An assessment of large-scale flood modelling based on LiDAR data     

Guénolé Choné  Pascale M. Biron  Thomas Buffin-Bélanger  Iulia Mazgareanu  Jeff C. Neal  Christopher C. Sampson 《水文研究》2021,35(8):e14333

Large-scale flood modelling approaches designed for regional to continental scales usually rely on relatively simple assumptions to represent the potentially highly complex river bathymetry at the watershed scale based on digital elevation models (DEMs) with a resolution in the range of 25–30 m. Here, high-resolution (1 m) LiDAR DEMs are employed to present a novel large-scale methodology using a more realistic estimation of bathymetry based on hydrogeomorphological GIS tools to extract water surface slope. The large-scale 1D/2D flood model LISFLOOD-FP is applied to validate the simulated flood levels using detailed water level data in four different watersheds in Quebec (Canada), including continuous profiles over extensive distances measured with the HydroBall technology. A GIS-automated procedure allows to obtain the average width required to run LISFLOOD-FP. The GIS-automated procedure to estimate bathymetry from LiDAR water surface data uses a hydraulic inverse problem based on discharge at the time of acquisition of LiDAR data. A tiling approach, allowing several small independent hydraulic simulations to cover an entire watershed, greatly improves processing time to simulate large watersheds with a 10-m resampled LiDAR DEM. Results show significant improvements to large-scale flood modelling at the watershed scale with standard deviation in the range of 0.30 m and an average fit of around 90%. The main advantage of the proposed approach is to avoid the need to collect expensive bathymetry data to efficiently and accurately simulate flood levels over extensive areas.  相似文献   

Data analysis pipeline for EChO end-to-end simulations     

Ingo P. Waldmann  E. Pascale 《Experimental Astronomy》2015,40(2-3):639-654

Atmospheric spectroscopy of extrasolar planets is an intricate business. Atmospheric signatures typically require a photometric precision of 1×10^?4 in flux over several hours. Such precision demands high instrument stability as well as an understanding of stellar variability and an optimal data reduction and removal of systematic noise. In the context of the EChO mission concept, we here discuss the data reduction and analysis pipeline developed for the EChO end-to-end simulator EChOSim. We present and discuss the step by step procedures required in order to obtain the final exoplanetary spectrum from the EChOSim ‘raw data’ using a simulated observation of the secondary eclipse of the hot-Neptune 55 Cnc e.  相似文献   

Reply to “Reply to comments on defining biominerals and organominerals: Direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157–179]” by R.S. Perry and M.A. Sephton: [Sedimentary Geology 213 (2009) 156]     

Christian Défarge  Pascale Gautret  Joachim Reitner  Jean Trichet 《Sedimentary Geology》2010,223(3-4):390-391

This is a reply to R.S. Perry and M.A. Sephton's “Reply to comments on defining biominerals and organominerals: direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157–179]” [Sedimentary Geology 213 (2009) 156].  相似文献   

Tectonic and climatic control of the changes in the sedimentary record of the Karnali River section (Siwaliks of western Nepal)   总被引：1，自引：0，他引：1  

Pascale  Huyghe  Jean-Louis  Mugnier  Ananta Prasad  Gajurel  Bernard  Delcaillau 《Island Arc》2005,14(4):311-327

Abstract A multidisciplinary study was conducted on the section of the Siwalik Group sediments, approximately 5000 m thick, exposed along the Karnali River. Analysis of facies, clay mineralogy and neodymium isotope compositions revealed significant changes in the sedimentary record, allowing discussion of their tectonic or climatic origin. Two major changes within the sedimentary fill were detected: the change from a meandering to a braided river system at ca 9.5 Ma and the change from a deep sandy braided to a shallow sandy braided river system at ca 6.5 Ma. The 9.5‐Ma change in fluvial style is contemporaneous with an abrupt increase of ?_Nd(0) values following a ?_Nd(0) minimum. This evolution indicates a change in source material and erosion of Lesser Himalayan rocks within the Karnali catchment basin between 13 and 10 Ma. The tectonic activity along the Ramgarh thrust caused this local exhumation. By changing the proximity and morphology of relief, the forward propagation of the basal detachment to the main boundary thrust was responsible for the high gradient and sediment load required for the development of the braided river system. The change from a deep sandy braided to a shallow sandy braided river system at approximately 6.5 Ma was contemporaneous with a change in clay mineralogy towards smectite‐/kaolinite‐dominant assemblages. As no source rock change and no burial effect are detected at that time, the change in clay mineralogy is interpreted as resulting from differences in environmental conditions. The facies analysis shows abruptly and frequently increasing discharges by 6.5 Ma, and could be linked to an increase in seasonality, induced by intensification of the monsoon climate. The major fluvial changes deciphered along the Karnali section have been recognized from central to western Nepal, although they are diachronous. The change in clay mineralogy towards smectite‐/kaolinite‐rich assemblages and the slight decrease of ?_Nd(0) have also been detected in the Bengal Fan sedimentary record, showing the extent and importance of the two major events recorded along the Karnali section.  相似文献   

Late Miocene – Recent exhumation of the central Himalaya and recycling in the foreland basin assessed by apatite fission-track thermochronology of Siwalik sediments, Nepal     

Peter van der Beek  Xavier Robert  Jean-Louis Mugnier  Matthias Bernet  Pascale Huyghe  Erika Labrin 《Basin Research》2006,18(4):413-434

Thermochronological analysis of detrital sediments derived from the erosion of mountain belts and contained in the sedimentary basins surrounding them allows reconstructing the long-term exhumation history of the sediment source areas. The effective closure temperature of the thermochronological system analysed determines the spatial and temporal resolution of the analysis through the duration of the lag time between closure of the system during exhumation and its deposition in the sedimentary basin. Here, we report apatite fission-track (AFT) data from 31 detrital samples collected from Miocene to Pliocene stratigraphic sections of the Siwalik Group in western and central Nepal, as well as three samples from modern river sediments from the same area, that complement detrital zircon fission-track (ZFT) and U–Pb data from the same samples presented in a companion paper. Samples from the upper part of the stratigraphic sections are unreset and retain a signal of source-area exhumation; they show spatial variations in source-area exhumation rates that are not picked up by the higher-temperature systems. More deeply buried samples have been partially reset within the Siwalik basin and provide constraints on the thermal and kinematic history of the fold-and-thrust belt itself. The results suggest that peak source-area exhumation rates have been constant at ∼1.8 km Myr⁻¹ over the last ∼7 Ma in central Nepal, whereas they ranged between 1 and ∼1.5 km Myr⁻¹ in western Nepal over the same time interval; these spatial variations may be explained by either a tectonic or climatic control on exhumation rates, or possibly a combination of the two. Increasing lag times within the uppermost part of the sections suggest an increasing component of apatites that have been recycled within the Siwalik belt and are corroborated by AFT ages of modern river sediment downstream as well as the record of the distal Bengal Fan. The most deeply buried and most strongly annealed samples record onset of exhumation of the frontal Siwaliks along the Himalayan frontal thrust at ∼2 Ma and continuous shortening at rates comparable with the present-day shortening rates from at least 0.3 Ma onward.  相似文献   

River dissolved and solid loads in the Lesser Antilles: New insight into basalt weathering processes   总被引：1，自引：0，他引：1  

Stareh Rad  Pascale Louvat  Caroline Gorge  Jrme Gaillardet  Claude Jean Allgre 《Journal of Geochemical Exploration》2006,88(1-3):308

We present here the first available estimations of chemical weathering and associated atmospheric CO₂ consumption rates as well as mechanical erosion rate for the Lesser Antilles. The chemical weathering (100–120 t/km²/year) and CO₂ consumption (1.1–1.4 × 10⁶ mol/km²/year) rates are calculated after subtraction of the atmospheric and hydrothermal inputs in the chemical composition of the river dissolved loads. These rates thus reflect only the low-temperature basalt weathering. Mechanical erosion rates (approx. 800–4000 t/km²/year) are estimated by a geochemical mass balance between the dissolved and solid loads and mean unaltered rock. The calculated chemical weathering rates and associated atmospheric CO₂ consumption rates are among the highest values worldwide but are still lower than those of other tropical volcanic islands and do not fit with the HCO₃⁻ concentration vs. 1/T correlation proposed by Dessert et al. (2001). The thick soils and explosive volcanism context of the Lesser Antilles are the two possible keys to this different weathering behaviour; the development of thick soils limits the chemical weathering and the presence of very porous pyroclastic flows allows an important water infiltration and thus subsurface weathering mechanisms, which are less effective for atmospheric CO₂ consumption.  相似文献   

The ARIEL Instrument Control Unit design     

M. Focardi  E. Pace  M. Farina  A. M. Di Giorgio  J. Colomé Ferrer  I. Ribas  C. Sierra Roig  L. Gesa Bote  J. C. Morales  J. Amiaux  C. Cara  J. L. Augurés  E. Pascale  G. Morgante  V. Da Deppo  M. Pancrazzi  V. Noce  S. Pezzuto  M. Frericks  F. Zwart  G. Bishop  K. Middleton  P. Eccleston  G. Micela  G. Tinetti 《Experimental Astronomy》2018,45(1):1-20

In this paper we present the electromagnetic modeling and beam pattern measurements of a 16-elements ultra wideband sparse random test array for the low frequency instrument of the Square Kilometer Array telescope. We discuss the importance of a small array test platform for the development of technologies and techniques towards the final telescope, highlighting the most relevant aspects of its design. We also describe the electromagnetic simulations and modeling work as well as the embedded-element and array pattern measurements using an Unmanned Aerial Vehicle system. The latter are helpful both for the validation of the models and the design as well as for the future instrumental calibration of the telescope thanks to the stable, accurate and strong radio frequency signal transmitted by the UAV. At this stage of the design, these measurements have shown a general agreement between experimental results and numerical data and have revealed the localized effect of un-calibrated cable lengths in the inner side-lobes of the array pattern.  相似文献   

Three-dimensional turbulent structures at a medium-sized confluence with and without an ice cover     

Pascale M. Biron  Thomas Buffin-Bélanger  Nancy Martel 《地球表面变化过程与地形》2019,44(15):3042-3056

River confluences are characterized by a complex mixing zone with three-dimensional (3D) turbulent structures which have been described as both streamwise-oriented structures and Kelvin–Helmholtz (KH) vertical-oriented structures. The latter are visible where there is a turbidity difference between the two tributaries, whereas the former are usually derived from mean velocity measurements or numerical simulations. Few field studies recorded turbulent velocity fluctuations at high frequency to investigate these structures, particularly at medium-sized confluences where logistical constraints make it difficult to use devices such as acoustic doppler velocimeter (ADV). This study uses the ice cover present at the confluence of the Mitis and Neigette Rivers in Quebec (Canada) to obtain long-duration, fixed measurements along the mixing zone. The confluence is also characterized by a marked turbidity difference which allows to investigate the mixing zone dynamics from drone imagery during ice-free conditions. The aim of the study is to characterize and compare the flow structure in the mixing zone at a medium-sized (~40 m) river confluence with and without an ice cover. Detailed 3D turbulent velocity measurements were taken under the ice along the mixing plane with an ADV through eight holes at around 20 positions on the vertical. For ice-free conditions, drone imagery results indicate that large (KH) coherent structures are present, occupying up to 50% of the width of the parent channel. During winter, the ice cover affects velocity profiles by moving the highest velocities towards the centre of the profiles. Large turbulent structures are visible in both the streamwise and lateral velocity components. The strong correlation between these velocity components indicates that KH vortices are the dominating coherent structures in the mixing zone. A spatio-temporal conceptual model is presented to illustrate the main differences on the 3D flow structure at the river confluence with and without the ice cover. © 2019 John Wiley & Sons, Ltd.  相似文献   

The trispectrum of the cosmic microwave background on subdegree angular scales: an analysis of the BOOMERanG data     

G. De Troia  P. A. R. Ade  J. J. Bock  J. R. Bond  A. Boscaleri  C. R. Contaldi  B. P. Crill  P. de Bernardis  P. G. Ferreira  M. Giacometti  E. Hivon  V. V. Hristov  M. Kunz  A. E. Lange  S. Masi  P. D. Mauskopf  T. Montroy  P. Natoli  C. B. Netterfield  E. Pascale  F. Piacentini  G. Polenta  G. Romeo  J. E. Ruhl 《Monthly notices of the Royal Astronomical Society》2003,343(1):284-292

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Geographic distribution of Tetracapsuloides bryosalmonae infected fish in Swiss rivers: an update     

Thomas Wahli  Daniel Bernet  Pascale April Steiner  Heike Schmidt-Posthaus 《Aquatic Sciences - Research Across Boundaries》2007,69(1):3-10

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