Morphodynamic interactions of continental shelf,beach and dunes: the Cabopino dune system in southern Mediterranean Spain     

Gonzalo Malvárez  Fatima Navas  Emilia Guisado-Pintado  Derek W.T. Jackson 《地球表面变化过程与地形》2019,44(8):1647-1658

The complex morphodynamic interactions between nearshore, shoreface and dune systems are usually simplified by studying these zones and their associated processes in isolation. However, the established relationships between each of them suggests that an integrated approach is required to examine the genesis, evolution and adaptation of the entire morphodynamic system. The Cabopino dune system in the southern Spanish Mediterranean Sea provides a clear example of a linked morphodynamic system in which a relatively large dune system has been generated and grown through the supply of sediments from an adjacent littoral supply environment. Here, we present a conceptual model of how the nearshore has provided suitable conditions for beach and dune development. We purport that synchronization of sediment activation in the marine and aeolian sections of the system have played a major role in this microtidal setting in which temporal aspects are not only tied to storm action, but to large sedimentary features moving alongshore. © 2019 John Wiley & Sons, Ltd.  相似文献   

Prediction of time to slope failure: a general framework   总被引：4，自引：1，他引：3  

A. Federico  M. Popescu  G. Elia  C. Fidelibus  G. Internò  A. Murianni 《Environmental Earth Sciences》2012,66(1):245-256

The prediction of time to slope failure (TSF) is a goal of major importance for both landslide researchers and practitioners. A reasonably accurate prediction of TSF allows human losses to be avoided, damages to property to be reduced and adequate countermeasures to be designed. A pure “phenomenological” approach based on the observation and interpretation of the monitored data is generally employed in TSF prediction. Such an approach infers TSF mainly from the ground surface displacements using regression techniques based on empirical functions. These functions neglect the rheological soil parameters in order to reduce the prediction uncertainties. This paper presents an overlook of the methods associated with this approach and proposes a unique expression encompassing most of the previously proposed equations for TSF prediction, thus offering a general framework useful for comparisons between different methods. The methods discussed in this paper provide an effective tool, and sometimes the only tool, for TSF prediction. The fundamental problem is always one of data quality. A full confidence in all assumptions and parameters used in the prediction model is rarely, if ever, achieved. Therefore, TSF prediction models should be applied with care and the results interpreted with caution. Documented case studies represent the most useful source of information to calibrate the TSF prediction models.  相似文献   

The role of infiltration processes in steep slope stability of pyroclastic granular soils: laboratory and numerical investigation   总被引：1，自引：0，他引：1  

Emilia Damiano  Lucio Olivares 《Natural Hazards》2010,52(2):329-350

Rainfall-induced landslides on steep slopes are a common feature in much of Italy’s mountain areas covered by shallow-pyroclastic deposits. Generally, these deposits are unsaturated and have a slope angle higher than 40°–50°; hence their stability is due to the positive effect of matric suction on soil shear strength. During rainfall, rainwater infiltration causes a decrease in suction, which in turn causes changes in soil mechanical and hydraulic properties, leading towards an instability process. However, the response of pyroclastic soil slopes to rainwater infiltration is not fully understood. The aim of this study is to link slope instability to the infiltration process on the basis of advanced geotechnical characterization, in situ monitoring and numerical analysis calibrated through a back-analysis of well-instrumented flume tests.  相似文献   

Three-dimensional seismic analysis of submarine slopes   总被引：1，自引：0，他引：1  

A. Azizian  R. Popescu 《Soil Dynamics and Earthquake Engineering》2006,26(9):870-887

Three-dimensional effects in seismic analysis of submarine slopes are assessed by comparing results of two- and three-dimensional (2D & 3D) analyses, in terms of predicted displacements, shear strains, and excess pore water pressure ratios. Limits of applicability of the 2D, plane strain analysis assumptions are quantitatively assessed. Some regression equations are also presented that express ratios of 3D vs. 2D predictions as a function of slope width/height ratio and earthquake peak acceleration. It is found that the results of 2D and 3D dynamic slope stability analysis are within a tolerance of about 15% for width/height ratios larger than 3–5, and 3D effects induced by lateral boundaries become insignificant for width/height ratios larger than 6–7. The results of the present dynamic, fully coupled, non-linear analyses are also compared with those of static slope stability analyses.  相似文献   

Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega‐Precovery software     

O. Vaduvescu  M. Popescu  I. Comsa  A. Paraschiv  D. Lacatus  A. Sonka  A. Tudorica  M. Birlan  O. Suciu  F. Char  M. Constantinescu  T. Badescu  M. Badea  D. Vidican  C. Opriseanu 《Astronomische Nachrichten》2013,334(7):718-728

The ESO/MPG WFI and the INT WFC wide field archives comprising 330 000 images were mined to search for serendip‐itous encounters of known Near Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 as‐teroids (44 PHAs and 108 other NEAs) were identified using the PRECOVERY software, their astrometry being measured on 761 images and sent to the Minor Planet Centre. Both recoveries and precoveries were reported, including prolonged orbital arcs for 18 precovered objects and 10 recoveries. We analyze all new opposition data by comparing the orbits fitted before and after including our contributions. We conclude the paper presenting “Mega‐Precovery”, a new online service focused on data mining of many instrument archives simultaneously for one or a few given asteroids. A total of 28 instrument archives have been made available for mining using this tool, adding together about 2.5 million images forming the “Mega‐Archive”  相似文献   

Climate signals in sediment mineralogy of Lake Baikal and Lake Hovsgol during the LGM-Holocene transition and the 1-Ma carbonate record from the HDP-04 drill core   总被引：1，自引：0，他引：1  

Emilia P. Solotchina  Alexander A. Prokopenko  Mikhail I. Kuzmin  Pavel A. Solotchin  Anastasia N. Zhdanova 《Quaternary International》2009,205(1-2):38

Modeling the bulk sediment XRD patterns allows insight into the environmental and depositional histories of two neighboring rift lake basins within the Baikal watershed. Parallel ¹⁴C-dated LGM-Holocene records in Lakes Baikal and Hovsgol are used to discuss the mineralogical signatures of regional climate change. In both basins, it is possible to distinguish ‘glacial’ and ‘interglacial’ mineral associations. Clay minerals comprise in excess of 50% of layered silicates in bulk sediment.The abundance of smectite (expandable) layers in mixed-layer illite–smectites and the total illite abundance are the main paleoclimatic indices in the clay mineral assemblage. Both indices exhibit coherent responses to the Bølling–Allerød and the Younger Dryas. The smectite layer index is not equivalent to the abundance of illite–smectite, because illite–smectite tends to transform into illite. Repeated wetting–drying cycles in soils and high abundance of expandable layers in illite–smectites (>42%) favor the process of illitization. This relationship is clearly shown in both Baikal and Hovsgol records for the first time. The opposite late Holocene trends in illite abundance in Lake Baikal and Lake Hovsgol records suggest that a sensitive optimal regime may exist for illite formation in the Baikal watershed with regard to warmth and effective moisture.The Lake Hovsgol sediments of the last glacial contain carbonates, suggesting a positive trend in the lake's water budget. A progressive change towards lower Mg content in carbonates indicates lowering mineralization of lake waters. This trend is consistent with the lithologic evidence for lake-level rise in the Hovsgol basin.The pattern of mineralogical changes during the past 20 ka is used to interpret bulk sediment and carbonate mineralogy of the long 81-m Lake Hovsgol drill core (HDP-04) with a basal age of 1 Ma. The interglacial-type silicate mineral associations are confined to several thin intervals; most of the sediment record is calcareous. Carbonates are represented by six main mineral phases: calcite, low-Mg calcite, intermediate/high-Mg calcite, dolomite, excess-Ca dolomite and metastable monohydrocalcite. These mineral phases tend to form stratigraphic successions indicative of progressive changes in lake water chemistry. Five sediment layers with abundant Mg-calcites in the HDP-04 section suggest deposition in a low standing lake with high mineralization (salinity) and high Mg/Ca ratios of lake waters. Lake Hovsgol sediments contain the oldest known monohydrocalcite, found tens of meters below lake bottom in sediments as old as 800 ka. This unusual find is likely due to the conditions favorable to preservation of this metastable carbonate.  相似文献   

The effects of source rocks and chemical weathering on the petrogenesis of siliciclastic sand from the Neto River (Calabria, Italy): implications for provenance studies     

Emilia Le Pera  Josè Arribas  Salvatore Critelli  & Amparo Tortosa 《Sedimentology》2001,48(2):357-378

Plutonic and gneissic rocks of the Sila Massif in the uppermost portion of the Neto drainage basin (Calabria, Southern Italy) weather and erode under a humid Mediterranean climate. During the development of weathering profiles, a combination of chemical weathering and granular disintegration processes occurred. Chemical weathering involves a loss of both plagioclase (mainly during grus generation) and K-feldspar (mainly during soil formation). This loss is attributed to transformation of plagioclase to clay minerals and to leaching and dissolution of K-feldspar. Sand composition is quartzofeldspathic and nearly homogeneous along the main channel of the Neto River, even where the river cuts across a blanket of sedimentary cover. Thus, fluvial transport does not alter sand composition within the Neto drainage basin. Petrographic indices are effective in (1) discriminating between contributions from similar (granite and gneiss) source rocks (Qm/F); (2) relating the provenance of plutoniclastic and gneissiclastic sand found in the headwaters to grus horizons (Qm/F; Q/Rg); and (3) distinguishing between upstream first-cycle and downstream multicycle sand (Q/Rg). This last distinction is further emphasized by considering both aphanitic and phaneritic varieties of rock fragments (RgRmRs diagram). Chemical weathering is the main sand producer within the regolithic environment in northern Calabria. In addition, rapid erosion resulting from steep slopes removes weathered products, and rapid and short transport leads to minimal sediment maturation. In general, the F/Q index is climate and relief dependent; thus, it should be used in conjunction with palaeoclimatic and palaeophysiographic evidence for provenance interpretations of ancient quartzofeldspathic sandstones.  相似文献   

Getting sued and other tales of the engineering life | Richard L. Meehan. Massachusetts Institute of Technology,London, 1981, xvi + 241 pp., £ stg.10.50     

M.E. Popescu  A.F. Chleborad 《Engineering Geology》1983,19(3):243-244

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Pace and Pattern of Recent Treeline Dynamics: Response of Ecotones to Climatic Variability in the Spanish Pyrenees   总被引：4，自引：0，他引：4  

J. Julio Camarero  Emilia Gutiérrez 《Climatic change》2004,63(1-2):181-200

Treeline ecotones are regarded as sensitive monitors of the recent climatic warming. However, it has been suggested that their sensitivity depends more on changes in tree density than on treeline position. We study these processes and the effect of climate, mainly air temperature, on tree recruitment and recent treeline dynamics. We selected three relatively undisturbed sites in the Spanish Pyrenees, dominated by Pinusuncinata, and analyzed their recent dynamics at local spatial (0.3–0.5 ha) and short temporal scales (100–300 years). We wanted to establish whether higher temperature was the only climatic factor causing an upward shift of the studied alpine treelines. The data we report show that treelines were ascending until a period of high interannual variability in mean temperature started (1950–95). During the late twentieth century, treeline fluctuation was less sensitive to climate than was the change in tree density within the ecotone. Tree recruitment and treeline position responded to contrasting climatic signals; tree recruitment was favored by high March temperatures whereas treeline position ascended in response to warm springs. We found a negative relationship between mean treeline-advance rate and March temperature variability. According to our findings, if the interannual variability of March temperature increases, the probability of successful treeline ascent will decrease.  相似文献   

Maps of recent vertical crustal movements in Romania: Similarities and differences     

Miron N. Popescu  Ion Dragoescu 《Journal of Geodynamics》1987,8(2-4)

A new map of recent crustal vertical movements (RCVM) in Romania, on the basis of high-precision geodetical measurements by the repeated levelling method, had become necessary firstly as a consequence of the great seismic event of March 4, 1977 with foci under the Vrancea Region (the most important seismic zone in the country) and secondly because many years had passed since the previous edition.Certainly, there are similitudes and differences between the two editions, and the authors will try to put these into evidence and explain them.The general view of the major geological units of Romania in both maps is the same: the mountain regions being zones of more or less continuous uplift, the plains showing subsidence movements and the plateau regions presenting a relative stability. Some modifications became apparent owing to the improvement of the national geodetical network on which the repeated levelling measurements were performed and following the choice of the Harbour of Constanţa as the fundamental point.  相似文献