Fowler-Nordheim-barriers vary in the range of up to approximately 4 eV but do not show a specific trend. It is discussed whether the negative slope in the Fowler-Nordheim-plot could in some cases be a misinterpreted trap filled limit in the case of space charge limited current

  10. The 3D Visualization of Slope Terrain in Sun Moon Lake.

    Science.gov (United States)

    Deng, F.; Gwo-shyn, S.; Pei-Kun, L.

    2015-12-01

    By doing topographical surveys in a reservoir, we can calculate siltation volume in the period of two measurements. It becomes basic requirement to provide more precise siltation value especially when the differential GPS positioning method and the multi-beams echo sounders have been prevailed; however, there are two problems making the result become challenging when doing the siltation-survey in reservoir. They are both relative with the difficulty in keeping survey accuracy to the area of side slope around the boundary of reservoir. Firstly, the efficiency or accuracy of horizontal positioning using the DGPS may decrease because of the satellite-blocking effect when the surveying ship nears the bank especially in the canyon type of reservoir. Secondly, measurement can only be acquired in the area covered by water using the echo sounder, such that the measuring data of side slope area above water surface are lack to decrease the accuracy or seriously affect the calculation of reservoir water volume. This research is to hold the terrain accuracy when measuring the reservoir side slope and the Sun Moon Lake Reservoir in central Taiwan is chosen as the experimental location. Sun Moon Lake is the most popular place for tourists in Taiwan and also the most important reservoir of the electricity facilities. Furthermore, it owns the biggest pumped-storage hydroelectricity in Asia. The water in the lake is self-contained, and its water supply has been input through two underground tunnels, such that a deposit fan is formed when the muds were settled down from the silty water of the Cho-Shui Shi. Three kinds of survey are conducted in this experiment. First, a close-range photogrammetry, around the border of the Sun Moon Lake is made, or it takes shoots along the bank using a camera linked with a computer running the software Pix4D. The result can provide the DTM data to the side slope above the water level. Second, the bathymetrical data can be obtained by sweeping the

  11. A modified risk evaluation method of slope failure in a heavy rain. For application to slopes in widespread area

    International Nuclear Information System (INIS)

    Suenaga, Hiroshi; Tanaka, Shiro; Kobayakawa, Hiroaki

    2015-01-01

    A risk evaluation method of slope failure has developed to combine gas-liquid two phase flow analysis as a rainfall infiltration analysis and elastic-plastic finite element analysis as a slope stability analysis and has applied to a slope field. This method, however, had a difficulty to apply to many slopes since it needed many parameters to calculate the risk of the slope failure. The method was simplified to lessen input parameters which included an inclination and length of a slope, a depth of bedrock and a rainfall pattern assuming that hydraulic properties and mechanical properties were similar for the same geological unit. The method was also modified to represent a water collection structure, a surface runoff, an existence of a forest road and a water level variation of a downward river / pond which could affect infiltration phenomena. Results of the simplification and the modification made it possible to enhance a prediction precision of the method and create a hazard map of slopes in widespread area. (author)

  12. Triangular facets of slope in the region of Tudela (Ebro Basin, Navarra, Spain)

    International Nuclear Information System (INIS)

    Marin, C.; Desir, G.; Gutierrez, M.

    2009-01-01

    Some triangular slope facets are localized to the south of Bardenas Reales (central-west of Ebro Basin), elaborated on Tudela Formation deposits, Aragonian in age. Three of them have been dated by OSL resulting on ages of 35,588±2,488 yr. BP, 35,355±2,446 yr. BP and 40.185±2,411 yr. BP. The origin of these facets is ought to an alternation between accumulation and incision phases produced by vegetation cover variation percentage. Those vegetation cover changes are estimated to be due to climatic changes. (Author) 21 refs.

  13. Numerical Computation of Homogeneous Slope Stability

    Directory of Open Access Journals (Sweden)

    Shuangshuang Xiao

    2015-01-01

    Full Text Available To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM and particle swarm optimization algorithm (PSO to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759 were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS.

  14. C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba.

    Directory of Open Access Journals (Sweden)

    Guadalupe de la Lanza Espino

    Full Text Available The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC, nitrogen (TN, phosphorus (TP, elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g(-1. Sites near the island's lower slope had lower TOC average concentrations (158-333 µmol g(-1 than those closer to the channel axis (averaging 341-516 µmol g(-1; p <0.05. The TN concentrations near the lower slope attained 0.11% (80 µmol g(-1, whereas, towards the channel axis, they decreased to 0.07% (55 µmol g(-1; p<0.05. The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4 indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol gv; 0.12% to 0.16% than those near the channel axis (50.0 to 66 µmol g(-1; 0.15 to 0.21%. C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP. We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed.

  15. A model of late quaternary landscape development in the Delaware Valley, New Jersey and Pennsylvania

    Science.gov (United States)

    Ridge, J.C.; Evenson, E.B.; Sevon, W.D.

    1992-01-01

    landscape stability were delayed until the Holocene by a lingering cold climate, slope erosion, colluvium and alluvial fan deposition, and eolian sedimentation. Late Quaternary erosion in the Delaware Valley was dominated by glacial and periglacial processes during glacial stages. During the warm interglacial stages, soils developed on a more stable landscape. These souls were easily colluviated by periglacial erosion during periods of intermittent cold climate. ?? 1992.

  16. High slope waste dumps – a proven possibility

    Directory of Open Access Journals (Sweden)

    Igor Svrkota

    2013-11-01

    Full Text Available This paper is an overview of dumping operations on High Slope Waste Dump at Veliki Krivelj open pit copper mine, RTB Bor, Serbia. The High Slope Waste Dump in Bor is the highest single slope waste dump in the world with the slope height of 405 m. The paper gives the basics and limitations of the designed dumping technology, the redesigned technology, gives an overview of the 13 year long operation and gathered experiences and addresses the main issues of dumping operations in high slope conditions as well as the present condition of the High Slope Waste Dump.

  17. The fate of SOC during the processes of water erosion and subsequent deposition: a field study.

    Science.gov (United States)

    van Hemelryck, H.; Govers, G.; van Oost, K.; Merckx, R.

    2009-04-01

    needed to be complemented by field measurements, to achieve a better quantification and understanding of SOC dynamics in real field situations after a relatively important erosion event. This study was conducted on an agricultural field in Belgium, located on a convex-concave hill slope. The field was planted with potatoes in parallel ridges, running up-and-down slope along the length of the field. As such a set of elongated miniature watersheds was delineated, in which water and eroded sediment were rapidly directed down slope, where a perpendicular potato ridge obstructed the sediment-laden runoff water, thereby inducing deposition. During one high-intensity rainfall event, a serious amount of soil material was eroded from the sideslopes of the ridges (avg. 28 ton ha-1) and deposited down slope. The C enrichment ratios of the deposited sediment were low (0.99) and hinted at the absence of selectivity with respect to SOM erosion and deposition. This probably resulted from the transport of eroded soil in aggregated form. Subsequently, three measurement sites (two replicates) were delimited: i) a footslope position where soil was deposited (DEPO), ii) a similar footslope position on locations where no soil deposition occurred (NON-DEPO) and iii) a linear slope segment of the field (SLOPE). On each measurement site non-steady state gas sampling chambers were installed in triplicate. During a 5-month period, CO2-efflux (as a measurement of heterotrophic soil respiration) was measured at regular time intervals (from 2-3 times a week to biweekly). Soil moisture and temperature were monitored as well. Additionally, intact cylindrical soil cores were sampled at each measurement site. The soil cores were incubated at 25 °C while moisture was kept constant. Using this setup, information on SOC dynamics could be collected in the sediment source areas (SLOPE) as well as in the sink areas (DEPO). By including NON-DEPO sites we were able to distinguish the effects of erosion from

  18. Combining 137Cs and topographic surveys for measuring soil erosion/deposition patterns in a rapidly accreting area

    International Nuclear Information System (INIS)

    Ritchie, J.C.

    2000-01-01

    Narrow, stiff grass hedges are biological barriers designed to slow runoff and capture soils carried in runoff water. This study was designed to measure quantitatively the deposition of soil up slope of a narrow, stiff grass hedge using topographic and 137 Cs surveys. Topographic surveys made in 1991, 1995, and 1998 measured 1 to 2 cm yr -1 of recent sediment deposited up slope of the grass hedge. 137 Cs analyses of soil samples were used to determine the medium-term (45 years) soil redistribution patterns. Erosion rates and patterns determined using 137 Cs measured medium-term erosion near the hedge do not reflect the recent deposition patterns near the grass hedge measured by topographic surveys. Using the combination of topographic and 137 Cs surveys allows a better understanding of the role of grass hedges as barriers for capturing eroding soils and suggest that the recent deposition is associated with the grass hedge but that there is still a net loss of soil near the hedge position over the past 45 years. (author)

  19. Arctic Submarine Slope Stability

    Science.gov (United States)

    Winkelmann, D.; Geissler, W.

    2010-12-01

    Submarine landsliding represents aside submarine earthquakes major natural hazard to coastal and sea-floor infrastructure as well as to coastal communities due to their ability to generate large-scale tsunamis with their socio-economic consequences. The investigation of submarine landslides, their conditions and trigger mechanisms, recurrence rates and potential impact remains an important task for the evaluation of risks in coastal management and offshore industrial activities. In the light of a changing globe with warming oceans and rising sea-level accompanied by increasing human population along coasts and enhanced near- and offshore activities, slope stability issues gain more importance than ever before. The Arctic exhibits the most rapid and drastic changes and is predicted to change even faster. Aside rising air temperatures, enhanced inflow of less cooled Atlantic water into the Arctic Ocean reduces sea-ice cover and warms the surroundings. Slope stability is challenged considering large areas of permafrost and hydrates. The Hinlopen/Yermak Megaslide (HYM) north of Svalbard is the first and so far only reported large-scale submarine landslide in the Arctic Ocean. The HYM exhibits the highest headwalls that have been found on siliciclastic margins. With more than 10.000 square kilometer areal extent and app. 2.400 cubic kilometer of involved sedimentary material, it is one of the largest exposed submarine slides worldwide. Geometry and age put this slide in a special position in discussing submarine slope stability on glaciated continental margins. The HYM occurred 30 ka ago, when the global sea-level dropped by app. 50 m within less than one millennium due to rapid onset of global glaciation. It probably caused a tsunami with circum-Arctic impact and wave heights exceeding 130 meters. The HYM affected the slope stability field in its neighbourhood by removal of support. Post-megaslide slope instability as expressed in creeping and smaller-scaled slides are

  20. Rock slope instabilities in Norway: First systematic hazard and risk classification of 22 unstable rock slopes

    Science.gov (United States)

    Böhme, Martina; Hermanns, Reginald L.; Oppikofer, Thierry; Penna, Ivanna

    2016-04-01

    Unstable rock slopes that can cause large failures of the rock-avalanche type have been mapped in Norway for almost two decades. Four sites have earlier been characterized as high-risk objects based on expertise of few researchers. This resulted in installing continuous monitoring systems and set-up of an early-warning system for those four sites. Other unstable rock slopes have not been ranked related to their hazard or risk. There are ca. 300 other sites known of which 70 sites were installed for periodic deformation measurements using multiple techniques (Global Navigation Satellite Systems, extensometers, measurement bolts, and others). In 2012 a systematic hazard and risk classification system for unstable rock slopes was established in Norway and the mapping approach adapted to that in 2013. Now, the first 22 sites were classified for hazard, consequences and risk using this classification system. The selection of the first group of sites to be classified was based on an assumed high hazard or risk and importance given to the sites by Norwegian media and the public. Nine of the classified 22 unstable rock slopes are large sites that deform inhomogeneously or are strongly broken up in individual blocks. This suggests that different failure scenarios are possible that need to be analyzed individually. A total of 35 failure scenarios for those nine unstable rock slopes were considered. The hazard analyses were based on 9 geological parameters defined in the classification system. The classification system will be presented based on the Gamanjunni unstable rock slope. This slope has a well developed back scarp that exposes 150 m preceding displacement. The lateral limits of the unstable slope are clearly visible in the morphology and InSAR displacement data. There have been no single structures observed that allow sliding kinematically. The lower extend of the displacing rock mass is clearly defined in InSAR data and by a zone of higher rock fall activity. Yearly

  1. Submarine landslides on the north continental slope of the South China Sea

    Science.gov (United States)

    Wang, Weiwei; Wang, Dawei; Wu, Shiguo; Völker, David; Zeng, Hongliu; Cai, Guanqiang; Li, Qingping

    2018-02-01

    Recent and paleo-submarine landslides are widely distributed within strata in deep-water areas along continental slopes, uplifts, and carbonate platforms on the north continental margin of the South China Sea (SCS). In this paper, high-resolution 3D seismic data and multibeam data based on seismic sedimentology and geomorphology are employed to assist in identifying submarine landslides. In addition, deposition models are proposed that are based on specific geological structures and features, and which illustrate the local stress field over entire submarine landslides in deep-water areas of the SCS. The SCS is one of the largest fluvial sediment sinks in enclosed or semi-enclosed marginal seas worldwide. It therefore provides a set of preconditions for the formation of submarine landslides, including rapid sediment accumulation, formation of gas hydrates, and fluid overpressure. A new concept involving temporal and spatial analyses is tested to construct a relationship between submarine landslides and different time scale trigger mechanisms, and three mechanisms are discussed in the context of spatial scale and temporal frequency: evolution of slope gradient and overpressure, global environmental changes, and tectonic events. Submarine landslides that are triggered by tectonic events are the largest but occur less frequently, while submarine landslides triggered by the combination of slope gradient and over-pressure evolution are the smallest but most frequently occurring events. In summary, analysis shows that the formation of submarine landslides is a complex process involving the operation of different factors on various time scales.

  2. Soil-landform-plant-community relationships of a periglacial landscape on Potter Peninsula, maritime Antarctica

    Science.gov (United States)

    Poelking, E. L.; Schaefer, C. E. R.; Fernandes Filho, E. I.; de Andrade, A. M.; Spielmann, A. A.

    2015-05-01

    Integrated studies on the interplay between soils, periglacial geomorphology and plant communities are crucial for the understanding of climate change effects on terrestrial ecosystems of maritime Antarctica, one of the most sensitive areas to global warming. Knowledge on physical environmental factors that influence plant communities can greatly benefit studies on the monitoring of climate change in maritime Antarctica, where new ice-free areas are being constantly exposed, allowing plant growth and organic carbon inputs. The relationship between topography, plant communities and soils was investigated on Potter Peninsula, King George Island, maritime Antarctica. We mapped the occurrence and distribution of plant communities and identified soil-landform-vegetation relationships. The vegetation map was obtained by classification of a QuickBird image, coupled with detailed landform and characterization of 18 soil profiles. The sub-formations were identified and classified, and we also determined the total elemental composition of lichens, mosses and grasses. Plant communities on Potter Peninsula occupy 23% of the ice-free area, at different landscape positions, showing decreasing diversity and biomass from the coastal zone to inland areas where sub-desert conditions prevail. There is a clear dependency between landform and vegetated soils. Soils that have greater moisture or are poorly drained, and with acid to neutral pH, are favourable for moss sub-formations. Saline, organic-matter-rich ornithogenic soils of former penguin rookeries have greater biomass and diversity, with mixed associations of mosses and grasses, while stable felsenmeers and flat rocky cryoplanation surfaces are the preferred sites for Usnea and Himantormia lugubris lichens at the highest surface. Lichens sub-formations cover the largest vegetated area, showing varying associations with mosses.

  3. Applications of Cs-137 and soil trapping methods for studying slope processes in the Carpathian foothills

    Directory of Open Access Journals (Sweden)

    Chelmicki, Wojciech

    1992-06-01

    Full Text Available Areas of soil degradation and sedimentation have been delimited within a single, representative for the Carpathian Foothills, slope profile. Two methods: Cs-137 and soil trapping have been used. Soil degradation on the slope used as a pastureland is generally small, with the most intensive degradation in the mid slope. Once the slope was cultivated the process of erosion and soil wash must have been more intensive which is evidenced by high Cs-137 content within the valley bottom deposits. High Cs-137 content within forested ecosystems results from good Cs-137 trapping efficiency of forests rather than from the soil deposition.

    [es] Aplicación del Cs-137 y de métodos de trampeo de suelo para estudiar procesos de ladera en el piedemonte de los Cárpatos. Se han delimitado las áreas afectadas por erosión y sedimentación en un perfil de ladera, representativo del piedemonte de los Cárpatos. Se han empleado dos métodos: Cesio-137 y trampas de sedimentos. Se ha demostrado que la erosión del suelo en laderas utilizadas para pastos es generalmente pequeña, apareciendo las degradaciones más intensas a media ladera. Cuando la ladera estaba cultivada, los procesos de erosión debían ser más intensos, como lo evidencia el alto contenido de Cs-137 en los depósitos de fondo de valle. El elevado contenido de Cs-137 en ecosistemas forestales se debe a la eficacia de los bosques para atrapar el Cs-137, más que a la sedimentación.
    [de] Anwendung der Cs-137 und der Fangmethode zur bestimmung der Hangvorgänge im Karpatenhügelland. Entlang eines Hangprofíls innerhalb des Karpatenhügellandes sind Stellen ermitteit worden an denen, entweder Erosion oder Deposition festgestellt wurden. Das wurde aufgrund zweier fvlethoden bestimmt: anhand des radioaktiven Cs-137 und der Menge des erodierten Materials in eigens für diesen Zweck hergestellten Auffangbehältern. Es wurde festgestellt, dass aufeinem ais Weide genutzten Han die Intensit

  4. Linking slope stability and climate change: the Nordfjord region, western Norway, case study

    Science.gov (United States)

    Vasskog, K.; Waldmann, N.; Ariztegui, D.; Simpson, G.; Støren, E.; Chapron, E.; Nesje, A.

    2009-12-01

    Valleys, lakes and fjords are spectacular features of the Norwegian landscape and their sedimentary record recall past climatic, environmental and glacio-isostatic changes since the late glacial. A high resolution multi-proxy study is being performed on three lakes in western Norway combining different geophysical methods and sediment coring with the aim of reconstructing paleoclimate and to investigate how the frequency of hazardous events in this area has changed through time. A very high resolution reflection seismic profiling revealed a series of mass-wasting deposits. These events, which have also been studied in radiocarbon-dated cores, suggest a changing impact of slope instability on lake sedimentation since the late glacial. A specially tailored physically-based mathematical model allowed a numerical simulation of one of these mass wasting events and related tsunami, which occurred during a devastating rock avalanche in 1936 killing 74 persons. The outcome has been further validated against historical, marine and terrestrial information, providing a model that can be applied to comparable basins at various temporal and geographical scales. Detailed sedimentological and geochemical studies of selected cores allows characterizing the sedimentary record and to disentangle each mass wasting event. This combination of seismic, sedimentary and geophysical data permits to extend the record of mass wasting events beyond historical times. The geophysical and coring data retrieved from these lakes is a unique trace of paleo-slope stability generated by isostatic rebound and climate change, thus providing a continuous archive of slope stability beyond the historical record. The results of this study provide valuable information about the impact of climate change on slope stability and source-to-sink processes.

  5. The Hydromechanics of Vegetation for Slope Stabilization

    Science.gov (United States)

    Mulyono, A.; Subardja, A.; Ekasari, I.; Lailati, M.; Sudirja, R.; Ningrum, W.

    2018-02-01

    Vegetation is one of the alternative technologies in the prevention of shallow landslide prevention that occurs mostly during the rainy season. The application of plant for slope stabilization is known as bioengineering. Knowledge of the vegetative contribution that can be considered in bioengineering was the hydrological and mechanical aspects (hydromechanical). Hydrological effect of the plant on slope stability is to reduce soil water content through transpiration, interception, and evapotranspiration. The mechanical impact of vegetation on slope stability is to stabilize the slope with mechanical reinforcement of soils through roots. Vegetation water consumption varies depending on the age and density, rainfall factors and soil types. Vegetation with high ability to absorb water from the soil and release into the atmosphere through a transpiration process will reduce the pore water stress and increase slope stability, and vegetation with deep root anchoring and strong root binding was potentially more significant to maintain the stability of the slope.

  6. Effects of erosion in the fate of soil organic carbon and soil aggregation in a burned Mediterranean hill-slope

    Science.gov (United States)

    Campo, Julian; Cammeraat, Erik; Gimeno-García, Eugenia; Andreu, Vicente

    2016-04-01

    The Intergovernmental Panel on Climate Change indicated a higher degree of confidence that meteorological conditions associated to climate change will be propitious to increasing extreme events manifested, among others, in bigger and more frequent wildfires (IPCC, 2014). Wildfires contribute to shaping the landscape, and also the geomorphological and hydrological processes that operate on soil are affected (Bento-Gonçalves et al., 2012). Whereas, it is well documented that wildfires produce significant changes on erosion processes, the associated fate of soil organic carbon (SOC) has received less attention. This research assesses this gap by studying the loss, redistribution, and stabilization of SOC in a Mediterranean forest hill-slope burned the 28-08-2014, with high severity fire, at the Natural Park of Sierra de Espadán, Spain (39°50'45.11"N, 0°22'20.52"W). To this end, soil was sampled (19-9-2014) in the foot's slope (depositional), middle part (transport) and top (eroding) at two depths (test>146 drops). Significant differences (ANOVA, pBS) and soil depths (topsoil>subsoil). However, no significant differences were observed among eroding (58.8+20.8 gC kg-1), transport (67.3+34.4 gC kg-1), and depositional zones (62.0+31.3 gC kg-1), which is not in agreement with other SOC redistribution studies (Wang et al., 2014). Significant differences (Kruskal-Wallis, pBS) but not between soil depths or hill-slope positions. In the first post-fire erosive rains occurred in the area (29-11-14), closest pluviometer (Sot de Ferrer: 4.5 km) registered a total daily rain up to 64.2 l m-2. In this event a total of 12.7 kg of sediment were collected (contributing area ≈0.25 ha), with a content of 252.6 gC kg-1 the total SOC transported or stored in the depositional zone can reach up to 3.2 kg. In the second erosive event (23-3-15: 103.2 l m-2), total sediment in the fences was 143.6 kg, with content of 112.2 gC kg-1, made a total SOC eroded of up to 16.1 kg. It is

  7. Cenozoic global sea level, sequences, and the New Jersey transect: Results from coastal plain and continental slope drilling

    Science.gov (United States)

    Miller, K.G.; Mountain, Gregory S.; Browning, J.V.; Kominz, M.; Sugarman, P.J.; Christie-Blick, N.; Katz, M.E.; Wright, J.D.

    1998-01-01

    The New Jersey Sea Level Transect was designed to evaluate the relationships among global sea level (eustatic) change, unconformity-bounded sequences, and variations in subsidence, sediment supply, and climate on a passive continental margin. By sampling and dating Cenozoic strata from coastal plain and continental slope locations, we show that sequence boundaries correlate (within ??0.5 myr) regionally (onshore-offshore) and interregionally (New Jersey-Alabama-Bahamas), implicating a global cause. Sequence boundaries correlate with ??18O increases for at least the past 42 myr, consistent with an ice volume (glacioeustatic) control, although a causal relationship is not required because of uncertainties in ages and correlations. Evidence for a causal connection is provided by preliminary Miocene data from slope Site 904 that directly link ??18O increases with sequence boundaries. We conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since ~42 Ma. We speculate that prior to this, the growth and decay of small ice sheets caused small-amplitude sea level changes (changes on mid-ocean ridges. Although our results are consistent with the general number and timing of Paleocene to middle Miocene sequences published by workers at Exxon Production Research Company, our estimates of sea level amplitudes are substantially lower than theirs. Lithofacies patterns within sequences follow repetitive, predictable patterns: (1) coastal plain sequences consist of basal transgressive sands overlain by regressive highstand silts and quartz sands; and (2) although slope lithofacies variations are subdued, reworked sediments constitute lowstand deposits, causing the strongest, most extensive seismic reflections. Despite a primary eustatic control on sequence boundaries, New Jersey sequences were also influenced by changes in tectonics, sediment supply, and climate. During the early to middle Eocene, low siliciclastic and

  8. Paleo-hydraulic Reconstructions of Topographically Inverted River Deposits on Earth and Mars

    Science.gov (United States)

    Hayden, A.; Lamb, M. P.; Fischer, W. W.; Ewing, R. C.; McElroy, B. J.

    2015-12-01

    River deposits are one of the keys to understanding the history of flowing water and sediment on Earth and Mars. Deposits of some ancient Martian rivers have been topographically inverted resulting in sinuous ridges visible from orbit. However, it is unclear what aspects of the fluvial deposits these ridges represent, so reconstructing paleo-hydraulics from ridge geometry is complicated. Most workers have assumed that ridges represent casts of paleo-river channels, such that ridge widths and slopes, for example, can be proxies for river widths and slopes at some instant in time. Alternatively, ridges might reflect differential erosion of extensive channel bodies, and therefore preserve a rich record of channel conditions and paleoenvironment over time. To explore these hypotheses, we examined well exposed inverted river deposits in the Jurassic Morrison and Early Cretaceous Cedar Mountain Formations across the San Rafael Swell of central Utah. We mapped features on foot and by UAV, measured stratigraphic sections and sedimentary structures to constrain deposit architecture and river paleo-hydraulics, and used field observations and drainage network analyses to constrain recent erosion. Our work partly confirms earlier work in that the local trend of the ridge axis generally parallels paleo-flow indicators. However, ridge relief is much greater than reconstructed channel depths, and ridge widths vary from zero to several times the reconstructed channel width. Ridges instead appear to record a rich history of channel lateral migration, floodplain deposition, and soil development over significant time. The ridge network is disjointed owing to active modern fluvial incision and scarp retreat. Our results suggest that ridge geometry alone contains limited quantitative information about paleo-rivers, and that stratigraphic sections and observations of sedimentary structures within ridge-forming deposits are necessary to constrain ancient river systems on Mars.

  9. Depositional facies and aqueous-solid geochemistry of travertine-depositing hot springs (Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, USA)

    Energy Technology Data Exchange (ETDEWEB)

    Fouke, B.W.; Farmer, J.D.; Des Marais, D.J.; Pratt, L.; Sturchio, N.C.; Burns, P.C.; Discipulo, M.K.

    2000-05-01

    Petrographic and geochemical analyses of travertine-depositing hot springs at Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, have been used to define five depositional facies along the spring drainage system. Spring waters are expelled in the vent facies at 71 to 73 C and precipitate mounded travertine composed of aragonite needle botryoids. The apron and channel facies (43--72 C) is floored by hollow tubes composed of aragonite needle botryoids that encrust sulfide-oxidizing Aquificales bacteria. The travertine of the pond facies (30--62 C) varies in composition from aragonite needle shrubs formed at higher temperatures to ridged networks of calcite and aragonite at lower temperatures. Calcite ice sheets, calcified bubbles, and aggregates of aragonite needles (fuzzy dumbbells) precipitate at the air-water interface and settle to pond floors. The proximal-slope facies (28--54 C), which forms the margins of terracette pools, is composed of arcuate aragonite needle shrubs that create small microterracettes on the steep slope face. Finally, the distal-slope facies (28--30 C) is composed of calcite spherules and calcite feather crystals. Despite the presence of abundant microbial mat communities and their observed role in providing substrates for mineralization, the compositions of spring-water and travertine predominantly reflect abiotic physical and chemical processes. Vigorous CO{sub 2} degassing causes a +2 unit increase in spring water pH, as well as Rayleigh-type covariations between the concentration of dissolved inorganic carbon and corresponding {delta}{sup 13}C. Travertine {delta}{sup 13}C and {delta}{sup 18}O are nearly equivalent to aragonite and calcite equilibrium values calculated from spring water in the higher-temperature ({approximately}50--73 C) depositional facies. Conversely, travertine precipitating in the lower-temperature (<{approximately}50 C) depositional facies exhibits {delta}{sup 13}C and {delta}{sup 18}O values that are as

  10. Internal waves and temperature fronts on slopes

    Directory of Open Access Journals (Sweden)

    S. A. Thorpe

    Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

    Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

  11. Deterministic estimation of hydrological thresholds for shallow landslide initiation and slope stability models: case study from the Somma-Vesuvius area of southern Italy

    Science.gov (United States)

    Baum, Rex L.; Godt, Jonathan W.; De Vita, P.; Napolitano, E.

    2012-01-01

    Rainfall-induced debris flows involving ash-fall pyroclastic deposits that cover steep mountain slopes surrounding the Somma-Vesuvius volcano are natural events and a source of risk for urban settlements located at footslopes in the area. This paper describes experimental methods and modelling results of shallow landslides that occurred on 5–6 May 1998 in selected areas of the Sarno Mountain Range. Stratigraphical surveys carried out in initiation areas show that ash-fall pyroclastic deposits are discontinuously distributed along slopes, with total thicknesses that vary from a maximum value on slopes inclined less than 30° to near zero thickness on slopes inclined greater than 50°. This distribution of cover thickness influences the stratigraphical setting and leads to downward thinning and the pinching out of pyroclastic horizons. Three engineering geological settings were identified, in which most of the initial landslides that triggered debris flows occurred in May 1998 can be classified as (1) knickpoints, characterised by a downward progressive thinning of the pyroclastic mantle; (2) rocky scarps that abruptly interrupt the pyroclastic mantle; and (3) road cuts in the pyroclastic mantle that occur in a critical range of slope angle. Detailed topographic and stratigraphical surveys coupled with field and laboratory tests were conducted to define geometric, hydraulic and mechanical features of pyroclastic soil horizons in the source areas and to carry out hydrological numerical modelling of hillslopes under different rainfall conditions. The slope stability for three representative cases was calculated considering the real sliding surface of the initial landslides and the pore pressures during the infiltration process. The hydrological modelling of hillslopes demonstrated localised increase of pore pressure, up to saturation, where pyroclastic horizons with higher hydraulic conductivity pinch out and the thickness of pyroclastic mantle reduces or is

  12. SaLEM (v1.0) - the Soil and Landscape Evolution Model (SaLEM) for simulation of regolith depth in periglacial environments

    Science.gov (United States)

    Bock, Michael; Conrad, Olaf; Günther, Andreas; Gehrt, Ernst; Baritz, Rainer; Böhner, Jürgen

    2018-04-01

    We propose the implementation of the Soil and Landscape Evolution Model (SaLEM) for the spatiotemporal investigation of soil parent material evolution following a lithologically differentiated approach. Relevant parts of the established Geomorphic/Orogenic Landscape Evolution Model (GOLEM) have been adapted for an operational Geographical Information System (GIS) tool within the open-source software framework System for Automated Geoscientific Analyses (SAGA), thus taking advantage of SAGA's capabilities for geomorphometric analyses. The model is driven by palaeoclimatic data (temperature, precipitation) representative of periglacial areas in northern Germany over the last 50 000 years. The initial conditions have been determined for a test site by a digital terrain model and a geological model. Weathering, erosion and transport functions are calibrated using extrinsic (climatic) and intrinsic (lithologic) parameter data. First results indicate that our differentiated SaLEM approach shows some evidence for the spatiotemporal prediction of important soil parental material properties (particularly its depth). Future research will focus on the validation of the results against field data, and the influence of discrete events (mass movements, floods) on soil parent material formation has to be evaluated.

  13. Erosion prediction for alpine slopes: a symbiosis of remote sensing and a physical based erosion model

    Science.gov (United States)

    Kaiser, Andreas; Neugirg, Fabian; Haas, Florian; Schindewolf, Marcus; Schmidt, Jürgen

    2014-05-01

    As rainfall simulations represent an established tool for quantifying soil detachment on cultivated area in lowlands and low mountain ranges, they are rarely used on steep slopes high mountain ranges. Still this terrain represents productive sediment sources of high morphodynamic. A quantitative differentiation between gravitationally and fluvially relocated material reveals a major challenge in understanding erosion on steep slopes: does solifluction as a result of melting in spring or heavy convective rainstorms during summer cause the essential erosion processes? This paper aims to answer this question by separating gravitational mass movement (solifluction, landslides, mudflow and needle ice) and runoff-induced detachment. First simulated rainstorm experiments are used to assess the sediment production on bare soil on a strongly inclined plot (1 m², 42°) in the northern limestone Alps. Throughout precipitation experiments runoff and related suspended sediments were quantified. In order to enlarge slope length virtually to around 20 m a runoff feeding device is additionally implemented. Soil physical parameters were derived from on-site sampling. The generated data is introduced to the physically based and catchment-scaled erosion model EROSION 3D to upscale plot size to small watershed conditions. Thus infiltration, runoff, detachment, transport and finally deposition can be predicted for single rainstorm events and storm sequences. Secondly, in order to separate gravitational mass movements and water erosion, a LiDAR and structure-from-motion based monitoring approach is carried out to produce high-resolution digital elevation models. A time series analysis of detachment and deposition from different points in time is implemented. Absolute volume losses are then compared to sediment losses calculated by the erosion model as the latter only generates data that is connected to water induced hillside erosion. This methodology will be applied in other watersheds

  14. Runoff from armored slopes

    International Nuclear Information System (INIS)

    Codell, R.B.

    1986-01-01

    Models exist for calculating overland flow on hillsides but no models have been found which explicitly deal with runoff from armored slopes. Flow on armored slopes differs from overland flow, because substantial flow occurs beneath the surface of the rock layer at low runnoff, and both above and below the surface for high runoff. In addition to the lack of a suitable model, no estimates of the PMP exist for such small areas and for very short durations. This paper develops a model for calculating runoff from armored embankments. The model considers the effect of slope, drainage area and ''flow concentration'' caused by irregular grading or slumping. A rainfall-duration curve based on the PMP is presented which is suitable for very small drainage areas. The development of the runoff model and rainfall-duration curve is presented below, along with a demonstration of the model on the design of a hypothetical tailings embankment

  15. Potential climatic refugia in semi-arid, temperate mountains: plant and arthropod assemblages associated with rock glaciers, talus slopes, and their forefield wetlands, Sierra Nevada, California, USA

    Science.gov (United States)

    Constance I. Millar; Robert D. Westfall; Angela Evenden; Jeffrey G. Holmquist; Jutta Schmidt-Gengenbach; Rebecca S. Franklin; Jan Nachlinger; Diane L. Delany

    2015-01-01

    Unique thermal and hydrologic regimes of rock-glacier and periglacial talus environments support little-studied mountain ecosystems. We report the first studies of vascular plant and arthropod diversity for these habitats in the central Sierra Nevada, California, USA. Surfaces of active rock glaciers develop scattered islands of soil that provide habitat for vegetation...

  16. Radiological monitoring of northern slopes of Mogoltau

    International Nuclear Information System (INIS)

    Murtazaev, Kh.; Boboev, B.D.; Bolibekov, Sh.; Akhmedov, M.Z.

    2010-01-01

    Present article is devoted to radiological monitoring of northern slopes of Mogoltau. The physicochemical properties of water of northern slopes of Mogoltau were studied. The radiation monitoring of northern slopes of Mogoltau was carried out during several years under various weather conditions. The exposure rate of human settlements of northern part of Mogoltau was defined.

  17. Stability of Slopes Reinforced with Truncated Piles

    Directory of Open Access Journals (Sweden)

    Shu-Wei Sun

    2016-01-01

    Full Text Available Piles are extensively used as a means of slope stabilization. A novel engineering technique of truncated piles that are unlike traditional piles is introduced in this paper. A simplified numerical method is proposed to analyze the stability of slopes stabilized with truncated piles based on the shear strength reduction method. The influential factors, which include pile diameter, pile spacing, depth of truncation, and existence of a weak layer, are systematically investigated from a practical point of view. The results show that an optimum ratio exists between the depth of truncation and the pile length above a slip surface, below which truncating behavior has no influence on the piled slope stability. This optimum ratio is bigger for slopes stabilized with more flexible piles and piles with larger spacing. Besides, truncated piles are more suitable for slopes with a thin weak layer than homogenous slopes. In practical engineering, the piles could be truncated reasonably while ensuring the reinforcement effect. The truncated part of piles can be filled with the surrounding soil and compacted to reduce costs by using fewer materials.

  18. Slope stability radar for monitoring mine walls

    Science.gov (United States)

    Reeves, Bryan; Noon, David A.; Stickley, Glen F.; Longstaff, Dennis

    2001-11-01

    Determining slope stability in a mining operation is an important task. This is especially true when the mine workings are close to a potentially unstable slope. A common technique to determine slope stability is to monitor the small precursory movements, which occur prior to collapse. The slope stability radar has been developed to remotely scan a rock slope to continuously monitor the spatial deformation of the face. Using differential radar interferometry, the system can detect deformation movements of a rough wall with sub-millimeter accuracy, and with high spatial and temporal resolution. The effects of atmospheric variations and spurious signals can be reduced via signal processing means. The advantage of radar over other monitoring techniques is that it provides full area coverage without the need for mounted reflectors or equipment on the wall. In addition, the radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, twenty-four hours a day. The system has been trialed at three open-cut coal mines in Australia, which demonstrated the potential for real-time monitoring of slope stability during active mining operations.

  19. A historical case in the Bolivia-Brazil natural gas pipeline: slope on the Curriola River; Caso historico no Gasoduto Bolivia-Brasil: encosta no Rio Curriola

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Hudson Regis; Vasconcellos, Carlos Renato Aragonez de [Transportadora Brasileira Gasoduto Bolivia-Brasil, S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    The Bolivia-Brazil Natural Gas Pipeline has 2.593 kilometers since Rio Grande City in Bolivia until Canoas City, in south Brazil. The pipeline crosses a lot of types of geological fields and difficult topography. The south spread of the gas pipeline is the most interesting because of its hard topography combined with the variety of geological materials, such as, colluvium deposits and debris flow areas. Curriola River is located at the kilometer 408, north part of Parana State. In this area, the pipeline crosses slopes of 45 degrees of inclination. The down part of Curriola's slope is composed by a non-resistance material (clay and little rock blocks) with a high porosity. Every year, during the rainy seasons, tension cracks are observed evidencing the earth movement. The slope stability is above the minimum expected for pipeline operation. The aim of this paper is to present the site characterization of the Curriola River Slope, together with all the investigation made in order to supply the studies with condensed information for the slope stabilization. (author)

  20. Large slope instabilities in Northern Chile and Southern Peru

    Science.gov (United States)

    Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea

    2014-05-01

    Deep canyon incision into Tertiary paleosurfaces and large slope instabilities along the canyon flanks characterize the landscape of western slope of the Andes of northern Chile and South Peru. This area belongs to the Coastal Escarpment and Precordillera and is formed by coarse-grained clastic and volcanoclastic formations. The area is characterized by intense seismicity and long-term hyperaridity (Atacama Desert). Landslides along the canyon flanks affect volumes generally up to 1 km3 and locally evolved in large rock avalanches. We prepared a landslide inventory covering an area of about 30,000 km2, extending from Iquique (Chile) to the South and Tacna (Peru) to the North. A total of 606 landslides have been mapped in the area by use of satellite images and direct field surveys, prevalently including large phenomena. The landslides range from 1 10-3 km2 to 464 km2 (Lluta landslide). The total landslide area, inclusive of the landslide scarp and of the deposit, amounts to about 2,130 km2 (about 7% of the area). The mega landslides can be classified as large block slides that can evolve in large rock avalanches (e.g. Minimini landslide). Their initiation seems to be strongly associated to the presence of secondary faults and large fractures transversal to the slope. These landslides show evidence suggesting a re-incision by the main canyon network. This seems particularly true for the Lluta collapse where the main 'landslide' mass is masked or deleted by the successive erosion. Other landslides have been mapped along the Coastal Escarpment and some of the major tectonic escarpments with an E-W trend. We examined area-frequency distributions of landslides by developing logarithmically binned, non-cumulative size frequency distributions that report frequency density as a function of landslide planar area A. The size frequency distribution presents a strong undersampling for smaller landslides, due to the extremely old age of the inventory. For landslides larger than

  1. Evaluation of seismic effects on the landslide deposits of Monte Salta (Eastern Italian Alps) using distinct element method

    Science.gov (United States)

    Marcato, G.; Fujisawa, K.; Mantovani, M.; Pasuto, A.; Silvano, S.; Tagliavini, F.; Zabuski, L.

    2007-11-01

    The aim of the paper is to present the modelling of the ground effects of seismic waves on a large debris deposit lying on a steep mountain slope, with particular attention paid to the potential triggering of slope movements. The study site is a mass of 2.5 million m3 rock fall deposit, named "Monte Salta Landslide", located on the northern slope of the Vajont valley, at the border between Veneto and Friuli Venezia Giulia regions in north-eastern Italy. Several historical landslide events were reported in the area in the past, first one dating back to the 17th century. The landslide deposit completely mantles the slope with a thick cover of rock blocks. The Mt. Salta landslide is conditioned by the presence of Mt. Borgà regional thrust, which uplifts Jurassic limestone on the top of Cretaceous rock units. Above the thrust zone, folded and highly fractured rock mass dips steeply towards the slope free face, producing highly unstable setting. The study area has been classified as high seismic hazard and different vulnerable elements can be affected by the remobilisation of debris, among which a village, a national road and a big quarry that was opened, with the intent to exploit the part of the landslide deposit for construction purposes. In this study, numerical analysis was performed, to simulate the slope behaviour using distinct element method and applying UDEC code. The 2-D models were built on three cross-sections and elasto-plastic behaviour was assumed, both for rock matrix and discontinuities. The earthquake effect was modelled in pseudo-dynamic way, i.e. by magnifying the acceleration and applying also its horizontal component. The expected seismic acceleration in the study area was calculated on the basis of previous studies as equal to 0.28 g. The results proved that the increase of the vertical component alone has a small influence on the deformational behaviour of the system. Hence, the acceleration vector was deviated at 5° and then at 10° from the

  2. Decision Guide for Roof Slope Selection

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, T.R.

    1988-01-01

    This decision guide has been written for personnel who are responsible for the design, construction, and replacement of Air Force roofs. It provides the necessary information and analytical tools for making prudent and cost-effective decisions regarding the amount of slope to provide in various roofing situations. Because the expertise and experience of the decision makers will vary, the guide contains both basic slope-related concepts as well as more sophisticated technical data. This breadth of information enables the less experienced user to develop an understanding of roof slope issues before applying the more sophisticated analytical tools, while the experienced user can proceed directly to the technical sections. Although much of this guide is devoted to the analysis of costs, it is not a cost-estimating document. It does, however, provide the reader with the relative costs of a variety of roof slope options; and it shows how to determine the relative cost-effectiveness of different options. The selection of the proper roof slope coupled with good roof design, a quality installation, periodic inspection, and appropriate maintenance and repair will achieve the Air Force's objective of obtaining the best possible roofing value for its buildings.

  3. Deltaic Depositional Systems, Evolution Characteristics, and Petroleum Potential, Palaeogene Sub-Basin, South China Sea

    Science.gov (United States)

    Li, Yuan; Wang, Hua; Zhang, Guotao

    2015-04-01

    Deltaic depositional systems are detailed characterized by morphology and facies in a Palaeogene continental sub-basin of Beibuwan Basin, South China Sea. Based on examination of 435 m of conventional cores from 30 wells, three major types of deltaic facies have been recognized: delta, beach and shoreface. Morphology and facies asymmetry between the down-drift and the up-drift sides present a typical asymmetric delta system:1) the down-rift, sourced primarily by the feeding river, are influenced by mixed river and wave processes. Deposits on this side are muddy and consist of barrier, bar, bay-fill, and bayhead delta facies with variable bioturbation intensity; 2)the up-rift, in contrast, is sourced by a second sediment source and typically consists of laterally continuous sandy beach and shoreface facies. Finally, two fundamentally different depositional models are established and reflect a different style of sequence stratigraphic patterns: 1) Multiple-stage faults slopes developed in the down-rift side feed fine grained sediment into two stages channelized front deltaic system; 2) Flexure slope break of the up-rift side, combining with deeper gradual slopes, conversely, feed coarser grained sediment from larger drainages into sandy beach and shoreface systems. Such a distinction has well explained the differentiation of the proven hydrocarbon reserves because the up-rift consists of well-sorted, mature, and laterally continuous homogeneous beach-shoreface reservoirs, whereas the down-rift, in contrast, is muddier and consists of less continuous, less mature, heterolithic reservoirs. The Delta asymmetry concepts and models don't only challenge the traditional definition of deltas in Fushan sub-basin, but also provides strong theoretical support for the future exploration. This process-based model may be applicable to many deep-water settings and provides a framework within which to interpret the stratigraphic and spatial distribution of these complex deposits.

  4. Determination of Redistribution of Erosion/Deposition Rate in Cultivated Area Using 137Cs Technique

    International Nuclear Information System (INIS)

    Nita Suhartini; Syamsul Abbas RAS; Barokah A; Ali Arman L

    2004-01-01

    The aim of the research is to determine the rate of redistribution of erosion/deposition in cultivated area. The application of 137 Cs technique was carried out at cultivated area in Bojong - Ciawi, with slope less than 10 o and slope length of about 2 km. A reference site was selected at the top of the slope, and this site is flat, open and covered with grass. Two sites in the cultivated area were selected as study site namely LU-I ( 15 x 25 ) m with the distance of 1000 m from the top, and LU-II (17.5 x 20) m with the distance of 1300 m from the top. Sampling of soil at reference site was done by using scraper (20 x 50) cm, while sampling at study site by using core sampling (di = 7 cm). Soil samples were brought to the laboratorium for preparation and analysis of 137 Cs content. Preparation are including of drying, weighing the total dry, sieving and crushing. Analysis of 137 Cs content was done using multi channel analyzer (MCA) that connected to high purity germanium (HPGe), at 661 keV, and the minimum counting time of 16 hours. To estimate the erosion/deposit rate, two mathematical model were used, namely Proportional Model (PM) and Mass Balance Model 1 (MBM1). The result for application of 137 Cs technique showed that MBM1 gives somewhat higher value for deposit rate and somewhat lower value for erosion than PM. Land use - I (LU-I) of Bojong - Ciawi was suffering from erosion with the erosion rate from 1 t/(ha.y) to 13 t/(ha.y), and LU-II has deposit rate from 1 t/(ha.y) to 50 t/(ha.y). (author)

  5. The great slippery-slope argument.

    Science.gov (United States)

    Burgess, J A

    1993-09-01

    Whenever some form of beneficent killing--for example, voluntary euthanasia--is advocated, the proposal is greeted with a flood of slippery-slope arguments warning of the dangers of a Nazi-style slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slippery-slope arguments that are sound and convincing, typical formulations of the Nazi-invoking argument are found to be seriously deficient both in logical rigour and in the social history and psychology required as a scholarly underpinning. As an antidote, an attempt is made both to identify some of the likely causes of genocide and to isolate some of the more modest but legitimate fears that lie behind slippery-slope arguments of this kind.

  6. Slope activity in Gale crater, Mars

    Science.gov (United States)

    Dundas, Colin M.; McEwen, Alfred S.

    2015-01-01

    High-resolution repeat imaging of Aeolis Mons, the central mound in Gale crater, reveals active slope processes within tens of kilometers of the Curiosity rover. At one location near the base of northeastern Aeolis Mons, dozens of transient narrow lineae were observed, resembling features (Recurring Slope Lineae) that are potentially due to liquid water. However, the lineae faded and have not recurred in subsequent Mars years. Other small-scale slope activity is common, but has different spatial and temporal characteristics. We have not identified confirmed RSL, which Rummel et al. (Rummel, J.D. et al. [2014]. Astrobiology 14, 887–968) recommended be treated as potential special regions for planetary protection. Repeat images acquired as Curiosity approaches the base of Aeolis Mons could detect changes due to active slope processes, which could enable the rover to examine recently exposed material.

  7. Slope Instability Risk Analysys of the Municipality of Comala, Colima , Mexico

    Science.gov (United States)

    Ramirez-Ruiz, J. J.

    2017-12-01

    Every year during the rainy season occur the problem of mass landslide in some areas of the community of Comala, Colima Mexico. Slope instability is studied in this volcanic region which is located in the southern part of the Volcan de Fuego de Colima. It occurs due to the combination of different factors existing in this area as: Precipitation, topography contrast, type and mechanical properties of deposits that constitute the rocks and soils of the region and the erosion due to the elimination of vegetation deck to develop and grow urban areas. To these geological factors we can extend the tectonic activity of the Western part of Mexico that originate high seismicity by the interaction of Cocos plate and North America plate forming the region of Graben de Colima, were is located this area. Here we will present a Zonification and determination of Slope Instability Risk Maps due to the rain and seismicity accelerators factors. This Study is parto of a proyect to reduce the risk of this phenomenon, it was carried out as part of the National Risk Map of Mexico analized using the CENAPRED methodology to zonificate the risk areas. The instability of slopes is determined both in its origin and in its development, by different mechanisms. In such a way that this process of instability can be grouped into four main categories: Falls or landslides, Flows, Slips and expansions or lateral landslides. Here it is presented the Risk analisis to this volcanic area that cover the municipality of Comala in the State of Colima, Mexico using the Susceptibility map, Risk Map and Risk analisis of the Municipality.

  8. Storm-Induced Slope Failure Susceptibility Mapping

    Science.gov (United States)

    2018-01-01

    A pilot study was conducted to characterize and map the areas susceptible to slope failure using state-wide available data. The objective was to determine whether it would be possible to provide slope-failure susceptibility mapping that could be used...

  9. Modern Instrumentation of a Historical Landslide to Understand Dynamic Processes Governing Slope Movement in a Hostile Environment.

    Science.gov (United States)

    Johnson, K. A.

    2017-12-01

    The Milepost 6.2 Landslide on Many Glacier Road in Glacier National Park, Montana, has been moving since construction of the roadway in the early 1900's. Movement of the slide has a direct impact on Park operations and requires regrading and reconstruction of the road on a nearly annual basis. Prior attempts to stabilize the slope were not effective. Despite the history of this slide, very little quality data was available to delineate the depth and shape of the slide or the groundwater pressures that influence slope stability due to only seasonal data collection and a hostile winter environment. Landslide dynamics are further complicated where the toe of the slide becomes submerged seasonally by Lake Sherburne. In addition, due to irrigation use the lake levels fluctuate rapidly with seasonal rise and drops commonly greater than 30 feet in elevation. Five Shape Accelerometer Array inclinometers (SAAs) were installed to depths between 60 and 200 feet, along with 10 vibrating wire piezometers, one tipping bucket rain gauge, and onsite data acquisition system with a real-time satellite communication link enabling year-round data collection. Measurements of groundwater pressures and slide dynamics were used to develop a well constrained 2-D dynamic model of slide movement. Movement is controlled by clayey zones in glacial till deposits that mantle the valley slopes, along with water pressures from groundwater in the slope and fluctuating lake levels at the toe of the slope. The SAAs document slide plane locations and rates of slide movement as it changes through the year in response to the dynamic hydrologic setting. SAAs document sliding of over 3 feet and continue to operate and generate additional data. The data collected enabled the design of an extensive horizontal drain system to lower the groundwater pressures and stabilize the slope. Continuous year-round monitoring allowed comparison of slope movement in response to changes in lake elevation and precipitation

  10. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

    Science.gov (United States)

    Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin M.; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

    2016-01-01

    One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100mm, and suggest that a significant amount of near-surface watermight be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

  11. Slope Estimation in Noisy Piecewise Linear Functions.

    Science.gov (United States)

    Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy

    2015-03-01

    This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure.

  12. Hydrology of two slopes in subarctic Yukon, Canada

    Science.gov (United States)

    Carey, Sean K.; Woo, Ming-Ko

    1999-11-01

    Two subarctic forested slopes in central Wolf Creek basin, Yukon, were studied in 1996-1997 to determine the seasonal pattern of the hydrologic processes. A south-facing slope has a dense aspen forest on silty soils with seasonal frost only and a north-facing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost. Snowmelt is advanced by approximately one month on the south-facing slope due to greater radiation receipt. Meltwater infiltrates its seasonally frozen soil with low ice content, recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow. Summer evaporation depletes this recharged moisture and any additional rainfall input, at the expense of surface or subsurface flow. The north-facing slope with an ice rich substrate hinders deep percolation. Snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies, and subsurface flow along pipes and within the matrix of the organic soil. During the summer, most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulder-clay. Evaporation on the north-facing slope declines as both the frost table and the water table descend in the summer. A water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the south-facing slope, whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component, principally within the organic layer. These results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments.

  13. Research on the stability evaluation of slope

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-08-15

    In order to create the guideline corresponding to a new regulatory standard, such as criteria in the ground-slope stability evaluation method, we have conducted an analysis and discussion of the shaking table test results using a large slope model. As a result, it was found that in that phase of the vertical motion and the horizontal motion affects the amplification characteristics of the ground motion, need to be considered in assessing the safety of the slope and the influence of the phase difference amplification or local. We also conduct a study on countermeasure construction slope by shaking table test, the effect of the countermeasure construction of pile and anchors deterrence could be confirmed. Focusing on the new method can reproduce the behavior of large deformation and discontinuity, with respect to the advancement of slope analysis, we identify issues on the maintenance and code applicability of each analysis method. (author)

  14. A Hybrid FEM-ANN Approach for Slope Instability Prediction

    Science.gov (United States)

    Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.

    2016-09-01

    Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.

  15. An alternative soil nailing system for slope stabilization: Akarpiles

    Science.gov (United States)

    Lim, Chun-Lan; Chan, Chee-Ming

    2017-11-01

    This research proposes an innovative solution for slope stabilization with less environmental footprint: AKARPILES. In Malaysia, landslide has become common civil and environmental problems that cause impacts to the economy, safety and environment. Therefore, effective slope stabilization method helps to improve the safety of public and protect the environment. This study focused on stabilizing surfacial slope failure. The idea of AKARPILES was generated from the tree roots system in slope stabilization. After the piles are installed in the slope and intercepting the slip plane, grout was pumped in and discharged through holes on the piles. The grout then filled the pores in the soil with random flow within the slip zone. SKW mixture was used to simulate the soil slope. There were two designs being proposed in this study and the prototypes were produced by a 3D printer. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. A series of tests were conducted on the single-pile-reinforced slope under vertical slope crest loading condition considering different slope gradients and nail designs. Parameters such as ultimate load, failure time and failure strain were recorded and compared. As comparison with the unreinforced slope, both designs of AKARPILES showed better but different performances in the model tests.

  16. Factors affecting seismic response of submarine slopes

    Directory of Open Access Journals (Sweden)

    G. Biscontin

    2006-01-01

    Full Text Available The response of submerged slopes on the continental shelf to seismic or storm loading has become an important element in the risk assessment for offshore structures and 'local' tsunami hazards worldwide. The geological profile of these slopes typically includes normally consolidated to lightly overconsolidated soft cohesive soils with layer thickness ranging from a few meters to hundreds of meters. The factor of safety obtained from pseudo-static analyses is not always a useful measure for evaluating the slope response, since values less than one do not necessarily imply slope failure with large movements of the soil mass. This paper addresses the relative importance of different factors affecting the response of submerged slopes during seismic loading. The analyses use a dynamic finite element code which includes a constitutive law describing the anisotropic stress-strain-strength behavior of normally consolidated to lightly overconsolidated clays. The model also incorporates anisotropic hardening to describe the effect of different shear strain and stress histories as well as bounding surface principles to provide realistic descriptions of the accumulation of the plastic strains and excess pore pressure during successive loading cycles. The paper presents results from parametric site response analyses on slope geometry and layering, soil material parameters, and input ground motion characteristics. The predicted maximum shear strains, permanent deformations, displacement time histories and maximum excess pore pressure development provide insight of slope performance during a seismic event.

  17. Analysis of Rainfall Infiltration Law in Unsaturated Soil Slope

    OpenAIRE

    Zhang, Gui-rong; Qian, Ya-jun; Wang, Zhang-chun; Zhao, Bo

    2014-01-01

    In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering t...

  18. Automated Means of Identifying Landslide Deposits using LiDAR Data using the Contour Connection Method Algorithm

    Science.gov (United States)

    Olsen, M. J.; Leshchinsky, B. A.; Tanyu, B. F.

    2014-12-01

    Landslides are a global natural hazard, resulting in severe economic, environmental and social impacts every year. Often, landslides occur in areas of repeated slope instability, but despite these trends, significant residential developments and critical infrastructure are built in the shadow of past landslide deposits and marginally stable slopes. These hazards, despite their sometimes enormous scale and regional propensity, however, are difficult to detect on the ground, often due to vegetative cover. However, new developments in remote sensing technology, specifically Light Detection and Ranging mapping (LiDAR) are providing a new means of viewing our landscape. Airborne LiDAR, combined with a level of post-processing, enable the creation of spatial data representative of the earth beneath the vegetation, highlighting the scars of unstable slopes of the past. This tool presents a revolutionary technique to mapping landslide deposits and their associated regions of risk; yet, their inventorying is often done manually, an approach that can be tedious, time-consuming and subjective. However, the associated LiDAR bare earth data present the opportunity to use this remote sensing technology and typical landslide geometry to create an automated algorithm that can detect and inventory deposits on a landscape scale. This algorithm, called the Contour Connection Method (CCM), functions by first detecting steep gradients, often associated with the headscarp of a failed hillslope, and initiating a search, highlighting deposits downslope of the failure. Based on input of search gradients, CCM can assist in highlighting regions identified as landslides consistently on a landscape scale, capable of mapping more than 14,000 hectares rapidly (help better define these regions of risk.

  19. Aspect-Driven Changes in Slope Stability Due to Ecohydrologic Feedbacks

    Science.gov (United States)

    Poulos, M. J.; Pierce, J. L.; Flores, A. N.; Benner, S. G.; Smith, T. J.; McNamara, J. P.

    2009-12-01

    Seasonally integrated variation in insolation drives feedbacks among evapotranspiration, soil moisture, weathering, and erosion that lead to pronounced contrasts in slope angles and vegetation on north and south-facing hillslopes. Spatial variations in insolation associated with north-south contrasts in topographic aspect leads to corresponding variation in local microclimates and ecohydrologic regimes that, in turn, impact spatial patterns of weathering and erosion, ultimately impacting slope angles on north and south-facing slopes. Aspect-sensitive environments appear to be poised on a balance point between ecohydrologic systems, and may be especially susceptible to climate change. In the semi-arid Colorado Plateau of northeastern Arizona, cliffs often form on south-facing slopes where soil moisture is insufficient for weathering of clay-cemented sandstone that is susceptible to hydration. In contrast, cliffs are rare on northerly slopes, which are dominated by mantles of weathered sandstone and colluvium (Burnett et al., 2008, doi:10.1029/2007JF000789). However, in semi-arid regions of the Idaho Batholith, preliminary results indicate some north-facing slopes are significantly steeper than south-facing slopes. We hypothesize that in semi-arid areas with observable increases in vegetation on north vs. south-facing slopes, north-facing slopes will be steeper due to increased soil cohesion, increased capture of wind-borne loess due to vegetative wind-baffling, and differences in the type and magnitude of erosive processes. In moister areas where aspect does not visibly control vegetation type and density, differences in slope angles with aspect should not be observed. We investigate tectonically quiescent regions of the mostly-homogenous granodioritic Idaho Batholith to locate areas sensitive to aspect-induced variations in insolation and compare slope characteristics on north and south-facing slopes. Hillslopes within the Dry Creek Experimental Watershed, in the

  20. Ground thermal conditions along a vertical transect with contrasted topography in a high mountain Mediterranean environment (Puigpedrós massif, eastern Pyrenees), from 2003 to 2014

    Science.gov (United States)

    Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Oliva, Marc; Gómez-Ortiz, Antonio

    2015-04-01

    During the Last Glaciation glaciers shaped the headwaters and valley floors in the Eastern Pyrenees above 2100-2200 m. Since the deglaciation of these high mountain environments, periglacial processes have generated rock glaciers, patterned ground and debris slopes. The role of soil temperatures is decisive regarding the contemporary activity of several processes: cryoturbation, solifluction, frost weathering, etc. Nowadays, periglacial processes are driven by a seasonal frozen layer extending 4-5 months. At 2100 m the seasonal frost reaches 20 cm depth, while at 2700 m reaches 50 cm depth. However, soil temperatures, and thus, periglacial processes are strongly controlled by the large interannual variability of the snow cover. With the purpose of understanding the rhythm and intensity of soil freezing/thawing we have set up several monitoring sites along a vertical transect from the high plateaus (2700 m) to the valley floors (1100 m) across the southern slope of the Puigpedrós massif (2914 m), in the Eastern Pyrenees. The monitoring of soil temperatures extends from 2003 to 2014. TinyTalk, UTL and Hobo loggers have been used in this study. These loggers were installed at depths of -5, -20 and -50 cm at five sites: Calmquerdós (2730 m), Malniu (2230 m), La Feixa (2150 m), Meranges (1600 m) and Das (1097 m). Air temperatures used as reference come from two automatic stations of the Catalan Meteorological Survey (Malniu, Das) as well as from two loggers installed in La Feixa and Meranges. Data shows the control of snow cover on the depth of the frozen layer and on the number of freeze-thaw cycles. Air temperatures at 2000-2200 m show a mean of 150 freeze-thaw cycles per year. In La Feixa, with very thin snow cover, only 67 cycles are recorded at 5 cm depth and 5 cycles at 50 cm depth. In Malniu, located at a higher elevation showing a thicker and longer snow cover, only 17 freeze-thaw cycles per year are recorded at 5 cm depth, with no cycles recorded at 50 cm

  1. The possible influence of terracettes on surface hydrology of steep-sloping and subalpine environments

    Science.gov (United States)

    Greenwood, Philip; Kuonen, Samuel; Fister, Wolfgang; Kuhn, Nikolaus

    2015-04-01

    Alpine and mountain slopes represent important pathways that link high altitude grazing areas to meadows and rangelands at lower elevations. Given the often acute gradients associated with such environments, they potentially represent highly efficient runoff conveyance routes that presumably facilitate the downslope movement of runoff and associated material during erosion events. Many such slopes host series of small steps, or `terracettes`. The position of terracette systems, usually juxtaposed across the natural downslope flow-path of acute slopes, lead us to hypothesise that their presence may influence typical hillslope processes by intercepting or capturing surface runoff during its downslope transit. Here we report preliminary results and some tentative conclusions from on-going work to explore this possibility. Google Earth was used to initially identify a ca. 400 m2 area of well-developed terracette system situated on a west-facing slope with gradients ranging from 25-40o (46-84%). A digital elevation model (DEM) of a section of the terracette system was constructed using spatial data taken from a relevant excerpt of a topographic map. The DEM was then queried using a flow accumulation algorithm and the results were displayed in a Geographic Information System (GIS). The output data provided 'proof of concept' that terracettes are able to capture surface runoff. A series of rainfall / runoff simulations was then performed on the same section of terracettes. Results from both components of the investigation indicate that certain sections of a terracette system intercepted surface runoff and acted as preferential flow-pathways during runoff events. By contrast, and despite being subjected to intense rainfall, some sections of the same terracette system did not generate surface runoff. Based on these contrasting findings, we cautiously predict that areas where surface runoff was not generated may actually act as depositional sites, or retention zones, and

  2. Analysis of rainfall infiltration law in unsaturated soil slope.

    Science.gov (United States)

    Zhang, Gui-rong; Qian, Ya-jun; Wang, Zhang-chun; Zhao, Bo

    2014-01-01

    In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering the characteristics of slope and rainfall, the key factors affecting rainfall infiltration of slope, including hydraulic properties, water storage capacity (θs - θr), soil types, rainfall intensities, and antecedent and subsequent infiltration rates on unsaturated soil slope, are discussed by using theory analysis and numerical simulation technology. Based on critical factors changing, this paper presents three calculation models of rainfall infiltrability for unsaturated slope, including (1) infiltration model considering rainfall intensity; (2) effective rainfall model considering antecedent rainfall; (3) infiltration model considering comprehensive factors. Based on the technology of system response, the relationship of rainfall and infiltration is described, and the prototype of regression model of rainfall infiltration is given, in order to determine the amount of rain penetration during a rain process.

  3. Fundamental aspects of plating technology. 5. The effect of strongly adsorbed species on the morphology of metal deposits

    Energy Technology Data Exchange (ETDEWEB)

    Popov, K I; Rodaljevic, Z P; Krstajic, N V; Novakovic, S D

    1985-07-01

    It is shown that the improvement in the quality of electrodeposits obtained from CdSO/sub 4/ solution in the presence of strongly adsorbed species compared with that of deposits obtained in the absence of such species is due to a decrease in the exchange current density and an increase in the Tafel slope for the deposition process in the former case.

  4. A method for determining average beach slope and beach slope variability for U.S. sandy coastlines

    Science.gov (United States)

    Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.

    2015-01-01

    The U.S. Geological Survey (USGS) National Assessment of Hurricane-Induced Coastal Erosion Hazards compares measurements of beach morphology with storm-induced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The wave-induced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storm-induced changes in beach slope can lead to differences on the order of 1 meter (m) in wave-induced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200-m alongshore section of coastline.

  5. Automatic approach to deriving fuzzy slope positions

    Science.gov (United States)

    Zhu, Liang-Jun; Zhu, A.-Xing; Qin, Cheng-Zhi; Liu, Jun-Zhi

    2018-03-01

    Fuzzy characterization of slope positions is important for geographic modeling. Most of the existing fuzzy classification-based methods for fuzzy characterization require extensive user intervention in data preparation and parameter setting, which is tedious and time-consuming. This paper presents an automatic approach to overcoming these limitations in the prototype-based inference method for deriving fuzzy membership value (or similarity) to slope positions. The key contribution is a procedure for finding the typical locations and setting the fuzzy inference parameters for each slope position type. Instead of being determined totally by users in the prototype-based inference method, in the proposed approach the typical locations and fuzzy inference parameters for each slope position type are automatically determined by a rule set based on prior domain knowledge and the frequency distributions of topographic attributes. Furthermore, the preparation of topographic attributes (e.g., slope gradient, curvature, and relative position index) is automated, so the proposed automatic approach has only one necessary input, i.e., the gridded digital elevation model of the study area. All compute-intensive algorithms in the proposed approach were speeded up by parallel computing. Two study cases were provided to demonstrate that this approach can properly, conveniently and quickly derive the fuzzy slope positions.

  6. Constraining the sedimentology and stratigraphy of submarine intraslope lobe deposits using exhumed examples from the Karoo Basin, South Africa

    OpenAIRE

    Flint, Stephen; Hodgson, David; Spychala, Yvonne; Mountney, Nigel

    2017-01-01

    Intraslope lobe deposits provide a process record of the infill of accommodation on submarine slopes and their recognition enables the accurate reconstruction of the stratigraphic evolution of submarine slope systems. Extensive exposures of discrete sand-prone packages in Units D/E and E, Fort Brown Formation, Karoo Basin, South Africa, permit analysis of the sedimentology and stacking patterns of three intraslope lobe complexes and their palaeogeographic reconstruction via bed-scale analysis...

  7. 30 CFR 77.1911 - Ventilation of slopes and shafts.

    Science.gov (United States)

    2010-07-01

    ... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1911 Ventilation of slopes and shafts. (a) All slopes and... connected to the slope or shaft opening with fireproof air ducts; (3) Designed to permit the reversal of the...

  8. Intertidal beach slope predictions compared to field data

    NARCIS (Netherlands)

    Madsen, A.J.; Plant, N.G.

    2001-01-01

    This paper presents a test of a very simple model for predicting beach slope changes. The model assumes that these changes are a function of both the incident wave conditions and the beach slope itself. Following other studies, we hypothesized that the beach slope evolves towards an equilibrium

  9. US North Slope gas and Asian LNG markets

    Science.gov (United States)

    Attanasi, E.D.

    1994-01-01

    Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology. ?? 1995.

  10. The great slippery-slope argument.

    OpenAIRE

    Burgess, J A

    1993-01-01

    Whenever some form of beneficent killing--for example, voluntary euthanasia--is advocated, the proposal is greeted with a flood of slippery-slope arguments warning of the dangers of a Nazi-style slide into genocide. This paper is an attempt systematically to evaluate arguments of this kind. Although there are slippery-slope arguments that are sound and convincing, typical formulations of the Nazi-invoking argument are found to be seriously deficient both in logical rigour and in the social hi...

  11. DOWNWARD SLOPING DEMAND CURVES FOR STOCK AND LEVERAGE

    Directory of Open Access Journals (Sweden)

    Liem Pei Fun

    2006-01-01

    Full Text Available This research attempts to investigate the effect of downward sloping demand curves for stock on firms' financing decisions. For the same size of equity issuance, firms with steeper slope of demand curves for their stocks experience a larger price drop in their share price compare to their counterparts. As a consequence, firms with a steeper slope of demand curves are less likely to issue equity and hence they have higher leverage ratios. This research finds that the steeper the slope of demand curve for firm's stock, the higher the actual leverage of the firm. Furthermore, firms with a steeper slope of demand curves have higher target leverage ratios, signifying that these firms prefer debt to equity financing in order to avoid the adverse price impact of equity issuance on their share price.

  12. Quantitative controls on location and architecture of carbonate depositional sequences: upper miocene, cabo de gata region, se Spain

    Science.gov (United States)

    Franseen, E.K.; Goldstein, R.H.; Farr, M.R.

    1998-01-01

    Sequence stratigraphy, pinning-point relative sea-level curves, and magnetostratigraphy provide the quantitative data necessary to understand how rates of sea-level change and different substrate paleoslopes are dominant controls on accumulation rate, carbonate depositional sequence location, and internal architecture. Five third-order (1-10 my) and fourth-order (0.1-1.0 my) upper Miocene carbonate depositional sequences (DS1A, DS1B, DS2, DS3, TCC) formed with superimposed higher-frequency sea-level cycles in an archipelago setting in SE Spain. Overall, our study indicates when areas of high substrate slope (> 15??) are in shallow water, independent of climate, the location and internal architecture of carbonate deposits are not directly linked to sea-level position but, instead, are controlled by location of gently sloping substrates and processes of bypass. In contrast, if carbonate sediments are generated where substrates of low slope ( 15.6 cm/ky to ??? 2 cm/ky and overall relative sea level rose at rates of 17-21.4 cm/ky. Higher frequency sea-level rates were about 111 to more than 260 cm/ky, producing onlapping, fining- (deepening-) upward cycles. Decreasing accumulation rates resulted from decreasing surface area for shallow-water sediment production, drowning of shallow-water substrates, and complex sediment dispersal related to the archipelago setting. Typical systems tract and parasequence development should not be expected in "bypass ramp" settings; facies of onlapping strata do not track base level and are likely to be significantly different compared to onlapping strata associated with coastal onlap. Basal and upper DS2 reef megabreccias (indicating the transition from cool to warmer climatic conditions) were eroded from steep upslope positions and redeposited downslope onto areas of gentle substrate during rapid sea-level falls (> 22.7 cm/ky) of short duration. Such rapid sea-level falls and presence of steep slopes are not conducive to formation of

  13. The Influence of Cultivation System on Distribution Profile Of 137cs and Erosion / Deposition Rate

    Directory of Open Access Journals (Sweden)

    Nita Suhartini

    2016-05-01

    Full Text Available 137Cs radiogenic content in the soil can be used to estimate the rate of erosion and deposition in an area occurring since 1950’s, by comparing the content of the 137Cs in observed site with those in a stable reference site. This experiment aimed to investigate the influence of cultivation type on distribution profile of 137Cs and distribution of erosion and deposition rate in cultivated area. A study site was small cultivated area with slope steepness <10o and length 2 km located in Bojong – Ciawi. For this purpose, the top of a slope was chosen for reference site and three plot sites were selected namely Land Use I that using simple cultivation, Land Use II that using simple cultivation with ridge and furrow, and Land Use III using machine cultivation. The results showed that cultivation could make a movement of 137Cs to the deeper layer and ridges and furrows cultivation system could minimized an erosion process. The net erosion and deposition for land Use I, II and III were -25 t/ha/yr , 24 t/ha/yr and -58 t/ha/yr, respectively.

  14. Conceptualizations of Slope: A Review of State Standards

    Science.gov (United States)

    Stanton, Michael; Moore-Russo, Deborah

    2012-01-01

    Since slope is a fundamental topic that is embedded throughout the U.S. secondary school curriculum, this study examined standards documents for all 50 states to determine how they address the concept of slope. The study used eleven conceptualizations of slope as categories to classify the material in the documents. The findings indicate that all…

  15. Performance of the APS optical slope measuring system

    International Nuclear Information System (INIS)

    Qian, Jun; Sullivan, Joe; Erdmann, Mark; Khounsary, Ali; Assoufid, Lahsen

    2013-01-01

    An optical slope measuring system (OSMS) was recently brought into operation at the Advanced Photon Source of the Argonne National Laboratory. This system is equipped with a precision autocollimator and a very accurate mirror-based pentaprism on a scanning stage and kept in an environment-controlled enclosure. This system has the capability to measure precision optics with sub-microradian rms slope errors as documented with a series of tests demonstrating accuracy, stability, reliability and repeatability. Measurements of a flat mirror with 0.2 μrad rms slope error are presented which show that the variation of the slope profile measurements with the mirror setting at different locations along the scanning direction is only 60 nrad and the corresponding height error profile has 2 nm rms. -- Highlights: ► This is the first time to present the APS OSMS in publication. ► The APS OSMS is capable to measure flat and near flat mirrors with slope error <100 nrad rms. ► The accuracy of the slope error measurements of a 350 mm long mirror is less than 60 nrad rms

  16. The effect of nutrient deposition on bacterial communities in Arctic tundra soil

    Science.gov (United States)

    Barbara J. Campbell; Shawn W. Polson; Thomas E. Hanson; Michelle C. Mack; Edward A.G. Schuur

    2010-01-01

    The microbial communities of high-latitude ecosystems are expected to experience rapid changes over the next century due to climate warming and increased deposition of reactive nitrogen, changes that will likely affect microbial community structure and function. In moist acidic tundra (MAT) soils on the North Slope of the Brooks Range, Alaska, substantial losses of C...

  17. Rock slope stability analysis along the North Carolina section of the Blue Ridge Parkway: Using a geographic information system (GIS) to integrate site data and digital geologic maps

    Science.gov (United States)

    Latham, R.S.; Wooten, R.M.; Cattanach, B.L.; Merschat, C.E.; Bozdog, G.N.

    2009-01-01

    In 2008, the North Carolina Geological Survey (NCGS) completed a five-year geologic and geohazards inventory of the 406-km long North Carolina segment of the Blue Ridge Parkway (BRP). The ArcGIS??? format deliverables for rock slopes include a slope movement and slope movement deposit database and maps and site-specific rock slope stability assessments at 158 locations. Database entries for known and potential rock slope failures include: location data, failure modes and dimensions, activity dates and levels, structural and lithologic data, the occurrence of sulfide minerals and acid-producing potential test results. Rock slope stability assessments include photographs of the rock cuts and show locations and orientations of rock data, seepage zones, and kinematic stability analyses. Assigned preliminary geologic hazard ratings of low, moderate and high indicate the generalized relative probability of rock fall and/or rock slide activity at a given location. Statistics compiled based on the database indicate some general patterns within the data. This information provides the National Park Service with tools that can aid in emergency preparedness, and in budgeting mitigation, maintenance and repair measures. Copyright 2009 ARMA, American Rock Mechanics Association.

  18. Evaluation of seismic effects on the landslide deposits of Monte Salta (Eastern Italian Alps using distinct element method

    Directory of Open Access Journals (Sweden)

    G. Marcato

    2007-11-01

    Full Text Available The aim of the paper is to present the modelling of the ground effects of seismic waves on a large debris deposit lying on a steep mountain slope, with particular attention paid to the potential triggering of slope movements.

    The study site is a mass of 2.5 million m3 rock fall deposit, named "Monte Salta Landslide", located on the northern slope of the Vajont valley, at the border between Veneto and Friuli Venezia Giulia regions in north-eastern Italy.

    Several historical landslide events were reported in the area in the past, first one dating back to the 17th century. The landslide deposit completely mantles the slope with a thick cover of rock blocks.

    The Mt. Salta landslide is conditioned by the presence of Mt. Borgà regional thrust, which uplifts Jurassic limestone on the top of Cretaceous rock units. Above the thrust zone, folded and highly fractured rock mass dips steeply towards the slope free face, producing highly unstable setting.

    The study area has been classified as high seismic hazard and different vulnerable elements can be affected by the remobilisation of debris, among which a village, a national road and a big quarry that was opened, with the intent to exploit the part of the landslide deposit for construction purposes.

    In this study, numerical analysis was performed, to simulate the slope behaviour using distinct element method and applying UDEC code. The 2-D models were built on three cross-sections and elasto-plastic behaviour was assumed, both for rock matrix and discontinuities. The earthquake effect was modelled in pseudo-dynamic way, i.e. by magnifying the acceleration and applying also its horizontal component. The expected seismic acceleration in the study area was calculated on the basis of previous studies as equal to 0.28 g.

    The results proved that the increase of the vertical component alone has a small influence on the deformational behaviour of the

  19. The logarithmic slope in diffractive DIS

    International Nuclear Information System (INIS)

    Gay Ducati, M.B.; Goncalves, V.P.; Machado, M.V.T.

    2002-01-01

    The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small-x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches

  20. Design of Rock Slope Reinforcement: An Himalayan Case Study

    Science.gov (United States)

    Tiwari, Gaurav; Latha, Gali Madhavi

    2016-06-01

    The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from site-specific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

  1. Integrating concepts and skills: Slope and kinematics graphs

    Science.gov (United States)

    Tonelli, Edward P., Jr.

    The concept of force is a foundational idea in physics. To predict the results of applying forces to objects, a student must be able to interpret data representing changes in distance, time, speed, and acceleration. Comprehension of kinematics concepts requires students to interpret motion graphs, where rates of change are represented as slopes of line segments. Studies have shown that majorities of students who show proficiency with mathematical concepts fail accurately to interpret motion graphs. The primary aim of this study was to examine how students apply their knowledge of slope when interpreting kinematics graphs. To answer the research questions a mixed methods research design, which included a survey and interviews, was adopted. Ninety eight (N=98) high school students completed surveys which were quantitatively analyzed along with qualitative information collected from interviews of students (N=15) and teachers ( N=2). The study showed that students who recalled methods for calculating slopes and speeds calculated slopes accurately, but calculated speeds inaccurately. When comparing the slopes and speeds, most students resorted to calculating instead of visual inspection. Most students recalled and applied memorized rules. Students who calculated slopes and speeds inaccurately failed to recall methods of calculating slopes and speeds, but when comparing speeds, these students connected the concepts of distance and time to the line segments and the rates of change they represented. This study's findings will likely help mathematics and science educators to better assist their students to apply their knowledge of the definition of slope and skills in kinematics concepts.

  2. Slope instabilities along the Western Andean Escarpment and the main canyons in Northern Chile

    Science.gov (United States)

    Crosta, G.; Hermanns, R. L.; Valbuzzi, E.; Dehls, J.; Yugsi Molina, F. X.; Sepulveda, S.

    2012-04-01

    The western slope of the Andes of northern Chile - southern Perù is generally subdivided from the west to the east into the morphological units of: the Coastal Cordillera, Central Depression, the Western Escarpment-Precordillera and the Western Andean Cordillera. The western escarpment and Precordillera are formed by the Azapa coarse-grained clastic formation (sandstones, conglomerates, mudstones) and the Oxaya (rhyodacitic ignimbrites) and Diablo volcanoclastic formations (Oligocene and Miocene). Important uplift has been suggested between the deposition of the Oxaya and Diablo formations. The entire area has been characterized by a long-term hyperaridity (Atacama desert), initially established between 20 and 15 Ma, and this caused a strong difference between the long term continuous uplift and low denudation rates. This long sector of the central western escarpment and Precordillera is incised by deep canyons and subparallel drainage network in the upper part. The drainage network developed in two main phases: a lower-middle Miocene phase with formation of a parallel poorly structured drainage network cutting into the Oxaya formation, and presently well preserved; the canyons have been incised in the initial topography starting around 9 Ma and up to about 3.8 Ma with subsequent refilling episodes. Valley incision (ave. rate of 0.2 mm yr-1) has been controlled by topographic uplift and less arid climate (after 7 Ma). As a consequence of these geologic and climatic settings the evolution of this area has been characterized by canyon incision and extremely large slope instabilities. These slope instabilities occur in the "interfluvial" sectors of the western escarpment and Precordillera and along the canyon flanks. Landslides affecting the preserved paleosurfaces, interested by the parallel drainage network in the Oxaya formation, involve volumes of various cubic kilometres (Lluta collapse, Latagualla Landslide) and can control the drainage network. These mega

  3. Discovery of a landscape-wide drape of late-glacial aeolian silt in the western Northern Calcareous Alps (Austria): First results and implications

    Science.gov (United States)

    Gild, Charlotte; Geitner, Clemens; Sanders, Diethard

    2018-01-01

    Aeolian deposits record palaeoenvironmental conditions and may coin soil properties. Whereas periglacial loess is extensively investigated for 200 years, the study of the intramontane wind-blown deposits of the Alps has just stuttered along. Herein, we describe a drape of polymictic siliciclastic silt interpreted as an aeolian deposit that veneers extensive areas in the western Northern Calcareous Alps (NCA), from kames terraces near valley floors up to last-glacial nunataks. The NCA - part of the Eastern Alps mountain range - consist mainly of Triassic carbonate rocks; these are overlain by deposits of the Last Glacial Maximum (LGM) and its deglacial-paraglacial aftermath (e.g., glacial tills, fluvio-lacustrine successions, alluvial fans, scree slopes) - and a regional drape of polymictic silt newly described herein. The drape is typically a few decimeters in thickness and slightly modified by soil formation; it consists mainly of well-sorted silt of quartz, feldspars, phyllosilicates (muscovite, chlorite, biotite), amphiboles and, rarely, calcite or dolomite. The drape is unrelated to the substrate: it overlies carbonate bedrock and - in lateral continuity - abandoned deposystems such as colluvial slopes of redeposited till, kames, alluvial fans, scree slopes, and rock avalanche deposits. The drape was spotted from near the present valley floors up to LGM nunataks, over a vertical range of some 2000 m; it is also present in catchments of the NCA that were not overridden by far-travelled ice streams and that lack metamorphic rock fragments. Two OSL quartz ages of the drape from two distinct locations (18.77 ± 1.55 ka; 17.81 ± 1.68 ka) fall into the early Alpine late-glacial interval shortly after the collapse of pleniglacial ice streams; this fits with geological and geomorphological evidence, respectively, that the drape should be of early late-glacial age, and that it accumulated during a specific interval of time. In the NCA, localized minor deposition of

  4. Stability Analysis of Tunnel-Slope Coupling Based on Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Tao Luo

    2015-07-01

    Full Text Available Subjects in tunnels, being constrained by terrain and routes, entrances and exits to tunnels, usually stay in the terrain with slopes. Thus, it is necessary to carry out stability analysis by treating the tunnel slope as an entity. In this study, based on the Janbu slices method, a model for the calculation of the stability of the original slope-tunnel-bank slope is established. The genetic algorithm is used to implement calculation variables, safety coefficient expression and fitness function design. The stability of the original slope-tunnel-bank slope under different conditions is calculated, after utilizing the secondary development function of the mathematical tool MATLAB for programming. We found that the bearing capacity of the original slopes is reduced as the tunnels are excavated and the safety coefficient is gradually decreased as loads of the embankment construction increased. After the embankment was constructed, the safety coefficient was 1.38, which is larger than the 1.3 value specified by China’s standards. Thus, the original slope-tunnel-bank slope would remain in a stable state.

  5. Investigation on the water retention curve of loose pyroclastic ashes of Campania (Italy) and its potential implications on slope stability

    Science.gov (United States)

    Comegna, Luca; Damiano, Emilia; Greco, Roberto; Olivares, Lucio; Piccolo, Marco; Picarelli, Luciano

    2017-04-01

    Loose pyroclastic soils in Campania cover a large amount of steep slopes in the area surrounding the volcanic complex of Somma-Vesuvius. The stability of such slopes is assured by the contribution of suction to soil shear strength, which decreases during rainy periods till the possible attainment of a failure condition. The resulting landslide may evolve in form of a fast flow, if at the onset of instability the soil is nearly saturated and undrained conditions establish, so that soil liquefaction arises. The attainment of instability near saturation is not uncommon, as it requires the slope to have an inclination close to the friction angle of the soil constituting the deposit. The pyroclastic ashes of Campania are typically silty sands with friction angle between 36° and 38°, and small or even null cohesion. Many of the flow-like landslides, occurred during the last decades, were indeed triggered along slopes with inclination around 40°, which are quite common in Campania. As a suction of few kPa may be enough to guarantee the stability of a slope, knowledge of the water retention curve of the soil constituting the deposit is mandatory to correctly predict soil conditions at failure. Several studies report that the pyroclastic ashes of Campania exhibit a quite complex water retention behavior, showing a bimodal porosity distribution and, in some cases, a marked hysteresis domain, possibly enhanced by air entrapment during the infiltration of steep wetting fronts. In this study, a series of vertical infiltration and evaporation cycles have been carried out over two reconstituted specimens, both 20cm high, of pyroclastic ashes collected at the slope of Cervinara. TDR probes and minitensiometers were buried at various depths to provide coupled measurements of soil water content and suction. In order to highlight the possible hysteretic effects due to air entrapment, different hydraulic boundary conditions were established at the base of the two specimens: in one

  6. assessment of slope stability around gilgel gibe-ii hydroelectric

    African Journals Online (AJOL)

    preferred customer

    1 Gilgel-Gibe II Hydroelectric Project, Fofa Town, Ethiopia ... Key words/phrases: Factor of safety, plane failure, slope design, slope .... condition of potential unstable slopes along the road between Fofa town and Gilgel-Gibe Hydro- power II.

  7. The influence of terracettes on surface hydrology and erosion on vegetated Alpine, mountain and steep-sloping environments

    Science.gov (United States)

    Kuhn, Nikolaus; (Phil) Greenwood, Philip

    2014-05-01

    of grazing and rangelands in Alpine, mountain and steeply sloping environments. With higher resolution data covering larger areas, as well as the possibility of using fallout radionuclide data to establish sediment residence times on depositional areas, it is envisioned that runoff and transportation of fine-sediment and sediment-associated nutrients and contaminants down these flow pathways could be modeled, predicted and their effects mitigated and perhaps eventually reduced.

  8. Model tests of geosynthetic reinforced slopes in a geotechnical centrifuge

    International Nuclear Information System (INIS)

    Aklik, P.

    2012-01-01

    Geosynthetic-reinforced slopes and walls became very popular in recent years because of their financial, technical, and ecological advantages. Centrifuge modelling is a powerful tool for physical modelling of reinforced slopes and offers the advantage to observe the failure mechanisms of the slopes. In order to replicate the gravity induced stresses of a prototype structure in a geometrically 1/N reduced model, it is necessary to test the model in a gravitational field N times larger than that of the prototype structure. In this dissertation, geotextile-reinforced slope models were tested in a geotechnical centrifuge to identify the possible failure mechanisms. Slope models were tested by varying slope inclination, tensile strengths of the geotextiles, and overlapping lengths. Photographs of the geotextile reinforced slope models in flight were taken with a digital camera and the soil deformations of geotextile reinforced slopes were evaluated with Particle Image Velocimetry (PIV). The experimental results showed that failure of the centrifuge models initiated at midheight of the slope, and occurred due to geotextile breakage instead of pullout. The location of the shear surface is independent of the tensile strength of the geotextile; it is dependent on the shear strength of the soil. It is logical to see that the required acceleration of the centrifuge at slope failure was decreased with increasing slope inclination. An important contribution to the stability of the slope models was provided by the overlapping of the geotextile layers. It has a secondary reinforcement effect when it was prolonged and passed through the shear surface. Moreover, the location of the shear surface observed with PIV analysis exactly matches the tears of the retrieved geotextiles measured carefully after the centrifuge testing. It is concluded that PIV is an efficient tool to instrument the slope failures in a geotechnical centrifuge.(author) [de

  9. The Novo Okno copper deposit of olistostrome origin (Bor, Eastern Serbia

    Directory of Open Access Journals (Sweden)

    Antonijević Ivan

    2011-01-01

    Full Text Available The copper deposit Novo Okno, uncovered at present, with non-ore and ore clasts of massive sulphides (from 0.5 to 50 m3 in size, has many distinctive features that indicate its olistostrome origin. The deposit is chaotic in structure, unstratified, with the lower surface unconformable over the underlying parent rock of the basin. It is a lens-like body, with the longer axis directed east and west, variable in thickness from 15 to 28 metres, about 335 metres long and less than 140 metres wide. These and other characteristics of the body indicate a unified, reworked, olistostrome copper deposit formed from primary ore bodies of the Bor mineral deposit and vulcanite, destroyed by volcanic explosion into blocks and rocks of Turonian age and extrusion and concurrent deposition on the land surface. Gravitational massive sliding of the consolidated rocks down the slopes of the volcanic relief and chaotic accumulation of ore and non-ore clasts (olistoliths in a marine basin evolved in the Upper Turonian and the Lower Senonian.

  10. Stability of the slopes around nuclear power plants in earthquake

    International Nuclear Information System (INIS)

    Ito, Hiroshi

    1983-01-01

    The evaluation of the stability of the slopes around the buildings of nuclear power plants is important especially with respect to earthquakes. In this connection, the behavior of a slope up to its destruction and the phenomena of the destruction have been examined in the case of an earthquake by both experiment and numerical analysis. The purpose is to obtain the data for the establishment of a method for evaluating the seismic stability of a slope and of the slope design standards. The following results are described: the behavior of a slope and its destruction characteristics in the slope destruction experiment simulating the seismic coefficient method; the vibration of a slope and its destruction characteristics in vibration destruction experiment; the validity of the method of numerical simulation analysis and of stability evaluation for the slope destruction and the vibration destruction experiments, and quantitative destruction mechanism; the comparison of the various stability evaluation methods and the evaluation of seismic forces. (Mori, K.)

  11. Erosion and sediment deposition evaluation on slopes under different tillage systems in the Cerrado region using the 137Cs fallout technique

    International Nuclear Information System (INIS)

    Arthur, Robson Clayton Jacques

    2010-01-01

    In Brazil, the expansion of agricultural areas causes several problems on natural resources. With the increasing occupation of the Cerrado region by agriculture, a series of environmental problems like deforestation, soil erosion and soil compaction are appearing and causing radical transformations in the natural landscape due to removing almost all native vegetation. The conventional tillage system (CTS) is considered an inadequate form of soil management for its frequently irremediable consequences of soil compaction and soil erosion, and the no till system (NTS) makes the maintenance of the soil conditions possible, letting them close to the natural environment, thus reducing rates of soil erosion. The objective of this work was to evaluate the efficiency of riparian forests in the retention of sediments originated for three different tillage systems, through the fallout 137 CS redistribution technique, the Universal Soil Loss Equation (USLE) and some physical and chemical parameters that indicate the structural conditions of the soils of Goiatuba and Jandaia-GO. In the three areas, soil profiles were collected in three layers of 20 cm (0-20, 20-40 and 40-60 cm) at distinct points located along linear transects in the direction of the maximum slope until the riparian forest. In the riparian forest of each area, trenches were opened and soil was sampled to evaluate the activity of 137 Cs and the physical and chemical parameters of soil. Detection of the activity of 137 Cs was made with a gamma ray detector model (GEM-20180P, EG and ORTEC) connected to a multichannel analyzer. The comparison of averages was made using the Tukey test at 5% level of significance. The. results indicated that, the three soil tillage systems presented high rates of soil erosion and deposition of sediments and the riparian forest of the areas under CTS, NTS and pasture, located downstream received great amounts of sediments, and that only the riparian forest of CTS was capable to trap

  12. On the influence of topographic, geological and cryospheric factors on rock avalanches and rockfalls in high-mountain areas

    Directory of Open Access Journals (Sweden)

    L. Fischer

    2012-01-01

    Full Text Available The ongoing debate about the effects of changes in the high-mountain cryosphere on rockfalls and rock avalanches suggests a need for more knowledge about characteristics and distribution of recent rock-slope instabilities. This paper investigates 56 sites with slope failures between 1900 and 2007 in the central European Alps with respect to their geological and topographical settings and zones of possible permafrost degradation and glacial recession. Analyses of the temporal distribution show an increase in frequency within the last decades. A large proportion of the slope failures (60% originated from a relatively small area above 3000 m a.s.l. (i.e. 10% of the entire investigation area. This increased proportion of detachment zones above 3000 m a.s.l. is postulated to be a result of a combination of factors, namely a larger proportion of high slope angles, high periglacial weathering due to recent glacier retreat (almost half of the slope failures having occurred in areas with recent deglaciation, and widespread permafrost occurrence. The lithological setting appears to influence volume rather than frequency of a slope failure. However, our analyses show that not only the changes in cryosphere, but also other factors which remain constant over long periods play an important role in slope failures.

  13. Field-trip guide for exploring pyroclastic density current deposits from the May 18, 1980, eruption of Mount St. Helens, Washington

    Science.gov (United States)

    Brand, Brittany D.; Pollock, Nicholas; Sarocchi, Damiano; Dufek, Josef; Clynne, Michael A.

    2017-07-05

    Pyroclastic density currents (PDCs) are one of the most dangerous phenomena associated with explosive volcanism. To help constrain damage potential, a combination of field studies, laboratory experiments, and numerical modeling are used to establish conditions that influence PDC dynamics and depositional processes, including runout distance. The objective of this field trip is to explore field relations that may constrain PDCs at the time of emplacement.The PDC deposits from the May 18, 1980, eruption of Mount St. Helens are well exposed along the steep flanks (10–30° slopes) and across the pumice plain (5–12° slopes) as far as 8 km north of the volcano. The pumice plain deposits represent deposition from a series of concentrated PDCs and are primarily thick (3–12 m), massive, and poorly sorted. In contrast, the steep east-flank deposits are stratified to cross-stratified, suggesting deposition from PDCs where turbulence strongly influenced transport and depositional processes.The PDCs that descended the west flank were largely nondepositional; they maintained a higher flow energy and carrying capacity than PDCs funneled through the main breach, as evidenced by the higher concentration of large blocks in their deposits. The PDC from the west flank collided with PDCs funneled through the breach at various points along the pumice plain. Evidence for flow collision will be explored and debated throughout the field trip.Evidence for substrate erosion and entrainment is found (1) along the steep eastern flank of the volcano, which has a higher degree of rough, irregular topography relative to the west flanks where PDCs were likely nonerosive, (2) where PDCs encountered debris-avalanche hummocks across the pumice plain, and (3) where PDCs eroded and entrained material deposited by PDCs produced during earlier phases of the eruption. Two features interpreted as large-scale (tens of meters wide) levees and a large (~200 m wide) channel scour-and-fill feature

  14. Assessing slope stability in unplanned settlements in developing countries.

    Science.gov (United States)

    Anderson, Malcolm G; Holcombe, Liz; Renaud, Jean-Philippe

    2007-10-01

    Unplanned housing in developing countries is often located on steep slopes. Frequently no building code is enforced for such housing and mains water is provided with no drainage provision. Both of these factors can be particularly significant in terms of landslide risk if, as is so often the case, such slopes lack any planned drainage provision. There is thus a need to develop a model that facilitates the assessment of slope stability in an holistic context, incorporating a wide range of factors (including surface cover, soil water topographic convergence, slope loading and point source water leakage) in order that appropriate advice can be given as to the general controls on slope stability in such circumstances. This paper outlines a model configured for this specific purpose and describes an application to a site in St. Lucia, West Indies, where there is active slope movement in an unplanned housing development on relatively steep topography. The model findings are in accord with the nature of the current failure at the site, provide guidance as to the significance of slope drainage and correspond to inferences drawn from an application of resistance envelope methods to the site. In being able to scenario test a uniquely wide range of combinations of factors, the model structure is shown to be highly valuable in assessing dominant slope stability process controls in such complex environments.

  15. Air pocket removal from downward sloping pipes

    NARCIS (Netherlands)

    Pothof, I.W.M.; Clemens, F.H.L.R.

    2012-01-01

    Air-water flow is an undesired condition in water pipelines and hydropower tunnels. Water pipelines and wastewater pressure mains in particular are subject to air pocket accumulation in downward sloping reaches, such as inverted siphons or terrain slopes. Air pockets cause energy losses and an

  16. Comparison of braided-stream depositional environment and uranium deposits at Saint Anthony underground mine

    International Nuclear Information System (INIS)

    Baird, C.W.; Martin, K.W.; Lowry, R.M.

    1980-01-01

    United Nuclear's Saint Anthony mine, located in the Laguna district, produces uranium ore from the Jackpile sandstone unit of the Morrison Formation. The Jackpile sediments were deposited in a fluvial environment characterized by aridity, gentle slope, distant source area, and limited flow volume. Resultant stratigraphy consists of an intricate assemblage of trough and tabular cross-stratification grading to near massive bedding at some locations. Interbedded with the Jackpile sands are green mudstones and siltstones that commonly display irregular thicknesses of less than 2 ft and that are laterally discontinuous. Major penecontemporaneous and postdepositional alteration of originally deposited sands, silts, and clays includes: 1) infiltration and filling of interstices by kaolinitic clays; 2) mobilization and relocation of organic carbonaceous material; and 3) geochemical alteration of mineral constituents and fixation of uranium ions in organic carbonaceous material. Mineralized zones of economic volume display a spatial relationship to bedding features indicative of loosely packed sand deposited in dune and trough foresets. This relationship indicates possible permeability control by initial stratigraphy upon the flow of mineralizing solutions. Additionally, the low-energy foreset environment facilitates the accumulation of low-specific-gravity carbonaceous material necessary for interaction with mineralizing solutions. Large volumes of loosely packed foreset sands accumulate in transverse bars in braided-stream environments. These structures have a great potential for conducting large volumes of mineralizing fluids and hosting economic quantities of uranium ore

  17. GIS/RS-based Rapid Reassessment for Slope Land Capability Classification

    Science.gov (United States)

    Chang, T. Y.; Chompuchan, C.

    2014-12-01

    Farmland resources in Taiwan are limited because about 73% is mountainous and slope land. Moreover, the rapid urbanization and dense population resulted in the highly developed flat area. Therefore, the utilization of slope land for agriculture is more needed. In 1976, "Slope Land Conservation and Utilization Act" was promulgated to regulate the slope land utilization. Consequently, slope land capability was categorized into Class I-IV according to 4 criteria, i.e., average land slope, effective soil depth, degree of soil erosion, and parent rock. The slope land capability Class I-VI are suitable for cultivation and pasture. Whereas, Class V should be used for forestry purpose and Class VI should be the conservation land which requires intensive conservation practices. The field survey was conducted to categorize each land unit as the classification scheme. The landowners may not allow to overuse land capability limitation. In the last decade, typhoons and landslides frequently devastated in Taiwan. The rapid post-disaster reassessment of the slope land capability classification is necessary. However, the large-scale disaster on slope land is the constraint of field investigation. This study focused on using satellite remote sensing and GIS as the rapid re-evaluation method. Chenyulan watershed in Nantou County, Taiwan was selected to be a case study area. Grid-based slope derivation, topographic wetness index (TWI) and USLE soil loss calculation were used to classify slope land capability. The results showed that GIS-based classification give an overall accuracy of 68.32%. In addition, the post-disaster areas of Typhoon Morakot in 2009, which interpreted by SPOT satellite imageries, were suggested to classify as the conservation lands. These tools perform better in the large coverage post-disaster update for slope land capability classification and reduce time-consuming, manpower and material resources to the field investigation.

  18. SaLEM (v1.0 – the Soil and Landscape Evolution Model (SaLEM for simulation of regolith depth in periglacial environments

    Directory of Open Access Journals (Sweden)

    M. Bock

    2018-04-01

    Full Text Available We propose the implementation of the Soil and Landscape Evolution Model (SaLEM for the spatiotemporal investigation of soil parent material evolution following a lithologically differentiated approach. Relevant parts of the established Geomorphic/Orogenic Landscape Evolution Model (GOLEM have been adapted for an operational Geographical Information System (GIS tool within the open-source software framework System for Automated Geoscientific Analyses (SAGA, thus taking advantage of SAGA's capabilities for geomorphometric analyses. The model is driven by palaeoclimatic data (temperature, precipitation representative of periglacial areas in northern Germany over the last 50 000 years. The initial conditions have been determined for a test site by a digital terrain model and a geological model. Weathering, erosion and transport functions are calibrated using extrinsic (climatic and intrinsic (lithologic parameter data. First results indicate that our differentiated SaLEM approach shows some evidence for the spatiotemporal prediction of important soil parental material properties (particularly its depth. Future research will focus on the validation of the results against field data, and the influence of discrete events (mass movements, floods on soil parent material formation has to be evaluated.

  19. Development of a GIS-based failure investigation system for highway soil slopes

    Science.gov (United States)

    Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.

    2015-06-01

    A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation ( P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

  20. Small scale tests on the progressive retreat of soil slopes

    Science.gov (United States)

    Voulgari, Chrysoula; Utili, Stefano; Castellanza, Riccardo

    2015-04-01

    In this paper, the influence due to the presence of cracks on the morphologic evolution of natural cliffs subject to progressive retreat induced by weathering is investigated through small scale laboratory tests. Weathering turns hard rocks into soft rocks that maintain the structure of the intact rocks, but are characterised by higher void ratios and reduced bond strengths; soft rocks are transformed into granular soils generally called residual soils. A number of landslides develop in slopes due to weathering which results in the progressive retrogression of the slope face and the further degradation within the weathering zone. Cracks, that are widely present, can be a result of weathering and they can cause a significant decrease in their stability, as they provide preferential flow channels which increase the soil permeability and decrease the soil strength. The geological models employed until now are mainly empirical. Several researchers have tried to study the stability of slopes through experimental procedures. Centrifuge modelling is widely used to investigate the failure of slopes. Small scale tests are also an important approach, in order to study the behaviour of a slope under certain conditions, such as the existence of water, as they allow the observation of the infiltration processes, the movement of the weathering front, deformation and failure. However, the deformation response of a slope subject to weathering is not yet thoroughly clarified. In this work, a set of experiments were conducted to investigate weathering induced successive landslides. Weathering was applied to the slope model by wetting the slope crest through a rainfall simulator device. The moisture content of the soil during the tests was monitored by soil moisture sensors that were buried inside the slope model. High resolution cameras were recording the behaviour of the slope model. GeoPIV was used to analyse the frames and obtain the deformations of the slope model during the

  1. Measuring and Modeling Root Distribution and Root Reinforcement in Forested Slopes for Slope Stability Calculations

    Science.gov (United States)

    Cohen, D.; Giadrossich, F.; Schwarz, M.; Vergani, C.

    2016-12-01

    Roots provide mechanical anchorage and reinforcement of soils on slopes. Roots also modify soil hydrological properties (soil moisture content, pore-water pressure, preferential flow paths) via subsurface flow path associated with root architecture, root density, and root-size distribution. Interactions of root-soil mechanical and hydrological processes are an important control of shallow landslide initiation during rainfall events and slope stability. Knowledge of root-distribution and root strength are key components to estimate slope stability in vegetated slopes and for the management of protection forest in steep mountainous area. We present data that show the importance of measuring root strength directly in the field and present methods for these measurements. These data indicate that the tensile force mobilized in roots depends on root elongation (a function of soil displacement), root size, and on whether roots break in tension of slip out of the soil. Measurements indicate that large lateral roots that cross tension cracks at the scarp are important for slope stability calculations owing to their large tensional resistance. These roots are often overlooked and when included, their strength is overestimated because extrapolated from measurements on small roots. We present planned field experiments that will measure directly the force held by roots of different sizes during the triggering of a shallow landslide by rainfall. These field data are then used in a model of root reinforcement based on fiber-bundle concepts that span different spacial scales, from a single root to the stand scale, and different time scales, from timber harvest to root decay. This model computes the strength of root bundles in tension and in compression and their effect on soil strength. Up-scaled to the stand the model yields the distribution of root reinforcement as a function of tree density, distance from tree, tree species and age with the objective of providing quantitative

  2. Effect of slope height and horizontal forces on the bearing capacity of strip footings near slopes in cohesionless soil

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

    2016-01-01

    , and in such cases the bearing capacity of the footing cannot be found using the existing methods. The present work comprises finite element based upper- and lower-bound calculations, using the geotechnical software OptumG2 to investigate the effect of the slope height and horizontal forces on the total bearing...... capacity, both without and with using superposition as presupposed in the traditional bearing capacity equation. The results for friction angles 30, 35 and 40 degrees, slope inclinations 1:2, 1:3 and 1:4, for selfweight and surcharge are given as charts showing the slope inclination factors suitable...

  3. Mapping on Slope Seepage Problem using Electrical Resistivity Imaging (ERI)

    Science.gov (United States)

    Hazreek, Z. A. M.; Nizam, Z. M.; Aziman, M.; Dan, M. F. Md; Shaylinda, M. Z. N.; Faizal, T. B. M.; Aishah, M. A. N.; Ambak, K.; Rosli, S.; Rais, Y.; Ashraf, M. I. M.; Alel, M. N. A.

    2018-04-01

    The stability of slope may influenced by several factors such as its geomaterial properties, geometry and environmental factors. Problematic slope due to seepage phenomenon will influenced the slope strength thus promoting to its failure. In the past, slope seepage mapping suffer from several limitation due to cost, time and data coverage. Conventional engineering tools to detect or mapped the seepage on slope experienced those problems involving large and high elevation of slope design. As a result, this study introduced geophysical tools for slope seepage mapping based on electrical resistivity method. Two spread lines of electrical resistivity imaging were performed on the slope crest using ABEM SAS 4000 equipment. Data acquisition configuration was based on long and short arrangement, schlumberger array and 2.5 m of equal electrode spacing interval. Raw data obtained from data acquisition was analyzed using RES2DINV software. Both of the resistivity results show that the slope studied consists of three different anomalies representing top soil (200 – 1000 Ωm), perched water (10 – 100 Ωm) and hard/dry layer (> 200 Ωm). It was found that seepage problem on slope studied was derived from perched water zones with electrical resistivity value of 10 – 100 Ωm. Perched water zone has been detected at 6 m depth from the ground level with varying thickness at 5 m and over. Resistivity results have shown some good similarity output with reference to borehole data, geological map and site observation thus verified the resistivity results interpretation. Hence, this study has shown that the electrical resistivity imaging was applicable in slope seepage mapping which consider efficient in term of cost, time, data coverage and sustainability.

  4. Variance-in-Mean Effects of the Long Forward-Rate Slope

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    2005-01-01

    This paper contains an empirical analysis of the dependence of the long forward-rate slope on the long-rate variance. The long forward-rate slope and the long rate are described by a bivariate GARCH-in-mean model. In accordance with theory, a negative long-rate variance-in-mean effect for the long...... forward-rate slope is documented. Thus, the greater the long-rate variance, the steeper the long forward-rate curve slopes downward (the long forward-rate slope is negative). The variance-in-mean effect is both statistically and economically significant....

  5. Exploring Soil Organic Carbon Deposits in a Bavarian Catchment

    Science.gov (United States)

    Kriegs, Stefanie; Hobley, Eleanor; Schwindt, Daniel; Völkel, Jörg; Kögel-Knabner, Ingrid

    2017-04-01

    The distribution of soil organic carbon (SOC) in the landscape is not homogeneous, but shows high variability from the molecular to the landscape scale. The aims of our work are 1.) to detect hot spots of SOC storage within different positions in a landscape; 2.) to outline differences (or similarities) between SOC characteristics of erosional and accumulative landscape positions; and 3.) to determine whether localised SOC deposits are dominated by fresh and labile organic matter (OM) or old and presumably stable OM. These findings are crucial for the evaluation of the landscapés vulnerability towards SOC losses caused by management or natural disturbances such as erosional rainfall events. Sampling sites of our study are located in a catchment at the foothills of the Bavarian Forest in south-east Germany. Within this area three landform positions were chosen for sampling: a) a slope with both erosional depletion and old colluvial deposits, b) a foothill with recent colluvial deposits and c) a floodplain with alluvial deposits. In order to consider both heterogeneity within a single landform position and between landforms several soil profiles were sampled at every position. Samples were taken to a maximal depth of 150 cm, depending on the presence of rocks or ground-water level, and analysed for bulk density, total carbon (TOC), inorganic carbon (IC) and texture. SOC densities and stocks were calculated. A two-step physical density fractionation using Sodium-Polytungstate (1.8 g/cm3 and 2.4 g/cm3) was applied to determine the contribution of the different soil organic matter fractions to the detected SOC deposits. Literature assumes deep buried SOC to be particularly old and stable, so we applied Accelerator Mass Spectrometry Radiocarbon Dating (AMS 14C) to bulk soil samples in order to verify this hypothesis. The results show that the floodplain soils contain higher amounts of SOC compared with slopes and foothills. Heterogeneity within the sites was smaller

  6. A study of soil erosion on a steep cultivated slope in the Mt. Gongga region near Luding, Sichuan, China, using the 137Cs technique

    International Nuclear Information System (INIS)

    Zhang, X.B.; Wen, A.B.; Quine, T.A.; Walling, D.E.

    2000-01-01

    This paper reports the results of an investigation of soil erosion on a steep cultivated slope in the Mt Gongga region of the Upper Yangtze River Basin, Southwest China, using the 137 Cs technique. The effective 137 Cs reference inventory for the study field, estimated from the bottom layer of a 137 Cs depth profile at the deposition zones, is 2373.9 Bq/m2, accounting for 65.8% the local 137 Cs reference inventory of 3607.7 Bq/m2. It strongly indicates that a considerable amount of 137 Cs input was lost prior to incorporation into the ploughing layer from the study field during the nuclear weapons testing period because of 137 Cs surface enrichment. The average erosion rate is estimated to be 4914 t/km 2 yr for a typical cultivated steep slope with an angle of 34 deg at the subtropical zone in the Mt Gongga region. It can reach to 22856 t/km 2 yr for a failure slope under cultivation. (author)

  7. Reorienting with terrain slope and landmarks.

    Science.gov (United States)

    Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F

    2013-02-01

    Orientation (or reorientation) is the first step in navigation, because establishing a spatial frame of reference is essential for a sense of location and heading direction. Recent research on nonhuman animals has revealed that the vertical component of an environment provides an important source of spatial information, in both terrestrial and aquatic settings. Nonetheless, humans show large individual and sex differences in the ability to use terrain slope for reorientation. To understand why some participants--mainly women--exhibit a difficulty with slope, we tested reorientation in a richer environment than had been used previously, including both a tilted floor and a set of distinct objects that could be used as landmarks. This environment allowed for the use of two different strategies for solving the task, one based on directional cues (slope gradient) and one based on positional cues (landmarks). Overall, rather than using both cues, participants tended to focus on just one. Although men and women did not differ significantly in their encoding of or reliance on the two strategies, men showed greater confidence in solving the reorientation task. These facts suggest that one possible cause of the female difficulty with slope might be a generally lower spatial confidence during reorientation.

  8. 30 CFR 56.3130 - Wall, bank, and slope stability.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Wall, bank, and slope stability. 56.3130... Mining Methods § 56.3130 Wall, bank, and slope stability. Mining methods shall be used that will maintain wall, bank, and slope stability in places where persons work or travel in performing their assigned...

  9. Slope stabilization guide for Minnesota local government engineers.

    Science.gov (United States)

    2017-06-01

    This user guide provides simple, costeffective methods for stabilizing locally maintained slopes along roadways in Minnesota. Eight slope stabilization techniques are presented that local government engineers can undertake using locally available ...

  10. Determination Of Slope Instability Using Spatially Integrated Mapping Framework

    Science.gov (United States)

    Baharuddin, I. N. Z.; Omar, R. C.; Roslan, R.; Khalid, N. H. N.; Hanifah, M. I. M.

    2016-11-01

    The determination and identification of slope instability are often rely on data obtained from in-situ soil investigation work where it involves the logistic of machineries and manpower, thus these aspects may increase the cost especially for remote locations. Therefore a method, which is able to identify possible slope instability without frequent ground walkabout survey, is needed. This paper presents the method used in prediction of slope instability using spatial integrated mapping framework which applicable for remote areas such as tropical forest and natural hilly terrain. Spatial data such as geology, topography, land use map, slope angle and elevation were used in regional analysis during desktop study. Through this framework, the occurrence of slope instability was able to be identified and was validate using a confirmatory site- specific analysis.

  11. Parametric study on the effect of rainfall pattern to slope stability

    Directory of Open Access Journals (Sweden)

    Hakim Sagitaningrum Fathiyah

    2017-01-01

    Full Text Available Landslide in Indonesia usually occurs during the rainy seasons. Previous studies showed that rainfall infiltration has a great effect on the factor of safety (FS of slopes. This research focused on the effect of rainfall pattern on the FS of unsaturated slope with different slope angle i.e.: 30°, 45°, and 60°. Three different rainfall patterns, which are normal, advanced, and delayed were considered in the analysis. The effects of low or high hydraulic conductivity of the soil are also observed. The analyses were conducted with SEEP/W for the seepage and SLOPE/W for the slope stability. It is found that the lowest FS for gentle slope is reached under the application of advanced rainfall pattern and the lowest FS for steep slope is reached under the application of delayed rainfall pattern. Reduction of FS is known to be the largest for gentle slope rather than steep slope due to negative pore water pressure reduction and the rising of ground water level. The largest FS reduction caused by rainfall was achieved for gentle slope under advanced rainfall pattern.

  12. The biogeochemistry of carbon in continental slope sediments: The North Carolina margin

    Energy Technology Data Exchange (ETDEWEB)

    Blair, N.; Levin, L.; DeMaster, D.; Plaia, G.; Martin, C.; Fornes, W.; Thomas, C.; Pope, R.

    1999-12-01

    The responses of the continental slope benthos to organic detritus deposition were studied with a multiple trace approach. Study sites were offshore of Cape Fear (I) and Cape Hatteras (III), N.C. (both 850 m water depth) and were characterized by different organic C deposition rates, macrofaunal densities (III>I in both cases) and taxa. Natural abundances of {sup 13}C and {sup 12}C in particulate organic carbon (POC), dissolved inorganic carbon (DIC) and macrofauna indicate that the reactive organic detritus is marine in origin. Natural abundance levels of {sup 14}C and uptake of {sup 13}C-labeled diatoms by benthic animals indicate that they incorporate a relatively young component of carbon into their biomass. {sup 13}C-labeled diatoms (Thalassiorsira pseudonana) tagged with {sup 210}Pb, slope sediment tagged with {sup 113}Sn and {sup 228}Th-labeled glass beads were emplaced in plots on the seafloor at both locations and the plots were sampled after 30 min., 1-1.5 d and 14 mo. At Site I, tracer diatom was intercepted at the surface primarily by protozoans and surface-feeding annelids. Little of the diatom C penetrated below 2 cm even after 14 months. Oxidation of organic carbon appeared to be largely aerobic. At Site III, annelids were primarily responsible for the initial uptake of tracer. On the time scale of days, diatom C was transported to a depth of 12 cm and was found in animals collected between 5-10 cm. The hoeing of tracer from the surface by the maldanid Praxillela sp. may have been responsible for some of the rapid nonlocal transport. Oxidation of the diatom organic carbon was evident to at least 10 cm depth. Anaerobic breakdown of organic matter is more important at Site III. Horizontal transport, which was probably biologically mediated, was an order of magnitude more rapid than vertical displacement over a year time scale. If the horizontal transport was associated with biochemical transformations of the organic matter, it may represent an

  13. First characterisation of the "Rumi-Pana" rock avalanche deposits (Famatina Range, La Rioja, Argentina)

    Science.gov (United States)

    Santiago Pullarello, José; Derron, Marc-Henri; Penna, Ivanna; Leiva, Alicia; Jaboyadoff, Michel

    2017-04-01

    Active mountain fronts are subject to large scale slope collapses which have the capacity to run long distances on piedmont areas. Along time, fluvial activity and other gravitatory processes can intensively erode and mask primary features related to the collapses. Therefore, to reconstruct the history of their occurrence, further analyses are needed, e.g. sedimentologic analyses. This work focuses on the occurrence of large rock avalanches in the Vinchina region, La Rioja (28°43'27.81'' S / 68°00'25.42'' W) on the western side of the Famatina range(Argentina). Here, photointerpretation of high resolution satellite images (Google Earth) allowed us to identify two rock avalanches, main scarps developed at 2575 and 2750 m a.s.l. . There are no absolute ages for these deposits, however, comparing their preservation degree with those dated further north (in similar climatic and landscape dynamics contexts [i]), we can suggest these rock avalanches took place during the Pleistocene. We carried out a fieldwork survey in this remote area, including classical landslide mapping, structural analysis, deposits characterization and sampling. The deposits reach the valley bottom (at around 1700 m a.s.l.) with runouts about 5 and 5.3 km long. In one of the cases, the morphology of the deposit is well preserved, allowing to reconstruct accurately its extension. However, in the second case, the deposits are strongly eroded by courses draining the mountain front, therefore further analyses should be done to reconstruct its extension. In addition to morphologic interpretations, a multiscale grain-size analysis was done to differentiate rock avalanches from other hillslope deposits: (1) 3D surface models of surface plots (5x5m) have been built by SfM photogrammetry; 2) classical sieving and 3) laser grain-size analysis of deposits. Samples were collected on different parts of the slope, but also along cross sections through the avalanche deposit. This deposits characterization will

  14. Role of slope on infiltration: A review

    Science.gov (United States)

    Morbidelli, Renato; Saltalippi, Carla; Flammini, Alessia; Govindaraju, Rao S.

    2018-02-01

    Partitioning of rainfall at the soil-atmosphere interface is important for both surface and subsurface hydrology, and influences many events of major hydrologic interest such as runoff generation, aquifer recharge, and transport of pollutants in surface waters as well as the vadose zone. This partitioning is achieved through the process of infiltration that has been widely investigated at the local scale, and more recently also at the field scale, by models that were designed for horizontal surfaces. However, infiltration, overland flows, and deep flows in most real situations are generated by rainfall over sloping surfaces that bring in additional effects. Therefore, existing models for local infiltration into homogeneous and layered soils and those as for field-scale infiltration, have to be adapted to account for the effects of surface slope. Various studies have investigated the role of surface slope on infiltration based on a theoretical formulations for the dynamics of infiltration, extensions of the Green-Ampt approach, and from laboratory and field experiments. However, conflicting results have been reported in the scientific literature on the role of surface slope on infiltration. We summarize the salient points from previous studies and provide plausible reasons for discrepancies in conclusions of previous authors, thus leading to a critical assessment of the current state of our understanding on this subject. We offer suggestions for future efforts to advance our knowledge of infiltration over sloping surfaces.

  15. VT Lidar Slope (2 meter) - 2012 - Bennington County

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Bennington County 2012 2.0m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  16. Slope Stability. CEGS Programs Publication Number 15.

    Science.gov (United States)

    Pestrong, Raymond

    Slope Stability is one in a series of single-topic problem modules intended for use in undergraduate and earth science courses. The module, also appropriate for use in undergraduate civil engineering and engineering geology courses, is a self-standing introduction to studies of slope stability. It has been designed to supplement standard…

  17. Slope Deformation Prediction Based on Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Lei JIA

    2013-07-01

    Full Text Available This paper principally studies the prediction of slope deformation based on Support Vector Machine (SVM. In the prediction process,explore how to reconstruct the phase space. The geological body’s displacement data obtained from chaotic time series are used as SVM’s training samples. Slope displacement caused by multivariable coupling is predicted by means of single variable. Results show that this model is of high fitting accuracy and generalization, and provides reference for deformation prediction in slope engineering.

  18. Electrical imaging and self-potential survayes to study the geological setting of the Quaternary, slope depositsin the Agri high valley (Southern Italy)

    OpenAIRE

    M. Schiattarella; S. Piscitelli; V. Lapenna; S. I. Giano

    2000-01-01

    We present the results of a geophysical survey carried out to outline the structural modelling of Quaternary slopedeposits in the northern part of the Agri high valley (Basilicata, Southern Italy). Quaternary folding and brittle deformations of the subaerial slope deposits have been studied combining electrical imaging and self-potential surveys with geological structural analysis. This integrated approach indicates that the area underwent both transpressional and transtensional tectonics dur...

  19. Effects of rye grass coverage on soil loss from loess slopes

    Directory of Open Access Journals (Sweden)

    Yuequn Dong

    2015-09-01

    Full Text Available Vegetative coverage is commonly used to reduce urban slope soil erosion. Laboratory experimental study on soil erosion under grass covered slopes is conventionally time and space consuming. In this study, a new method is suggested to study the influences of vegetation coverage on soil erosion from a sloped loess surface under three slope gradients of 5°, 15°, and 25°; four rye grass coverages of 0%, 25%, 50%, and 75%; and three rainfall intensities of 60, 90, and 120 mm/h with a silt-loamy loess soil. Rye grasses were planted in the field with the studied soil before being transplanted into a laboratory flume. Grass was allowed to resume growth for a period before the rain simulation experiment. Results showed that the grass cover reduced soil erosion by 63.90% to 92.75% and sediment transport rate by 80.59% to 96.17% under different slope gradients and rainfall intensities. The sediment concentration/sediment transport rate from bare slope was significantly higher than from a grass-covered slope. The sediment concentration/transport rate from grass-covered slopes decreased linearly with grass coverage and increased with rainfall intensity. The sediment concentration/transport rate from the bare slope increased as a power function of slope and reached the maximum value at the gradient of about 25°, whereas that from grass-covered slope increased linearly and at much lower levels. The results of this study can be used to estimate the effect of vegetation on soil erosion from loess slopes.

  20. Soil erosion processes on sloping land using REE tracer

    International Nuclear Information System (INIS)

    Shen Zhenzhou; Liu Puling; Yang Mingyi; Lian Zhenlong; Ju Tongjun; Yao Wenyi; Li Mian

    2007-01-01

    Sheet erosion is the main performance in the slope soil erosion process at the primary stage of natural rainfall. For three times of rainfall during experiment, the ratios of sheet erosion to total erosion account for 71%, 48% and 49% respectively, which showed that the sloping erosion was still at the primary stage from sheet erosion to rill erosion. With the rainfall going, the rill erosion amount increase. It showed that soil erosion was changing from sheet erosion to rill erosion. The sources of sediment from different sections of the plot were analyzed, and the results indicated that whatever the sheet erosion changed, the ratio erosion of upper part of surface soil was always lower than 10%. Sheet erosion came mainly from the lower section of surface soil. With the ratios to the amount of total rill erosion changes, the rill erosion amount of each section regularly changes too. The general conclusion is that when the rainfall ends, relative erosion of different slope element to the foot of slope is: 1 meter away accounts for 16%, 2-4 meters away is 6% and 5-9 meters away is 3%. The ratio of rill erosion amount of these three slope element is 5:2:1, which shows the rill erosion amount are mainly from the slope element of 4 meters from the foot of slope. (authors)

  1. Eros: Shape, topography, and slope processes

    Science.gov (United States)

    Thomas, P.C.; Joseph, J.; Carcich, B.; Veverka, J.; Clark, B.E.; Bell, J.F.; Byrd, A.W.; Chomko, R.; Robinson, M.; Murchie, S.; Prockter, L.; Cheng, A.; Izenberg, N.; Malin, M.; Chapman, C.; McFadden, L.A.; Kirk, R.; Gaffey, M.; Lucey, P.G.

    2002-01-01

    Stereogrammetric measurement of the shape of Eros using images obtained by NEAR's Multispectral Imager provides a survey of the major topographic features and slope processes on this asteroid. This curved asteroid has radii ranging from 3.1 to 17.7 km and a volume of 2535 ?? 20 km3. The center of figure is within 52 m of the center of mass provided by the Navigation team; this minimal difference suggests that there are only modest variations in density or porosity within the asteroid. Three large depressions 10, 8, and 5.3 km across represent different stages of degradation of large impact craters. Slopes on horizontal scales of ???300 m are nearly all less than 35??, although locally scarps are much steeper. The area distribution of slopes is similar to those on Ida, Phobos, and Deimos. Regions that have slopes greater than 25?? have distinct brighter markings and have fewer large ejecta blocks than do flatter areas. The albedo patterns that suggest downslope transport of regolith have sharper boundaries than those on Phobos, Deimos, and Gaspra. The morphology of the albedo patterns, their lack of discrete sources, and their concentration on steeper slopes suggest transport mechanisms different from those on the previously well-observed small bodies, perhaps due to a reduced relative effectiveness of impact gardening on Eros. Regolith is also transported in talus cones and in connected, sinuous paths extending as much as 2 km, with some evident as relatively darker material. Talus material in at least one area is a discrete superposed unit, a feature not resolved on other small bodies. Flat-floored craters that apparently contain ponded material also suggest discrete units that are not well mixed by impacts. ?? 2002 Elsevier Science (USA).

  2. Unstable slope management program.

    Science.gov (United States)

    2009-08-01

    This Rapid Response Project gathered information on existing unstable slope management programs, with a : focus on asset management practices in the United States and overseas. On the basis of this study, the research : team summarized and recommende...

  3. Rock slope design guide.

    Science.gov (United States)

    2011-04-01

    This Manual is intended to provide guidance for the design of rock cut slopes, rockfall catchment, and : rockfall controls. Recommendations presented in this manual are based on research presented in Shakoor : and Admassu (2010) entitled Rock Slop...

  4. Rock Slope Design Criteria

    Science.gov (United States)

    2010-06-01

    Based on the stratigraphy and the type of slope stability problems, the flat lying, Paleozoic age, sedimentary : rocks of Ohio were divided into three design units: 1) competent rock design unit consisting of sandstones, limestones, : and siltstones ...

  5. A Geomorfologia e a datação de gravuras de Foz Côa. Metodologia e desenvolvimento de um caso de investigação científica

    Directory of Open Access Journals (Sweden)

    Fernando Rebelo

    1997-06-01

    Full Text Available THE GEOMORPHOLOGY AND THE DATING OF THE ENGRAVINGS OF FOZ CÔA - METHODOLOGY AND DEVELOPMENT OF A SCIENTIFIC RESEARCH CASE - Several alternative interpretations of the age of the engravings at Foz Côa are presented. One derivation is based on the climatic and paleo-climatic characteristics of the area as well as the hydrological characteristics of the Côa River, especially its propensity for flooding. This interpretation involves the assumption that the smooth rock surface on which the engravings are found is of late-glacial origin. Another approach at establishing an age is based on the hardness of the rock schists and the near vertical slopes of the smooth surfaces in which the engravings are etched. And another interpretation is related to the burial of the engravings by debris flow and the effects of frost action on the rock surfaces. Evidence of the effects of ice on the rock surface along with the presence of periglacial deposits, similar to other known and previously-dated engravings, leads to the identification of a paleolithic age for the engravings found in the Foz Côa area.

  6. Newton slopes for Artin-Schreier-Witt towers

    DEFF Research Database (Denmark)

    Davis, Christopher; Wan, Daqing; Xiao, Liang

    2016-01-01

    We fix a monic polynomial f(x)∈Fq[x] over a finite field and consider the Artin-Schreier-Witt tower defined by f(x); this is a tower of curves ⋯→Cm→Cm−1→⋯→C0=A1, with total Galois group Zp. We study the Newton slopes of zeta functions of this tower of curves. This reduces to the study of the Newton...... slopes of L-functions associated to characters of the Galois group of this tower. We prove that, when the conductor of the character is large enough, the Newton slopes of the L-function form arithmetic progressions which are independent of the conductor of the character. As a corollary, we obtain...

  7. The slope-background for the near-peak regimen of photoemission spectra

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Gomez, A., E-mail: aherrera@qro.cinvestav.mx [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Bravo-Sanchez, M. [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Chihuahua, Chihuahua 31109 (Mexico); Vazquez-Lepe, M.O. [Departamento de Ingeniería de Proyectos, Universidad de Guadalajara, Jalisco 44430 (Mexico)

    2013-08-15

    Highlights: •We propose a method that accounts for the change in the background slope of XPS data. •The slope-background can be derived from Tougaard–Sigmund's transport theory. •The total background is composed by Shirley–Sherwood and Tougaard type backgrounds. •The slope-background employs one parameter that can be related to REELS spectra. •The slope, in conjunction with the Shirley–Sherwood background, provides better fits. -- Abstract: Photoemission data typically exhibits a change on the intensity of the background between the two sides of the peaks. This step is usually very well reproduced by the Shirley–Sherwood background. Yet, the change on the slope of the background in the near-peak regime, although usually present, is not always as obvious to the eye. However, the intensity of the background signal associated with the evolution of its slope can be appreciable. The slope-background is designed to empirically reproduce the change on the slope. Resembling the non-iterative Shirley method, the proposed functional form relates the slope of the background to the integrated signal at higher electron kinetic energies. This form can be predicted under Tougaard–Sigmund's electron transport theory in the near-peak regime. To reproduce both the step and slope changes on the background, it is necessary to employ the slope-background in conjunction with the Shirley–Sherwood background under the active-background method. As it is shown for a series of materials, the application of the slope-background provides excellent fits, is transparent to the operator, and is much more independent of the fitting range than other background methods. The total area assessed through the combination of the slope and the Shirley–Sherwood backgrounds is larger than when only the Shirley–Sherwood background is employed, and smaller than when the Tougaard background is employed.

  8. Preliminary Analysis of Slope Stability in Kuok and Surrounding Areas

    Directory of Open Access Journals (Sweden)

    Dewandra Bagus Eka Putra

    2016-12-01

    Full Text Available The level of slope influenced by the condition of the rocks beneath the surface. On high level of slopes, amount of surface runoff and water transport energy is also enlarged. This caused by greater gravity, in line with the surface tilt from the horizontal plane. In other words, topsoil eroded more and more. When the slope becomes twice as steep, then the amount of erosion per unit area be 2.0 - 2.5 times more. Kuok and surrounding area is the road access between the West Sumatra and Riau which plays an important role economies of both provinces. The purpose of this study is to map the locations that have fairly steep slopes and potential mode of landslides. Based on SRTM data obtained,  the roads in Kuok area has a minimum elevation of + 33 m and a maximum  + 217.329 m. Rugged road conditions with slope ranging from 24.08 ° to 44.68 ° causing this area having frequent landslides. The result of slope stability analysis in a slope near the Water Power Plant Koto Panjang, indicated that mode of active failure is toppling failure or rock fall and the potential zone of failure is in the center part of the slope.

  9. The High Resolution Imaging Science Experiment (HiRISE) during MRO's Primary Science Phase (PSP)

    Science.gov (United States)

    McEwen, A.S.; Banks, M.E.; Baugh, N.; Becker, K.; Boyd, A.; Bergstrom, J.W.; Beyer, R.A.; Bortolini, E.; Bridges, N.T.; Byrne, S.; Castalia, B.; Chuang, F.C.; Crumpler, L.S.; Daubar, I.; Davatzes, A.K.; Deardorff, D.G.; DeJong, A.; Alan, Delamere W.; Dobrea, E.N.; Dundas, C.M.; Eliason, E.M.; Espinoza, Y.; Fennema, A.; Fishbaugh, K.E.; Forrester, T.; Geissler, P.E.; Grant, J. A.; Griffes, J.L.; Grotzinger, J.P.; Gulick, V.C.; Hansen, C.J.; Herkenhoff, K. E.; Heyd, R.; Jaeger, W.L.; Jones, D.; Kanefsky, B.; Keszthelyi, L.; King, R.; Kirk, R.L.; Kolb, K.J.; Lasco, J.; Lefort, A.; Leis, R.; Lewis, K.W.; Martinez-Alonso, S.; Mattson, S.; McArthur, G.; Mellon, M.T.; Metz, J.M.; Milazzo, M.P.; Milliken, R.E.; Motazedian, T.; Okubo, C.H.; Ortiz, A.; Philippoff, A.J.; Plassmann, J.; Polit, A.; Russell, P.S.; Schaller, C.; Searls, M.L.; Spriggs, T.; Squyres, S. W.; Tarr, S.; Thomas, N.; Thomson, B.J.; Tornabene, L.L.; Van Houten, C.; Verba, C.; Weitz, C.M.; Wray, J.J.

    2010-01-01

    The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter (MRO) acquired 8 terapixels of data in 9137 images of Mars between October 2006 and December 2008, covering ???0.55% of the surface. Images are typically 5-6 km wide with 3-color coverage over the central 20% of the swath, and their scales usually range from 25 to 60 cm/pixel. Nine hundred and sixty stereo pairs were acquired and more than 50 digital terrain models (DTMs) completed; these data have led to some of the most significant science results. New methods to measure and correct distortions due to pointing jitter facilitate topographic and change-detection studies at sub-meter scales. Recent results address Noachian bedrock stratigraphy, fluvially deposited fans in craters and in or near Valles Marineris, groundwater flow in fractures and porous media, quasi-periodic layering in polar and non-polar deposits, tectonic history of west Candor Chasma, geometry of clay-rich deposits near and within Mawrth Vallis, dynamics of flood lavas in the Cerberus Palus region, evidence for pyroclastic deposits, columnar jointing in lava flows, recent collapse pits, evidence for water in well-preserved impact craters, newly discovered large rayed craters, and glacial and periglacial processes. Of particular interest are ongoing processes such as those driven by the wind, impact cratering, avalanches of dust and/or frost, relatively bright deposits on steep gullied slopes, and the dynamic seasonal processes over polar regions. HiRISE has acquired hundreds of large images of past, present and potential future landing sites and has contributed to scientific and engineering studies of those sites. Warming the focal-plane electronics prior to imaging has mitigated an instrument anomaly that produces bad data under cold operating conditions. ?? 2009 Elsevier Inc.

  10. Geomorphological mapping of ice-free areas using polarimetric RADARSAT-2 data on Fildes Peninsula and Ardley Island, Antarctica

    Science.gov (United States)

    Schmid, T.; López-Martínez, J.; Guillaso, S.; Serrano, E.; D'Hondt, O.; Koch, M.; Nieto, A.; O'Neill, T.; Mink, S.; Durán, J. J.; Maestro, A.

    2017-09-01

    Satellite-borne Synthetic Aperture Radar (SAR) has been used for characterizing and mapping in two relevant ice-free areas in the South Shetland Islands. The objective has been to identify and characterize land surface covers that mainly include periglacial and glacial landforms, using fully polarimetric SAR C band RADARSAT-2 data, on Fildes Peninsula that forms part of King George Island, and Ardley Island. Polarimetric parameters obtained from the SAR data, a selection of field based training and validation sites and a supervised classification approach, using the support vector machine were chosen to determine the spatial distribution of the different landforms. Eight periglacial and glacial landforms were characterized according to their scattering mechanisms using a set of 48 polarimetric parameters. The mapping of the most representative surface covers included colluvial deposits, stone fields and pavements, patterned ground, glacial till and rock outcrops, lakes and glacier ice. The overall accuracy of the results was estimated at 81%, a significant value when mapping areas that are within isolated regions where access is limited. Periglacial surface covers such as stone fields and pavements occupy 25% and patterned ground over 20% of the ice-free areas. These are results that form the basis for an extensive monitoring of the ice-free areas throughout the northern Antarctic Peninsula region.

  11. Effects of slope smoothing in river channel modeling

    Science.gov (United States)

    Kim, Kyungmin; Liu, Frank; Hodges, Ben R.

    2017-04-01

    In extending dynamic river modeling with the 1D Saint-Venant equations from a single reach to a large watershed there are critical questions as to how much bathymetric knowledge is necessary and how it should be represented parsimoniously. The ideal model will include the detail necessary to provide realism, but not include extraneous detail that should not exert a control on a 1D (cross-section averaged) solution. In a Saint-Venant model, the overall complexity of the river channel morphometry is typically abstracted into metrics for the channel slope, cross-sectional area, hydraulic radius, and roughness. In stream segments where cross-section surveys are closely spaced, it is not uncommon to have sharp changes in slope or even negative values (where a positive slope is the downstream direction). However, solving river flow with the Saint-Venant equations requires a degree of smoothness in the equation parameters or the equation set with the directly measured channel slopes may not be Lipschitz continuous. The results of non-smoothness are typically extended computational time to converge solutions (or complete failure to converge) and/or numerical instabilities under transient conditions. We have investigated using cubic splines to smooth the bottom slope and ensure always positive reference slopes within a 1D model. This method has been implemented in the Simulation Program for River Networks (SPRNT) and is compared to the standard HEC-RAS river solver. It is shown that the reformulation of the reference slope is both in keeping with the underlying derivation of the Saint-Venant equations and provides practical numerical stability without altering the realism of the simulation. This research was supported in part by the National Science Foundation under grant number CCF-1331610.

  12. Dynamic stability and failure modes of slopes in discontinuous rock mass

    International Nuclear Information System (INIS)

    Shimizu, Yasuhiro; Aydan, O.; Ichikawa, Yasuaki; Kawamoto, Toshikazu.

    1988-01-01

    The stability of rock slopes during earthquakes are of great concern in rock engineering works such as highway, dam, and nuclear power station constructions. As rock mass in nature is usually discontinuous, the stability of rock slopes will be geverned by the spatial distribution of discontinuities in relation with the geometry of slope and their mechanical properties rather than the rock element. The authors have carried out some model tests on discontinuous rock slopes using three different model tests techniques in order to investigate the dynamic behaviour and failure modes of the slopes in discontinuous rock mass. This paper describes the findings and observations made on model rock slopes with various discontinuity patterns and slope geometry. In addition some stability criterions are developed and the calculated results are compared with those of experiments. (author)

  13. Infinite slope stability under steady unsaturated seepage conditions

    Science.gov (United States)

    Lu, Ning; Godt, Jonathan W.

    2008-01-01

    We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework.

  14. Surface drainage in leveled land: Implication of slope

    Directory of Open Access Journals (Sweden)

    Antoniony S. Winkler

    Full Text Available ABSTRACT In the lowlands of Rio Grande do Sul, land leveling is mostly carried out with no slope for the purpose of rice production. In this environment, soils with a low hydraulic conductivity are predominant owing to the presence of a practically impermeable B-horizon near the surface. Land leveling leads to soil accommodation resulting in the formation of depressions where water accumulates after heavy rainfalls, subsequently leading to problems with crops implanted in succession to rice, such as soybeans. The objective of this research was to quantify the areas and volumes of water accumulation in soil as a function of the slope of land leveling. Five typical leveled lowland areas were studied as a part of this research. The original areas presented slopes of 0, 0.20, 0.25, 0.28 and 0.40%, which were used to generate new digital elevation models with slopes between 0 and 0.5%. These newly generated digital models were used to map the depressions with surface water storage. In conclusion, land leveling with slopes higher than 0.1% is recommended to minimize problems with superficial water storage in rice fields.

  15. Biogeomorphological influence of slope processes and sedimentology on vascular talus vegetation in the southern Cascades, California

    Science.gov (United States)

    Pérez, Francisco L.

    2012-02-01

    following rubble removal often exposes plant roots. Debris deposition can completely bury plants; some may survive sedimentation, producing new shoots that grow through accumulated debris. Shrubs may propagate by layering, as adventitious roots develop along buried stems; or produce new clones along their roots. Slope processes may damage and transport plant pieces downhill; some species can sprout from severed, displaced root or stem fragments. Vegetation interacts with several geomorphic processes, including debris flows, grain flows, rockfall, snow avalanches, frost creep, and runoff. Larger plants may alter local patterns of debris movement and deposition, damming cascading debris on their upslope side and deflecting sediments laterally to plant margins, where they form narrow elongated stone stripes.

  16. New possibilities for slope stability assessment of spoil banks

    Energy Technology Data Exchange (ETDEWEB)

    Radl, A [Palivovy Kombinat, Vresova (Czechoslovakia)

    1991-03-01

    Discusses problems associated with slope stability of spoil banks consisting of sedimentary rocks from brown coal surface mining. Effects of rock physical properties on slope stability are analyzed: grain size distribution, compression strength, moisture content, angle of internal friction, etc. Mechanism of plastic slope deformation which occurs during a landslide is evaluated. Formulae for calculating slope stability considering stress distribution in a spoil bank (including all the main factors that influence stresses) are derived. Practical use of the gamma-gamma logging and logging schemes used in geodetic surveys of unstable spoil banks in Czechoslovakia (the Vintirov spoil bank in the Sokolov brown coal district) are discussed. 5 refs.

  17. 3D geodetic monitoring slope deformations

    Directory of Open Access Journals (Sweden)

    Weiss Gabriel

    1996-06-01

    Full Text Available For plenty of slope failures that can be found in Slovakia is necessary and very important their geodetic monitoring (because of their activity, reactivisations, checks. The paper gives new methodologies for these works, using 3D terrestrial survey technologies for measurements in convenient deformation networks. The design of an optimal type of deformation model for various kinds of landslides and their exact processing with an efficient testing procedure to determine the kinematics of the slope deformations are presented too.

  18. Direction of Auditory Pitch-Change Influences Visual Search for Slope From Graphs.

    Science.gov (United States)

    Parrott, Stacey; Guzman-Martinez, Emmanuel; Orte, Laura; Grabowecky, Marcia; Huntington, Mark D; Suzuki, Satoru

    2015-01-01

    Linear trend (slope) is important information conveyed by graphs. We investigated how sounds influenced slope detection in a visual search paradigm. Four bar graphs or scatter plots were presented on each trial. Participants looked for a positive-slope or a negative-slope target (in blocked trials), and responded to targets in a go or no-go fashion. For example, in a positive-slope-target block, the target graph displayed a positive slope while other graphs displayed negative slopes (a go trial), or all graphs displayed negative slopes (a no-go trial). When an ascending or descending sound was presented concurrently, ascending sounds slowed detection of negative-slope targets whereas descending sounds slowed detection of positive-slope targets. The sounds had no effect when they immediately preceded the visual search displays, suggesting that the results were due to crossmodal interaction rather than priming. The sounds also had no effect when targets were words describing slopes, such as "positive," "negative," "increasing," or "decreasing," suggesting that the results were unlikely due to semantic-level interactions. Manipulations of spatiotemporal similarity between sounds and graphs had little effect. These results suggest that ascending and descending sounds influence visual search for slope based on a general association between the direction of auditory pitch-change and visual linear trend.

  19. How hydrological factors initiate instability in a model sandy slope

    OpenAIRE

    Terajima, Tomomi; Miyahira, Ei-ichiro; Miyajima, Hiroyuki; Ochiai, Hirotaka; Hattori, Katsumi

    2013-01-01

    Knowledge of the mechanisms of rain-induced shallow landslides can improve the prediction of their occurrence and mitigate subsequent sediment disasters. Here, we examine an artificial slope's subsurface hydrology and propose a new slope stability analysis that includes seepage force and the down-slope transfer of excess shear forces. We measured pore water pressure and volumetric water content immediately prior to a shallow landslide on an artificial sandy slope of 32°: The direction of the ...

  20. Effects of the gate dielectric on the subthreshold transport of carbon nanotube network transistors grown by using plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Jeong, Seung Geun; Park, Wan Jun

    2010-01-01

    In this study, we investigated the subthreshold slope of random network carbon nanotube transistors with different geometries and passivations. Single-wall carbon nanotubes with lengths of 1-2 m were grown by using plasma-enhanced chemical vapor deposition to form the transistor channels. A critical channel length, where the subthreshold slope was saturated, of 7 μm was obtained. This was due to the percolational behavior of the nanotube random networks. With the dielectric passivation, the subthreshold slope was dramatically reduced from 9 V/decade to 0.9 V/decade by reducing interfacial trap sites, which then reduced the interface capacitance between the nanotube network and the gate dielectric.

  1. Analytic observations for the d=1+ 1 bridge site (or single-step) deposition model

    International Nuclear Information System (INIS)

    Evans, J.W.; Kang, H.C.

    1991-01-01

    Some exact results for a reversible version of the d=1+1 bridge site (or single-step) deposition model are presented. Exact steady-state properties are determined directly for finite systems with various mean slopes. These show explicitly how the asymptotic growth velocity and fluctuations are quenched as the slope approaches its maximum allowed value. Next, exact hierarchial equations for the dynamics are presented. For the special case of ''equilibrium growth,'' these are analyzed exactly at the pair-correlation level directly for an infinite system. This provided further insight into asymptotic scaling behavior. Finally, the above hierarchy is compared with one generated from a discrete form of the Kardar--Parisi--Zhang equations. Some differences are described

  2. [Analysis of related factors of slope plant hyperspectral remote sensing].

    Science.gov (United States)

    Sun, Wei-Qi; Zhao, Yun-Sheng; Tu, Lin-Ling

    2014-09-01

    In the present paper, the slope gradient, aspect, detection zenith angle and plant types were analyzed. In order to strengthen the theoretical discussion, the research was under laboratory condition, and modeled uniform slope for slope plant. Through experiments we found that these factors indeed have influence on plant hyperspectral remote sensing. When choosing slope gradient as the variate, the blade reflection first increases and then decreases as the slope gradient changes from 0° to 36°; When keeping other factors constant, and only detection zenith angle increasing from 0° to 60°, the spectral characteristic of slope plants do not change significantly in visible light band, but decreases gradually in near infrared band; With only slope aspect changing, when the dome meets the light direction, the blade reflectance gets maximum, and when the dome meets the backlit direction, the blade reflectance gets minimum, furthermore, setting the line of vertical intersection of incidence plane and the dome as an axis, the reflectance on the axis's both sides shows symmetric distribution; In addition, spectral curves of different plant types have a lot differences between each other, which means that the plant types also affect hyperspectral remote sensing results of slope plants. This research breaks through the limitations of the traditional vertical remote sensing data collection and uses the multi-angle and hyperspectral information to analyze spectral characteristics of slope plants. So this research has theoretical significance to the development of quantitative remote sensing, and has application value to the plant remote sensing monitoring.

  3. Stability of sulfur slopes on Io

    Science.gov (United States)

    Clow, G. D.; Carr, M. H.

    1980-01-01

    The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

  4. New knowledge on the temperature-entropy saturation boundary slope of working fluids

    International Nuclear Information System (INIS)

    Su, Wen; Zhao, Li; Deng, Shuai

    2017-01-01

    The slope of temperature-entropy saturation boundary of working fluids has a significant effect on the thermodynamic performance of cycle processes. However, for the working fluids used in cycles, few studies have been conducted to analyze the saturated slope from the molecular structure and mixture composition. Thus, in this contribution, an analytical expression on the slope of saturated curve is obtained based on the highly accurate Helmholtz energy equation. 14 pure working fluids and three typical binary mixtures are employed to analyze the influence of molecular groups and mixture compositions on the saturated slope, according to the correlated parameters of Helmholtz energy equation. Based on the calculated results, a preliminary trend is demonstrated that with an increase of the number of molecular groups, the positive liquid slope of pure fluids increases and the vapor slope appears positive sign in a narrow temperature range. Particularly, for the binary mixtures, the liquid slope is generally located between the corresponding pure fluids', while the vapor slope can be infinity by mixing dry and wet fluids ingeniously. It can be proved through the analysis of mixtures' saturated slope that three types of vapor slope could be obtained by regulating the mixture composition. - Highlights: • The saturated slope is derived from the Helmholtz function for working fluids. • The effect of molecular structure on the saturated slope is analyzed. • The variation of saturated slope with the mixture composition is investigated.

  5. Slope wavenumber spectrum models of capillary and capillary-gravity waves

    Institute of Scientific and Technical Information of China (English)

    贾永君; 张杰; 王岩峰

    2010-01-01

    Capillary and capillary-gravity waves possess a random character, and the slope wavenumber spectra of them can be used to represent mean distributions of wave energy with respect to spatial scale of variability. But simple and practical models of the slope wavenumber spectra have not been put forward so far. In this article, we address the accurate definition of the slope wavenumber spectra of water surface capillary and capillary-gravity waves. By combining the existing slope wavenumber models and using th...

  6. Hydraulic experiment on formation mechanism of tsunami deposit and verification of sediment transport model for tsunamis

    Science.gov (United States)

    Yamamoto, A.; Takahashi, T.; Harada, K.; Sakuraba, M.; Nojima, K.

    2017-12-01

    An underestimation of the 2011 Tohoku tsunami caused serious damage in coastal area. Reconsideration for tsunami estimation needs knowledge of paleo tsunamis. The historical records of giant tsunamis are limited, because they had occurred infrequently. Tsunami deposits may include many of tsunami records and are expected to analyze paleo tsunamis. However, present research on tsunami deposits are not able to estimate the tsunami source and its magnitude. Furthermore, numerical models of tsunami and its sediment transport are also important. Takahashi et al. (1999) proposed a model of movable bed condition due to tsunamis, although it has some issues. Improvement of the model needs basic data on sediment transport and deposition. This study investigated the formation mechanism of tsunami deposit by hydraulic experiment using a two-dimensional water channel with slope. In a fixed bed condition experiment, velocity, water level and suspended load concentration were measured at many points. In a movable bed condition, effects of sand grains and bore wave on the deposit were examined. Yamamoto et al. (2016) showed deposition range varied with sand grain sizes. In addition, it is revealed that the range fluctuated by number of waves and wave period. The measurements of velocity and water level showed that flow was clearly different near shoreline and in run-up area. Large velocity by return flow was affected the amount of sand deposit near shoreline. When a cutoff wall was installed on the slope, the amount of sand deposit repeatedly increased and decreased. Especially, sand deposit increased where velocity decreased. Takahashi et al. (1999) adapted the proposed model into Kesennuma bay when the 1960 Chilean tsunami arrived, although the amount of sand transportation was underestimated. The cause of the underestimation is inferred that the velocity of this model was underestimated. A relationship between velocity and sediment transport has to be studied in detail, but

  7. Deciphering Depositional Signals in the Bed-Scale Stratigraphic Record of Submarine Channels

    Science.gov (United States)

    Sylvester, Z.; Covault, J. A.

    2017-12-01

    Submarine channels are important conduits of sediment transfer from rivers and shallow-marine settings into the deep sea. As such, the stratigraphic record of submarine-channel systems can store signals of past climate- and other environmental changes in their upstream sediment-source areas. This record is highly fragmented as channels are primarily locations of sediment bypass; channelized turbidity currents are likely to leave a more complete record in areas away from and above the thalweg. However, the link between the thick-bedded axial channel deposits that record a small number of flows and the much larger number of thin-bedded turbidites forming terrace- and levee deposits is poorly understood. We have developed a relatively simple two-dimensional model that, given a number of input flow parameters (mean velocity, grain size, duration of deposition, flow thickness), predicts the thickness and composition of the turbidite that is left behind in the channel and in the overbank areas. The model is based on a Rouse-type suspended sediment concentration profile and the Garcia-Parker entrainment function. In the vertical direction, turbidites tend to rapidly become thinner and finer-grained with height above thalweg, due to decreasing concentration. High near-thalweg concentrations result in thick axial beds. However, an increase in flow velocity can result in high entrainment and no deposition at the bottom of the channel, yet a thin layer of sand and mud is still deposited higher up on the channel bank. If channel thalwegs are largely in a bypass condition, relatively minor velocity fluctuations result in a few occasionally preserved thick beds in the axis, and numerous thin turbidites - and a more complete record - on the channel banks. We use near-seafloor data from the Niger Delta slope and an optimization algorithm to show how our model can be used to invert for likely flow parameters and match the bed thickness and grain size of 100 turbidites observed in a

  8. An emerging methodology of slope hazard assessment for natural gas pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Z.J.; O' Neil, G.; Rizkalla, M. [TransCanada PipeLines Ltd., Calgary, AB (Canada)

    2000-07-01

    A new slope assessment methodology has been developed by TransCanada PipeLines Ltd. in an effort to switch from a reactive to a proactive hazard management approach and to optimize maintenance expenditure. The company operates 37,000 km of natural gas gathering and transmission pipelines, portions of which traverse slopes and stream crossings. The newly developed rainfall-ground movement model provides site-specific ground movement predictions for approximately 1100 slopes and establishes a risk-ranked list of slopes upon which maintenance decisions can be based. The input to the predictive model is derived from internal and public information regarding site conditions. This information serves as input to a pipe-soil interaction model to determine the probability of pipeline failure for each slope. The ground movement for this model is limited to creep-type which is typically less than 100 mm per year. Landslides are not addressed in this paper. A system-wide database has been constructed for slopes to prioritize the slope movement hazards. The slope information includes geotechnical data such as bedrock geology, surficial geology, slope details, precipitation and erosion potential. Information related to the pipeline includes the location, age, size, as well as design pressure and temperature. 13 refs., 2 figs.

  9. Engineering and Design: Characterization and Measurement of Discontinuities in Rock Slopes

    National Research Council Canada - National Science Library

    1983-01-01

    This ETL provides guidance for characterizing and measuring rock discontinuities on natural slopes or slopes constructed in rock above reservoirs, darn abutments, or other types of constructed slopes...

  10. Drifter observations of the Hebrides slope current and nearby circulation patterns

    Directory of Open Access Journals (Sweden)

    M. Burrows

    1999-02-01

    Full Text Available The mean flow at and around the Hebrides and Shetland Shelf slope is measured with ARGOS tracked drifters. Forty-two drifters drogued at 50 m were deployed in three circles over the Hebrides slope at 56.15°N in two releases, one on 5th December, 1995 and the second on 5-9th May, 1996. The circles span a distance of some 20 km from water depths of 200 m to 1200 m. Drifters are initially advected poleward along-slope by the Hebrides slope current at between 0.05 and 0.70 m s-1 in a laterally constrained (25-50 km wide jet-like flow. Drifters released in winter remained in the slope current for over 2000 km whilst summer drifters were lost from the slope current beyond the Wyville-Thomson Ridge, a major topographic feature at 60°N. Dispersion from the slope region into deeper waters occurs at bathymetric irregularities, particularly at the Anton Dohrn Seamount close to which the slope current is found to bifurcate, both in summer and winter, and at the Wyville-Thomson Ridge where drifters move into the Faeroe Shetland Channel. Dispersion onto the continental shelf occurs sporadically along the Hebrides slope. The initial dispersion around the Hebrides slope is remarkably sensitive to initial position, most of the drifters released in shallower water moving onto the shelf, whilst those in 1000 m or more are mostly carried away from the slope into deeper water near the Anton Dohrn Seamount. The dispersion coefficients estimated in directions parallel and normal to the local direction of the 500 m contour, approximately the position of the slope current core, are approximately 8.8 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during winter, and 11.4 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during summer. At the slope there is a minimum in across-slope mean velocity, Reynolds stress, and across-slope eddy correlations. The mean across-slope velocity associated with mass flux is about 4 × 10-3 m s-1 shelfward across the shelf break

  11. Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow

    Directory of Open Access Journals (Sweden)

    L. Merino-Martín

    2012-05-01

    Full Text Available Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment source patches and sinks are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted field research to study the hydrological role of patches and slopes along an "overland flow gradient" (gradient of overland flow routing through the slopes caused by different amounts of run-on coming from upslope in three reclaimed mining slopes of Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated with seven vegetation patches (characterized by plant community types and cover. Two types of sink patches were identified: shrub Genista scorpius patches could be considered as "deep sinks", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata. Finally, we identified the volume of overland flow routing along the slope as a major controlling factor of "hydrological diversity" (heterogeneity of hydrological behaviours quantified as Shannon diversity index: when overland flow increases at the slope scale hydrological diversity diminishes.

  12. A study of three-dimensional gravity currents on a uniform slope

    Science.gov (United States)

    Ross, Andrew N.; Linden, P. F.; Dalziel, Stuart B.

    2002-02-01

    In many geophysical, environmental and industrial situations, a finite volume of fluid with a density different to the ambient is released on a sloping boundary. This leads to the formation of a gravity current travelling up, down and across the slope. We present novel laboratory experiments in which the dense fluid spreads both down-slope (and initially up-slope) and laterally across the slope. The position, shape and dilution of the current are determined through video and conductivity measurements for moderate slopes (5° to 20°). The entrainment coefficient for different slopes is calculated from the experimental results and is found to depend very little on the slope. The value agrees well with previously published values for entrainment into gravity currents on a horizontal surface. The experimental measurements are compared with previous shallow-water models and with a new wedge integral model developed and presented here. It is concluded that these simplified models do not capture all the significant features of the flow. In the models, the current takes the form of a wedge which travels down the slope, but the experiments show the formation of a more complicated current. It is found that the wedge integral model over-predicts the length and width of the gravity current but gives fair agreement with the measured densities in the head. The initial stages of the flow, during which time the wedge shape develops, are studied. It is found that although the influence of the slope is seen relatively quickly for moderate slopes, the time taken for the wedge to develop is much longer. The implications of these findings for safety analysis are briefly discussed.

  13. The analyzing stratum formation and sediment environment using TEM for finding sandstone type uranium deposits in Mahuangquan area

    International Nuclear Information System (INIS)

    Zhao Xigang; He Jianguo; Zhao Cuiping; Lou Hansheng

    2010-01-01

    Transient electromagnetic method (TEM) is used to detect deep geological information for insidious sandstone type uranium deposits in Mahuangquan area. TEM surveying data is processed to build the relation between resistance rate and different petrology, to ensure three large electronic strata, and to explain the space position of sediment center and alluvial fan. Combining with ore control factors of sandstone type uranium deposit, it can conclude that the slope area and the alluvial fan are the key areas for further exploration work. (authors)

  14. Potential Risk Assessment of Mountain Torrent Disasters on Sloping Fields in China

    Science.gov (United States)

    GAO, X.

    2017-12-01

    China's sloping fields have the problems of low production and serious soil erosion, and mountain torrent disasters will bring more serious soil and water loss to traditional extensive exploitation of sloping field resources. In this paper, China's sloping fields were classified into three grades, such as slightly steep, steep and very steep grade. According to the geological hazards prevention and control regulation, the historical data of China's mountain torrent disasters were spatially interpolated and divided into five classes, such as extremely low, low, middle, high and extremely high level. And the risk level map of mountain torrents was finished in ArcGIS. By using overlaying analysis on sloping fields and risk level map, the potential risk regionalization map of sloping fields in various slope grades was obtained finally. The results shows that the very steep and steep sloping fields are mainly distributed in the first or second stage terraces in China. With the increase of hazard risk level, the area of sloping fields decreases rapidly and the sloping fields in extremely low and low risk levels of mountain torrents reach 98.9%. With the increase of slope grade, the area of sloping fields in various risk levels also declines sharply. The sloping fields take up approximately 60 65% and 26 30% in slightly steep and steep grade areas separately at different risk level. The risk regionalization map can provide effective information for returning farmland to forests or grassland and reducing water and soil erosion of sloping fields in the future.

  15. Adriatic storm surges and related cross-basin sea-level slope

    Science.gov (United States)

    Međugorac, Iva; Orlić, Mirko; Janeković, Ivica; Pasarić, Zoran; Pasarić, Miroslava

    2018-05-01

    Storm surges pose a severe threat to the northernmost cities of the Adriatic coast, with Venice being most prone to flooding. It has been noted that some flooding episodes cause significantly different effects along the eastern and western Adriatic coasts, with indications that the difference is related to cross-basin sea-level slope. The present study aims to determine specific atmospheric conditions under which the slope develops and to explore connection with increased sea level along the two coastlines. The analysis is based on sea-level time series recorded at Venice and Bakar over the 1984-2014 interval, from which 38 most intensive storm-surge episodes were selected, and their meteorological backgrounds (ERA-Interim) were studied. The obtained sea-level extremes were grouped into three categories according to their cross-basin sea-level slope: storm surges that slope strongly westward (W type), those that slope eastward (E type) and ordinary storm surges (O type). Results show that the slope is controlled by wind action only, specifically, by the wind component towards a particular coast and by the cross-basin shear of along-basin wind. Meteorological fields were used to force an oceanographic numerical model in order to confirm the empirically established connection between the atmospheric forcing and the slope. Finally, it has been found that the intensity of storm surges along a particular Adriatic coast is determined by an interplay of sea-level slopes in the along and cross-basin directions.

  16. QRS slopes for assessment of myocardial damage in chronic chagasic patients

    International Nuclear Information System (INIS)

    Pueyo, E; Laciar, E; Anzuola, E; Laguna, P; Jane, R

    2007-01-01

    In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease

  17. Slope Stability of Geosynthetic Clay Liner Test Plots

    Science.gov (United States)

    Fourteen full-scale field test plots containing five types of geosynthetic clay liners (GCLs) were constructed on 2H:IV and 3H:IV slopes for the purpose of assessing slope stability. The test plots were designed to simulate typical final cover systems for landfill. Slides occurr...

  18. Assessment of rock mass decay in artificial slopes

    NARCIS (Netherlands)

    Huisman, M.

    2006-01-01

    This research investigates the decay of rock masses underlying slopes, and seeks to quantify the relations of such decay with time and geotechnical parameters of the slope and rock mass. Decay can greatly affect the geotechnical properties of rocks within engineering timescales, and may induce a

  19. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter...

  20. Submarine slope failures due to pipe structure formation.

    Science.gov (United States)

    Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H

    2018-02-19

    There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

  1. Geologic Map and Engineering Properties of the Surficial Deposits of the Tok Area, East-Central Alaska

    Science.gov (United States)

    Carrara, Paul E.

    2007-01-01

    The Tok area 1:100,000-scale map, through which the Alaska Highway runs, is in east-central Alaska about 160 km west of the Yukon border. The surficial geologic mapping in the map area is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tok map area contains parts of three physiographic provinces, the Alaska Range, the Yukon-Tanana Upland, and the Northway-Tanana Lowland. The high, rugged, glaciated landscape of the eastern Alaska Range dominates the southwestern map area. The highest peak, an unnamed summit at the head of Cathedral Rapids Creek No. 2, rises to 2166 m. The gently rolling hills of the Yukon-Tanana Upland, in the northern map area, rise to about 1000 m. The Northway-Tanana Lowland contains the valley of the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 470 and 520 m. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large (450 km2), nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. Because the map area is dominated by various surficial deposits, the map depicts 26 different surficial units consisting of man-made, alluvial, colluvial, eolian, lacustrine, organic, glaciofluvial, glacial, and periglacial deposits. The accompanying table provides information concerning the various units including their properties, characteristics, resource potential, and associated hazards in this area of the upper Tanana valley.

  2. Food-web dynamics and isotopic niches in deep-sea communities residing in a submarine canyon and on the adjacent open slopes

    Science.gov (United States)

    Demopoulos, Amanda W.J.; McClain-Counts, Jennifer; Ross, Steve W.; Brooke, Sandra; Mienis, Furu

    2017-01-01

    Examination of food webs and trophic niches provide insights into organisms' functional ecology, yet few studies have examined trophodynamics within submarine canyons, where the interaction of canyon morphology and oceanography influences habitat provision and food deposition. Using stable isotope analysis and Bayesian ellipses, we documented deep-sea food-web structure and trophic niches in Baltimore Canyon and the adjacent open slopes in the US Mid-Atlantic Region. Results revealed isotopically diverse feeding groups, comprising approximately 5 trophic levels. Regression analysis indicated that consumer isotope data are structured by habitat (canyon vs. slope), feeding group, and depth. Benthic feeders were enriched in 13C and 15N relative to suspension feeders, consistent with consuming older, more refractory organic matter. In contrast, canyon suspension feeders had the largest and more distinct isotopic niche, indicating they consume an isotopically discrete food source, possibly fresher organic material. The wider isotopic niche observed for canyon consumers indicated the presence of feeding specialists and generalists. High dispersion in δ13C values for canyon consumers suggests that the isotopic composition of particulate organic matter changes, which is linked to depositional dynamics, resulting in discrete zones of organic matter accumulation or resuspension. Heterogeneity in habitat and food availability likely enhances trophic diversity in canyons. Given their abundance in the world's oceans, our results from Baltimore Canyon suggest that submarine canyons may represent important havens for trophic diversity.

  3. Slope stability probability classification, Waikato Coal Measures, New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, P.; Gillard, G.R.; Moore, T.A. [CRL Energy, PO Box 29-415, Christchurch (New Zealand); Campbell, R.N.; Fergusson, D.A. [Solid Energy North, Private Bag 502, Huntly (New Zealand)

    2001-01-01

    Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically by mechanical tests and discontinuity measurements. Using these measurements slope stability probability classifications (SSPC) have been quantified based on an adaptation of Hack's [Slope Stability Probability Classification, ITC Delft Publication, Enschede, Netherlands, vol. 43, 1998, 273 pp.] SSPC system, which places less influence on rock quality designation and unconfined compressive strength than previous slope/rock mass rating systems. The Hack weathering susceptibility rating has been modified by using chemical index of alteration values determined from XRF major element analyses. Slaking is an important parameter in slope stability in the Waikato Coal Measures lithologies and hence, a non-subjective method of assessing slaking in relation to the chemical index of alteration has been introduced. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The main modifications of Hack's SSPC system are the introduction of rock intact strength derived from the modified Mohr-Coulomb failure criterion, which has been adapted for varying moisture content, weathering state and confining pressure. It is suggested that the subjectivity in assessing intact rock strength within broad bands in the initial SSPC system is a major weakness of the initial system. Initial results indicate a close relationship between rock mass strength values, calculated from rock mass friction angles and rock mass cohesion values derived from two established rock mass classification methods (modified Hoek-Brown failure criteria and MRMR) and the adapted SSPC system. The advantage of the modified SSPC system is that slope stability probabilities based on discontinuity-independent and discontinuity-dependent data and a

  4. Drifter observations of the Hebrides slope current and nearby circulation patterns

    Directory of Open Access Journals (Sweden)

    M. Burrows

    Full Text Available The mean flow at and around the Hebrides and Shetland Shelf slope is measured with ARGOS tracked drifters. Forty-two drifters drogued at 50 m were deployed in three circles over the Hebrides slope at 56.15°N in two releases, one on 5th December, 1995 and the second on 5-9th May, 1996. The circles span a distance of some 20 km from water depths of 200 m to 1200 m. Drifters are initially advected poleward along-slope by the Hebrides slope current at between 0.05 and 0.70 m s-1 in a laterally constrained (25-50 km wide jet-like flow. Drifters released in winter remained in the slope current for over 2000 km whilst summer drifters were lost from the slope current beyond the Wyville-Thomson Ridge, a major topographic feature at 60°N. Dispersion from the slope region into deeper waters occurs at bathymetric irregularities, particularly at the Anton Dohrn Seamount close to which the slope current is found to bifurcate, both in summer and winter, and at the Wyville-Thomson Ridge where drifters move into the Faeroe Shetland Channel. Dispersion onto the continental shelf occurs sporadically along the Hebrides slope. The initial dispersion around the Hebrides slope is remarkably sensitive to initial position, most of the drifters released in shallower water moving onto the shelf, whilst those in 1000 m or more are mostly carried away from the slope into deeper water near the Anton Dohrn Seamount. The dispersion coefficients estimated in directions parallel and normal to the local direction of the 500 m contour, approximately the position of the slope current core, are approximately 8.8 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during winter, and 11.4 × 103 m2 s-1 and 0.36 × 103 m2 s-1, respectively, during summer. At the slope there is a minimum in across-slope mean velocity, Reynolds stress, and

  5. Wind-driven export of Weddell Sea slope water

    Science.gov (United States)

    Meijers, A. J. S.; Meredith, M. P.; Abrahamsen, E. P.; Morales Maqueda, M. A.; Jones, D. C.; Naveira Garabato, A. C.

    2016-10-01

    The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the three-dimensional oceanic circulation. Here we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and 5 years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh, westward flowing current. This is often bottom-intensified between 600 and 2000 dbar with velocities of over 20 cm s-1, transporting an average of 1.5 ± 1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modeled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual time scales the density of the slope current is negatively correlated (r > 0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 6-13 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind stress/export relationship and find that it is most consistent with wind-driven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediate-level waters to lower latitudes.

  6. Dynamic and Static Combination Analysis Method of Slope Stability Analysis during Earthquake

    OpenAIRE

    Liang Lu; Zongjian Wang; Xiaoyuan Huang; Bin Zheng; Katsuhiko Arai

    2014-01-01

    The results of laboratory model tests for simulating the slope failure due to vibration, including unreinforced slope and the slope reinforced by using geotextile, show that the slope failure occurs when a cumulative plastic displacement exceeds a certain critical value. To overcome the defects of conventional stability analysis, which evaluates the slope characteristics only by its strength parameters, a numerical procedure considering the stiffness and deformation of materials and geosynthe...

  7. Filling of a Salt-withdrawal Minibasin on the Continental Slope by Turbidity Currents: Experimental study

    Science.gov (United States)

    Violet, J.; Evans, C.; Sheets, B.; Paola, C.; Pratson, L.; Parker, G.

    2001-12-01

    We report on the transport and deposition of sediment by turbidity currents in an experimental basin designed to model salt-withdrawal minibasins found along the northern continental slope of the Gulf of Mexico. The experiment was performed in two stages in the subsiding EXperimental EarthScape facility (XES) at St. Anthony Falls Laboratory, University of Minnesota. Stage I consisted of 15 turbidity-current events in the following sequence: one 36-minute continuous event, six 1.85-minute small pulses, one 3.8-minute large pulse, six more small pulses, one more large pulse, and finally one more continuous event. The continuous events and the small pulses had a flow discharge of 1.5 liters/s and the large pulse had a flow discharge of 4.5 liters/s. The flows all had a volume concentration of sediment of 0.05. The sediment comprised three grades of silica with nominal diameters of 20 microns (45%), 45 microns (40%) and 110 microns (15%). The basin subsided continuously during Stage I. Stage II consisted of the same sequence of events as Stage I, but with no further subsidence. The sand content was eliminated during the latter part of Stage II. The deposit was imaged as it developed during the experiment using high-frequency sonar. The sonar records show indications of incipient self-channelization as well as clear erosion, bypass, and deposition. Erosion was promoted by large pulse events and the absence of sand. The deposit shows well developed lamination and normal grading.

  8. A preliminary pit slope stability study Kvanefjeld, South Greenland

    International Nuclear Information System (INIS)

    Kalvig, P.

    1983-11-01

    On the basis of 1300 field measurements of joint planes, four individual structural regions have been outlined in the Kvanefjeld area. Potential failure planes and planes which are unlikely to be involved in slope failures are identified. Failures seem, not likely to occur on walls dipping SW or NE respectively, but may occur on walls dipping NM. The factors of safety for each region are calculated in order to determine the sensibility of the overall slope to different overall slope angles. The factors of safety does only exceed the required factor of safety of 1.5 in one of the structural regions. Changing the overall pit slope inclination from 55deg to 45deg improves the security, but even still not satisfactorily for two of the regions. At 45deg overall pit slope in parts of the pit implies additional 14.3 x 10 6 tonnes of non-mineralized material to be mined, thus resulting in a total mineralized- to non-mineralized material ratio about 1.0: 1.7. (author)

  9. Influences of Holocene sea level, regional tectonics, and fluvial, gravity and slope currents induced sedimentation on the regional geomorphology of the continental slope off northwestern India

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Almeida, F.

    the Holocene sea level. The Bombay high area has slope breaks between 400 and 600 m, whereas off Saurashtra steep breaks in the slope occur between 560 and 960 m depth. Further southwards, at the slope, elevations and depressions are present. Variations...

  10. Shallow structure and stratigraphy of the carbonate West Florida continental slope and their implications to sedimentation and geohazards

    Science.gov (United States)

    Doyle, Larry J.

    1983-01-01

    An 1800-joule sparker survey of the West Florida continental slope between about 26?N and 29?15?N showed a top bed of Pleistocene age forming an irregular drape over a surface that is probably Pliocene. The contact between the top two layers is unconformable in the south and, in some places, shows karst collapse and solution features. Karst topography grades into a more hummocky erosional surface to the north, which in turn smoothes out; the contact become conformable still further north. A period of folding, which is widespread over the outer portion of the study area and which may be related to large scale mass wasting, occurred at about the same time represented by the unconformity. Significant subsidence has occurred as late as Pleistocene. The surface layer thins to a minimum (0 in the south) at about 525-meters water depth and then thickens again dramatically to the west, downslope. This thinning is interpreted to be due to the Loop Current, which flows from north to south in the area and which acts to block deposition and scour the bottom. Despite the fact that the margin is dominated by carbonates, usually associated with low sedimentation rates, there is widespread evidence of mass wasting affecting ancient and surficial deposits on the outer part of the upper slope. Three potential groups of geohazards identified are: 1. Potential bottom failure in areas where a thin top layer overlies the karst surface. 2. Potential for sliding and slumping. 3. Scour due to currents which could also affect drilling and engineering activities.

  11. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

    2011-02-01

    The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

  12. Velocity-based analysis of sediment incipient deposition in rigid boundary open channels.

    Science.gov (United States)

    Aksoy, Hafzullah; Safari, Mir Jafar Sadegh; Unal, Necati Erdem; Mohammadi, Mirali

    2017-11-01

    Drainage systems must be designed in a way to minimize undesired problems such as decrease in hydraulic capacity of the channel, blockage and transport of pollutants due to deposition of sediment. Channel design considering self-cleansing criteria are used to solve the sedimentation problem. Incipient deposition is one of the non-deposition self-cleansing design criteria that can be used as a conservative method for channel design. Experimental studies have been carried out in five different cross-section channels, namely trapezoidal, rectangular, circular, U-shape and V-bottom. Experiments were performed in a tilting flume using four different sizes of sands as sediment in nine different channel bed slopes. Two well-known methods, namely the Novak & Nalluri and Yang methods are considered for the analysis of sediment motion. Equations developed using experimental data are found to be in agreement with the literature. It is concluded that the design velocity depends on the shape of the channel cross-section. Rectangular and V-bottom channels need lower and higher incipient deposition velocities, respectively, in comparison with other channels.

  13. VT Lidar Slope (1.6 meter) - 2012 - Addison County

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Addison County 2012 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  14. VT Lidar Slope (1.6 meter) - 2010 - Missisquoi Upper

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Missisquoi Upper 2010 1.6m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  15. A note on coarse-grained gravity-flow deposits within proterozoic lacustrine sedimentary rocks, Transvaal sequence, South Africa

    Science.gov (United States)

    Eriksson, P. G.

    A widely developed, thin, coarse-matrix conglomerate occurs within early Proterozoic lacustrine mudrocks in the Transvaal Sequence, South Africa. The poorly sorted tabular chert clasts, alternation of a planar clast fabric with disorientated zones, plus normal and inverse grading in the former rock type suggest deposition by density-modified grain-flow and high density turbidity currents. The lower fan-delta slope palæenvironment inferred for the conglomerate is consistent with the lacustrine interpretation for the enclosing mudrock facies. This intracratonic setting contrasts with the marine environment generally associated with density-modified grain-flow deposits.

  16. The Bairendaba silver polymetallic deposit in Inner Mongolia, China: characteristics of ore-forming fluid and genetic type of ore deposit

    Science.gov (United States)

    Wang, Ying; Xie, Yuling; Wu, Haoran

    2018-02-01

    Bairendaba silver-polymetallic deposit is located in the middle south of the Xing Meng orogenic belt, and in the silver-polymetallic metallogenic belt on the west slope of the southern of Great Xing’an Range. Based on studying of the fluid inclusion, we discuss the characteristics of ore-forming fluid and the metallic genesis of the Bairendaba silver-polymetallic deposit. By means of the analysis of the fluid inclusions, homogenization temperature, salinity and composition were studied in quartz and fluorite. The result is as the follows: with homogenization temperatures of fluid inclusions in quartz veins being 196∼312 °C, the average 244.52 °C, and fluid salinity 2.90∼9.08 wt%NaCl; with homogenization temperatures of fluid inclusions in fluorite being 127∼306 °C, the average 196.92 °C, and fluid salinity 2.90∼9.34 wt% NaCl. The ore-forming fluid is mainly composed of water and the gas. The results of laser Raman analysis show that the gas phase is mainly CH4. It shows that the ore-forming fluid is characterized by medium-low temperature and low-salinity system. The temperature of ore-forming fluid is from high to low, and the salinity from high to low, and the meteoric water or metamorphic water is added during deposit. According to the geological characteristics of the mining area, it is considered that the genetic type of the ore deposit should be the fault-controlled and the medium-low temperature hydrothermal deposit related to magmatic hydrothermal activities.

  17. Simulating the seismic behaviour of soil slopes and embankments

    DEFF Research Database (Denmark)

    Zania, Varvara; Tsompanakis, Yiannis; Psarropoulos, Prodromos

    2010-01-01

    In the current study the clarification of the main assumptions, related to the two most commonly used methods of seismic slope stability analysis (pseudostatic and permanent deformation) is attempted. The seismic permanent displacements and the corresponding seismic coefficients were determined via...... parametric dynamic numerical analyses taking into account not only the main parameters dominating the seismic slope stability, but also the inherent assumptions of the applied approaches that affect the obtained results. The investigation conclude to a realistic procedure for seismic slope stability...

  18. Estimating the erosion and deposition rates in a small watershed by the 137Cs tracing method

    International Nuclear Information System (INIS)

    Li Mian; Li Zhanbin; Yao Wenyi; Liu Puling

    2009-01-01

    Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the 137 Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The 137 Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed

  19. Robustness for slope stability modelling under deep uncertainty

    Science.gov (United States)

    Almeida, Susana; Holcombe, Liz; Pianosi, Francesca; Wagener, Thorsten

    2015-04-01

    Landslides can have large negative societal and economic impacts, such as loss of life and damage to infrastructure. However, the ability of slope stability assessment to guide management is limited by high levels of uncertainty in model predictions. Many of these uncertainties cannot be easily quantified, such as those linked to climate change and other future socio-economic conditions, restricting the usefulness of traditional decision analysis tools. Deep uncertainty can be managed more effectively by developing robust, but not necessarily optimal, policies that are expected to perform adequately under a wide range of future conditions. Robust strategies are particularly valuable when the consequences of taking a wrong decision are high as is often the case of when managing natural hazard risks such as landslides. In our work a physically based numerical model of hydrologically induced slope instability (the Combined Hydrology and Stability Model - CHASM) is applied together with robust decision making to evaluate the most important uncertainties (storm events, groundwater conditions, surface cover, slope geometry, material strata and geotechnical properties) affecting slope stability. Specifically, impacts of climate change on long-term slope stability are incorporated, accounting for the deep uncertainty in future climate projections. Our findings highlight the potential of robust decision making to aid decision support for landslide hazard reduction and risk management under conditions of deep uncertainty.

  20. On Front Slope Stability of Berm Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    2013-01-01

    The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison...... with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model...... test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height...

  1. The Relationship Between Lithology and Slope Morphology in the Tucson Mountains, Arizona.

    Directory of Open Access Journals (Sweden)

    Kamel Khanchoul

    2008-05-01

    Full Text Available The relationship between lithology and slope morphology is investigated at eight sites on granitic, andesitic, andsedimentary hillslopes in the Tucson Mountains, Arizona. Several methods are used in the study. Topographic profi lesare constructed. Skewness indices, slope length, and mean slope angles of the different slope profi les are computed andcompared with each other. Debris size analysis has permitted for some profi les, the determination of hillfront/piedmontjunctions. The nature and structural characteristics of the bedrock are the ones that determine the hillslope morphologyin this semi-arid region. There are, as a matter of fact, variations in profi les on the same bedrock nature but differentlyexposed. More precise morphologic studies have been also done in comparing the different lithologic pairs. They havepermitted to show some similarities in shapes. The granitic-andesitic slopes and andesiic-sedimentary slopes are thebest comparisons which show the relationship between lithology and slope morphology. The granitic-sedimentary sloperelationship is shown in the hillfront concavities, mountain front and piedmont mean slope angles.

  2. Application of distinct element method of toppling failure of slope

    International Nuclear Information System (INIS)

    Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Ito, Hiroshi

    1984-01-01

    The authors have pointed out, in the latest report, that DEM (Distinct Element Method) seems to be a very helpful numerical method to examine the stability of fissured rock slopes, in which toppling failure would occur during earthquakes. In this report, the applicability of DEM for such rock slopes is examined through the following comparisons between theoretical results and DEM results, referring Voegele's works (1982): (1) Stability of one block on a slope. (2) Failure of a rock block column composed of 10 same size rectangular blocks. (3) Cable force required to make a slope stable. Through above 3 comparisons, it seems that DEM give the reasonable results. Considering that these problems may not be treated by the other numerical methods such as FEM and so on, so DEM seems to be a very useful method for fissured rock slope analysis. (author)

  3. A national strategy for a long-term monitoring of permafrost and periglacial processes and their relationship to natural hazard prevention in Austria

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas; Bartsch, Annett; Gitschthaler, Christoph; Reisenhofer, Stefan; Weyss, Gernot; Riedl, Claudia; Avian, Michael

    2016-04-01

    About 2.5% (~2000 km²) of the national territory of Austria is influenced by permafrost conditions. A slightly smaller area of Austria is additionally affected by deep seasonal frost which is, however, similarly exposed to intensive physical weathering and related geomorphic processes. Currently, 23 skiing resorts, 31 water reservoirs and 42 mountain huts are either directly or indirectly influenced by permafrost and associated processes in Austria as determined from regional permafrost models. Ground thermal changes most likely affect the ground stability and infrastructure in those areas. Therefore, changes in the distribution and characteristics of permafrost and seasonal frost are of high economic and ecological importance. A range of Austrian institutions are interested in systematic permafrost monitoring (several universities, geological surveys, the Austrian torrent and avalanche control agency or several different alpine clubs). However, to date no coordinated monitoring network has been established on a national scale and a strategy for long-term permafrost/periglacial observation did not exist so far. Such a national strategy has been developed in 2015 within the permAT project funded through the StartClim2014-program. During permAT an extensive literature review and data search as well as a workshop with 40 participants (scientists, stakeholder and policy maker) were accomplished. The workshop allowed the integration of national as well as international colleagues into the strategy development. Results of permAT clearly demonstrate that the number of present permafrost/periglacial monitoring sites is far too little in Austria. Only few alpine areas of Austria are well represented by the existing monitoring activities but large areas lack such instrumentations. Furthermore, permafrost boreholes exist at only three sites in central Austria (all contribution to the GTN-P network) and there is a lack of knowledge about thermal conditions and recent changes

  4. Estimating significances of differences between slopes: A new methodology and software

    Directory of Open Access Journals (Sweden)

    Vasco M. N. C. S. Vieira

    2013-09-01

    Full Text Available Determining the significance of slope differences is a common requirement in studies of self-thinning, ontogeny and sexual dimorphism, among others. This has long been carried out testing for the overlap of the bootstrapped 95% confidence intervals of the slopes. However, the numerical random re-sampling with repetition favours the occurrence of re-combinations yielding largely diverging slopes, widening the confidence intervals and thus increasing the chances of overlooking significant differences. To overcome this problem a permutation test simulating the null hypothesis of no differences between slopes is proposed. This new methodology, when applied both to artificial and factual data, showed an enhanced ability to differentiate slopes.

  5. Mega-tsunami deposits or evidence of uplift within the Hawaiian Islands

    Science.gov (United States)

    Keating, B. H.

    2004-12-01

    For several years there has been a controversy over the origin of coral-bearing deposits on the island of Lanai (Hawaii). Studies underway have expanded the study of marine deposits from Lanai to adjacent islands. Coral-bearing deposits are present at elevations up to 190 m on Lanai, 90 m on Maui, 90 m on Molokai, 30 m Oahu, 30 m on Niihau, roughly 75 m on Kauai (as well as a few m above sea level on the Kohala Volcano on the island of Hawaii). The deposits show a persistent pattern of increased weathering, color change, increasing age and increase in the number of fossils now extinct in Hawaiian waters, with elevation above modern sea level. Changes in slope are also observed reflecting changing relative sea level. A review of radiometric ages suggests in-situ corals as well as marine conglomerates were deposited near sea level and were contemporaneous. The distribution, stratigraphy and age of marine sediments around the islands are consistent with a history of uplift combined with changing sea level. We document the age, rock and fossil characteristics and distribution of sub-aerially exposed marine sediments, in the Hawaiian Island chain. We suggest that the Hawaiian Islands have experienced lithospheric adjustments during the last 500,000 years that have left marine deposits exposed above sea level.

  6. New data on OSL dating of Early Khalynian deposits of Northern Caspian

    Science.gov (United States)

    Sychev, Nikita; Yanina, Tamara; Svitoch, Alexander; Kurbanov, Redzhep; Badyukova, Ekaterina

    2016-04-01

    Ponto-Caspian region is the key region the study of which can provide information about the paleogeographic history of the central Eurasia, particularly revealing the history of the East European Plain, the Caucasus and Central Asia. However, despite the long history of the study, today there is no accepted general stratigraphic scheme of the Caspian Sea. One of the most interesting and important stages of Late Pleistocene history of Caspian is Khalynian transgression which is divided into two major phases: early and ate. In the Caspian lowland Lower Khalynian stage are represented by a unique type of deposit - "chocolate clays". A distinctive feature of these sediments is widely distributed among Lower Khalynian deposits of Northern Caspian and the Volga region. All clay deposits are confined to the diverse origins of depression before-Khalynian relief. Chocolate clays formation consists of facies: mono-clay (typological), layered, sand- and silty-clay (Svitoch, Yanina, 1997). Determining the age of chocolate clays by optically stimulated luminescence (OSL) in our view will allow bettering the understanding of their genesis. Age of chocolate clays of Lower Volga was widely dated using the radiocarbon. However, the existing chronology is controversial, raises a number of issues, primarily due to the material of which are used for dating - thin shells of Caspian mollusks of the Didacna Eichw. genus, which are characterized by a significant isotopic exchange with the enclosing sediments (Arslanov, 2015). Lower Volga region is characterized by very complex geological structure of the Late Pleistocene deposits (alternating continental aeolian, alluvial and slope sediments with marine Caspian deposits of different age). There are many conflicting opinions, not only with respect to paleogeographic features of the area, but also to its precise chronology. The differences in opinion over the age of the individual stages of development of the Caspian Sea (transgressions and

  7. Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains, USA

    Science.gov (United States)

    Nanus, Leora; Clow, David W.; Saros, Jasmine E.; Stephens, Verlin C.; Campbell, Donald H.

    2012-01-01

    Spatially explicit estimates of critical loads of nitrogen (N) deposition (CLNdep) for nutrient enrichment in aquatic ecosystems were developed for the Rocky Mountains, USA, using a geostatistical approach. The lowest CLNdep estimates (-1 yr-1) occurred in high-elevation basins with steep slopes, sparse vegetation, and abundance of exposed bedrock and talus. These areas often correspond with areas of high N deposition (>3 kg N ha-1 yr-1), resulting in CLNdep exceedances ≥1.5 ± 1 kg N ha-1 yr-1. CLNdep and CLNdep exceedances exhibit substantial spatial variability related to basin characteristics and are highly sensitive to the NO3- threshold at which ecological effects are thought to occur. Based on an NO3- threshold of 0.5 μmol L-1, N deposition exceeds CLNdep in 21 ± 8% of the study area; thus, broad areas of the Rocky Mountains may be impacted by excess N deposition, with greatest impacts at high elevations.

  8. The contribution of particle swarm optimization to three-dimensional slope stability analysis.

    Science.gov (United States)

    Kalatehjari, Roohollah; Rashid, Ahmad Safuan A; Ali, Nazri; Hajihassani, Mohsen

    2014-01-01

    Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes.

  9. Pile-Reinforcement Behavior of Cohesive Soil Slopes: Numerical Modeling and Centrifuge Testing

    Directory of Open Access Journals (Sweden)

    Liping Wang

    2013-01-01

    Full Text Available Centrifuge model tests were conducted on pile-reinforced and unreinforced cohesive soil slopes to investigate the fundamental behavior and reinforcement mechanism. A finite element analysis model was established and confirmed to be effective in capturing the primary behavior of pile-reinforced slopes by comparing its predictions with experimental results. Thus, a comprehensive understanding of the stress-deformation response was obtained by combining the numerical and physical simulations. The response of pile-reinforced slope was indicated to be significantly affected by pile spacing, pile location, restriction style of pile end, and inclination of slope. The piles have a significant effect on the behavior of reinforced slope, and the influencing area was described using a continuous surface, denoted as W-surface. The reinforcement mechanism was described using two basic concepts, compression effect and shear effect, respectively, referring to the piles increasing the compression strain and decreasing the shear strain of the slope in comparison with the unreinforced slope. The pile-soil interaction induces significant compression effect in the inner zone near the piles; this effect is transferred to the upper part of the slope, with the shear effect becoming prominent to prevent possible sliding of unreinforced slope.

  10. The Contribution of Particle Swarm Optimization to Three-Dimensional Slope Stability Analysis

    Science.gov (United States)

    A Rashid, Ahmad Safuan; Ali, Nazri

    2014-01-01

    Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes. PMID:24991652

  11. Slope-velocity equilibrium and evolution of surface roughness on a stony hillslope

    Science.gov (United States)

    Nearing, Mark A.; Polyakov, Viktor O.; Nichols, Mary H.; Hernandez, Mariano; Li, Li; Zhao, Ying; Armendariz, Gerardo

    2017-06-01

    Slope-velocity equilibrium is hypothesized as a state that evolves naturally over time due to the interaction between overland flow and surface morphology, wherein steeper areas develop a relative increase in physical and hydraulic roughness such that flow velocity is a unique function of overland flow rate independent of slope gradient. This study tests this hypothesis under controlled conditions. Artificial rainfall was applied to 2 m by 6 m plots at 5, 12, and 20 % slope gradients. A series of simulations were made with two replications for each treatment with measurements of runoff rate, velocity, rock cover, and surface roughness. Velocities measured at the end of each experiment were a unique function of discharge rates, independent of slope gradient or rainfall intensity. Physical surface roughness was greater at steeper slopes. The data clearly showed that there was no unique hydraulic coefficient for a given slope, surface condition, or rainfall rate, with hydraulic roughness greater at steeper slopes and lower intensities. This study supports the hypothesis of slope-velocity equilibrium, implying that use of hydraulic equations, such as Chezy and Manning, in hillslope-scale runoff models is problematic because the coefficients vary with both slope and rainfall intensity.

  12. The Contribution of Particle Swarm Optimization to Three-Dimensional Slope Stability Analysis

    Directory of Open Access Journals (Sweden)

    Roohollah Kalatehjari

    2014-01-01

    Full Text Available Over the last few years, particle swarm optimization (PSO has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D slope stability analysis. This paper applied PSO in three-dimensional (3D slope stability problem to determine the critical slip surface (CSS of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes.

  13. Analysis of the Fetch Dependency of the Slope of Wind-Water Waves

    OpenAIRE

    Proß, Christin

    2016-01-01

    In this thesis mean square slope has been calculated from slope images which were recorded by the Imaging Slope Gauge (ISG) at the annular wind-wave tank Aeolotron in Heidelberg. The calculations have been realized using three different methods, which are, (i) calculation of the variance, (ii) integration of the slope power spectrum and (iii) fitting the probability distribution function of slope with a model function. The resulting values have been compared to each other and t...

  14. Study on Character of Micro-Canal Deposit and Its Significance in Petroleum Geology --Case study of Tuo-147-well in north zone of Dongying depression

    Institute of Scientific and Technical Information of China (English)

    吴李泉; 曹代勇; 刘里勤; 刘艳华

    2003-01-01

    Exploration on reservoir of glutenite segment in steep slope zone of half graben-like basin is one of the hot spot targets at present and in the future for new reservoirs; And the study of sediment character of sandy-conglomerate bodies is the keystone and also the difficult problem. Taking Tuo-147-well area in north zone of Dongying depression as an example, the micro-canal sedimentation was researched. The result shows that many micro-canals exist at the end of slope grain-flow in steep slope zone of half graben-like basin; The micro-canals grow at the end of subaqueous grain-flow deposited bodies of 3rd member of the Shahejie formation. The main condition of micro-canal formation is the slope angle less than 18° and a long suitable sedimentary slope. These micro-canals may communicate the reservoir of glutenite segment in steep slope zone and the hydrocarbon stratum as a bridge role. Therefore, it is significant in theory and practice for discovering a series of micro-canals at the end of slope grain-flow in steep slope zone of half graben-like basin.

  15. Exotic clasts, debris flow deposits and their significance for reconstruction of the Istebna Formation (Late Cretaceous - Paleocene, Silesian Basin, Outer Carpathians)

    Science.gov (United States)

    Strzeboński, Piotr; Kowal-Kasprzyk, Justyna; Olszewska, Barbara

    2017-08-01

    The different types of calcareous exotic clasts (fragments of pre-existing rocks), embedded in the Paleocene siliciclastic deposits of the Istebna Formation from the Beskid Mały Mountains (Silesian Unit, Western Outer Carpathians), were studied and differentiated through microfacies-biostratigraphical analysis. Calcareous exotics of the Oxfordian- Kimmeridgian age prevail, representing a type of sedimentation comparable to that one documented for the northern Tethyan margin. The Tithonian exotic clasts (Štramberk-type limestones), which are much less common, were formed on a carbonate platform and related slope. The sedimentary paleotransport directions indicate the Silesian Ridge as a main source area for all exotics, which were emplaced in the depositional setting of the flysch deposits. The exotics constitute a relatively rare local component of some debrites. Proceedings of the sedimentological facies analysis indicate that these mass transport deposits were accumulated en-masse by debris flows in a deep-water depositional system in the form of a slope apron. Exotics prove that clasts of the crystalline basement and, less common, fragments of the sedimentary cover, originated from long-lasting tectonic activity and intense uplift of the source area. Mass transport processes and mass accumulation of significant amounts of the coarse-grained detrital material in the south facial zone of the Silesian Basin during the Early Paleogene was due to reactivation of the Silesian Ridge and its increased denudation. Relative regression and erosion of the emerged older flysch deposits were also forced by this uplift. These processes were connected with the renewed diastrophic activity in the Alpine Tethys.

  16. Advance in prediction of soil slope instabilities

    Science.gov (United States)

    Sigarán-Loría, C.; Hack, R.; Nieuwenhuis, J. D.

    2012-04-01

    Six generic soils (clays and sands) were systematically modeled with plane-strain finite elements (FE) at varying heights and inclinations. A dataset was generated in order to develop predictive relations of soil slope instabilities, in terms of co-seismic displacements (u), under strong motions with a linear multiple regression. For simplicity, the seismic loads are monochromatic artificial sinusoidal functions at four frequencies: 1, 2, 4, and 6 Hz, and the slope failure criterion used corresponds to near 10% Cartesian shear strains along a continuous region comparable to a slip surface. The generated dataset comprises variables from the slope geometry and site conditions: height, H, inclination, i, shear wave velocity from the upper 30 m, vs30, site period, Ts; as well as the input strong motion: yield acceleration, ay (equal to peak ground acceleration, PGA in this research), frequency, f; and in some cases moment magnitude, M, and Arias intensity, Ia, assumed from empirical correlations. Different datasets or scenarios were created: "Magnitude-independent", "Magnitude-dependent", and "Soil-dependent", and the data was statistically explored and analyzed with varying mathematical forms. Qualitative relations show that the permanent deformations are highly related to the soil class for the clay slopes, but not for the sand slopes. Furthermore, the slope height does not constrain the variability in the co-seismic displacements. The input frequency decreases the variability of the co-seismic displacements for the "Magnitude-dependent" and "Soil-dependent" datasets. The empirical models were developed with two and three predictors. For the sands it was not possible because they could not satisfy the constrains from the statistical method. For the clays, the best models with the smallest errors coincided with the simple general form of multiple regression with three predictors (e.g. near 0.16 and 0.21 standard error, S.E. and 0.75 and 0.55 R2 for the "M

  17. Analysing hydro-mechanical behaviour of reinforced slopes through centrifuge modelling

    Science.gov (United States)

    Veenhof, Rick; Wu, Wei

    2017-04-01

    Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydro-mechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of medium-fine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

  18. Impact of Rain Water Infiltration on the Stability of Earth Slopes

    Directory of Open Access Journals (Sweden)

    Muhammad Farooq Ahmed

    2016-12-01

    Full Text Available Slope failure occurs very often in natural and man-made slopes which are subjected to frequent changes in ground water level, rapid drawdown, rainfall and earthquakes. The current study discusses the significance of water infiltration, pore water pressure and degree of saturation that affect the stability of earth slopes. Rainwater infiltration not only mechanically reduces the shear strength of a slope material, but also chemically alters the mineral composition of the soil matrix. It results in the alteration of macro structures which in turn decreases the factor of safety. A few case studies are discussed in this paper to quantitatively observe the variation in factor of safety (FOS of various earth slopes by changing the degree of saturation. The results showed that most of the earth slopes get failed or become critical when the degree of saturation approaches to 50 % or more.

  19. Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard

    Science.gov (United States)

    Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.

    2016-12-01

    Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers

  20. Holocene and Late Glacial sedimentation near steep slopes in southern Lake Baikal

    Directory of Open Access Journals (Sweden)

    Michael Sturm

    2015-07-01

    Full Text Available We here present new data on sedimentation at and near the steep north-slopes of southern Lake Baikal. Short sediment cores were taken at 550 m and at 1366 m water depth, within 3600 m offshore Cape Ivanovskii at the station of the Baikal Deep Underwater NEUTRINO Telescope. The sediments within 3600 m off the northern coast of Southern Lake Baikal are dominated by pelagic deposition. Our data reveal surprisingly little influence from terrigenous material from adjacent coastal areas, tributaries and their catchment. At the shallow-water site (at 550 m water depth, 700 m off shore just 27 cm thick homogenous sediments have accumulated during the Holocene on top of Pleistocene deposits resulting in Holocene sedimentation rates of 0.003 cm a-1. The very low rates are caused by long-term persistent winnowing of fine particles caused by week contour currents along the slope. The uppermost sediments are oxidized down to 22 cm. Very low concentrations of Corg, Sibio and Ntot in Pleistocene sediments increase dramatically within the Holocene. The heavy mineral fraction of the shallow-water sediments contains up to 33.6 % olivine and up to 2.4 % spinel. These rare minerals originate from white marbles of the nearby coastal outcrop Belaya Vyemka of the Early Precambrian Sharyzalgaiskaya Series. At the deep-water site (at 1366 m water depth, 3600 m off shore Holocene sedimentation rates are 10-times higher (0.036 cm a-1. Sediment oxidation occurs just within the uppermost 2 cm. Of the two rare type minerals of the Sharyzalgaiskaya Series spinel does not occur at all and olivine is represented by very diminished concentrations. This indicates insignificant influx of terrestrial material from the nearby shore to the deep-water site . Distal turbidites of far-off sources are intercalated to pelagic sediments at the deep-water site. Breakdown events of deltas at the SE- and S-coast of the basin are suggested to be responsible for the formation of the turbidites

  1. How Do Adults Perceive, Analyse and Measure Slope?

    Science.gov (United States)

    Duncan, Bruce; Chick, Helen

    2013-01-01

    Slope is a mathematical concept that is both fundamental to the study of advanced calculus and commonly perceived in everyday life. The measurement of steepness of terrain as a ratio is an example of an everyday application the concept of slope. In this study, a group of pre-service teachers were tested for their capacity to mathematize the…

  2. Stability of submarine slopes in the northern South China Sea: a numerical approach

    Science.gov (United States)

    Zhang, Liang; Luan, Xiwu

    2013-01-01

    Submarine landslides occur frequently on most continental margins. They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations. In this paper, submarine slope stability is evaluated using a 2D limit equilibrium method. Considerations of slope, sediment, and triggering force on the factor of safety (FOS) were calculated in drained and undrained ( Φ=0) cases. Results show that submarine slopes are stable when the slope is 13° with earthquake peak ground acceleration (PGA) of 0.5 g; whereas with a weak layer, a PGA of 0.2 g could trigger instability at slopes >10°, and >3° for PGA of 0.5 g. The northern slope of the South China Sea is geomorphologically stable under static conditions. However, because of the possibility of high PGA at the eastern margin of the South China Sea, submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope. Therefore, submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake, the most important factor for triggering submarine slides on the northern slope of the South China Sea. Considering the distribution of PGA, we consider the northern slope of the South China Sea to be stable, excluding the Taiwan Bank slope, which is tectonically active.

  3. The last Scandinavian ice sheet in northwestern Russia: ice flow patterns and decay dynamics

    DEFF Research Database (Denmark)

    Demidov, L.; Houmark-Nielsen, Michael; Kjær, Kurt Henrik

    2006-01-01

    in Russia than previously outlined and the time of termination at 18-16 cal. kyr BP was almost 10 kyr delayed compared to the southwestern part of the ice sheet. We argue that the lithology of the ice sheets' substrate, and especially the location of former proglacial lake basins, influenced the dynamics......Advance of the Late Weichselian (Valdaian) Scandinavian Ice Sheet (SIS) in northwestern Russia took place after a period of periglacial conditions. Till of the last SIS, Bobrovo till, overlies glacial deposits from the previous Barents and Kara Sea ice sheets and marine deposits of the Last...

  4. A simplified approach for slope stability analysis of uncontrolled waste dumps.

    Science.gov (United States)

    Turer, Dilek; Turer, Ahmet

    2011-02-01

    Slope stability analysis of municipal solid waste has always been problematic because of the heterogeneous nature of the waste materials. The requirement for large testing equipment in order to obtain representative samples has identified the need for simplified approaches to obtain the unit weight and shear strength parameters of the waste. In the present study, two of the most recently published approaches for determining the unit weight and shear strength parameters of the waste have been incorporated into a slope stability analysis using the Bishop method to prepare slope stability charts. The slope stability charts were prepared for uncontrolled waste dumps having no liner and leachate collection systems with pore pressure ratios of 0, 0.1, 0.2, 0.3, 0.4 and 0.5, considering the most critical slip surface passing through the toe of the slope. As the proposed slope stability charts were prepared by considering the change in unit weight as a function of height, they reflect field conditions better than accepting a constant unit weight approach in the stability analysis. They also streamline the selection of slope or height as a function of the desired factor of safety.

  5. Filling of a Salt-withdrawal Minibasin on the Continental Slope by Turbidity Currents: Futher Research and Results

    Science.gov (United States)

    Violet, J. A.; Sheets, B. A.; Paola, C.; Pratson, L. F.; Parker, G.

    2002-12-01

    We illustrate further research results on the transport and deposition of sediment by turbidity currents in an experimental basin, designed to model salt-withdrawal minibasins found along the northern continental slope of the Gulf of Mexico. The experiment was performed in 2001 in the subsiding EXperimental EarthScape facility (XES) at St. Anthony Falls Laboratory, University of Minnesota. The run consisted of two stages that each contained the same sequence of events, which were of three different variations (1.85-minute pulses of 1.5 liters/s discharges, 3.8-minute pulses of 4.5 liters/s discharges, or 36 minute events of 1.5 liters/s discharges). The sediment comprised three grades of silica with nominal diameters of 20 microns (45%), 45 microns (40%) and 110 microns (15%) and all flows had a volume concentration of sediment of 5%. The only difference between stage I and II was that no subsidence occurred during stage II, and that the 110 micron sand was removed from the flows late in stage II to study the effects of a smaller mean flow-grainsize. Research since the run has focused on the correction of high-frequency sonar data taken during the run, digital photography taken of dried deposit stratigraphy and grainsize data also taken at various locations in the dried deposit. The sonar data is utilized in the creation of post-event topographies and isopach maps to illustrate what the controls on erosion, deposition, flow path, deposit thickness and even the channelization of early flow events are. Comparisons of the stratigraphy and the grainsize data with the conclusions from the sonar data are made, as sonar is also constructed in a manner that exhibits synthetic or predicted stratigraphy (before compaction). Finally the stratigraphy is structurally described in the proximal, medial, and distal segments of the deposit and comparisons to the field are made.

  6. GEOSPATIAL DATA INTEGRATION FOR ASSESSING LANDSLIDE HAZARD ON ENGINEERED SLOPES

    Directory of Open Access Journals (Sweden)

    P. E. Miller

    2012-07-01

    Full Text Available Road and rail networks are essential components of national infrastructures, underpinning the economy, and facilitating the mobility of goods and the human workforce. Earthwork slopes such as cuttings and embankments are primary components, and their reliability is of fundamental importance. However, instability and failure can occur, through processes such as landslides. Monitoring the condition of earthworks is a costly and continuous process for network operators, and currently, geospatial data is largely underutilised. The research presented here addresses this by combining airborne laser scanning and multispectral aerial imagery to develop a methodology for assessing landslide hazard. This is based on the extraction of key slope stability variables from the remotely sensed data. The methodology is implemented through numerical modelling, which is parameterised with the slope stability information, simulated climate conditions, and geotechnical properties. This allows determination of slope stability (expressed through the factor of safety for a range of simulated scenarios. Regression analysis is then performed in order to develop a functional model relating slope stability to the input variables. The remotely sensed raster datasets are robustly re-sampled to two-dimensional cross-sections to facilitate meaningful interpretation of slope behaviour and mapping of landslide hazard. Results are stored in a geodatabase for spatial analysis within a GIS environment. For a test site located in England, UK, results have shown the utility of the approach in deriving practical hazard assessment information. Outcomes were compared to the network operator’s hazard grading data, and show general agreement. The utility of the slope information was also assessed with respect to auto-population of slope geometry, and found to deliver significant improvements over the network operator’s existing field-based approaches.

  7. Nonmonotonic and spatial-temporal dynamic slope effects on soil erosion during rainfall-runoff processes

    Science.gov (United States)

    Wu, Songbai; Yu, Minghui; Chen, Li

    2017-02-01

    The slope effect on flow erosivity and soil erosion still remains a controversial issue. This theoretical framework explained and quantified the direct slope effect by coupling the modified Green-Ampt equation accounting for slope effect on infiltration, 1-D kinematic wave overland flow routing model, and WEPP soil erosion model. The flow velocity, runoff rate, shear stress, interrill, and rill erosion were calculated on 0°-60° isotropic slopes with equal horizontal projective length. The results show that, for short-duration rainfall events, the flow erosivity and erosion amounts exhibit a bell-shaped trend which first increase with slope gradient, and then decrease after a critical slope angle. The critical slope angles increase significantly or even vanish with increasing rainfall duration but are nearly independent of the slope projective length. The soil critical shear stress, rainfall intensity, and temporal patterns have great influences on the slope effect trend, while the other soil erosion parameters, soil type, hydraulic conductivity, and antecedent soil moisture have minor impacts. Neglecting the slope effect on infiltration would generate smaller erosion and reduce critical slope angles. The relative slope effect on soil erosion in physically based model WEPP was compared to those in the empirical models USLE and RUSLE. The trends of relative slope effect were found quite different, but the difference may diminish with increasing rainfall duration. Finally, relatively smaller critical slope angles could be obtained with the equal slope length and the range of variation provides a possible explanation for the different critical slope angles reported in previous studies.

  8. Influence of flow on thawing of underwater slopes and the pace ...

    African Journals Online (AJOL)

    ... hydraulic laboratory of department of architecture & civil engineering RUDN University was performed studies of destruction of underwater and above-water coastal slopes in conditions simulating permafrost, depending on the soil type, the initial slope, and the slope angle. It was shown by authors, the speed of erosion of ...

  9. The Impact of Vegetative Slope on Water Flow and Pollutant Transport through Embankments

    Directory of Open Access Journals (Sweden)

    Liting Sheng

    2017-06-01

    Full Text Available Embankments are common structures along rivers or lakes in riparian zones in plain areas. They should have natural slopes instead of slopes covered by concrete or other hard materials, in order to rebuild sustainable ecosystems for riparian zones. This study was conducted to evaluate the effects of vegetative slopes on water flow and pollutant transport through the embankments. Three embankments with different slope treatments (a bare slope, a slope covered in centipede grass, a slope covered in tall fescue were examined, and three inflow applications of pollute water with different concentration of total nitrogen (TN and total phosphorus (TP used to simulate different agricultural non-point pollution levels. The results showed that the water flux rates of the three embankments were relatively stable under all inflow events, and almost all values were higher than 80%. The embankments with vegetative slopes had better nitrogen removal than the bare slope under all events, and the one with tall fescue slope was best, but the benefits of vegetative slopes decreased with increasing inflow concentration. Moreover, there were no significant differences between the embankments on phosphorus removal, for which the reductions were all high (above 90% with most loads remaining in the front third of embankment bodies. Overall, the embankments with vegetative slopes had positive effects on water exchange and reducing non-point pollutant into lake or river water, which provides a quantitative scientific basis for the actual layout of lakeshores.

  10. Slope failure investigation management system.

    Science.gov (United States)

    2013-03-01

    Highway slopes are exposed to a variety of environmental and climatic conditions, such as deforestation, cycles of : freezing and thawing weather, and heavy storms. Over time, these climatic conditions, in combination with other : factors such as geo...

  11. Application of distinct element method to toppling failure of slopes

    International Nuclear Information System (INIS)

    Ishida, Tsuyoshi; Hibino, Satoshi; Kitahara, Yoshihiro; Asai, Yoshiyuki.

    1985-01-01

    Recently, the stability of slopes during earthquakes has become to be an important engineering problem, especially in case of the earthquake-proof design of nuclear power plants. But, for fissured rock slopes, some problems are remained unresolved, because they can not be treated as continua. The authors have been investigating toppling failure of slopes, from a point of view which regards a fissured rock mass as an assemblage of rigid blocks. DEM (Distinct Element Method) proposed by Cundall (1974) seems to be very helpful to such a investigation. So, in this paper, the applicability of DEM to toppling failure of slopes is examined through the comparison between DEM results and theoretical or experimental results using 3 simple models. (author)

  12. Slope earthquake stability

    CERN Document Server

    Changwei, Yang; Jing, Lian; Wenying, Yu; Jianjing, Zhang

    2017-01-01

    This book begins with the dynamic characteristics of the covering layerbedrock type slope, containing monitoring data of the seismic array, shaking table tests, numerical analysis and theoretical derivation. Then it focuses on the landslide mechanism and assessment method. It also proposes a model that assessing the hazard area based on the field investigations. Many questions, exercises and solutions are given. Researchers and engineers in the field of Geotechnical Engineering and Anti-seismic Engineering can benefit from it.

  13. Geosynthetic clay liners - slope stability field study

    International Nuclear Information System (INIS)

    Carson, D.A.; Daniel, D.E.; Koerner, R.M.; Bonaparte, R.

    1997-01-01

    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project

  14. DESIGN INFORMATION REPORT: PROTECTION OF WASTEWATER LAGOON INTERIOR SLOPES

    Science.gov (United States)

    A problem common to many wastewater treatment and storage lagoons is erosion of the interior slopes. Erosion may be caused by surface runoff and wind-induced wave action. The soils that compose the steep interior slopes of lagoons are especially susceptible to erosion and slumpin...

  15. The quadruped robot adaptive control in trotting gait walking on slopes

    Science.gov (United States)

    Zhang, Shulong; Ma, Hongxu; Yang, Yu; Wang, Jian

    2017-10-01

    The quadruped robot can be decomposed into a planar seven-link closed kinematic chain in the direction of supporting line and a linear inverted pendulum in normal direction of supporting line. The ground slope can be estimated by using the body attitude information and supporting legs length. The slope degree is used in feedback, to achieve the point of quadruped robot adaptive control walking on slopes. The simulation results verify that the quadruped robot can achieves steady locomotion on the slope with the control strategy proposed in this passage.

  16. Features emergence and development of landslides on the slopes, composed of loess sediments

    Directory of Open Access Journals (Sweden)

    Bida S.V.

    2014-12-01

    Full Text Available The conditions of hollows formation in the waterproof layer during the process of quaternary deposits formation on the territory of Ukraine were being considered. It was shown that even the hollow is the center of landslides due to discharge them through groundwater flow from the plateau. Presented research aimed at studying the stability of slopes, are held within a comprehensive program of anti measures for 2005-2014, approved by the Cabinet of Ministers of Ukraine from September 22, 2004 №1256, ind. 33. Is established that for an effective fight against landslides or prevent their occurrence develop the necessary classifications dells and their detailed description. The study features hollows dedicated studies. In addition with modern relief formation processes in Ukraine are related to geological activity rivers, it should be noted the significant role erosion of surface water flows throughout geological history. Particular attention should be paid to the role of temporary water flows, the result of erosion of which is the formation of depressions in the surface sediments - dells, ravines, gullies. Determined that the origin of hollows most has erosion character, but out denudation, and other glacial basin. Found that movement of groundwater is happening in these basins, leads to suffusion loess soils, causing them to shift fluid-plastic well fluid condition and, consequently, reduce the strength characteristics of soils. Places groundwater withdrawals on the slopes are the most dangerous in terms of the possibility of landslides.

  17. The coupled response to slope-dependent basal melting

    Science.gov (United States)

    Little, C. M.; Goldberg, D. N.; Sergienko, O. V.; Gnanadesikan, A.

    2009-12-01

    Ice shelf basal melting is likely to be strongly controlled by basal slope. If ice shelves steepen in response to intensified melting, it suggests instability in the coupled ice-ocean system. The dynamic response of ice shelves governs what stable morphologies are possible, and thus the influence of melting on buttressing and grounding line migration. Simulations performed using a 3-D ocean model indicate that a simple form of slope-dependent melting is robust under more complex oceanographic conditions. Here we utilize this parameterization to investigate the shape and grounding line evolution of ice shelves, using a shallow-shelf approximation-based model that includes lateral drag. The distribution of melting substantially affects the shape and aspect ratio of unbuttressed ice shelves. Slope-dependent melting thins the ice shelf near the grounding line, reducing velocities throughout the shelf. Sharp ice thickness gradients evolve at high melting rates, yet grounding lines remain static. In foredeepened, buttressed ice shelves, changes in grounding line flux allow two additional options: stable or unstable retreat. Under some conditions, slope-dependent melting results in stable configurations even at high melt rates.

  18. Detailed analysis of the Valdes slide: a landward facing slope failure off Chile

    Science.gov (United States)

    Anasetti, Andrea; Krastel, Sebastian; Weinrebe, Willy; Klaucke, Ingo; Bialas, Jorge

    2010-05-01

    The Chilean continental margin is a very active area interested by important tectonic movements and characterized by a fast morphological evolution. Geophysical data acquired during cruise JC 23, aboard RV JAMES COOK in March/April 2008 and previous cruises cover most of the active Chilean continental margin between 33° and 37° S. Integrated interpretation of multi-beam bathymetric, sub-bottom profiles, side-scan sonar and seismic data allowed the identification of a number of slope failures. The main topic of this project is the morphological and sedimentological analysis of the Valdes slide, a medium-sized submarine landslide offshore the city of Talcahuano (300 km south of Santiago). In contrast to most other slides along continental margins, the Valdes slide is located on the landward facing eastern slope of a submarine ridge. This setting has important implications for the associated tsunami wave field (first arrival of positive amplitude). We measured geometrical parameters of the failure and adjacent slope. The slide affected an area of 19 km2 between ~1060 m and >1700 m water depths. Its is ~ 6 km long, up to 3 km wide and involved a total sedimentary volume of about 0,8 km3. The failure process was characterized by a multiple-event and we assume its tsunami potential to be high. Using the high resolution bathymetric data and the seismic profiles along the slide deposit it was possible to reconstruct the original morphology of the area in order to understand the relation between the slide event and the structural evolution of the ridge. Through the analysis of the data and bibliographic information about the Chilean margin, we analyzed potential trigger mechanisms for the landslide. The Valdes slide is situated on a steep ridge flank. The ridge follows an elongated fault zone running app. parallel to the margin. This fault zone has a dextral component which in combination with the faults elongation results in a compressional regime that is superimposed on

  19. Deposits of the 1983 and 1993 tsunamis on the coast of Primorye

    Science.gov (United States)

    Ganzey, L. A.; Razjigaeva, N. G.; Nishimura, Yu.; Grebennikova, T. A.; Gorbunov, A. O.; Kaistrenko, V. M.; Naumov, Yu. A.; Lebedev, I. I.

    2017-07-01

    Deposits of the two strongest tsunamis of the 20th century have been found on the eastern coast of Primorye. The tsunamis had epicenters in the Sea of Japan west of the coast of Hokkaido. The distribution and preservation of deposits in bays of different geomorphological structure have been analyzed. The best defined sedimentary covers occur in the upper part of sections in low-lying areas of bay shores, where the wave runup was more than 3 m. The best preserved deposits have been observed in bays attributed to loworder streams. Variations of the structural composition of tsunami deposits formed by traction processes associated with the tsunamis have been analyzed depending on distance from the shoreline; the sources of material have been identified. Tsunami waves transported sand not only from beaches, ancient storm ridges, and terraces, but also from the underwater coastal slope; waves also grabbed material from estuarine lagoons and lakes located in the shore inundation zone. Deposits include marine diatoms with dominant sublittoral planktonic and benthic species, which suggests that the material was transported from a depth no more than 15 m. Deep-sea species of diatoms and their fragments have been encountered. Among freshwater diatoms are species with different ecological identities, indicating erosion and redeposition of material transported from various sources.

  20. Posterior Slope of the Tibia Plateau in Malaysian Patients Undergoing Total Knee Replacement

    Directory of Open Access Journals (Sweden)

    R Yoga

    2009-05-01

    Full Text Available The posterior slope of the tibial plateau is an important feature to preserve during knee replacement. The correct slope aids in the amount of flexion and determines if the knee will be loose on flexion. This is a study on the posterior tibial plateau slope based on preoperative and postoperative radiographs of 100 consecutive patients who had total knee replacements. The average posterior slope of the tibia plateau was 10.1 degrees. There is a tendency for patients with higher pre-operative posterior tibial plateau slope to have higher post-operative posterior tibial plate slope.

  1. Coupling a 1D Dual-permeability Model with an Infinite Slope Stability Approach to Quantify the Influence of Preferential Flow on Slope Stability

    NARCIS (Netherlands)

    Shao, W.; Bogaard, T.A.; Su, Y.; Bakker, M.

    2016-01-01

    In this study, a 1D hydro-mechanical model was developed by coupling a dual-permeability model with an infinite slope stability approach to investigate the influence of preferential flow on pressure propagation and slope stability. The dual-permeability model used two modified Darcy-Richards

  2. [Composition and stability of soil aggregates in hedgerow-crop slope land].

    Science.gov (United States)

    Pu, Yu-Lin; Lin, Chao-Wen; Xie, De-Ti; Wei, Chao-Fu; Ni, Jiu-Pai

    2013-01-01

    Based on a long-term experiment of using hedgerow to control soil and water loss, this paper studied the composition and stability of soil aggregates in a hedgerow-crop slope land. Compared with those under routine contour cropping, the contents of > 0.25 mm soil mechanical-stable and water-stable aggregates under the complex mode hedgerow-crop increased significantly by 13.3%-16.1% and 37.8% -55.6%, respectively. Under the complex mode, the contents of > 0.25 mm soil water-stable aggregates on each slope position increased obviously, and the status of > 0.25 mm soil water-stable aggregates being relatively rich at low slope and poor at top slope was improved. Planting hedgerow could significantly increase the mean mass diameter and geometric mean diameter of soil aggregates, decrease the fractal dimension of soil aggregates and the destruction rate of > 0.25 mm soil aggregates, and thus, increase the stability and erosion-resistance of soil aggregates in slope cropland. No significant effects of slope and hedgerow types were observed on the composition, stability and distribution of soil aggregates.

  3. Saturated and unsaturated stability analysis of slope subjected to rainfall infiltration

    Directory of Open Access Journals (Sweden)

    Gofar Nurly

    2017-01-01

    Full Text Available This paper presents results of saturated and unsaturated stability analysis of typical residual slopes subjected to rainfall infiltration corresponds to 50 years rainfall return period. The slope angles considered were 45° and 70°. The saturated stability analyses were carried out for original and critical ground water level commonly considered by practicing engineer. The analyses were conducted using limit equilibrium method. Unsaturated stability analyses used combination of coupled stress–pore-water pressure analysis to evaluate the effect of rainfall infiltration on the deformation and transient pore-water pressure on slope stability. Slope stability analyses were performed at some times during and after rainfall infiltration. Results show that the critical condition for slope made by sandy material was at the end of rainfall while for clayey material was at some specified times after the rainfall ceased. Unsaturated stability analysis on sandy soil gives higher factor of safety because the soil never reached saturation. Transient analysis using unsaturated soil concept could predict more critical condition of delayed failure of slopes made up of clayey soil.

  4. GIS-based seismic shaking slope vulnerability map of Sicily (Central Mediterranean)

    Science.gov (United States)

    Nigro, Fabrizio; Arisco, Giuseppe; Perricone, Marcella; Renda, Pietro; Favara, Rocco

    2010-05-01

    Earthquakes often represent very dangerouses natural events in terms of human life and economic losses and their damage effects are amplified by the synchronous occurrence of seismically-induced ground-shaking failures in wide regions around the seismogenic source. In fact, the shaking associated with big earthquakes triggers extensive landsliding, sometimes at distances of more than 100 km from the epicenter. The active tectonics and the geomorphic/morphodinamic pattern of the regions affected by earthquakes contribute to the slopes instability tendency. In fact, earthquake-induced groun-motion loading determines inertial forces activation within slopes that, combined with the intrinsic pre-existing static forces, reduces the slope stability towards its failure. Basically, under zero-shear stress reversals conditions, a catastrophic failure will take place if the earthquake-induced shear displacement exceeds the critical level of undrained shear strength to a value equal to the gravitational shear stress. However, seismic stability analyses carried out for various infinite slopes by using the existing Newmark-like methods reveal that estimated permanent displacements smaller than the critical value should also be regarded as dangerous for the post-earthquake slope safety, in terms of human activities use. Earthquake-induced (often high-speed) landslides are among the most destructive phenomena related to slopes failure during earthquakes. In fact, damage from earthquake-induced landslides (and other ground-failures), sometimes exceeds the buildings/infrastructures damage directly related to ground-shaking for fault breaking. For this matter, several hearthquakes-related slope failures methods have been developed, for the evaluation of the combined hazard types represented by seismically ground-motion landslides. The methodologies of analysis of the engineering seismic risk related to the slopes instability processes is often achieved through the evaluation of the

  5. Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stynes, J. K.; Ihas, B.

    2012-04-01

    The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

  6. Physical properties of P and B doped microcrystalline SI:H deposited by PECVD

    International Nuclear Information System (INIS)

    Rubino, A.; Addonizio, M.L.; Conte, G.; Nobile, G.; Terzini, E.

    1993-01-01

    Boron and phosphorus doped high conductivity microcrystalline thin films were deposited in a PECVD reactor. This paper reports conductivities as high as 3 and 41 S/cm for B and P doped materials respectively on films deposited at 210 degrees C. The conductivity, as well as, the microcrystalline fraction increase for the n layer with decreasing RF power, while, for the p material, an increase of power is needed to improve the film characteristics. The conductivity prefactor, as well as, the conductivity itself as a function of the activation energy show a slope inversion for both n and p materials at an activation energy of about 40 meV and 80 meV respectively. Different possible transport mechanisms are examined in order to explain the experimental data

  7. Reclamation of slopes left after surface mining

    Energy Technology Data Exchange (ETDEWEB)

    Zmitko, J [Banske Projekty, Teplice (Czech Republic)

    1993-03-01

    Discusses land reclamation of abandoned slopes from brown coal surface mining in the North Bohemian brown coal basin in the Czech Republic. Problems associated with reclamation of landslide areas in two former coal mines are evaluated: the Otokar mine in Kostany (mining from 1956 to 1966) and the CSM mine in Pozorka (mining from 1955 to 1967). Land reclamation was introduced 25 years after damage occurred. The following aspects are analyzed: hydrogeologic conditions, range of landslides, types of rocks in landslide areas, water conditions, methods for stabilizing slopes, safety aspects.

  8. Measurement of Posterior Tibial Slope Using Magnetic Resonance Imaging.

    Science.gov (United States)

    Karimi, Elham; Norouzian, Mohsen; Birjandinejad, Ali; Zandi, Reza; Makhmalbaf, Hadi

    2017-11-01

    Posterior tibial slope (PTS) is an important factor in the knee joint biomechanics and one of the bone features, which affects knee joint stability. Posterior tibial slope has impact on flexion gap, knee joint stability and posterior femoral rollback that are related to wide range of knee motion. During high tibial osteotomy and total knee arthroplasty (TKA) surgery, proper retaining the mechanical and anatomical axis is important. The aim of this study was to evaluate the value of posterior tibial slope in medial and lateral compartments of tibial plateau and to assess the relationship among the slope with age, gender and other variables of tibial plateau surface. This descriptive study was conducted on 132 healthy knees (80 males and 52 females) with a mean age of 38.26±11.45 (20-60 years) at Imam Reza hospital in Mashhad, Iran. All patients, selected and enrolled for MRI in this study, were admitted for knee pain with uncertain clinical history. According to initial physical knee examinations the study subjects were reported healthy. The mean posterior tibial slope was 7.78± 2.48 degrees in the medial compartment and 6.85± 2.24 degrees in lateral compartment. No significant correlation was found between age and gender with posterior tibial slope ( P ≥0.05), but there was significant relationship among PTS with mediolateral width, plateau area and medial plateau. Comparison of different studies revealed that the PTS value in our study is different from other communities, which can be associated with genetic and racial factors. The results of our study are useful to PTS reconstruction in surgeries.

  9. A more general model for the analysis of the rock slope stability

    Indian Academy of Sciences (India)

    slope stability analysis, the joint surfaces are assumed to be continuous along the potential ... of rock slope stability has many applications in the design of rock slopes, roofs and walls of .... cases the wedge failure analysis can be applied.

  10. Tufa in Northern England: depositional facies, carbonate mineral fabrics, and role of biomineralization

    Science.gov (United States)

    Manzo, E.; Mawson, M.; Perri, E.; Tucker, M. E.

    2009-04-01

    Tufas are widely scattered in northern England, being concentrated in areas of limestone (Carboniferous and Permian), where there are springs, seepages, streams and waterfalls with waters supersatured in respect of calcite. Some deposits are clearly related to faults. Tufas have been examined in Gordale and Malham (SW Yorkshire), Teesdale and Weardale (Co. Durham), Sunderland (Tyne & Wear) and Great Asby Fell (Cumbria). A variety of tufa types are developed: spring-related pisoids and moss tufa, fluviatile barrage and waterfall tufa, and seepage and spring tufa with microbial oncoids in a paludal setting. We present preliminary data and observations on tufa in the Teesdale area, which forms along the valley-side adjacent to the River Tees. Locally here, a tiny stream draining agricultural land runs over a sandstone outcrop at the top of a 30 metre high slope; water descends the 30-60 degrees slope, creating tiny waterfalls and pools across an area reaching 10 metres wide, on the way down towards the river. Three main facies are recognizable in the tufa deposits: carbonate crusts, moss tufa and pisoids. In the upper part of the slope tufa occurs as sub-vertical 0.5-5 cm thick carbonate crusts forming "sheets" with a bulbous external surface covered by a green biofilm, with some insect larvae. Encrustations form upon surfaces of rock exposures and pebbles, and coat plant fragments (leaves, twigs, pine cones). Tufa precipitation, particularly on mosses, liverworts and leaves (moss tufa), creates a series of rimmed pools, a few decimetres across and centimetres deep. Apart from the presence of moss, which gives the tufa has a vacuolar texture, the main constituents are cyanobacteria and diatoms. The moss tufa deposit may reach a metre or more in height and several metres in width, notably towards the base of the slope, adjacent to the river. Within the small pools on the slope, pisoids and partially calcified plant remains accumulate. They also occur abundantly in the

  11. VT Data - Lidar Slope (0.7m) 2015, Windham County

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata applies to the following collection area(s): Windham County 2015 0.7m and related SLOPE datasets. Created using ArcGIS "SLOPE"...

  12. Documentation and evaluation of slope instabilities and other geological phenomena in the Geopark Bohemian Paradise (Czech Republic)

    Science.gov (United States)

    Krejčí, Oldřich; Krejčí, Vladimíra; Švábenická, Lilian; Hartvich, Filip

    2016-04-01

    Geographically, the area is part of the Bohemian Cretaceous Basin, the unit Jičín Hilly land. Since October 2005, the area belongs to the European Geopark UNESCO Bohemian Paradise. The reason of the protection is a major complex of rocks, natural forest communities and geomorphological valuable territory. The territory has been newly geologically mapped in a scale of 1 : 25,000. Sediments of the Czech Cretaceous Basin covers an area of 181 km2 and were deposited transgressively on the Permian - Carboniferous and crystalline basement of the Bohemian Massif. Except for locally developed basal sediments of fluvial origin they are mostly shallow marine sediments. Middle Turonian to Lower Coniacian rocks of the Jizera lithofacies are dominant by calcareous sandstones deposited under extremely dynamic conditions. Scattered alkaline volcanics penetrate the older formations as small intrusions and form locally preserved bodies at the surface. Area is strongly predisposed to the development of various types of landforms by structural segmentation of the Cretaceous sandstones and claystones and by Plio-Pleistocene inverse erosion. Numerous archival manuscripts are available from this area together with published geological, engineering-geological, geomorphological and historical papers. This is due to the fact that in 1926 a large landslide destroyed a substantial part of the village Dneboh, situated on the slope below a rock castle Drabske Svetnicky. Drabske Svetnicky is a ruin of a 13th century castle. It is located on the ragged edge of a sandstone cliff high above surrounding landscape. The castle covers a group of seven sandstone rocks, connected with wooden bridges. In the 50ies of the 20th century, an increased attention was paid to Drabske Svetnicky by experts on medieval architecture and a restoration of the original state of the castle rock was accomplished. Remnants of pottery and other findings suggest that the plateau region of the castle was first inhabited

  13. Effect of rainfall on the reliability of an infinite slope

    OpenAIRE

    Yuan, J.; Papaioannou, I.; Mok, C. M.; Straub, D.

    2014-01-01

    Rainfall is one of the most common factors triggering landslides, since infiltration of water into the soil has a significant impact on pore water pressure buildup that affects slope stability. In this study, the influence of the wetting front development on the reliability of an infinite slope is analyzed. The failure condition of the slope is expressed in terms of the factor of safety. Rainfall infiltration is simulated by a time-dependent model, based on the Green and Ampt assumptions. The...

  14. Discussion on the Safety Factors of Slopes Recommended for Small Dams

    Directory of Open Access Journals (Sweden)

    Jan Vrubel

    2017-01-01

    Full Text Available The design and assessment of the slope stability of small embankment dams is usually not carried out using slope stability calculations but rather by the comparison of proposed or existing dam slopes with those recommended by technical standards or guidelines. Practical experience shows that in many cases the slopes of small dams are steeper than those recommended. However, most of such steeper slopes at existing dams do not exhibit any visible signs of instability, defects or sliding. For the dam owner and also for dam stability engineers, the safety of the slope, expressed e.g. via a factor of safety, is crucial. The aim of this study is to evaluate the safety margin provided by recommended slopes. The factor of safety was evaluated for several dam shape and layout variants via the shear strength reduction method using PLAXIS software. The study covers various dam geometries, dam core and shoulder positions and parameter values of utilised soils. Three load cases were considered: one with a steady state seepage condition and two with different reservoir water level drawdown velocities – standard and critical. As numerous older small dams lack a drainage system, variants with and without a toe drain were assessed. Calculated factors of safety were compared with required values specified by national standards and guidelines.

  15. Experimental study on slope sliding and debris flow evolution with and without barrier

    Directory of Open Access Journals (Sweden)

    Ji-kun Zhao

    2015-01-01

    Full Text Available A constitutive model on the evolution of debris flow with and without a barrier was established based on the theory of the Bingham model. A certain area of the Laoshan Mountain in Nanjing, Jiangsu Province, in China was chosen for experimental study, and the slope sliding and debris flow detection system was utilized. The change curve of the soil moisture content was attained, demonstrating that the moisture content of the shallow soil layer increases faster than that of the deep soil layer, and that the growth rate of the soil moisture content of the steep slope is large under the first weak rainfall, and that of the gentle slope is significantly affected by the second heavy rainfall. For the steep slope, slope sliding first occurs on the upper slope surface under heavy rainfall and further develops along the top platform and lower slope surface, while under weak rainfall the soil moisture content at the lower part of the slope first increases because of the high runoff velocity, meaning that failure occurring there is more serious. When a barrier was placed at a high position on a slope, debris flow was separated and distributed early and had less ability to carry solids, and the variation of the greatest depth of erosion pits on soil slopes was not significant.

  16. Determination of depositional beryllium-10 fluxes in the area of the Laptev sea

    Energy Technology Data Exchange (ETDEWEB)

    Strobl, C.; Schulz, V.; Schaeper, S.; Molnar, M.; Baumann, S.; Mangini [Heidelberger Akademie der Wissenschaften, Heidelberg (Germany); Kubik, P.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    A huge amount of continental {sup 10}Be is delivered to the Arctic Ocean through the rivers. Our investigations show that the most extensive part of it is deposited directly in the shelf areas. The determined sedimentation flux densities in the continental slope and in the Central Arctic Ocean are in the range of the assumed atmospheric input of {sup 10}Be and therefore clearly lower than in the shelf areas. (author) 1 fig., 2 refs.

  17. Amplitude of late Miocene sea-level fluctuations from karst development in reef-slope deposits (SE Spain)

    Science.gov (United States)

    Reolid, Jesús; Betzler, Christian; Braga, Juan Carlos

    2016-11-01

    A prograding late Miocene carbonate platform in southern Spain revealing different sea-level pinning points was analysed with the aim to increase the accuracy of reconstruction of past sea-level changes. These pinning points are distinct diagenetic zones (DZ) and the position of reef-framework deposits. DZ1 is defined by the dissolution of bioclastic components and DZ2 by calcitic cement precipitation in dissolution pores. Calcite cements are granular and radiaxial fibrous, and are of meteoric origin as deduced from cathodoluminescence, EDX spectroscopy, as well as from δ13C and δ18O isotope analyses. DZ3 has moldic porosity after aragonitic bioclasts with minor granular calcitic cements. DZ1 and DZ2 indicate karstification and the development of a coastal palaeoaquifer during a sea-level lowstand. DZ3 diagenetic features are related to the final subaerial exposure of the section during the Messinian Salinity Crisis. Facies and diagenetic data reveal a complete cycle of sea-level fall (23 ± 1 m) and rise (31 ± 1 m). A robust age model based on magneto- and cyclostratigraphy for these deposits places this cycle between 5.89 and 5.87 Ma. Therefore, for the first time, this work allows a direct comparison of an outcrop with a pelagic marine proxy record of a specific Neogene sea-level fluctuation.

  18. The budget between transportation and accumulation of organic carbon and total nitrogen in black soil at a sloping farmland

    International Nuclear Information System (INIS)

    Fang Huajun; Zhang Xiaoping; Liang Aizhen

    2006-01-01

    Based on the rate of soil redistribution at a sloping farmland using 137 Cs tracer technique and spatial variation of soil organic carbon (SOC) and total nitrogen (TN), the spatial distribution of SOC and TN loss and the budget between transportation and accumulation for recently 50 years was calculated. The results showed that the rate of soil redistribution ranged from -24.61 t/hm 2 /a to 33.56 t/hm 2 /a, most of study area was in medium and weakly erosion phase and accounted for 83.66%; and the area of soil deposition accounted for 15.62%; The variation of the loss of SOC and TN was consistent with that of soil redistribution, shoulder-slope had the most serious loss with the rate of 407.57 kg/hm 2 /a for SOC and 39.94 kg/hm 2 /a for TN, back-slope and summit had the secondly loss with the average rate of 244.2 kg/hm 2 /a for SOC and -20.56 kg/hm 2 /a for TN. For the whole area, relative loss of SOC and TN more than 50% accounted for 10.45% and 11.21%, respectively; The net loss of sediment in the study area was 45.54 t/a for recent 48 years, among which SOC and TN were 612.62 kg/a and 47.20 kg/a, respectively, which was 52% more than that of without consideration of the enrichment of sediment on soil organic matter. (authors)

  19. Large-scale slope failure and active erosion occurring in the southwest Ryukyu fore-arc area

    Directory of Open Access Journals (Sweden)

    T. Matsumoto

    2001-01-01

    Full Text Available The southwestern Ryukyu area east of Taiwan Island is an arcuate boundary between Philippine Sea Plate and Eurasian Plate. The topographic features in the area are characterised by (1 a large-scale amphitheatre off Ishigaki Island, just on the estimated epicentre of the tsunamigenic earthquake in 1771, (2 lots of deep sea canyons located north of the amphitheatre, (3 15–20 km wide fore-arc basin, (4 15–20 km wide flat plane in the axial area of the trench, (5 E-W trending half grabens located on the fore-arc area, etc., which were revealed by several recent topographic survey expeditions. The diving survey by SHINKAI6500 in the fore-arc area on a spur located 120 km south of Ishigaki Island was carried out in 1992. The site is characterised dominantly by rough topography consisting of a series of steep slopes and escarpments. A part of the surface is eroded due to the weight of the sediment itself and consequently the basement layer is exposed. The site was covered with suspended particles during the diving, due to the present surface sliding and erosion. The same site was resurveyed in 1997 by ROV KAIKO, which confirmed the continuous slope failure taking place in the site. Another example that was observed by KAIKO expedition in 1997 is a largescale mud block on the southward dipping slope 80 km south of Ishigaki Island. This is apparently derived from the shallower part of the steep slope on the southern edge of the fan deposit south of Ishigaki Island. The topographic features suggest N-S or NE-SW tensional stress over the whole study area. In this sense, the relative motion between the two plates in this area is oblique to the plate boundary. So, the seaward migration of the plate boundary may occur due to the gravitational instability at the boundary of the two different lithospheric structures. This is evidenced by a lack of accretionary sediment on the fore-arc and the mechanism of a recent earthquake which occurred on 3 May 1998 in

  20. Estimating the erosion and deposition rates in a small watershed by the {sup 137}Cs tracing method

    Energy Technology Data Exchange (ETDEWEB)

    Li Mian [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China)], E-mail: hnli-mian@163.com; Li Zhanbin [Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China); Yao Wenyi [Yellow River Institute of Hydraulic Research, Key Laboratory of Sediment Research of Yellow River of Ministry of Water Resources, Zhengzhou, Henan 450003 (China); Liu Puling [Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100 (China)

    2009-02-15

    Understanding the erosion and deposition rates in a small watershed is important for designing soil and water conservation measures. The objective of this study is to estimate the net soil loss and gain at points with various land use types and landform positions in a small watershed in the Sichuan Hilly Basin of China by the {sup 137}Cs tracing technique. Among various land use types, the order of erosion rate was bare rock > sloping cultivated land > forest land. The paddy field and Caotu (a kind of cultivated land located at the foot of hills) were depositional areas. The erosion rate under different landform was in this order: hillside > saddle > hilltop. The footslope and the valley were depositional areas. The {sup 137}Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small watershed.

  1. Earthquake-induced soft-sediment deformation structures in Late Pleistocene lacustrine deposits of Issyk-Kul lake (Kyrgyzstan)

    Science.gov (United States)

    Gladkov, A. S.; Lobova, E. U.; Deev, E. V.; Korzhenkov, A. M.; Mazeika, J. V.; Abdieva, S. V.; Rogozhin, E. A.; Rodkin, M. V.; Fortuna, A. B.; Charimov, T. A.; Yudakhin, A. S.

    2016-10-01

    This paper discusses the composition and distribution of soft-sediment deformation structures induced by liquefaction in Late Pleistocene lacustrine terrace deposits on the southern shore of Issyk-Kul Lake in the northern Tien Shan mountains of Kyrgyzstan. The section contains seven deformed beds grouped in two intervals. Five deformed beds in the upper interval contain load structures (load casts and flame structures), convolute lamination, ball-and-pillow structures, folds and slumps. Deformation patterns indicate that a seismic trigger generated a multiple slump on a gentle slope. The dating of overlying subaerial deposits suggests correlation between the deformation features and strong earthquakes in the Late Pleistocene.

  2. The effects of the mineral phase on C stabilization mechanisms and the microbial community along an eroding slope transect

    Science.gov (United States)

    Doetterl, S.; Opfergelt, S.; Cornelis, J.; Boeckx, P. F.; van oost, K.; Six, J.

    2013-12-01

    , hence, providing physical protection of C. Oxalate extractable amorphous and poorly crystalline minerals are correlated to C, especially for the more recalcitrant C fractions, but only at the depositional site. However, decreasing contents of oxalate extractable elements with depth indicate a temporal limitation of this stabilization mechanism and this is also supported by the results of our lignin extraction. Non-expandable clay minerals experience a relative enrichment at the depositional site while expandable clay minerals experience the same at the eroding site. These changes in clay mineralogy along the slope are partly responsible for the abundance of silt and clay associated C. The changes in soil mineralogy and micro-scale environmental conditions led to an adaptation of the microbial community in comparison to sites not affected by soil redistribution.

  3. Time-dependent evolution of rock slopes by a multi-modelling approach

    Science.gov (United States)

    Bozzano, F.; Della Seta, M.; Martino, S.

    2016-06-01

    This paper presents a multi-modelling approach that incorporates contributions from morpho-evolutionary modelling, detailed engineering-geological modelling and time-dependent stress-strain numerical modelling to analyse the rheological evolution of a river valley slope over approximately 102 kyr. The slope is located in a transient, tectonically active landscape in southwestern Tyrrhenian Calabria (Italy), where gravitational processes drive failures in rock slopes. Constraints on the valley profile development were provided by a morpho-evolutionary model based on the correlation of marine and river strath terraces. Rock mass classes were identified through geomechanical parameters that were derived from engineering-geological surveys and outputs of a multi-sensor slope monitoring system. The rock mass classes were associated to lithotechnical units to obtain a high-resolution engineering-geological model along a cross section of the valley. Time-dependent stress-strain numerical modelling reproduced the main morpho-evolutionary stages of the valley slopes. The findings demonstrate that a complex combination of eustatism, uplift and Mass Rock Creep (MRC) deformations can lead to first-time failures of rock slopes when unstable conditions are encountered up to the generation of stress-controlled shear zones. The multi-modelling approach enabled us to determine that such complex combinations may have been sufficient for the first-time failure of the S. Giovanni slope at approximately 140 ka (MIS 7), even without invoking any trigger. Conversely, further reactivations of the landslide must be related to triggers such as earthquakes, rainfall and anthropogenic activities. This failure involved a portion of the slope where a plasticity zone resulted from mass rock creep that evolved with a maximum strain rate of 40% per thousand years, after the formation of a river strath terrace. This study demonstrates that the multi-modelling approach presented herein is a useful

  4. Forecasting slope failures from space-based synthetic aperture radar (SAR) measurements

    Science.gov (United States)

    Wasowski, J.; Bovenga, F.; Nutricato, R.; Nitti, D. O.; Chiaradia, M. T.; Tijani, K.; Morea, A.

    2017-12-01

    New space-borne radar sensors enable multi-scale monitoring of potentially unstable slopes thanks to wide-area coverage (tens of thousands km2), regular long-term image acquisition schedule with increasing re-visit frequency (weekly to daily), and high measurement precision (mm). In particular, the recent radar satellite missions e.g., COSMO-SkyMed (CSK), Sentinel-1 (S-1) and improved multi-temporal interferometry (MTI) processing techniques allow timely delivery of information on slow ground surface displacements. Here we use two case study examples to show that it is possible to capture pre-failure slope strains through long-term MTI-based monitoring. The first case is a retrospective investigation of a huge 500ML m3 landslide, which occurred in Sept. 2016 in a large, active open-cast coal mine in central Europe. We processed over 100 S-1 images acquired since Fall 2014. The MTI results showed that the slope that failed had been unstable at least since 2014. Importantly, we detected consistent displacement trends and trend changes, which can be used for slope failure forecasting. Specifically, we documented significant acceleration in slope surface displacement in the two months preceding the catastrophic failure. The second case of retrospectively captured pre-failure slope strains regards our earlier study of a small 50 m long landslide, which occurred on Jan. 2014 and caused the derailment of a train on the railway line connecting NW Italy to France. We processed 56 CSK images acquired from Fall 2008 to Spring 2014. The MTI results revealed pre-failure displacements of the engineering structures on the slope subsequently affected by the 2014 slide. The analysis of the MTI time series further showed that the displacements had been occurring since 2009. This information could have been used to forewarn the railway authority about the slope instability hazard. The above examples indicate that more frequent and consistent image acquisitions by the new radar

  5. Assessment of slope stability and remedial measures around Gilgel ...

    African Journals Online (AJOL)

    A road constructed from Fofa town to Gilgel Gibe-II powerhouse in south-western Ethiopia passes through an extremely rugged terrain characterized by steep hill slopes and deep valleys. The present study has been carried out to identify potentially unstable slope sections and to work out proper remedial measures. In order ...

  6. Depositional environment of a fan delta in a Vistulian proglacial lake (Skaliska Basin, north-eastern Poland

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2013-06-01

    Full Text Available The study reconstructed the environment of a fan delta filling the vast end depression of the Skaliska Basin, and its overlying aeolian deposits. The formation of the large fan delta is associated with the presence of an ice-dammed lake functioning during the retreat of the Vistulian Glaciation (MIS 2. The examined material was collected from five boreholes. Sediments were analysed for their granulometric composition and subjected to analyses of frosting and rounding of quartz grains. Grain size analysis showed that the fan delta deposits are built of sand sediments of very low lateral and vertical variability. The fan delta was supplied with fluvioglacial sediments. Accumulation of sediments occurred in shallow water with a very low-gradient slope. The exposed fan delta became a site conducive to aeolian processes after the lake waters fell and the Skaliska Basin depression dried. Dune deposits overlying the fan were affected by short-distance transport so they did not acquire features typical for aeolian deposits.

  7. Mercury in sediments from shelf and continental slope at Campos Basin near Rio de Janeiro, Brazil

    Science.gov (United States)

    Araujo, Beatriz; Hintelmann, Holger; Dimock, Brian; Gomes de Almeida, Marcelo; Falcão, Ana Paula; de Rezende, Carlos Eduardo

    2016-04-01

    upper slope we can observe some points with ligther isotopes. the Some in the transect D, located closer to the cost (25 and 50 m of depth), showed the most negative isotope signature. This transect receives direct influence from the Paraíba do Sul river, so the Hg composition may be explained the riverine contribution characterized by Hg of different origin. Moreover, the negative δ202Hg values mainly observed in some stations in the shelf region, can be caused by process such as degassing of dissolved Hg0, volatilization, microbial reduction and photoreduction, which tend to deplete the lighter Hg isotopes in the product Hg0. Likewise, process such as physical settling of Hg adsorbed to particles and atmospheric deposition of Hg could also be a possible cause of the lower δ202Hg values. In addition, the positive Δ199Hg values could be caused due atmospheric Hg deposition, which represents a significant source in the biogeochemical cycle of Hg in oceans.

  8. Elevated occipital β-amyloid deposition is associated with widespread cognitive impairment in logopenic progressive aphasia.

    Science.gov (United States)

    Whitwell, Jennifer L; Lowe, Val J; Duffy, Joseph R; Strand, Edythe A; Machulda, Mary M; Kantarci, Kejal; Wille, Samantha M; Senjem, Matthew L; Murphy, Matthew C; Gunter, Jeffrey L; Jack, Clifford R; Josephs, Keith A

    2013-12-01

    Most subjects with logopenic variant of primary progressive aphasia (lvPPA) have β-amyloid (Aβ) deposition on Pittsburgh Compound B positron emission tomography (PiB-PET), usually affecting prefrontal and temporoparietal cortices, with less occipital involvement. To assess clinical and imaging features in lvPPA subjects with unusual topographic patterns of Aβ deposition with highest uptake in occipital lobe. Thirty-three lvPPA subjects with Aβ deposition on PiB-PET were included in this case-control study. Line plots of regional PiB uptake were created, including frontal, temporal, parietal and occipital regions, for each subject. Subjects in which the line sloped downwards in occipital lobe (lvPPA-low), representing low uptake, were separated from those where the line sloped upwards in occipital lobe (lvPPA-high), representing unusually high occipital uptake compared to other regions. Clinical variables, atrophy on MRI, hypometabolism on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), and presence and distribution of microbleeds and white matter hyperintensities (WMHs) were assessed. Seventeen subjects (52%) were classified as lvPPA-high. Mean occipital PiB uptake in lvPPA-high was higher than all other regions and higher than all regions in lvPPA-low. The lvPPA-high subjects performed more poorly on cognitive testing, including executive and visuospatial testing, but the two groups did not differ in aphasia severity. Proportion of microbleeds and WMH was higher in lvPPA-high than lvPPA-low. Parietal hypometabolism was greater in lvPPA-high than lvPPA-low. Unusually high occipital Aβ deposition is associated with widespread cognitive impairment and different imaging findings in lvPPA. These findings help explain clinical heterogeneity in lvPPA and suggest that Aβ influences severity of overall cognitive impairment but not aphasia.

  9. Determination of slope failure using 2-D resistivity method

    Science.gov (United States)

    Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson

    2017-07-01

    Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

  10. [Effects of slopes on nitrogen transport along with runoff from sloping plots on a lateritic red soil amended with sewage sludge].

    Science.gov (United States)

    Chen, Yan-Hui; Chen, Ming-Hua; Wang, Guo; Chen, Wen-Xiang; Yang, Shun-Cheng; Chai, Peng

    2010-10-01

    The effects of different slopes on nitrogen transport along with runoff from sloping plots amended with sewage sludge on a lateritic red soil were studied under simulated rainfall conditions. When the sludge was broadcasted and mixed with surface soils (BM), the MTN (total nitrogen of mixing sample), STN (total nitrogen of settled sample), TPN (total particulate nitrogen), TSN (total suspended nitrogen), TDN (total dissolved nitrogen) and NH4(+) -N concentrations and nitrogen loss amounts in runoff of all treatments were highest at 1 day or 18 days after application. The highest concentrations and the loss amounts of MTN and STN in the slope runoff for the BM treatment increased with slope degree, showing increasing pollution risks to the surface waters. The STN concentration and loss amounts from the 25 degrees plots were 126.1 mg x L(-1) and 1788.6 mg x m(-2), respectively, being 4.6 times and 5.8 times of the corresponding values from the 10 degrees plots, respectively. Then the concentrations and the loss amounts of nitrogen (except NO3(-) -N) from the BM plots diminished rapidly first and then tended to be stable with dwindling differences between the slopes. The loss of MTN and STN in early runoff (1 day and 18 days) accounted for 68.6% -73.4% and 62.3% -66.7% of the cumulative loss amounts during the experimental period for all the broadcasted treatments. Runoff loss coefficients of MTN increased in the order of 20 degrees > 25 degrees > 15 degrees > 10 degrees. Nitrogen was largely lost in dissolved species while large portion of NH4(+) -N was lost with particulates.

  11. Conceptual model for reinforced grass on inner dike slopes

    NARCIS (Netherlands)

    Verhagen, H.J.; ComCoast

    2005-01-01

    A desk study has been carried out in order to develop a conceptual model for the erosion of inner dike slopes with reinforced grass cover. Based on the results the following can be concluded: The presence of a geosynthetic in a grass slope can be taken into account in the EPM method by increasing

  12. Submarine slope failures along the convergent continental margin of the Middle America Trench

    Science.gov (United States)

    Harders, Rieka; Ranero, CéSar R.; Weinrebe, Wilhelm; Behrmann, Jan H.

    2011-06-01

    We present the first comprehensive study of mass wasting processes in the continental slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ˜1300 km of the Middle America Trench of the Central America Subduction Zone and deep-towed side-scan sonar data. We found abundant evidence of large-scale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the continental slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting plate affect mass wasting processes of the continental slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the continental margin, in some cases reaching the plate boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed continental slope. Offshore Nicaragua, the ocean plate is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing plate has no large seamounts but

  13. Effect of Angle of Attack on Slope Climbing Performance

    Science.gov (United States)

    Creager, Colin M.; Jones, Lucas; Smith, Lauren M.

    2017-01-01

    Ascending steep slopes is often a very difficult challenge for off-road vehicles, whether on Earth or on extraterrestrial bodies. This challenge is even greater if the surface consists of loose granular soil that does not provide much shear strength. This study investigated how the path at which a vehicle traverses a slope, specifically the angle that it is commanded to drive relative to the base of the hill (the angle of attack), can affect its performance. A vehicle was driven in loose sand at slope angles up to 15 degrees and angles of attack ranging from 10 to 90 degrees. A novel photogrammetry technique was implemented to both track vehicle motion and create a three-dimensional profile of the terrain. This allowed for true wheel sinkage measurements. The study showed that though low angles of attack result in lower wheel slip and sinkage, the efficiency of the vehicles uphill motion increased at higher angles of attack. For slopes up to 15 degrees, a 90 degree angle of attack provided the greatest likelihood of successful ascent.

  14. Occurrence of inter-eruption debris flow and hyperconcentrated flood-flow deposits on Vesuvio volcano, Italy

    Science.gov (United States)

    Lirer, L.; Vinci, A.; Alberico, I.; Gifuni, T.; Bellucci, F.; Petrosino, P.; Tinterri, R.

    2001-02-01

    In the period between AD 79 and AD 472 eruptions, inter-eruption debris flow and hyperconcentrated-flood-flow deposits were deposited in the Somma-Vesuvio areas. These deposits, forming cliffs at the Torre Bassano and Torre Annunziata, were generated by highly erosive floods, whose erosive capacity was enhanced by acceleration due to the steepness of the volcano slopes. In this type of deposits were distinguished five depositional facies (from A to E) outcropping well at Torre Bassano where they are stacked in three fining-upward (FU) sequences, probably representing three forestepping — backstepping episodes in the emplacement area of gravity flows. These five facies from coarse to fine are interpreted to represent the downcurrent evolution of particular composite sediment gravity flows characterized by horizontal segregation of the main grain-size population. The blocking of these highly concentrated composite parent flows would first produce the deposition of the coarse front part to form facies A and then the overriding of this deposit by the bipartite flow, which constitutes the body of the flow. This flow is composed of a highly concentrated basal inertia carpet responsible for the deposition of facies B, C and D and an upper hyperconcentrated flood flow that forms facies E, through traction plus fallout processes, respectively. Finally, the occurrence of "lahar" type events at Somma-Vesuvio region even at present times is discussed.

  15. After the slippery slope: Dutch experiences on regulating active euthanasia.

    Science.gov (United States)

    Boer, Theo A

    2003-01-01

    "When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward." If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery slope argument, however, is by definition limited by its reference to future developments which cannot empirically be sustained. Experience in the Netherlands--where a law regulating active euthanasia was accepted in April 2001--may shed light on the strengths as well as the weaknesses of the slippery slope argument in the context of the euthanasia debate. This paper consists of three parts. First, it clarifies the Dutch legislation on euthanasia and explains the cultural context in which it originated. Second, it looks at the argument of the slippery slope. A logical and an empirical version are distinguished, and the latter, though philosophically less interesting, proves to be most relevant in the discussion on euthanasia. Thirdly, it addresses the question whether Dutch experiences in the process of legalizing euthanasia justify the fear of the slippery slope. The conclusion is that Dutch experiences justify some caution.

  16. Physical Analysis Work for Slope Stability at Shah Alam, Selangor

    Science.gov (United States)

    Ishak, M. F.; Zaini, M. S. I.

    2018-04-01

    Slope stability analysis is performed to assess the equilibrium conditions and the safe design of a human-made or natural slope to find the endangered areas. Investigation of potential failure and determination of the slope sensitivity with regard to safety, reliability and economics were parts of this study. Ground anchor is designed to support a structure in this study. Ground anchor were implemented at the Mechanically Stabilized Earth (MSE) wall along Anak Persiaran Jubli Perak to overcome the further cracking of pavement parking, concrete deck and building of the Apartments. A result from the laboratory testing of soil sample such as index test and shear strength test were applied to the Slope/W software with regard to the ground anchors that were implemented. The ground anchors were implemented to increase the value of the factor of safety (FOS) of the MSE Wall. The value of the factor of safety (FOS) before implementing the ground anchor was 0.800 and after the ground anchor was implemented the value increase to 1.555. The increase percentage of factor of safety by implementing on stability of slope was 94.38%.

  17. Discharge Coefficient of Rectangular Short-Crested Weir with Varying Slope Coefficients

    Directory of Open Access Journals (Sweden)

    Yuejun Chen

    2018-02-01

    Full Text Available Rectangular short-crested weirs are widely used for simple structure and high discharge capacity. As one of the most important and influential factors of discharge capacity, side slope can improve the hydraulic characteristics of weirs at special conditions. In order to systemically study the effects of upstream and downstream slope coefficients S1 and S2 on overflow discharge coefficient in a rectangular short-crested weir the Volume of Fluid (VOF method and the Renormalization Group (RNG κ-ε turbulence model are used. In this study, the slope coefficient ranges from V to 3H:1V and each model corresponds to five total energy heads of H0 ranging from 8.0 to 24.0 cm. Comparisons of discharge coefficients and free surface profiles between simulated and laboratory results display a good agreement. The simulated results show that the difference of discharge coefficients will decrease with upstream slopes and increase with downstream slopes as H0 increases. For a given H0, the discharge coefficient has a convex parabolic relation with S1 and a piecewise linearity relation with S2. The maximum discharge coefficient is always obtained at S2 = 0.8. There exists a difference between upstream and downstream slope coefficients in the influence range of free surface curvatures. Furthermore, a proposed discharge coefficient equation by nonlinear regression is a function of upstream and downstream slope coefficients.

  18. Overnight changes in the slope of sleep slow waves during infancy.

    Science.gov (United States)

    Fattinger, Sara; Jenni, Oskar G; Schmitt, Bernhard; Achermann, Peter; Huber, Reto

    2014-02-01

    Slow wave activity (SWA, 0.5-4.5 Hz) is a well-established marker for sleep pressure in adults. Recent studies have shown that increasing sleep pressure is reflected by an increased synchronized firing pattern of cortical neurons, which can be measured by the slope of sleep slow waves. Thus we aimed at investigating whether the slope of sleep slow waves might provide an alternative marker to study the homeostatic regulation of sleep during early human development. All-night sleep electroencephalography (EEG) was recorded longitudinally at 2, 4, 6, and 9 months after birth. Home recording. 11 healthy full-term infants (5 male, 6 female). None. The slope of sleep slow waves increased with age. At all ages the slope decreased from the first to the last hour of non rapid-eye-movement (NREM) sleep, even when controlling for amplitude differences (P why the steepest slope was found in the occipital derivation. Our results provide evidence that the homeostatic regulation of sleep develops early in human infants.

  19. Temporal behavior of deep-seated gravitational slope deformations: A review

    Czech Academy of Sciences Publication Activity Database

    Pánek, T.; Klimeš, Jan

    2016-01-01

    Roč. 156, MAY (2016), s. 14-38 ISSN 0012-8252 Institutional support: RVO:67985891 Keywords : deep-seated gravitational slope deformations * catastrophic slope failures * deformation rates * dating * monitoring Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 7.051, year: 2016

  20. DRENA: A model for the transport of nuclides in drainage slopes

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-01-01

    This report presents documentation and a user's manual for program DRENA, a mathematical model of nuclides transfer in simple slopes and sections of a drainage catchment. Mathematical equations and physical principles utilized to develop the code are presented in section 2. The flowchart and some mathematic and numerical details are presented in Section 3. Section 4 presents an overview of how problems should be set up to properly use the code as well as the detailed input instructions and output results formats. One example problem, including sample input data sets and output data, are presented in Section 5. The complete program listings including comments are presented in the Appendices. Nuclides are assumed to enter the catchment via atmospheric deposition and then carried by the water runoff and the dragged sediments. The desorption/adsorption dynamics between water and sediments are considered to be in the equilibrium given by a Kd parameter, a distribution coefficient. Codell's and Einstein expressions for the caudal and concentration of dragged sediments are utilized. (Author)

  1. DRENA: A model for the transport of nuclides in drainage slopes

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-01-01

    This report presents documentation and a user's manual for program DRENA, a mathematical model of nuclides transfer in simple slopes and sections of a drainage catchment. Mathematical equations and physical principles utilized to develop the code are presented in section 2. The flowchart and some mathematic and numerical details are presented in Section 3. Section 4 presents an overview of how problems should be set up to properly use the code as well as the detailed input instructions and output results formats. One example problem, including sample input data sets and output data, are presented in Section 5. The complete program listings including comments are presented in the Appendices. Nuclides are assumed to enter the catchment via atmospheric deposition and then carried by the water runoff and the dragged sediments. The desorption/adsorption dynamics between water and sediments are considered to be in the equilibrium given by a Kd parameter, a distribution coefficient. Codell's and Einstein expressions for the caudal and concentration of dragged sediments are utilized. (Author) 36 refs

  2. DRENA: A model for the transport of nuclides in drainage slopes

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Olivares, A.; Aguero, A.; Pinedo, P.

    1994-07-01

    This report presents documentation and a user's manual for program DRENA, a mathematical model of nuclides transfer in simple slopes and sections of a drainage catchment. Mathematical equations and physical principles utilized to develop the code are presented in section 2. The flowchart and some mathematic and numerical details are presented in Section 3. Section 4 presents an overview of how problems should be set up to properly use the code as well as the detailed input instructions and output results formats. One example problem, including sample input data sets and output data, are presented in Section 5. The complete program listings including comments are presented in the Appendices. Nuclides are assumed to enter the catchment via atmospheric deposition and then carried by the water runoff and the dragged sediments. The desorption/adsorption dynamics between water and sediments are considered to be in the equilibrium given by a Kd parameter, a distribution coefficient. Codell's and Einstein expressions for the caudal and concentration of dragged sediments are utilized. (Author) 36 refs.

  3. DRENA: A model for the transport of nuclides in drainage slopes

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Olivares, A; Aguero, A; Pinedo, P

    1994-07-01

    This report presents documentation and a user's manual for program DRENA, a mathematical model of nuclides transfer in simple slopes and sections of a drainage catchment. Mathematical equations and physical principles utilized to develop the code are presented in section 2. The flowchart and some mathematic and numerical details are presented in Section 3. Section 4 presents an overview of how problems should be set up to properly use the code as well as the detailed input instructions and output results formats. One example problem, including sample input data sets and output data, are presented in Section 5. The complete program listings including comments are presented in the Appendices. Nuclides are assumed to enter the catchment via atmospheric deposition and then carried by the water runoff and the dragged sediments. The desorption/adsorption dynamics between water and sediments are considered to be in the equilibrium given by a Kd parameter, a distribution coefficient. Codell's and Einstein expressions for the caudal and concentration of dragged sediments are utilized. (Author) 36 refs.

  4. DEPOSITIONAL ARCHITECTURE, FACIES CHARACTER AND GEOCHEMICAL SIGNATURE OF THE TIVOLI TRAVERTINES (PLEISTOCENE, ACQUE ALBULE BASIN, CENTRAL ITALY

    Directory of Open Access Journals (Sweden)

    GIOVANNA DELLA PORTA

    2017-08-01

    Full Text Available Facies character, diagenesis, geochemical signature, porosity, permeability, and geometry of the upper Pleistocene Tivoli travertines were investigated integrating information from six borehole cores, drilled along a 3 km N-S transect, and quarry faces, in order to propose a revised depositional model. Travertines overlie lacustrine and alluvial plain marls, siltstones, sandstones and pyroclastic deposits from the Roman volcanic districts. In the northern proximal area, with respect to the inferred hydrothermal vents, travertines accumulated in gently-dipping, decametre-scale shallow pools of low-angle terraced slopes. The intermediate depositional zone, 2 km southward, consisted of smooth and terraced slopes dipping S and E. In the southernmost distal zone, travertine marshes dominated by coated vegetation and Charophytes interfingered with lacustrine siltstones and fluvial sandstones and conglomerates. Travertine carbon and oxygen stable isotope data confirm the geothermal origin of the precipitating spring water. The travertine succession is marked by numerous intraclastic/extraclastic wackestone to rudstone beds indicative of non-deposition and erosion during subaerial exposure, due to temporary interruption of the vent activity or deviation of the thermal water flow. These unconformities identify nine superimposed travertine units characterized by aggradation in the proximal zone and southward progradation in the intermediate to distal zones. The wedge geometry of the travertine system reflects the vertical and lateral superimposition of individual fan-shaped units in response to changes in the vent location, shifting through time to lower elevations southward. The complexity of the travertine architecture results from the intermittent activity of the vents, their locations, the topographic gradient, thermal water flow paths and the rates and modes of carbonate precipitation.

  5. Analysis of rainfall characteristics and its related disasters of slag disposal pit of a certain Gold-Copper Deposit in Fujian province

    Science.gov (United States)

    Pan, Huali; Hu, Mingjian; Ou, Guoqiang

    2017-04-01

    According to the geological investigation in Fujian province, the total number of geological disasters was 9513, in which the number of landslide, collapse, unstable slope and surface collapse was 5816, 1888, 1591, 103 and 115 respectively. The main geological disaster was the landslide with 61.1% of total geological disasters. Among all these geological disasters, only 6.0% was relative stable, 17.0% was basic stable, nearly 76.0% was unstable. The slope disaster was the main geological disaster, if the unstable slope was the potential landslide or collapse; the slope collapse was 98.0% of all geological disasters. The rainfall, in particular the heavy rain, was direct dynamic factor for geological disasters, but the occurrence probability of geological disasters was different because of the sensitivity of the geological environment though of the same intensity rainfall. To obtain the characteristics of soil erosion under the rainfall condition, the rainfall characteristics and its related disasters of slag disposal pit of a certain Gold-Copper Deposit in Fujian province was analyzed by the meteorological and rainfall data. According to the distribution of monitoring stations of hydrological and rainfall in Longyan city of Fujian province and the location of gold-copper deposit, the Shanghang monitoring station of hydrological and rainfall was chosen, which is the nearest one to the gold-copper deposit. Then main parameters of the prediction model, the antecedent precipitation, the rainfall on the day and the rainfall threshold, were calculated by using the rainfall data from 2002 to 2010. And the relationship between geological disasters and the rainfall characteristics were analyzed. The results indicated that there was high risk for the debris flow with landslide collapse when either the daily rainfall was more than 100.0 mm, or the total rainfall was more than 136.0mm in the gold-copper deposit and the Shanghang region. At the same time, although there was few

  6. [Community structure of soil fauna in Eucalyptus grandis plantations at different slope locations].

    Science.gov (United States)

    Zhao, Yu; Zhong, Yu; Zhang, Jian; Yang, Wan-qin

    2010-09-01

    To understand the effects of slope location on the community structure of soil fauna in Eucalyptus grandis plantation, an investigation was made on the soil fauna in 3 E. grandis plantations at different slope locations in the hilly area of Sichuan Province from January to October 2009. A total of 39,2762 individuals were observed, belonging to 146 groups, 7 phyla, 16 classes, and 31 orders. The community composition, trophic group, diversity, and seasonal dynamics of soil fauna in the plantations all varied with slope. The abundance of macro-fauna, xeric meso- and micro-fauna, saprophagous macro-fauna, and omnivorous xeric meso- and micro-fauna increased with the decrease of slope, indicating that soil fauna had sensitive responses to the soil environmental factors affected by slope. Significant differences in the diversity of soil saprophagous macro-fauna and hygrophilous meso- and micro-fauna were observed at different slope locations, suggesting that these two faunal groups could be used as the indicators of the habitat heterogeneity of E. grandis plantations at different slope. Overall, slope location had definite effects on the community structure and distribution of soil fauna in the E. grandis plantations, but the effects were not statistically significant.

  7. Observations and models of simple nocturnal slope flows

    International Nuclear Information System (INIS)

    Doran, J.C.; Horst, J.W.

    1983-01-01

    Measurements of simple nocturnal slope winds were taken on Rattlesnake Mountain, a nearly ideal two-dimensional ridge. Tower and tethered balloon instrumentation allowed the determination of the wind and temperature characteristics of the katabatic layer as well as the ambient conditions. Two cases were chosen for study; these were marked by well-defined surface-based temperature inversions and a low-level maximum in the downslope wind component. The downslope development of the slope flow could be determined from the tower measurements, and showed a progressive strenghtening of the katabatic layer. Hydraulic models developed by Manins and Sawford (1979a) and Briggs (1981) gave useful estimates of drainage layer depths, but were not otherwise applicable. A simple numerical model that relates the eddy diffusivity to the local turbulent kinetic energy was found to give good agreement with the observed wind and temperature profiles of the slope flows

  8. Characterization of Unstable Rock Slopes Through Passive Seismic Measurements

    Science.gov (United States)

    Kleinbrod, U.; Burjanek, J.; Fäh, D.

    2014-12-01

    Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. An analysis of ambient vibrations of unstable rock slopes might be a new alternative to the already existing methods, e.g. geotechnical displacement measurements. Systematic measurements have been performed recently in Switzerland to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. Each measurement setup included a reference station, which was installed on a stable part close to the instability. Recorded ground motion is highly directional in the unstable parts of the rock slope, and significantly amplified with respect to stable areas. These effects are strongest at certain frequencies, which were identified as eigenfrequencies of the unstable rock mass. In most cases the directions of maximum amplification are perpendicular to open cracks and in good agreement with the deformation directions obtained by geodetic measurements. Such unique signatures might improve our understanding of slope structure and stability. Thus we link observed vibration characteristics with available results of detailed geological characterization. This is supported by numerical modeling of seismic wave propagation in fractured media with complex topography.For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

  9. Granular flows on erodible layers: type and evolution of flow and deposit structures

    Science.gov (United States)

    Crosta, G.; De Blasio, F.; De Caro, M.; Volpi, G.; Frattini, P.

    2012-04-01

    The interaction of a fast moving landslide mass with the basal layer over which movement takes place has been discussed in previous contributions. Nevertheless, the evolution of the structures within the moving mass and the erodible layer are still to be described in detail (Hungr and Evans, 2004; Crosta et al., 1992, 2006, 2009, 2011; Dufresne et al., 2010; Mangeney et al., 2010) and modeling results (Crosta et al., 2006, 2009, 2011; Mangeney et al., 2010). We present some of the results from a campaign of laboratory experiments aimed at studying the evolution of a granular flow at the impact with and during the successive spreading over a cohesionless erodible layer. We performed these test to study the processes and to collect data and evidences to compare them with the results of numerical simulations and to verify capabilities of numerical codes. The laboratory setup consists of an inclined slope and an horizontal sector where release and transport, and deposition take place, respectively. Materials used for the tests are: a uniform rounded siliceous sand (Hostun sand; 0.125-0.5 mm) commonly adopted in lab tests because free of scale effects, and a gravel made of angular elements (12 mm in ave. size). Both the materials have been tested in dry conditions. Different slope angles have been tested (40, 45, 50, 55, 50, 66°) as well as different thicknesses of the erodible layer (0, 0.5, 1, 2 cm) and volumes of the released material (1.5, 3, 5, 9.6 liters). Tests have been monitored by means of a high speed camera and the pre- and post-failure geometries have been surveyed by means of a laser scanner. Deposit description allowed also the computation of volumes and the characterization of the different structures developed and frozen into the deposit. Experiments allowed us to observe the extreme processes occurring during the movement and the mise en place of the deposits. In particular, we observe the formation of a clear wave-like feature developing during the

  10. Flow under standing waves Part 2. Scour and deposition in front of breakwaters

    DEFF Research Database (Denmark)

    Gislason, Kjartan; Fredsøe, Jørgen; Sumer, B. Mutlu

    2009-01-01

    and routines for, updating the computational mesh based on the mass balance of sediment. Laboratory experiments of scour also were conducted in a wave flume to obtain data for model verification. Both in the numerical simulations and in the laboratory experiment, two kinds of breakwaters were used: A vertical......A 3-D general purpose Navier-Stokes solver was used to calculate the 2-D flow in front of the breakwater. The k-omega, SST (shear-stress transport) model was selected as the turbulence model. The morphologic model of the present code couples the flow solution with a sediment transport description......-wall breakwater; and a sloping-wall breakwater (Slope: 1:1.5). Numerically obtained scour-deposition profiles were compared with the experiments. The numerical results show that the equilibrium scour depth normalized by the wave height decreases with increasing water-depth-to-wave-length ratio. Although...

  11. Antarctic Ice Sheet Slope and Aspect Based on Icesat's Repeat Orbit Measurement

    Science.gov (United States)

    Yuan, L.; Li, F.; Zhang, S.; Xie, S.; Xiao, F.; Zhu, T.; Zhang, Y.

    2017-09-01

    Accurate information of ice sheet surface slope is essential for estimating elevation change by satellite altimetry measurement. A study is carried out to recover surface slope of Antarctic ice sheet from Ice, Cloud and land Elevation Satellite (ICESat) elevation measurements based on repeat orbits. ICESat provides repeat ground tracks within 200 meters in cross-track direction and 170 meters in along-track direction for most areas of Antarctic ice sheet. Both cross-track and along-track surface slopes could be obtained by adjacent repeat ground tracks. Combining those measurements yields a surface slope model with resolution of approximately 200 meters. An algorithm considering elevation change is developed to estimate the surface slope of Antarctic ice sheet. Three Antarctic Digital Elevation Models (DEMs) were used to calculate surface slopes. The surface slopes from DEMs are compared with estimates by using in situ GPS data in Dome A, the summit of Antarctic ice sheet. Our results reveal an average surface slope difference of 0.02 degree in Dome A. High resolution remote sensing images are also used in comparing the results derived from other DEMs and this paper. The comparison implies that our results have a slightly better coherence with GPS observation than results from DEMs, but our results provide more details and perform higher accuracy in coastal areas because of the higher resolution for ICESat measurements. Ice divides are estimated based on the aspect, and are weakly consistent with ice divides from other method in coastal regions.

  12. Characterization of the Morphometry of Impact Craters Hosting Polar Deposits in Mercury's North Polar Region

    Science.gov (United States)

    Talpe Matthieu; Zuber, Maria T.; Yang, Di; Neumann, Gregory A.; Solomon, Sean C.; Mazarico, Erwan; Vilas, Faith

    2012-01-01

    Earth-based radar images of Mercury show radar-bright material inside impact craters near the planet s poles. A previous study indicated that the polar-deposit-hosting craters (PDCs) at Mercury s north pole are shallower than craters that lack such deposits. We use data acquired by the Mercury Laser Altimeter on the MESSENGER spacecraft during 11 months of orbital observations to revisit the depths of craters at high northern latitudes on Mercury. We measured the depth and diameter of 537 craters located poleward of 45 N, evaluated the slopes of the northern and southern walls of 30 PDCs, and assessed the floor roughness of 94 craters, including nine PDCs. We find that the PDCs appear to have a fresher crater morphology than the non-PDCs and that the radar-bright material has no detectable influence on crater depths, wall slopes, or floor roughness. The statistical similarity of crater depth-diameter relations for the PDC and non-PDC populations places an upper limit on the thickness of the radar-bright material (< 170 m for a crater 11 km in diameter) that can be refined by future detailed analysis. Results of the current study are consistent with the view that the radar-bright material constitutes a relatively thin layer emplaced preferentially in comparatively young craters.

  13. Instability and deformation in the sedimentary cover on the upper slope of the southern Aquitaine continental margin, north of the Capbreton canyon (Bay of Biscay

    Directory of Open Access Journals (Sweden)

    Eliane Gonthier

    2006-06-01

    Full Text Available Acoustic and core data have recently been collected on the shelf break and the upper part of the slope of the south Aquitaine continental margin. They reveal the major role played by mass-flow gravity processes in deposit erosion and redistribution, modelling of the sea-bed, and transfer of sediment toward the deep-sea. The study region is bounded in the south by the Capbreton canyon. The northern area, which shows a smooth morphology, is characterised by small-scale deformations due to sediment creep or low-amplitude slide processes. The deformations are associated with mini listric-like faults that bound packets of sediments in which the deposit geometry is typical of constructional sediment waves. These sediment waves result from the interaction of depositional and gravity deformation processes. In the southern area, closer to the canyon, wave-like structures are still present but mostly of smaller size. They only result from gravity deformation processes without any evidence of constructional processes. In the vicinity of the Capbreton canyon, the shelf break and upper slope have a much more uneven morphology with sedimentary reliefs, escarpments and depressions directed toward the canyon thalweg. The depressions look like slide scars, and could be the result of regressive slides initiated at the top of the canyon flank. The age of the sliding event responsible for the formation of the depression observed today could be middle to upper Quaternary. Since their formation, these depressions act as conduits that channel the transfer of shelf sediment into the canyon, as demonstrated by the occurrence of a meandering channel on the sea-floor of one depression.

  14. Late Quaternary paleoenvironmental records from the Chatanika River valley near Fairbanks (Alaska)

    Science.gov (United States)

    Schirrmeister, Lutz; Meyer, Hanno; Andreev, Andrei; Wetterich, Sebastian; Kienast, Frank; Bobrov, Anatoly; Fuchs, Margret; Sierralta, Melanie; Herzschuh, Ulrike

    2016-09-01

    ice and sediments of unit C. Pollen data show that spruce forests and wetlands dominated the area. The macrofossil remains of Picea, Larix, and Alnus incana ssp. tenuifolia also prove the existence of boreal coniferous forests during the mid-Wisconsin interstadial, which were replaced by treeless tundra-steppe vegetation during the late Wisconsin stadial. Unit C is discordantly overlain by the 2-m-thick late Holocene deposits of unit D. The pollen record of unit D indicates boreal forest vegetation similar to the modern one. The permafrost record from the Vault Creek tunnel reflects more than 90 ka of periglacial landscape dynamics triggered by fluvial and eolian accumulation, and formation of ice-wedge polygons and post-depositional deformation by slope processes. The record represents a typical Wisconsin valley-bottom facies in Central Alaska.

  15. A new design equation for drained stability of conical slopes in cohesive-frictional soils

    Directory of Open Access Journals (Sweden)

    Boonchai Ukritchon

    2018-04-01

    Full Text Available New plasticity solutions to the drained stability of conical slopes in homogeneous cohesive-frictional soils were investigated by axisymmetric finite element limit analysis. Three parameters were studied, i.e. excavated height ratios, slope inclination angles, and soil friction angles. The influences of these parameters on the stability factor and predicted failure mechanism of conical slopes were discussed. A new design equation developed from a nonlinear regression of the lower bound solution was proposed for drained stability analyses of a conical slope in practice. Numerical examples were given to demonstrate a practical application of the proposed equation to stability evaluations of conical slopes with both associated and non-associated flow rules. Keywords: Limit analysis, Slope stability, Conical slope, Unsupported excavation, Cohesive-frictional soils

  16. Influences of geological parameters to probabilistic assessment of slope stability of embankment

    Science.gov (United States)

    Nguyen, Qui T.; Le, Tuan D.; Konečný, Petr

    2018-04-01

    This article considers influences of geological parameters to slope stability of the embankment in probabilistic analysis using SLOPE/W computational system. Stability of a simple slope is evaluated with and without pore–water pressure on the basis of variation of soil properties. Normal distributions of unit weight, cohesion and internal friction angle are assumed. Monte Carlo simulation technique is employed to perform analysis of critical slip surface. Sensitivity analysis is performed to observe the variation of the geological parameters and their effects on safety factors of the slope stability.

  17. Analysis of local slopes at the InSight landing site on Mars

    Science.gov (United States)

    Fergason, Robin L.; Kirk, Randolph L.; Cushing, Glen; Galuszka, Donna M.; Golombek, Matthew P.; Hare, Trent M.; Howington-Kraus, Elpitha; Kipp, Devin M; Redding, Bonnie L.

    2017-01-01

    To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1-meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1-meter baselines of 3.2°. In addition, a mosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse 9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline program dem_mosaic produced the best results. For the HRSC-CTX-HiRISE DTM mosaic, more than 99 % of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

  18. Effect of bottom slope on the nonlinear triad interactions in shallow water

    Science.gov (United States)

    Chen, Hongzhou; Tang, Xiaocheng; Zhang, Ri; Gao, Junliang

    2018-05-01

    This paper aims at investigating the effect of bottom slope to the nonlinear triad interactions for irregular waves propagating in shallow water. The physical experiments are conducted in a wave flume with respect to the transformation of waves propagating on three bottom slopes ( β = 1/15, 1/30, and 1/45). Irregular waves with different type of breaking that are mechanically generated based on JONSWAP spectra are used for the test. The obviously different variations of spectra measured on each bottom reveal a crucial role of slope effect in the energy transfer between harmonics. The wavelet-based bispectrum were used to examine the bottom slope effect on the nonlinear triad interactions. Results show that the different bottom slopes which waves are propagated on will cause a significant discrepancy of triad interactions. Then, the discussions on the summed bicoherence which denote the distribution of phase coupling on each frequency further clarify the effect of bottom slope. Furthermore, the summed of the real and imaginary parts of bispectrum which could reflect the intensity of frequency components participating in the wave skewness and asymmetry were also investigated. Results indicate that the value of these parameters will increase as the bottom slope gets steeper.

  19. Direct observations of the Antarctic Slope Current transport at 113°E

    Science.gov (United States)

    Peña-Molino, B.; McCartney, M. S.; Rintoul, S. R.

    2016-10-01

    The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time-mean flow consists of a surface-intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom-intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time-mean transport of the ASC is -29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

  20. Water-rock interaction under peri-glacial conditions: example of the secondary carbonates of the Broegger Peninsula (Spitzbergen)

    International Nuclear Information System (INIS)

    Marlin, C.; Dever, L.

    1998-01-01

    Measurements of the isotopic and chemical contents of soil water and carbonates at different field sites in Spitzbergen were undertaken to study the precipitation conditions of soil secondary calcites under the current peri-glacial climate. A main experimental site ('cote 80') has been established located on a fluvio-glacial terrasse at 80 m.a.s.l. near Ny Alesund (79 deg N, 12 deg. E). The active layer is at around 1.2 m depth on a continuous permafrost. The soil temperatures measured every 5 cm from the surface to the permafrost show that the freezing fronts move both the surface and permafrost, converging at around 0.6 m depth where the system is closed. During the beginning of the freezing period, the solute content increases in the residual water according to the distribution coefficient between water and ice. Calcite precipitation occurs in a second stage as indicated by the simultaneous decrease of the calcite saturation index and increase of the concentration of non-interactive elements. Chemical and isotopic ( 18 O, 2 H, 13 C et 14 C) analyses have been made on the different samples with a mineralogical description of the carbonate coatings obtained by SEM and microprobe analyses. The isotopic values result from a mixing between recent calcites and 'old' calcites. The recent calcites are probably in isotopic equilibrium with the present day solutions. The 'old calcites' have precipitated under colder conditions than today. The low radiocarbon activities (10.2 to 24.8 pcm) of the 'cote 80' site indicate that the 'old calcites' have precipitated during the last interglacial period or an inter-stadial period of the Pleistocene. The good relationship between the carbon- 14 activity and the carbon- 13 content indicates that the beginning of the pedogenesis is not identical at all sites and is dependent on the timing of deglaciation and vulnerability of rocks to frost-weathering. (authors)

  1. Interesting insights into instability of slopes and rock fall in the morphodynamic Himalayan terrane

    Science.gov (United States)

    Singh, T. N.; Vishal, V.; Pradhan, S. P.

    2015-12-01

    Himalayan mountain ranges are tectonically and seismically very active and experience many disastrous events with time due to slope failure. Frequent failures of rock cut slopes cause obstruction in traffic and often lead to fatalities. In recent years, the number of tragedies has increased when associated with regional phenomena such at the Kedarnath tragedy of 2013 and the Gorkha earthquake of 2015. The influence of such phenomena on the stability of slopes along important national highways and key settlement areas only raise the risk to lives and property. We conducted a multi-approach investigation for some key slopes along the National Highway 58 in Uttarakhand Himalaya, India. A very detailed field work was conducted to identify the unstable slopes and those with some history of failure. The pertinent geomechanical characteristics of the representative rock samples were determined in the laboratory. Based on the structural data, kinematic analysis was carried out. Finally the slopes were simulated using FDM based simulator, Flac/Slope for analysing the health of the slopes and Rockfall 4.0 to investigate the phenomenon of rockfall along the Highway. It was found that few slopes were weak due to the inherent weak rock materials while few slopes made up of high strength rocks were effectively weak due to prone-to-failure orientation of the joints. Quantification of bounce-height of rock blocks during fall, their energy, velocity and displacement along the slope was also done. Using 3-D simulations, few critically-stable slopes that appear to be stable, were identified. Little ground movement could be capable of triggering a large scale failure in the area. Slopes in the studied region are under threat to failure and need immediate proper planning using the suggested remedial measures.

  2. Green technologies for reducing slope erosion.

    Science.gov (United States)

    2010-01-01

    As climate change alters precipitation patterns, departments of transportation will increasingly face the problem of : slope failures, which already cost California millions of dollars in repair work annually. Caltrans hopes to prevent : these failur...

  3. Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope.

    Science.gov (United States)

    Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

    2017-03-15

    By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes.

  4. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    Science.gov (United States)

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad

    2010-01-01

    In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au, or barite. Numerous occurrences of hydrothermal zebra dolomite (HZD), comprised of alternating layers of dark replacement and light void-filling sparry or saddle dolomite, are present in Paleozoic platform and slope carbonate rocks on the eastern side of the Great Basin physiographic province. Locally, it is associated with mineral deposits of barite, Ag-Pb-Zn, and Au. In this paper the spatial distribution of HZD occurrences, their stratigraphic position, morphological characteristics, textures and zoning, and chemical and stable isotopic compositions were determined to improve understanding of their age, origin, and relation to dolostone, ore deposits, and the tectonic evolution of the Great Basin. In northern and central Nevada, HZD is coeval and cogenetic with Late Devonian and Early Mississippian Sedex Au, Zn, and barite deposits and may be related to Late Ordovician Sedex barite deposits. In southern Nevada and southwest California, it is cogenetic with small MVT Ag-Pb-Zn deposits in rocks as young as Early Mississippian. Over Paleozoic time, the Great Basin was at equatorial paleolatitudes with episodes of arid paleoclimates. Several occurrences of HZD are crosscut by Mesozoic or Cenozoic intrusions, and some host younger pluton-related polymetallic replacement and Carlin-type gold deposits. The distribution of HZD in space (carbonate platform, margin, and slope) and stratigraphy (Late Neoproterozoic Ediacaran-Mississippian) roughly parallels that of dolostone and both are prevalent in Devonian strata. Stratabound HZD is best developed in Ediacaran and Cambrian units, whereas

  5. Critical Loads of Atmospheric Nitrogen Deposition for Aquatic Ecosystems in Yosemite and Sequoia and Kings Canyon National Parks

    Science.gov (United States)

    Nanus, L.; Clow, D. W.; Sickman, J. O.

    2016-12-01

    High-elevation aquatic ecosystems in Yosemite (YOSE) and Sequoia and Kings Canyon (SEKI) National Parks are impacted by atmospheric nitrogen (N) deposition associated with local and regional air pollution. Documented effects include elevated surface water nitrate concentrations, increased algal productivity, and changes in diatom species assemblages. Annual wet inorganic N deposition maps, developed at 1-km resolution for YOSE and SEKI to quantify N deposition to sensitive high-elevation ecosystems, range from 1.0 to over 5.0 kg N ha-1 yr-1. Critical loads of N deposition for nutrient enrichment of aquatic ecosystems were quantified and mapped using a geostatistical approach, with N deposition, topography, vegetation, geology, and climate as potential explanatory variables. Multiple predictive models were created using various combinations of explanatory variables; this approach allowed us to better quantify uncertainty and more accurately identify the areas most sensitive to atmospherically deposited N. The lowest critical loads estimates and highest exceedances identified within YOSE and SEKI occurred in high-elevation basins with steep slopes, sparse vegetation, and areas of neoglacial till and talus. These results are consistent with previous analyses in the Rocky Mountains, and highlight the sensitivity of alpine ecosystems to atmospheric N deposition.

  6. Denudational slope processes on weathered basalt in northern California: 130 ka history of soil development, periods of slope stability and colluviation, and climate change

    Science.gov (United States)

    McDonald, Eric; Harrison, Bruce; Baldwin, John; Page, William; Rood, Dylan

    2017-04-01

    The geomorphic history of hillslope evolution is controlled by multiple types of denudational processes. Detailed analysis of hillslope soil-stratigraphy provides a means to identify the timing of periods of slope stability and non-stability, evidence of the types of denudational processes, and possible links to climatic drivers. Moreover, the degree of soil formation and the presence of buried or truncated soils provide evidence of the relative age of alternating periods of colluviation and stability. We use evaluation of soil stratigraphy, for a small forested hillslope (soils and slope colluvium are derived from highly weathered basalt. Stratigraphic interpretation is reinforced with soil profile development index (PDI) derived age estimates, tephrochronology, luminescence ages on colluvium, and He3 nuclide exposure dates. Soils formed along hilltop ridges are well developed and reflect deep (>2-3 m) in-situ weathering of the basalt bedrock. PDI age estimates and He3 exposure dates indicate that these hilltop soils had been in place for 100-130 ka, implying a long period of relative surface stability. At about 40-30 ka, soil stratigraphy indicates the onset of 3 distinct cycles of denudation of the hilltop and slopes. Evidence for changes in stability and onset of soil erosion is the presence of several buried soils formed in colluvium downslope of the hilltop. These buried soils have formed in sediment derived from erosion of the hilltop soils (i.e. soil parent material of previously weathered soil matrix and basalt cobbles). The oldest buried soil indicates that slope stability was re-established between 32-23 ka, with stability and soil formation lasting to about 10 ka. Soil-stratigraphy indicates that two additional intervals of downslope transport of sediment between 6-10 ka, and 2-5 ka. Soil properties indicate that the primary method of downslope transport is largely due to tree throw and faunal burrowing. Onset of slope instability at 40-30 ka appears to

  7. The Isopach Mapping of Volcanic Deposits of Mount Samalas 1257 AD Based on the Values of Resistivity and Physical Properties

    Directory of Open Access Journals (Sweden)

    Hiden Hiden

    2017-08-01

    Full Text Available A detailed study had been conducted on the sediment of Mount Samalas’ volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES and 2D mapping show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m than in areas of alluvial (<25 m. The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km.

  8. Concentrations, Deposition, and Effects of Nitrogenous Pollutants in Selected California Ecosystems

    Directory of Open Access Journals (Sweden)

    Andrzej Bytnerowicz

    2001-01-01

    Full Text Available Atmospheric deposition of nitrogen (N in California ecosystems is ecologically significant and highly variable, ranging from about 1 to 45 kg/ha/year. The lowest ambient concentrations and deposition values are found in the eastern and northern parts of the Sierra Nevada Mountains and the highest in parts of the San Bernardino and San Gabriel Mountains that are most exposed to the Los Angeles air pollution plume. In the Sierra Nevada Mountains, N is deposited mostly in precipitation, although dry deposition may also provide substantial amounts of N. On the western slopes of the Sierra Nevada, the majority of airborne N is in reduced forms as ammonia (NH3 and particulate ammonium (NH4+ from agricultural activities in the California Central Valley. In southern California, most of the N air pollution is in oxidized forms as nitrogen oxides (NOx, nitric acid (HNO3, and particulate nitrate (NO3– resulting from fossil fuel combustion and subsequent complex photochemical reactions. In southern California, dry deposition of gases and particles provides most (up to 95% of the atmospheric N to forests and other ecosystems. In the mixed-conifer forest zone, elevated deposition of N may initially benefit growth of vegetation, but chronic effects may be expressed as deterioration of forest health and sustainability. HNO3 vapor alone has a potential for toxic effects causing damage of foliar surfaces of pines and oaks. In addition, dry deposition of predominantly HNO3 has lead to changes in vegetation composition and contamination of ground- and stream water where terrestrial N loading is high. Long-term, complex interactions between N deposition and other environmental stresses such as elevated ozone (O3, drought, insect infestations, fire suppression, or intensive land management practices may affect water quality and sustainability of California forests and other ecosystems.

  9. Finding evidence for density fluctuation effects on electron cyclotron heating deposition profiles on DIII-D

    International Nuclear Information System (INIS)

    Brookman, M. W.; Austin, M. E.; Petty, C. C.

    2015-01-01

    Theoretical work, computation, and results from TCV [J. Decker “Effect of density fluctuations on ECCD in ITER and TCV,” EPJ Web of Conf. 32, 01016 (2012)] suggest that density fluctuations in the edge region of a tokamak plasma can cause broadening of the ECH deposition profile. In this paper, a GUI tool is presented which is used for analysis of ECH deposition as a first step towards looking for this broadening, which could explain effects seen in previous DIII-D ECH transport studies [K.W. Gentle “Electron energy transport inferences from modulated electron cyclotron heating in DIII-D,” Phys. Plasmas 13, 012311 (2006)]. By applying an FFT to the T e measurements from the University of Texas’s 40-channel ECE Radiometer, and using a simplified thermal transport equation, the flux surface extent of ECH deposition is determined. The Fourier method analysis is compared with a Break-In-Slope (BIS) analysis and predictions from the ray-tracing code TORAY. Examination of multiple Fourier harmonics and BIS fitting methods allow an estimation of modulated transport coefficients and thereby the true ECH deposition profile. Correlations between edge fluctuations and ECH deposition in legacy data are also explored as a step towards establishing a link between fluctuations and deposition broadening in DIII-D

  10. Finding evidence for density fluctuation effects on electron cyclotron heating deposition profiles on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Brookman, M. W., E-mail: brookmanmw@fusion.gat.com; Austin, M. E. [Institute for Fusion Studies, University of Texas at Austin, MS 13-505, 3483 Dunhill St, San Diego, CA 92121-1200 (United States); Petty, C. C. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States)

    2015-12-10

    Theoretical work, computation, and results from TCV [J. Decker “Effect of density fluctuations on ECCD in ITER and TCV,” EPJ Web of Conf. 32, 01016 (2012)] suggest that density fluctuations in the edge region of a tokamak plasma can cause broadening of the ECH deposition profile. In this paper, a GUI tool is presented which is used for analysis of ECH deposition as a first step towards looking for this broadening, which could explain effects seen in previous DIII-D ECH transport studies [K.W. Gentle “Electron energy transport inferences from modulated electron cyclotron heating in DIII-D,” Phys. Plasmas 13, 012311 (2006)]. By applying an FFT to the T{sub e} measurements from the University of Texas’s 40-channel ECE Radiometer, and using a simplified thermal transport equation, the flux surface extent of ECH deposition is determined. The Fourier method analysis is compared with a Break-In-Slope (BIS) analysis and predictions from the ray-tracing code TORAY. Examination of multiple Fourier harmonics and BIS fitting methods allow an estimation of modulated transport coefficients and thereby the true ECH deposition profile. Correlations between edge fluctuations and ECH deposition in legacy data are also explored as a step towards establishing a link between fluctuations and deposition broadening in DIII-D.

  11. Interaction of tectonic and depositional processes that control the evolution of the Iberian Gulf of Cadiz margin

    Science.gov (United States)

    Maldonado, A.; Nelson, C.H.

    1999-01-01

    This study provides an integrated view of the growth patterns and factors that controlled the evolution of the Gulf of Cadiz continental margin based on studies of the tectonic, sedimentologic and oceanographic history of the area. Seven sedimentary regimes are identified, but there are more extensive descriptions of the late Cenozoic regimes because of the larger data base. The regimes of the Mesozoic passive margin include carbonate platforms, which become mixed calcareous-terrigenous deposits during the Late Cretaceous-early Tertiary. The Oligocene and Early Miocene terrigenous regimes developed, in contrast, over the active and transcurrent margins near the African-Iberian plate boundary. The top of the Gulf of Cadiz olistostrome, emplaced in the Late Miocene, is used as a key horizon to define the 'post-orogenic' depositional regimes. The Late Miocene progradational margin regime is characterized by a large terrigenous sediment supply to the margin and coincides with the closing of the Miocene Atlantic-Mediterranean gateways. The terrigenous drift depositional regime of the Early Pliocene resulted from the occurrence of high eustatic sea level and the characteristics of the Mediterranean outflow currents that developed after the opening of the Strait of Gibraltar. The Late Pliocene and Quaternary regimes are dominated by sequences of deposits related to cycles of high and low sea levels. Deposition of shelf-margin deltas and slope wedges correlate with regressive and low sea level regimes caused by eustasy and subsidence. During the highstand regimes of the Holocene, inner shelf prograding deltas and deep-water sediment drifts were developed under the influence of the Atlantic inflow and Mediterranean outflow currents, respectively. A modern human cultural regime began 2000 years ago with the Roman occupation of Iberia; human cultural effects on sedimentary regimes may have equalled natural factors such as climate change. Interplay of tectonic and

  12. RMS slope of exponentially correlated surface roughness for radar applications

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    2000-01-01

    In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum...

  13. Venusian extended ejecta deposits as time-stratigraphic markers

    Science.gov (United States)

    Izenberg, Noam R.

    1992-01-01

    most of the ambiguous cases. Results from the preliminary survey indicate that extended ejecta deposits are effective time-statigraphic markers for the localities. If stratigraphic relationships between the deposits and surrounding units are studied on a case-by-case basis over the whole planet, they should provide useful constraints on Venus history and development of the surface through time. The continuation of the research will expand the study to include the entire crater population and the Magellan emissivity, altimetry, reflectivity, and rms slope datasets.

  14. The empirical slippery slope from voluntary to non-voluntary euthanasia.

    Science.gov (United States)

    Lewis, Penney

    2007-01-01

    This article examines the evidence for the empirical argument that there is a slippery slope between the legalization of voluntary and non-voluntary euthanasia. The main source of evidence in relation to this argument comes from the Netherlands. The argument is only effective against legalization if it is legalization which causes the slippery slope. Moreover, it is only effective if it is used comparatively-to show that the slope is more slippery in jurisdictions which have legalized voluntary euthanasia than it is in jurisdictions which have not done so. Both of these elements are examined comparatively.

  15. Impact of weathering on slope stability in soft rock mass

    Directory of Open Access Journals (Sweden)

    Predrag Miščević

    2014-06-01

    Full Text Available Weathering of soft rocks is usually considered as an important factor in various fields such as geology, engineering geology, mineralogy, soil and rock mechanics, and geomorphology. The problem of stability over time should be considered for slopes excavated in soft rocks, in case they are not protected against weathering processes. In addition to disintegration of material on slope surface, the weathering also results in shear strength reduction in the interior of the slope. Principal processes in association with weathering are discussed with the examples of marl hosted on flysch formations near Split, Croatia.

  16. Soil-atmosphere interaction in unsaturated cut slopes

    Directory of Open Access Journals (Sweden)

    Tsiampousi Aikaterini

    2016-01-01

    Full Text Available Interaction between atmosphere and soil has only recently attracted significant interest. Soil-atmosphere interaction takes place under dynamic climatic conditions, which vary throughout the year and are expected to suffer considerable alterations due to climate change. However, Geotechnical Analysis has traditionally been limited to simplistic approaches, where winter and summer pore water pressure profiles are prescribed. Geotechnical Structures, such as cut slopes, are known to be prone to large irreversible displacements under the combined effect of water uptake by a complex vegetation root system and precipitation. If such processes take place in an unsaturated material the complexity of the problem renders the use of numerical analysis essential. In this paper soil-atmosphere interaction in cut slopes is studied using advanced, fully coupled partially saturated finite element analyses. The effect of rainfall and evapotranspiration is modelled through sophisticated boundary conditions, applying actual meteorological data on a monthly basis. Stages of low and high water demand vegetation are considered for a period of several years, before simulating the effect of vegetation removal. The analysis results are presented with regard to the serviceability and stability of the cut slope.

  17. Effects of Rainfall Characteristics on the Stability of Tropical Residual Soil Slope

    Directory of Open Access Journals (Sweden)

    Rahardjo Harianto

    2016-01-01

    Full Text Available Global climate change has a significant impact on rainfall characteristics, sea water level and groundwater table. Changes in rainfall characteristics may affect stability of slopes and have severe impacts on sustainable urban living. Information on the intensity, frequency and duration of rainfall is often required by geotechnical engineers for performing slope stability analyses. Many seepage analyses are commonly performed using the most extreme rainfall possible which is uneconomical in designing a slope repair or slope failure preventive measure. In this study, the historical rainfall data were analyzed and investigated to understand the characteristics of rainfall in Singapore. The frequency distribution method was used to estimate future rainfall characteristics in Singapore. New intensity-duration-frequency (IDF curves for rainfall in Singapore were developed for six different durations (10, 20, 30 min and 1, 2 and 24 h and six frequencies (2, 5, 10, 25, 50 and 100 years. The new IDF curves were used in the seepage and slope stability analyses to determine the variation of factor of safety of residual soil slopes under different rainfall intensities in Singapore.

  18. Slope stability analysis using limit equilibrium method in nonlinear criterion.

    Science.gov (United States)

    Lin, Hang; Zhong, Wenwen; Xiong, Wei; Tang, Wenyu

    2014-01-01

    In slope stability analysis, the limit equilibrium method is usually used to calculate the safety factor of slope based on Mohr-Coulomb criterion. However, Mohr-Coulomb criterion is restricted to the description of rock mass. To overcome its shortcomings, this paper combined Hoek-Brown criterion and limit equilibrium method and proposed an equation for calculating the safety factor of slope with limit equilibrium method in Hoek-Brown criterion through equivalent cohesive strength and the friction angle. Moreover, this paper investigates the impact of Hoek-Brown parameters on the safety factor of slope, which reveals that there is linear relation between equivalent cohesive strength and weakening factor D. However, there are nonlinear relations between equivalent cohesive strength and Geological Strength Index (GSI), the uniaxial compressive strength of intact rock σ ci , and the parameter of intact rock m i . There is nonlinear relation between the friction angle and all Hoek-Brown parameters. With the increase of D, the safety factor of slope F decreases linearly; with the increase of GSI, F increases nonlinearly; when σ ci is relatively small, the relation between F and σ ci is nonlinear, but when σ ci is relatively large, the relation is linear; with the increase of m i , F decreases first and then increases.

  19. Evidence of rock slope breathing using ground-based InSAR

    Science.gov (United States)

    Rouyet, Line; Kristensen, Lene; Derron, Marc-Henri; Michoud, Clément; Blikra, Lars Harald; Jaboyedoff, Michel; Lauknes, Tom Rune

    2017-07-01

    Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) campaigns were performed in summer 2011 and 2012 in the Romsdalen valley (Møre & Romsdal county, western Norway) in order to assess displacements on Mannen/Børa rock slope. Located 1 km northwest, a second GB-InSAR system continuously monitors the large Mannen rockslide. The availability of two GB-InSAR positions creates a wide coverage of the rock slope, including a slight dataset overlap valuable for validation. A phenomenon of rock slope breathing is detected in a remote and hard-to-access area in mid-slope. Millimetric upward displacements are recorded in August 2011. Analysis of 2012 GB-InSAR campaign, combined with the large dataset from the continuous station, shows that the slope is affected by inflation/deflation phenomenon between 5 and 10 mm along the line-of-sight. The pattern is not homogenous in time and inversions of movement have a seasonal recurrence. These seasonal changes are confirmed by satellite InSAR observations and can possibly be caused by hydrogeological variations. In addition, combination of GB-InSAR results, in situ measurements and satellite InSAR analyses contributes to a better overview of movement distribution over the whole area.

  20. The water content of recurring slope lineae on Mars

    Science.gov (United States)

    Edwards, Christopher S.; Piqueux, Sylvain

    2016-01-01

    Observations of recurring slope lineae (RSL) from the High-Resolution Imaging Science Experiment have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5–3 wt %. In addition, distinct high thermal inertia regolith signatures expected with crust-forming evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any) and/or low enough volumes to prevent their formation. Alternatively, observed salts may be preexisting in soils at low abundances (i.e., near or below detection limits) and largely immobile. These RSL-rich surfaces experience ~100 K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on time scales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis or at least significantly limit the water content of Martian RSL.

  1. Significance of the actual nonlinear slope geometry for catastrophic failure in submarine landslides.

    Science.gov (United States)

    Puzrin, Alexander M; Gray, Thomas E; Hill, Andrew J

    2015-03-08

    A simple approach to slope stability analysis of naturally occurring, mild nonlinear slopes is proposed through extension of shear band propagation (SBP) theory. An initial weak zone appears in the steepest part of the slope where the combined action of gravity and seismic loads overcomes the degraded peak shear resistance of the soil. If the length of this steepest part is larger than the critical length, the shear band will propagate into the quasi-stable parts of the slope, where the gravitational and seismically induced shear stresses are smaller than the peak but larger than the residual shear strength of the soil. Growth of a shear band is strongly dependent on the shape of the slope, seismic parameters and the strength of soil and less dependent on the slope inclination and the sensitivity of clay. For the slope surface with faster changing inclination, the criterion is more sensitive to the changes of the parameters. Accounting for the actual nonlinear slope geometry eliminates the main challenge of the SBP approach-determination of the length of the initial weak zone, because the slope geometry can be readily obtained from submarine site investigations. It also helps to identify conditions for the early arrest of the shear band, before failure in the sliding layer or a change in loading or excess pore water pressures occurs. The difference in the size of a landslide predicted by limiting equilibrium and SBP approaches can reach orders of magnitude, potentially providing an explanation for the immense dimensions of many observed submarine landslides that may be caused by local factors acting over a limited portion of the slope.

  2. Long-Term Drainage from the Riprap Side Slope of a Surface Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhuanfang

    2017-07-01

    Surface barriers designed to isolate underground nuclear waste in place are expected to function for at least 1000 years. To achieve this long design life, such barriers need to be protected with side slopes against wind- and water-induced erosion and damage by natural or human activities. However, the side slopes are usually constructed with materials coarser than the barrier. Their hydrological characteristics must be understood so that any drainage from them is considered in the barrier design and will not compromise the barrier function. The Prototype Hanford Barrier, an evapotranspiration-capillary (ETC) barrier, was constructed in 1994 at the Hanford Site in southeastern Washington state, with a gravel side slope and a riprap side slope. The soil water content in the gravel side slope and drainage from both side slopes have been monitored since the completion of construction. The monitoring results show that under natural precipitation the annual drainage rates from the two types of side slopes were very similar and about 5 times the typical recharge from local soil with natural vegetation and 40 times the barrier design criterion. The higher recharge from the side slopes results in some of the drainage migrating laterally to the region beneath the ETC barrier. This edge effect of the enhanced drainage was evaluated for a period of 1000 years by numerical simulation. The edge effect was quantified by the amount of water across the barrier edges and the affecting distance of the barrier edges. These results indicate that design features can be adjusted to reduce the edge effect when necessary.

  3. The study on length and diameter ratio of nail as preliminary design for slope stabilization

    Science.gov (United States)

    Gunawan, Indra; Silmi Surjandari, Niken; Muslih Purwana, Yusep

    2017-11-01

    Soil nailing technology has been widely applied in practice for reinforced slope. The number of studies for the effective design of nail-reinforced slopes has also increased. However, most of the previous study was focused on a safety factor of the slope; the ratio of length and diameter itself has likely never been studied before. The aim of this study is to relate the length and diameter ratio of the nail with the safety factor of the 20 m height of sand slope in the various angle of friction and steepness of the slope. Simplified Bishop method was utilized to analyze the safety factor of the slope. This study is using data simulation to calculate the safety factor of the slope with soil nailing reinforcement. The results indicate that safety factor of slope stability increases with the increase of length and diameter ratio of the nail. At any angle of friction and steepness of the slope, certain effective length and diameter ratio was obtain. These results may be considered as a preliminary design for slope stabilization.

  4. Efficiency of subsoiling depth according to the slope of the land

    Directory of Open Access Journals (Sweden)

    Daniel Pena Pereira

    2012-12-01

    Full Text Available The effectiveness of subsoiling by measuring the depths achieved in different classes of slope of a forest plantation was evalu