Use of targets to track 3D displacements in highly vegetated areas affected by landslides     

Martin Franz  Dario Carrea  Antonio Abellán  Marc-Henri Derron  Michel Jaboyedoff 《Landslides》2016,13(4):821-831

Monitoring landslides with terrestrial laser scanning (TLS) is currently a well-known technique. One problem often encountered is the vegetation that produces shadow areas on the scans. Indeed, the points behind a given obstacle are hidden and thus occluded on the point cloud. Thereby, locations monitored with terrestrial laser scanner are mostly rock instabilities and few vegetated landslides, being difficult or even impossible to survey vegetated slopes using this method with its classical non-full wave form. The Peney landslide (Geneva, Switzerland) is partially vegetated by bushes and trees, and in order to monitor its displacements during the drawdown of the Verbois reservoir located at its base, an alternative solution has been found. We combined LiDAR technique with 14 targets made of polystyrene placed at different locations inside and outside the landslide area. The obtained displacements were compared with classical measurement methods (total station and extensometer), showing good resemblance of results, indicating that the use of targets in highly vegetated areas could be an efficient alternative for mass movements monitoring.  相似文献   

Climate and human land-use as a driver of Lake Narlay (Eastern France,Jura Mountains) evolution over the last 1200 years: implication for methane cycle     

Simon Belle  Valérie Verneaux  Laurent Millet  David Etienne  Andrea Lami  Simona Musazzi  Jean-Louis Reyss  Michel Magny 《Journal of Paleolimnology》2016,55(1):83-96

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The effects of migration on <Emphasis Type="Italic">ca.</Emphasis> 100-year-old arsenic-rich mine tailings in Cobalt,Ontario, Canada     

Dale D. Sprague  Frederick A. Michel  Jesse C. Vermaire 《Environmental Earth Sciences》2016,75(5):405

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A New Computational Model of High-Order Stochastic Simulation Based on Spatial Legendre Moments     

Lingqing Yao  Roussos Dimitrakopoulos  Michel Gamache 《Mathematical Geosciences》2018,50(8):929-960

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The mid-depth circulation of the northwestern tropical Atlantic observed by floats     

Matthias Lankhorst  David Fratantoni  Michel Ollitrault  Philip Richardson  Uwe Send  Walter Zenk 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(10):1615-1632

A comprehensive analysis of velocity data from subsurface floats in the northwestern tropical Atlantic at two depth layers is presented: one representing the Antarctic Intermediate Water (AAIW, pressure range 600–1050 dbar), the other the upper North Atlantic Deep Water (uNADW, pressure range 1200–2050 dbar). New data from three independent research programs are combined with previously available data to achieve blanket coverage in space for the AAIW layer, while coverage in the uNADW remains more intermittent. Results from the AAIW mainly confirm previous studies on the mean flow, namely the equatorial zonal and the boundary currents, but clarify details on pathways, mostly by virtue of the spatial data coverage that sets float observations apart from e.g. shipborne or mooring observations. Mean transports in each of five zonal equatorial current bands is found to be between 2.7 and 4.5 Sv. Pathways carrying AAIW northward beyond the North Brazil Undercurrent are clearly visible in the mean velocity field, in particular a northward transport of 3.7 Sv across 16°N between the Antilles islands and the Mid-Atlantic Ridge. New maps of Lagrangian eddy kinetic energy and integral time scales are presented to quantify mesoscale activity. For the uNADW, mean flow and mesoscale properties are discussed as data availability allows. Trajectories in the uNADW east of the Lesser Antilles reveal interactions between the Deep Western Boundary Current (DWBC) and the basin interior, which can explain recent hydrographic observations of changes in composition of DWBC water along its southward flow.  相似文献   

Reconstruction of Horizontal Plasma Motions at the Photosphere from Intensitygrams: A Comparison Between DeepVel,LCT, FLCT,and CST     

Benoit Tremblay  Thierry Roudier  Michel Rieutord  Alain Vincent 《Solar physics》2018,293(4):57

Direct measurements of plasma motions in the photosphere are limited to the line-of-sight component of the velocity. Several algorithms have therefore been developed to reconstruct the transverse components from observed continuum images or magnetograms. We compare the space and time averages of horizontal velocity fields in the photosphere inferred from pairs of consecutive intensitygrams by the LCT, FLCT, and CST methods and the DeepVel neural network in order to identify the method that is best suited for generating synthetic observations to be used for data assimilation. The Stein and Nordlund (Astrophys. J. Lett.753, L13, 2012) magnetoconvection simulation is used to generate synthetic SDO/HMI intensitygrams and reference flows to train DeepVel. Inferred velocity fields show that DeepVel performs best at subgranular and granular scales and is second only to FLCT at mesogranular and supergranular scales.  相似文献   

Light Curve Modelling and Evolutionary Status of the Short Period Binary 1SWASP J092328.76+435044     

M. M. Elkhateeb  M. I. Nouh  R. Michel  A. Haroon  E. Elkholy 《Astrophysical Bulletin》2018,73(1):66-76

Light curve modeling for the newly discovered super contact low-mass WUMa system 1SWASPJ092328.76+435044 was carried out by using a new BVR complete light curves. A spotted model was applied to treat the asymmetry of the light curves. The output model was obtained by means of Wilson–Devinney code, which reveals that the massive component is hotter than the less massive one with about ΔT ～ 40 K. A total of six new times of minima were estimated. The evolutionary state of the system components was investigated based on the estimated physical parameters.  相似文献   

Morphological and sedimentary impacts and recovery on a mixed sandy to pebbly seabed exposed to marine aggregate extraction (Eastern English Channel,France)     

Sophie Le Bot  Robert Lafite  Matthieu Fournier  Agnès Baltzer  Michel Desprez 《Estuarine, Coastal and Shelf Science》2010

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Should Bouchet's hypothesis be taken into account in rainfall‐runoff modelling? An assessment over 308 catchments     

Ludovic Oudin  Claude Michel  Vazken Andrassian  Franois Anctil  Ccile Loumagne 《水文研究》2005,19(20):4093-4106

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Sediment infiltration traps: their use to monitor salmonid spawning habitat in headwater tributaries of the Cascapédia River,Québec     

Andr E. Zimmermann  Michel Lapointe 《水文研究》2005,19(20):4161-4177

Sediment infiltration can clog salmon nests and reduce egg survival. As a countermeasure, environmental managers often deploy infiltration traps to monitor sediment infiltration. Traps provide a repeatable means of measuring infiltration and enable comparisons to be made between sites. Results from infiltration rates measured with traps have also been used to estimate infilling rates into salmon nests. Application of these data is questionable, as the composition of the bed and the amount of fine sediment within the bed is known to affect infiltration rates. Thus, infiltration rates measured with infiltration traps may differ from the infiltration rates occurring in redd and riffle gravels. To examine how relationships between sediment infiltration rates varied between four watersheds, we continuously monitored suspended sediment transport, shear stress and infiltration rates at four sites over 5 months. We also compared infiltration rates measured with infiltration traps with changes in the hydraulic conductivity and subsurface grain size distribution of adjacent artificially constructed salmon nests and natural riffle gravels. Among the four watersheds, clear differences in sediment infiltration rates were observed. The differences correlated with the subsurface silt content but no strong relationship existed between land‐use or basin physiography/geology. Despite observing an average of 30 kg m⁻² of sediment finer than 2 mm being deposited in the infiltration traps during the study, no change in redd or riffle substrate was observed. If the deposition rates measured with the traps reflect the processes in redds, enough sediment would have been deposited to inhibit egg emergence. However, no reduction in egg survival to the eyed stage was observed. In summary, our results show that infiltration traps with clean gravels can be used to detect intersite differences in sediment transport regimes. Extrapolations of sediment infiltration rates measured with such collectors to estimate infiltration rates in redds or riffles is, however, flawed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献