Search results for "rain"
showing 10 items of 10658 documents
Soil erosion processes in European vineyards: A qualitative comparison of rainfall simulation measurements in Germany, Spain and France
2016
Small portable rainfall simulators are considered a useful tool to analyze soil erosion processes in cultivated lands. European research groups in Spain (Valencia, Málaga, Lleida, Madrid and La Rioja), France (Reims) and Germany (Trier) have used different rainfall simulators (varying in drop size distribution and fall velocities, kinetic energy, plot forms and sizes, and field of application) to study soil loss, surface flow, runoff and infiltration coefficients in different experimental plots (Valencia, Montes de Málaga, Penedès, Campo Real and La Rioja in Spain, Champagne in France and Mosel-Ruwer valley in Germany). The measurements and experiments developed by these research teams give…
13C composition of dissolved organic carbon in upland forested catchments of the Morvan Mountains (France): Influence of coniferous and deciduous veg…
2007
10 pages; International audience; One of the main environmental changes caused by human activities is that of land use. These changes influence the quantity and quality of the dissolved organic matter (DOM) fluxes through the vegetation–soil–stream system. The aim of this work is to evaluate the influence of the substitution of native deciduous forests by well managed coniferous forests on dissolved organic carbon (DOC) fluxes and their associated carbon isotopic composition (d13CDOC). DOC fluxes and d13CDOC were monitored for 2 years in the streams of four similar upland forested catchments in the Morvan Mountains (France). Mean annual DOC concentrations and fluxes were 2–4 times lower in …
Soil moisture modelling of a SMOS pixel: interest of using the PERSIANN database over the Valencia Anchor Station
2010
In the framework of Soil Moisture and Ocean Salinity (SMOS) Calibration/Validation (Cal/Val) activities, this study addresses the use of the PERSIANN-CCS<sup>1</sup>database in hydrological applications to accurately simulate a whole SMOS pixel by representing the spatial and temporal heterogeneity of the soil moisture fields over a wide area (50×50 km<sup>2</sup>). The study focuses on the Valencia Anchor Station (VAS) experimental site, in Spain, which is one of the main SMOS Cal/Val sites in Europe. <br><br> A faithful representation of the soil moisture distribution at SMOS pixel scale (50×50 km<sup>2</sup>) requires an accurate estimation…
The influence of rock heterogeneity on the scaling properties of simulated and natural stylolites
2009
International audience; Stylolites are among the most prominent deformation patterns in sedimentary rocks that document localized pressure solution. Recent studies revealed that stylolite roughness is characterized by two distinct scaling regimes. The main goal of the present study is to decipher whether this complex scaling behavior of stylolites is caused by the composition of the host-rock, i.e. heterogeneities in the material, or is governed by inherent processes on respective scales, namely the transition from a surface energy to an elastic energy dominated regime, as theoretically predicted. For this purpose we have developed a discrete numerical technique, based on a lattice spring m…
Modelling of stylolite geometries and stress scaling
2012
International audience; In this contribution we present numerical simulations of stylolite growth to decipher the effects of initial rock heterogeneity and stress on their morphology. We show that stylolite growth in a rock with a uniform grain size produces different patterns than stylolite growth in a rock with a bimodal grain size distribution. Strong pinning of large heterogeneities produce stylolite structures that are dominated by pronounced teeth, whereas a uniform grain size leads to spikes and a roughness that shows variable wavelengths. We compare the simulated stylolites with natural examples and show that the model can reproduce the real structures. In addition we show that stro…
Tectonics of the Northern Bresse region (France) during the Alpine cycle
2003
International audience; Combining fieldwork and surface data, we have reconstructed the Cenozoic structural and tectonic evolution of the Northern Bresse. Analysis of drainage network geometry allowed to detect three major fault zones trending NE-SW, E-W and NW-SE, and smooth folds with NNE trending axes, all corroborated with shallow well data in the graben and fieldwork on edges. Cenozoic paleostress succession was determined through fault slip and calcite twin inversions, taking into account data of relative chronology. A N-S major compression, attributed to the Pyrenean orogenesis, has activated strike-slip faults trending NNE along the western edge and NE-SW in the graben. After a tran…
Natural gas hydrate investigations by synchrotron radiation X-ray cryo-tomographic microscopy (SRXCTM)
2008
[1] We report the 3D microstructure analyses of natural gas hydrates sampled from Gulf of Mexico. The samples were characterized by synchrotron radiation X-ray cryo-tomographic microscopy (SRXCTM) using the ‘TOMCAT’ beam line at the Swiss Light Source (SLS). The SRXCTM demonstrates its applicability to unlock some microscopic features of the marine hydrates, in particular of crystallite size and grain boundary network. The gas hydrate domains are surrounded by a network of pores of typically a few micrometers, which are largely due to decomposition. Out of the SRXCTM data, the porosity, total volume of the voids, the void surface area and number of the total gas-filled voids have been calcu…
Aseismic strain episodes at Campi Flegrei Caldera, Italy
2021
Since 2004 a research project has been developed to monitor subsurface deformation of Italian volcanoes using borehole strainmeters and long-baseline tiltmeters. Six Sacks-Evertson dilatometers were installed around Campi Flegrei caldera and Vesuvius during 2004–2005 (Scarpa et al., 2007), and in 2008 these instruments were supplemented by two arrays of 28–280 m long water-tube tiltmeters in underground tunnels. Relevant strainmeter and tiltmeter data have been collected and analysed from the instruments installed near Campi Flegrei caldera during the recent unrest episodes. In the period 2004–2005 strain, tilt and GPS data from Campi Flegrei indicate the onset of surface deformation that a…
Multi-centennial summer and winter precipitation variability in southern South America
2010
[1] We present the first spatially and temporally highly resolved gridded reconstruction of multi-centennial precipitation variability for southern South America (SSA). A novel reconstruction approach of deriving 10,000 ensemble members based on varying predictor networks and methodological settings allows the identification of spatiotemporal changes in SSA precipitation and associated uncertainties. The summer and winter reconstructions back to AD 1498 and AD 1590, respectively, provide new evidence for multi-centennial increase in summer precipitation and an opposing decrease in winter precipitation into the 20th century. The drying in winter is significant over large parts of SSA, wherea…
Climate variability and lake ecosystem responses in western Scandinavia (Norway) during the last Millennium
2017
This paper provides a high-resolution temperature reconstruction for the last Millennium from Lake Atnsjøen, SE Norway (61°52′31″N, 10°10′37″E). The sedimentary record reveals strong influence of the large-scale global climate patterns on the local climate in southern part of Eastern Norway. We reconstructed mean July air temperature using Chironomidae-based transfer function and fossil Chironomidae assemblages. The reconstruction was supported by a selection of climate-sensitive geochemical and paleoecological sedimentary proxies of terrestrial and aquatic origin, including Cladocera, pollen and macrofossils. Presented results revealed that summer temperatures were 1–2 °C warmer than the m…