Search results for "erosion"
showing 10 items of 637 documents
Hydro-mechanical behaviour of shallow Opalinus Clay shale
2019
In Switzerland, Opalinus Clay shale has been selected as the host formation for radioactive waste disposal. The minimum required depth of the repository is related to the long-lasting isolation required for the disposal (1 million years). During this period, possible erosion scenarios affecting the repository need to be analysed. Opalinus Clay from shallow depths (< 70 m) was sourced from a borehole in Northern Switzerland, where the formation was affected by a considerable exhumation process. This work aims to investigate the impact of the mentioned phenomenon on the hydro-mechanical behaviour of Opalinus Clay through one-dimensional consolidation and permeability measurements. Laboratory …
Quantifying the thermo-mechanical impact of plume arrival on continental break-up
2013
Abstract The arrival of a plume head at Earth's continental lithosphere is often considered to be an important factor for continental break-up. However, the impact of plume impingement on strength and duration of a rift remains unclear. In this study, we quantify the mechanical and thermal influence of a plume (i.e. lithosphere erosion) on continental break-up. To do that we apply the three-dimensional numerical code SLIM3D that features realistic elasto-visco-plastic rheology. We model the thermo-mechanical response of a segment of Earth's lithosphere that is affected both by extension as well as plume-related lithosphere erosion in order to evaluate the influence on the overall force budg…
Testing a theoretical resistance law for overland flow under simulated rainfall with different types of vegetation
2020
Abstract In this paper a recently theoretically deduced flow resistance equation, based on a power-velocity profile, was tested using data collected for overland flow under simulated rainfall carried out in plots with vegetation. The available data were obtained exploring a wide range of rainfall intensities (from 60 to 181 mm h−1) and slopes (from 3.6 to 39.6%), and with four different types of vegetation. The database, including measurements of flow velocity, water depth, cross sectional flow area, wetted perimeter and bed slope, was divided in four datasets (one for each vegetation type), which allowed the calibration of the relationship between the velocity profile parameter Γ, the slop…
Testing the USLE-M family of models at the Sparacia experimental site in south Italy
2017
The modified Universal Soil Loss Equation (USLE-M) was empirically deduced by a statistical analysis of the original data set of soil loss measurements used to derive the Universal Soil Loss Equation (USLE). The USLE-M, including the effect of runoffin the event rainfall-runofferosivity factor, is characterized by a better capacity to predict event soil loss. At first, in this paper, using the soil erosion representative variables of USLE-M and the reference condition adopted in the USLE, the dimensional analysis and the self-similarity theory are applied to theoretically deduce a multiplicative equation similar to the USLE-M. Then using the database of the Sparacia experimental site, the a…
Measuring rill erosion at plot scale by a drone-based technology
2015
The traditional direct method (i.e. metric ruler and rillmeter) of monitoring rill erosion at plot scale is time consuming and invasive since it modifies the surface of the rilled area. Measuring rill features using a drone-based technology is considered a non-invasive method allowing a fast field relief. In the experimental Sparacia area a survey by a quadricopter Microdones md4-200 was carried out and this relief allowed the generation of a Digital Elevation Model (DEM), with a mesh size of 1 cm and a resolution elevation equal to 2 mm, for three plots (L, G and C) affected by rill erosion. At first for the experimental L plot, which is 44 m long, the rill features were surveyed by a “man…
Effect of cultivation techniques on the hydrodynamic and mechanical behaviour of the "Lauragais-terreforts"
1993
The effect of various seed bed preparations on hydrodynamic and mechanical parameters was studied experimentally by simulated rainfall on clayeyloamy soils Lauragais, which had developed on chalky molasse on a slope greater than 12 %. The level of soaked up rain ("pluie d'imbibition", Pi) is closely connected to the inital degree of saturation of the soil ; it varies from 10 to 24 mm when the soil is humid and increases when the soil is dry (14 to 47 mm). But when the soil surface is crusted the Pi is less and seems to be no longer controlled by the degree of water in the soil. Treatments with fine structural elements show the fewest possibilities of infiltration during the soaking up stage…
Water erosion prediction by stochastic and empirical models in the Mediterranean: A case study in Northern Sicily (Italy)
2012
The present thesis aimed to explore the methodological advantages as well as limitations in applying different modelling approaches to predict water soil erosion in Mediterranean environments. The research was accomplished in the central northern part of Sicily (Italy), considering this region to be representative of Mediterranean environmental conditions. In this region soil degradation problems, due to water erosion are becoming more and more serious. Consequently, defining models being able to predict erosion susceptibility and to discriminate environmental factors causing erosion is important to protect soil resources. The prediction of the spatial distribution of soil erosion processes…
Post-fire practices benefits on vegetation recovery and soil conservation in a Mediterranean area
2021
Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG. [Abstract] Post-fire practices (PFP) aim to reduce soil erosion and favour vegetation recovery, but their effectiveness is spatially heterogeneous and under debate because of the economic and environmental costs. This study evaluates the different changes (Δ) of canopy cover (CC), sediment connectivity (SC) and local topography in four areas affected by the Pinet fire in eastern Spain (August 8th, 2018) and managed with: totally burnt with tree removal and long log erosion barriers (LEBs) (Pinet-1), partially burnt without PFP (Pinet-2), totally burnt with tree removal and short LEBs (Pinet-3), and totally burnt wit…
Sediment yield from glacio-lacustrine calcareous deposits during the postglacial period in the Combe d’Ain (Jura, France)
1998
The middle valley of the river Ain (Jura) cuts through glacio-lacustrine deposits laid down in an ice-dammed lake during the most recent glacial advance. The total volume eroded is about 6·21 ×10 8 m 3 for a surface area of 3·7 ×10 7 m 2 . Erosion occurred between 18 ka BP and 6 ka BP, i.e. over a duration of some 12 ka. Sediment yield from the area was of the order of 2500 t km -2 a -1 , which is comparable with modern-day sediment yield from NW African badlands. These high values are ascribed to the amenability of glacio-lacustrine deposits to mechanical weathering and to the rapid geomorphological changes that affected glacial and paraglacial sedimentary cover after the retreat of the ic…
Sediment Transport and Hydrodynamic Parameters of Tsunami Waves Recorded in Onshore Geoarchives
2014
In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial…