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Oliveira, Henrique Balona de Sá. "Wind erosion of biochar-amended soil: a wind tunnel experiment". Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14312.
Pełny tekst źródłaBiochar application to soils has been reported in the scientific community as a possible means of improving agricultural productivity and, at the same time, as a powerful tool for carbon sequestration and climate change mitigation. However, current knowledge of biochar effects on soil functions and possible environmental threats is still not enough for a full-scale implementation. Erosion is one of the most serious and irreversible threats to soil and there is still no information if biochar may increase or decrease soil erosion rates. Soil erosion by wind is of particular interest for biochar, because of the low particle density and potential human exposure. The purpose of this study was to fill this knowledge gap by investigating the wind erosion potential of biochar-amended soil with a focus on the effect of soil moisture content, using a laboratory wind tunnel. Firstly, experimental tests were implemented in the DAO wind tunnel to define a robust wind erosion methodology in a facility only used for smoke studies. Sediment collecting methods, dust fraction analysis and wind velocity range were the main factors that required investigation. The erosion of biochar-amended soil (10% m m-1) and control soil (sandy soil) was simulated by positioning a tray divided in a sample area and an area for creeping particles, inside the test section of the wind tunnel. To determine the effect of soil moisture content on the erosion potential, four moisture contents were used: 0.2%, 1.7%, 4% and 8% (gravimetric). The wind tunnel simulations were performed with the duration of 15 minutes at a wind velocity of 7 m s-1. The samples of collected sediment were oven-dried and weighed to give the sediment loss as consequence of the erosion event. Results on the erosion simulations for control and biochar-amended soil with the wind flow velocity of 7 m s-1 (small erosion event) indicated that only biochar particles were displaced. Erosion of biochar-amended soil was similar for 0.2%, 1.7% and 4.0% and despite a sediment loss reduction of 50% from 4% MC to the higher MC, 8%, this latter was not identified as the threshold MC for the moment when erosion ceases to exist. As for mineral particles, after 4% MC there was no sediment collected indicating this MC as the threshold, even though a reduced mass of particles eroded for the smaller MCs. Further future tests are needed to build a more comprehensive understanding of wind erosion of biochar-amended soils. Relevant factors to include are: higher wind velocities representative of medium and high erosion events, as well as higher MCs to identify when erosion of biochar particles will stop completely. Secondly, based on the results found in the present study, other soil types and biochar types warrant further investigation. Studies like this contribute for the understanding of the effects of biochar application to soil functions, as well as the behaviour and fate of this material, which are indispensable for the development of adequate biochar regulations and policies.
A aplicação de biochar no solo tem sido referida na comunidade científica como um possível meio para melhorar a produtividade agrícola e, ao mesmo tempo, como um instrumento para sequestro de carbono e mitigação de alterações climáticas. Contudo, o conhecimento actual sobre os efeitos do biochar nas funções do solo e possíveis ameaças ambientais não é, ainda, suficiente para uma implementação em larga escala. A erosão é uma das mais sérias e irreversíveis ameaças ao solo e não existe, ainda, informação se o biochar pode aumentar ou reduzir os níveis de erosão. A erosão do solo pelo vento é de particular interesse para o biochar, devido à reduzida densidade das partículas e à potencial exposição humana. O objectivo deste trabalho foi preencher esta falha ao investigar o potencial de erosão do solo melhorado com biochar com enfoque no efeito do teor de humidade, usando um túnel de vento. Primeiramente, testes experimentais foram implementados no túnel de vento do DAO para definir uma metodologia robusta de erosão eólica numa estrutura, até então, apenas usada para estudos de dispersão de poluentes. A colecta do sedimento, análise de fracção de poeiras e a gama de velocidades foram os factores principais que necessitaram de investigação. A erosão de solo com biochar (10% m m-1) e de solo de controle (solo arenoso) foi simulada posicionando um tabuleiro dividido em área de amostra e área para partículas de rolamento, dentro da secção de teste do túnel de vento. Para determinar o efeito do teor de humidade do solo no potencial de erosão, quatro teores de humidade foram usados: 0.2%, 1.7%, 4% and 8% (gravimétricos). As simulações no túnel de vento foram realizadas com a duração de 15 minutos a uma velocidade do vento de 7 m s-1. As amostras de sedimento colectado foram secas e pesadas para fornecerem a perda de sedimento como consequência do evento de erosão. Os resultados das simulações de erosão para o controle e o solo melhorado com biochar, com a velocidade de 7 m s-1 (reduzido evento de erosão) indicaram que apenas partículas de biochar foram movidas. Erosão de solo com biochar foi semelhante para 0.2%, 1.7% and 4.0% e, apesar da redução da perda de sedimento em 50% do teor de 4% para para o teor mais alto, 8%, este último não foi identificado como sendo o limiar para o momento em que a erosão deixa de existir. Relativamente às partículas minerais, após o teor de 4% não houve sedimento colectado indicando este teor de humidade como o limiar, ainda que uma massa reduzida de partículas tenha sofrido erosão para teores mais reduzidos. Testes futuros são necessários para gerar um melhor conhecimento acerca de erosão de solo com biochar pelo vento. Factores relevantes a incluir são: maiores velocidades do vento, representativas de eventos de erosão médios e elevados, tal como maiores teores de humidade para identificar quando a erosão de partículas de biochar pára por completo. Em segundo lugar, com base nos resultados observados neste estudo, outro tipos de solo e biochar impõe mais investigação.Estudos como este contribuem para perceber os efeitos da aplicação de biochar nos solos, bem como o comportamento e destino deste material, que são indispensáveis para o desenvolvimento de regulamentos e políticas adequadas sobre biochar.
Fernandes, Royston. "Wind erosion in presence of vegetation". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0194.
Pełny tekst źródłaAtmospheric mineral dust resulting from aeolian soil erosion affects the Earth system. Their size-distribution (PSD) plays a key role on atmospheric radiation balance, cloud formation, atmospheric chemistry, and the productivity of terrestrial and marine ecosystems. However, climate models still fail to reproduce accurately the suspended dust PSD. This is explained by the poor representation of the dust emission mechanisms and the associated surface wind speed in these large-scale models. This is particularly true in the presence of surface roughnesses such as vegetation in semiarid regions. This thesis aims at improving the understanding of dust emission in semi-arid environments, characterized by heterogeneous surfaces with sparse seasonal vegetation. To this end, a combination of numerical and field experiments was employed, with investigations progressing from a bare erodible soil to surfaces with sparse vegetation.A review of the existing dust emission schemes showed ambiguities in the parametrization of the processes influencing the emitted dust. A sensitivity analysis, using a 1D dust dispersal model, demonstrated (i) the importance of surface dust PSD and inter-particle cohesive bond parametrization on the emitted dust PSD, and (ii) the importance of the deposition process on the net dust flux PSD. Based on this analysis, a new emission scheme was incorporated into a 3D erosion model, coupled with a Large Eddy Simulation (LES) airflow model, and evaluated first on a bare surface against the WIND-O-V’s 2017 field experiment in Tunisia. The model was able to reproduce the near-surface turbulent transport dissimilarity between dust and momentum observed during the experiment. This means that momentum and dust are not always transported by the same turbulent eddies. The model demonstrated that the main cause of this dissimilarity is the dust emission intermittency, which varies as a function of wind intensity and fetch.The role of sparse vegetation on the net emitted dust flux was then explored using the WIND-O-V’s 2018 experiment, conducted at the same site as the 2017 experiment. The resulting field measurements were used to evaluate the 3D erosion model, including vegetation characteristics. A comparison between the 2017 and 2018 experiments confirmed that sparse vegetation reduces dust emission by increasing the erosion threshold friction velocity, which depends on vegetation characteristics and wind direction relative to the vegetation arrangement. During the 2018 experiment, the net emitted dust flux PSD varied continuously, unlike the 2017 experiment, with a progressive impoverishment in coarse particles (1.50 μm). This impoverishment was found independent of the vegetation, and resulted from the depletion of coarse particles at the surface due to longer emission periods in 2018 without surface tillage or precipitation. This non-influence of vegetation on the dust flux PSD was validated by the similarity of the dust flux PSD at the beginning of the 2018 experiment, when the vegetation was at its maximum height, with the one of the 2017 experiment without vegetation. It was further confirmed by the simulations that demonstrated (i) negligible re-deposition of coarse particles on to vegetation during emission events, and (ii) negligible effect of the turbulence induced by the vegetation on the PSD of the net emitted dust flux.Our 3D erosion model appears as a promising tool for characterizing dust emissions over heterogeneous surfaces typical of semi-arid regions and for deriving dust emission schemes for climate models as a function of surface roughness properties
Chane, Kon Laurent. "Wind erosion modelling of stockpiles and embankments". Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408520.
Pełny tekst źródłaVisser, Saskia M. "Modelling nutrient erosion by wind and water in northern Burkina Faso /". Wageningen : Wageningen University and Research Centre, 2004. http://www.mannlib.cornell.edu/cgi-bin/toc.cgi?5046904.
Pełny tekst źródłaSmith, Stewart Ellis. "An instrument for measuring turbulence during wind erosion". Thesis, Smith, Stewart Ellis (1996) An instrument for measuring turbulence during wind erosion. PhD thesis, Murdoch University, 1996. https://researchrepository.murdoch.edu.au/id/eprint/52753/.
Pełny tekst źródłaOzturk, Mehmet. "The Factors Affecting Wind Erosion in Southern Utah". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7610.
Pełny tekst źródłaAnderson, Robert Stewart. "Sediment transport by wind : saltation, suspension, erosion and ripples /". Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/6703.
Pełny tekst źródłaArmstrong, John C. "Wind erosion and long period climate change on Mars /". Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/5447.
Pełny tekst źródłaWu, Jianzhao. "Numerical simulation of wind erosion : application to dune migration". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC016/document.
Pełny tekst źródłaWind erosion is a complex dynamic process consisting in an atmospheric boundary layer, aeolian particle transport, sand dune deformation and their intricate interactions. This thesis undertakes this problems by conducting three-dimensional numerical simulations of solid particle transport over a fixed or deformable sand dune. Turbulent flow is calculated by a developed numerical solver (Large-eddy simulation (LES) coupled with immersed boundary method (IBM)). Solid particle trajectories are tracked by a Lagrangian approach. Particle entrainment, particle-surface interactions and particle deposition are taken into account by physical comprehensive wind erosion models. Firstly, a new numerical solver has been developed to simulate turbulent flows over moving boundaries by introducing the IBM into LES. Two canonical simulation cases of a turbulent boundary layer flow over a Gaussian dune and over a sinusoidal dune are performed to examine the accuracy of the developed solver. Recirculation region characteristics, mean streamwise velocity profiles, Reynolds stress profiles as well as the friction velocity over the dune are presented. In the Gaussian case, a good agreement between experimental data and simulated results demonstrates the numerical ability of the improved solver. In the sinusoidal case, the developed solver with wall modeling over the immersed boundary shows a better performance than the pure one, when a relatively coarse grid is used. Secondly, physical comprehensive modeling of wind erosion is described in detail, based on the forces acting an individual particle. An instantaneous entrainment model for both lifting and rolling-sliding modes is proposed to initialize particle incipient motions. Lagrangian governing equations of aeolian particle motion are presented and used to simulate the trajectories of solid particles. Particularly, Lagrangian governing equations of bed-load particle motion are originally deduced and applied to model the particle rolling-sliding movement on the bed surface. In addition, particle-surface interactions are taken into account by probabilistic rebound/splash models. Thirdly, numerical simulations of particle transport over a fixed Gaussian dune and over a deformable sinusoidal dune are carried out. In the fixed Gaussian case, an overall good agreement on the particle concentration profiles over the dune between the simulated results and the experimental data of Simoens et al. (2015) preliminarily validates the ability and accuracy of the developed numerical solver coupled with physical comprehensive wind erosion models. In the deformable sinusoidal case, the simulated dune shapes are compared with the experimental ones of Ferreira and Fino (2012). A good agreement between them is observed at t = 2.0 min and an obvious underestimate of the dune shape is shown at t = 4.0 min and t = 6.0 min. By analyzing the simulated results, it is shown that the recirculation zone behind the dune is gradually reduced as the dune deforms and that windward erosion and lee side deposition is observed. It is also shown after testing that the splash entrainment is important for the lee side erosion. Moreover, a preliminary attempt is presented to apply an improved splash model with accounting for the bed slope effect to the simulation of sand dune deformation. A better performance on the simulated dune shape is achieved at t = 4.0 min in comparison with the experimental one
Gonzales, Howell B. "Aerodynamics of wind erosion and particle collection through vegetative controls". Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20382.
Pełny tekst źródłaBiological & Agricultural Engineering
Mark E. Casada
Ronaldo G. Maghirang
Wind erosion is an important problem in many locations, including the Great Plains, that needs to be controlled to protect soil and land resources. This research was conducted to assess the effectiveness of vegetation (specifically, standing vegetation and tree barriers) as controls for wind erosion. Specific objectives were to: (1) measure sand transport and abrasion on artificial standing vegetation, (2) determine porosity and drag of a single row of Osage orange (Maclura pomifera) barrier, (3) assess effectiveness of Osage orange barriers in reducing dust, (4) predict airflow through standing vegetation, and (5) predict airflow and particle collection through Osage orange barriers. Wind tunnel tests were conducted to measure wind speed profiles, relative abrasion energies, and sand discharge rates for bare sand and for two vegetation heights (150 and 220 mm) at various densities of vegetation. Results showed that vegetation density was directly related to threshold velocity and inversely related to sand discharge. The coefficient of abrasion was adversely affected by saltation discharge but did not depend on wind speed. Field tests measured the aerodynamic and optical porosities of Osage orange trees using wind profiles and image analysis, respectively, and an empirical relationship between the two porosities was derived. Vertical wind profiles were also used to estimate drag coefficients. Optical porosity correlated well with the drag coefficient. Field measurements also showed a row of Osage orange barrier resulted in particulate concentration reduction of 15 to 54% for PM2.5 and 23 to 65% for PM10. A computational fluid dynamics (CFD) software (OpenFOAM) was used to predict airflow in a wind tunnel with artificial standing vegetation. Predicted wind speeds differed slightly from the measured values, possibly due to oscillatory motions of the standing vegetation not accounted for in the CFD simulation. OpenFOAM was also used to simulate airflow and particle transport through a row of Osage orange barrier. Predicted and measured wind speeds agreed well. Measured dust concentration reduction at two points (upwind and downwind) were also similar to the predicted results.
Hallward, Jennifer R. "An investigation of the areas of potential wind erosion in the Cape Province, Republic of South Africa". Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/17064.
Pełny tekst źródłaSoil erosion is regarded as a serious problem throughout the world. Erosion is caused by both water and wind. Although the two usually occur together, wind erosion has received little attention with the exception of the problems associated with croplands. Wind erosion can, however, also be a serious problem in natural grazing lands. In this research project an attempt is made to determine the areas of potential wind erosion in the Cape Province through the use of two different models. The models used were developed and applied in semi-arid areas and thus were considered to be applicable in South Africa. The models used are: The Wind Erosion Equation developed by Chepil, Woodruff and Siddoway in the United States; and Lynch and Edward's Model for the Analysis of Limited Climatic Data, developed in Australia. There are two aspects to soil erosion by wind - the erodibility of the soil as determined by moisture, grains size, aggregates, plant cover and surface topography; and soil erosivity as determined by wind strength and duration. Methods to control wind erosion are based on decreasing erosivity through the establishment of shelterbelts and by decreasing erodibility through improving plant cover, aggregate stability and moisture retention properties. Efforts at wind erosion measurement are generally ineffective. A number of models have been developed to overcome these difficulties and to allow for prediction of soil loss. Two of these models are applied to conditions in the Cape Province. This area covers a wind range of climatic, soil and agricultural conditions and as such provides an appropriate area for their application. It is, however, concluded that neither of these models can be directly applied to conditions in the Cape Province. The seasonal rainfall distribution and the uneven distribution of the data points contribute to the ineffectiveness of the models. The greatest problem, however, is the importance of management in determining whether or not wind erosion occurs. As a result, although the models illustrate the general climatic trends affecting the susceptibility of an area to wind erosion, the lack of a management factor accounts for the lack of detail.
Sayah, Selim. "Efficiency of brushwood fences in shore protection against wind-wave induced erosion /". Lausanne : Laboratoire de constructions hydrauliques, 2006. http://library.epfl.ch/theses/?nr=3424.
Pełny tekst źródłaZiemann, Astrid, Klaus Arnold i Hans-Jürgen Schönfeldt. "Studie zur Beurteilung des Winderosionsschutzes durch Erstaufforstung, Gehölzstreifen und Ackerbau im Nordraum Leipzig". Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-215481.
Pełny tekst źródłaOn the one hand, the wind erosion and the associated sediment transport behind extensive forest areas, which are typically for the northern area of Leipzig, and behind narrow shelterbelts were examined in this study. Recommendations for the favourable properties of such protective arrangements with reference to the maximal shelter effect against sediment transport follow from this analyses. On the other hand, the :frequency of the potential occurrence of erosion will be proofed by data of a representatively meteorological station. Critically meteorological conditions appear two times per year corresponding to the statistical analyses
Sundram, Irra T. Mohana. "Empirical and modeling studies on the physical and radiative properties of windblown dust over the Columbia Plateau". Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Spring2005/i%5Fsundram%5F011105.pdf.
Pełny tekst źródłaParsons, Katherine. "Not all droughts are equal: understanding the climate drivers of wind erosion (ENSO, SAM and IOD)". Thesis, Griffith University, 2017. http://hdl.handle.net/10072/373953.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
Copeland, Natalie Suzanne. "Evaluating a wood-strand material for wind erosion control and air quality protection". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Fall2007/n_copeland_113007.pdf.
Pełny tekst źródłaShaw, Susan Calder. "Bedload transport of mixed-sized sediments by wind /". Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6742.
Pełny tekst źródłaLu, Hua Mathematics UNSW. "An Integrated Wind Erosion Modelling System with Emphasis on Dust Emission and Transport". Awarded by:University of New South Wales. Mathematics, 2000. http://handle.unsw.edu.au/1959.4/17476.
Pełny tekst źródłaMacdonald, Hamish. "The infuence of hail on wind turbine blade leading edge erosion and damage". Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=28875.
Pełny tekst źródłaZambrano, Cruzatty Luis Eduardo. "Advancements for the Numerical Simulation of Free Fall Penetrometers and the Analysis of Wind Erosion of Sands". Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104861.
Pełny tekst źródłaDoctor of Philosophy
With global warming and climate change, it is expected that the frequency and intensity of storms will increase. This increment will put extra stress on coastal sediments such as beach sand and coastal dunes, making them prone to erosion. Coastal dunes lose their ability to withstand storms as they erode, potentially making coastal flooding more frequent. In light of this, all stakeholders involved in the protection against coastal disasters must have the tools to predict, prepare for, and mitigate for situations like the ones stated above. An essential aspect of the prediction component is dependent on a successful sediment characterization, for example, determining how much wind the sand can withstand before it erodes. Free-fall penetrometers (FFP) are devices designed to conduct the characterization mentioned above. However, the procedures used to perform this characterization are mainly based on empirical or semi-empirical expressions. Computer models, capable of simulating the physics behind FFP testing, can bring more insight into the process of interaction between FFP devices, sands, and water and can be the basis to improve the characterization methods. The latter results can be utilized for instance to predict wind erosion, including several properties of the sand, such as its mineralogy and shape. This study contributes to developing the computer simulations of FFP deployment and the wind erosion prediction models. Eventually, these developments can help engineers and coastal managers to anticipate and prepare for more frequent coastal hazards.
Batt, Kenneth Leslie School of Mathematics UNSW. "The observation and modelling of winds over South Eastern Australia". Awarded by:University of New South Wales. School of Mathematics, 2004. http://handle.unsw.edu.au/1959.4/23472.
Pełny tekst źródłaAubault, Hélène. "Estimating the Impacts of Pastoral Activities Upon Wind Erosion in the Arid and Semi-arid Rangelands of Eastern Australia". Thesis, Griffith University, 2014. http://hdl.handle.net/10072/368144.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
Bendoni, Michele [Verfasser], i Hocine [Akademischer Betreuer] Oumeraci. "Salt marsh edge erosion due to wind-induced waves / Michele Bendoni ; Betreuer: Hocine Oumeraci". Braunschweig : Technische Universität Braunschweig, 2015. http://d-nb.info/117581881X/34.
Pełny tekst źródłaField, Jason Paul. "Differential Response of Wind and Water Erosion under Climatic Extremes and Alternate Land Management Practices". Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195786.
Pełny tekst źródłaZiemann, Astrid, Klaus Arnold i Hans-Jürgen Schönfeldt. "Studie zur Beurteilung des Winderosionsschutzes durch Erstaufforstung, Gehölzstreifen und Ackerbau im Nordraum Leipzig". Universität Leipzig, 2000. https://ul.qucosa.de/id/qucosa%3A15158.
Pełny tekst źródłaOn the one hand, the wind erosion and the associated sediment transport behind extensive forest areas, which are typically for the northern area of Leipzig, and behind narrow shelterbelts were examined in this study. Recommendations for the favourable properties of such protective arrangements with reference to the maximal shelter effect against sediment transport follow from this analyses. On the other hand, the :frequency of the potential occurrence of erosion will be proofed by data of a representatively meteorological station. Critically meteorological conditions appear two times per year corresponding to the statistical analyses.
Ihde, Nicholas Adam. "Implications of residue removal on soil quality in southwest Kansas". Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/8755.
Pełny tekst źródłaDepartment of Agronomy
DeAnn R. Presley
Through the 2007 Energy Independence and Security Act, the U.S. government has set goals to decrease fossil fuel use and sustainably produce ethanol from biomass, rather than existing corn grain-based ethanol. In southwest Kansas, crop residues are necessary to protect soil from erosion and to contribute to soil organic carbon (SOC) levels, a key factor in most desirable characteristics of soil quality, and are positively related to soil and crop productivity. Our objective was to quantify the effect of different residue management treatments (residue continuously retained, residue continuously removed, and alternating year residue removal) on soil physical properties, chemical properties, and corn yield. For 2.5 years, measurements and samples were collected from a Hugoton loam (L) and Bigbow fine sandy loam (FSL) in southwest Kansas. Residue continuously removed decreased water stable aggregates ≥ 0.25 mm and mean weight diameter of aggregates in contrast to residue continuously retained treatments following two winter seasons at the Bigbow FSL site. In residue continuously removed treatment for the Bigbow FSL, dry aggregate size distribution (ASD) measurements at the soil surface in the fine sandy loam had higher levels of soil % < 0.84 mm (wind erodible fraction) during the winter season of 2008-2009 and 2009-2010 by 6% and 15%, respectively. No significant differences in wet aggregate stability and ASD were measured at the Hugoton L site. Soil temperature and moisture levels monitored during the winter season showed a higher frequency of freeze-thaw cycles, which can be destructive to aggregates, in residue continuously removed plots. During the winter seasons of 2008-2009 and 2009-2010, the residue continuously removed treatments experienced three more freeze-thaw cycles than the residue continuously retained treatments in the Bigbow FSL soil. Bulk density measurements were variable, and no significant differences due to residue treatment were observed in both the loam and fine sandy loam. Total C, N, and exchangeable K were significantly different in residue continuously retained and removed plots due to residue treatment following 1 year of establishment of the study in the FSL. Total C was 14 g kg-1 and 8.7 g kg-1 in the residue continuously retained and removed treatments, respectively. Total N was 0.3 g kg-1 higher in the residue continuously retained versus the residue continuously removed treatment in the FSL. Irrigated continuous corn in southwest Kansas produces a lot of biomass, and has been reported to create emergence problems in the past. Corn emergence was slightly higher in residue continuously removed treatments in both the spring of 2009 and 2010, but differences were insignificant. No significant treatment effects on corn grain yield were observed in the duration of the study.
Malcum, Karin Ceroni. "Avaliação dos efeitos de telas porosas sobre a aerodinâmica de pilhas de carvão". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/12125.
Pełny tekst źródłaThe effects of using wind fences to reduce wind-blown coal dust were studied through wind tunnel tests. The mean and fluctuating pressure distributions over the surface of reduced coal pile models were measured. The tests were performed at a 1/125 scaled model of a typical coal pile. Different fence porosities (68%, 53%, 37%, 0%) as well as different fence positions and heights were tested. Further to the pressure measurements, the field velocities over the surface and surroundings of the piles were obtained through hot-wire anemometry measurements. The fence with no porosity (0%) caused and increase in the re-circulating zone behind the fence, therefore increasing the negative pressures over the pile surface, being soon disregarded. The fences with porosities ranging from 53% to 68% were most effective in reducing the pressure fluctuations on the windward face of the pile, without increasing significantly the mean pressures over it. These pressures are closely related to the dust emissions from the surface, directly affecting the surrounding environment. Although most effective for reducing pressure fluctuations, the best combined effect together with the drag surface velocities were found for the fences with intermediate porosities. The 37% porosity fence was the most effective in reducing the oblique wind induced peak pressures.
Marzen, Miriam Britt [Verfasser], i Johannes B. [Akademischer Betreuer] Ries. "Wind-driven rain: A new challenge for soil erosion research / Miriam Britt Marzen ; Betreuer: Johannes B. Ries". Trier : Universität Trier, 2017. http://d-nb.info/1197703721/34.
Pełny tekst źródłaKeegan, Mark Hugh. "Wind turbine blade leading edge erosion : an investigation of rain droplet and hailstone impact induced damage mechanisms". Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24077.
Pełny tekst źródłaMarzen, Miriam [Verfasser], i Johannes B. [Akademischer Betreuer] Ries. "Wind-driven rain: A new challenge for soil erosion research / Miriam Britt Marzen ; Betreuer: Johannes B. Ries". Trier : Universität Trier, 2017. http://d-nb.info/1197703721/34.
Pełny tekst źródłaGonzales, Howell B. "Cattle feedlot dust – laser diffraction analysis of size distribution and estimation of emissions from unpaved roads and wind erosion". Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/7041.
Pełny tekst źródłaDepartment of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Large cattle feedlots emit considerable amounts of particulate matter (PM), including TSP (total suspended particulates), PM[subscript]10 (PM with equivalent aerodynamic diameter of 10 μm or less), and PM[subscript]2.5 (PM with equivalent aerodynamic diameter of 2.5 μm or less). Particulate emissions result from pen surface disturbance by cattle hoof action, vehicle traffic on unpaved roads and alleyways, and wind erosion. Research is needed to determine concentrations of various size fractions, size distribution, and emission rates from various sources in feedlots. This research was conducted to measure particle size distribution using laser diffraction method and estimate emissions from unpaved roads and wind erosion. Particle size distribution and concentrations of PM[subscript]10 and PM[subscript]2.5 at a commercial cattle feedlot in Kansas (Feedlot 1) were measured over a 2-yr period. The feedlot had a capacity of 30,000 head and total pen area of 50 ha and was equipped with a sprinkler system for dust control. Collocated low-volume samplers for TSP, PM[subscript]10, and PM[subscript]2.5 were used to measure concentrations of TSP, PM[subscript]10, and PM[subscript]2.5 at the upwind and downwind edges of the feedlot. Dust samples that were collected by TSP samplers were analyzed with a laser diffraction analyzer to determine particle size distribution. Particle size distribution at the downwind edge of the feedlot was also measured with micro-orifice uniform deposit impactor (MOUDI). The laser diffraction method and MOUDI did not differ significantly in mean geometric mean diameter (13.7 vs. 13.0 μm) but differed in mean geometric standard deviation (2.9 vs. 2.3). From laser diffraction and TSP data, PM[subscript]10 and PM[subscript]2.5 concentrations were also calculated and were not significantly different from those measured by low-volume PM[subscript]10 and PM[subscript]2.5 samplers (122 vs. 131 μg/m[superscript]3 for PM[subscript]10; 26 vs. 35 μg/m[superscript]3 for PM[subscript]2.5). Both PM[subscript]10 and PM[subscript]2.5 fractions decreased as pen surface moisture contents increased, while the PM[subscript]2.5/PM[subscript]10 ratio did not change much with pen surface moisture content. Published emission models were used to estimate PM[subscript]10 emissions from unpaved roads and wind erosion at Feedlot 1 and another nearby feedlot (Feedlot 2). Feedlot 2 had a capacity of 30,000 head, total pen surface area of 59 ha, and used water trucks for dust control. Estimated PM[subscript]10 emissions from unpaved roads and wind erosion were less than 20% of total PM[subscript]10 emissions obtained from inverse dispersion modeling. Further research is needed to establish the applicability of published emission estimation models for cattle feedlots.
Tommasini, Laura. "Analysis of wind-wave induced erosion in the Venice Lagoon in the last four centuries: field observations and modelling". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425751.
Pełny tekst źródłaI sistemi mareali sono soggetti ad innumerevoli forzanti interne ed esterne, le cui interazioni e feedbacks influenzano l’evoluzione morfologica delle principali strutture morfologiche che caratterizzano gli ambienti a marea:i canali, le barene e i bassifondi. Sono stati svolti innumerevoli studi che descrivono i diversi processi che determinano l’evoluzione degli ambienti lagunari (e.g., l’idrodinamica dei canali a marea, le conseguenze delle correnti di marea e delle onde da vento sulla dinamica dei sedimenti, i meccanismi di evoluzione laterale e orizzontale delle barene, l’incremento del livello del medio mare, gli interventi antropici). Capire i meccanismi di feedback positivi esistenti tra l’erosione delle barene, l’allargamento e approfondimento dei bassifondi e la generazione di moto ondoso più energetico con l’aiuto di dati di campo e di modelli numerici risulta un passo fondamentale per prevedere la risposta delle strutture morfologiche degli ambienti a marea ai futuri cambiamenti ambientali. Al fine di raggiungere questo obiettivo, abbiamo, in primo luogo, ampliato la nostra conoscenza delle configurazioni storiche della Laguna di Venezia attraverso la ricostruzione batimetrica della più antica mappa, risalente al 1611, che forniva una rappresentazione realistica delle strutture morfologiche lagunari. Questo ha consentito di conseguenza di approfondire l’analisi dei cambiamenti idrodinamici che si sono verificati negli ultimi quattro secoli. Abbiamo in seguito confrontato diversi approcci adottati in modelli esistenti, al fine di investigare e comprendere le implicazioni delle diverse assunzioni e formulazioni utilizzate per modellare la dinamica delle onde da vento in bacini a marea poco profondi. Di seguito, abbiamo analizzato gli effetti dell’azione delle onde da vento sui bordi delle barene e il cambiamento del campo di moto ondoso negli ultimi quattro secoli, allo scopo di enfatizzare ulteriormente i feedbacks esistenti tra l’erosione generale della Laguna di Venezia e l’aumento della potenza delle onde. Infine, abbiamo analizzato gli sforzi di attrito al fondo ottenuti per diverse configurazioni della Laguna di Venezia, in modo da supportare la possibilità di descrivere l’erosione del fondo indotta da onde da vento come un processo di Poisson marcato. I principali risultati di questo lavoro hanno evidenziato che: I) i più gravosi cambiamenti morfodinamici nella Laguna di Venezia sono iniziati nell’ultimo secolo e sono stati innescati principalmente dagli interventi antropici; II) le assunzioni adottate in diversi approcci modellistici fortemente influenzano il calcolo dello sforzo di attrito al fondo dovuto alle onde da vento, in particolare quando si considerano profondità molto ridotte; III) il tasso di erosione delle barene è linearmente correlato alla potenza generata dalle onde da vento; IV) la tendenza erosiva della Laguna di Venezia negli ultimi quattro secoli può essere spiegata dall’aumento della potenza media e dall’analisi della distribuzione dello sforzo di attrito al fondo; V) i processi erosivi dovuti alle onde da vento in sistemi lagunari possono essere descritti come processi di Poisson marcato in tutte le configurazioni passate e per quella attuale, questo produce importanti conseguenze per quanto riguarda la previsione di scenari futuri e implicazioni per la modellazione morfodinamica a lungo termine degli ambienti a marea.
Ikazaki, Kenta. "Development of a Land Management Practice for Wind Erosion Control and Improvement of Crop Production in the Sahel, West Africa". Kyoto University, 2010. http://hdl.handle.net/2433/120464.
Pełny tekst źródła0048
新制・課程博士
博士(農学)
甲第15421号
農博第1806号
新制||農||979(附属図書館)
学位論文||H22||N4520(農学部図書室)
27899
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 間藤 徹
学位規則第4条第1項該当
Trosclair, Kevin J. "Wave transformation at a saltmarsh edge and resulting marsh edge erosion: observations and modeling". ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1777.
Pełny tekst źródłaButler, Harry, i n/a. "Local Source Influences Upon the Structure of Dust Plumes in the Channel Country of Western Queensland, Australia". Griffith University. Australian School of Environmental Studies, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051103.155627.
Pełny tekst źródłaPessarakli, Mohammad, David D. Breshears, James Walworth, Jason P. Field i Darin J. Law. "Candidate halophytic grasses for addressing land degradation: Shoot responses of Sporobolus airoides and Paspalum vaginatum to weekly increasing NaCl concentration". TAYLOR & FRANCIS INC, 2017. http://hdl.handle.net/10150/623948.
Pełny tekst źródłaButler, Harry. "Local Source Influences Upon the Structure of Dust Plumes in the Channel Country of Western Queensland, Australia". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/368072.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Australian Environmental Studies
Full Text
He, Yuxin. "Crop residue management and its impacts on soil properties". Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19043.
Pełny tekst źródłaAgronomy
DeAnn R. Presley
Crop residue removal for livestock feeding and biofuel production at large scales must be evaluated to assess impacts on soil productivity and properties. Among all the potential negative impacts, wind erosion is a major concern in the central Great Plains. We conducted an on-farm study from 2011 to 2013 by removing crop residue at five levels (0, 25, 50, 75, and 100%) to determine the effects of crop residue removal on soil wind erosion parameters such as dry aggregate size distribution including soil wind erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) and geometric standard deviation (GSD), dry aggregate stability, and soil surface roughness. The sub-model of Wind Erosion Prediction System (WEPS) developed by the USDA-ARS, Single-event Wind Erosion Evaluation Program (SWEEP) is a stand-alone companion software package that can be applied to simulate soil loss and dust emission from a single windstorm event. We applied measured data (i.e. EF, GMD, GSD, and roughness) to SWEEP for predicting wind velocity that can initiate wind erosion and soil loss under each crop residue removal condition with wind velocity at 13 m sˉ¹. The threshold wind velocity to initiate wind erosion generally decreased with increase in crop residue removal levels, particularly for residue removal >75%. The total amount of soil loss in 3 hours ranged from about 0.2 to 2.5 kg mˉ² and depends on soil condition and crop residue cover. On the other hand, high-yielding crops can produce abundant crop residue, which then raises the question that if a farmer wants to reduce residue, what could they do without removing it? The application of fertilizer on crop residue to stimulate microbial activity and subsequent decomposition of the residue is often debated. We conducted wheat straw decomposition field experiments under different fertilizer rates and combinations at three locations in western Kansas following wheat harvest in 2011 and 2012. A double shear box apparatus instrumented with a load cell measured the shear stress required to cut wheat straw and photomicrography was used to measure the cross-sectional area of wheat straw after shearing. Total C and N were also analyzed. The fertilizer rate and timing of application during summer 2012 and Fall 2013 at the Hays site had impacts on wheat straw shear stress at break point. Across site years, earlier (fall) fertilizer application generally resulted in lower remaining aboveground biomass as compared to a spring application. Multivariate and linear regressions suggested that N and C:N ratio partially explain the results observed with respect to treatment effects on winter wheat residue decomposition.
Furieri, Bruno. "Erosion éolienne de tas de stockage de matières granulaires sur sites industriels : amélioration des méthodes de quantification des émissions". Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2012. http://tel.archives-ouvertes.fr/tel-00853659.
Pełny tekst źródłaFerreira, Maria Clara Schuwartz. "Influence de particules non-érodables dans le processus d'érosion éolienne". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S012/document.
Pełny tekst źródłaWind erosion process can lead to several environmental consequences: desertification, land degradation, air pollution, etc. This last one is related to particulate matter emissions from granular materials commonly found on industrial sites, such as ore and coal. The particle size distribution of these granular materials usually consist of a mixture of a wide range of diameters, which include larger particles that are non-erodible even with strong gusts of wind. The non-erodible particles play a protective role for erodible particles, paving the surface and reducing emissions. The main objective of this thesis is to estimate more accurately emissions due to wind erosion considering the influence of the pavement caused by non-erodible particles. An analytical model was proposed to quantify emissions from particle beds and stockpiles with a wide size distribution. The effects of pavement process are incorporated in the model through the decrease of the mean friction velocity on the erodible surface as the non-erodible particles accumulate. Previous works have defined a mathematical relation between the evolution of the friction velocity over the erodible surface and the geometry of the roughness elements. Nonetheless, the formulation was only valid to limited cover rates of non-erodible particles. Numerical simulations were carried out in this work to extend the formulation in order to include other cases encountered in real situations (with larger amounts of non-erodible particles). The proposed emission model describes the relationship between the minimum value of friction velocity (at which emissions cease), taking advantage of the numerical findings, and the final eroded depth of the bed, which in turn, provides the emitted mass. Wind tunnel experiments were carried out in order to better understand the pavement phenomenon and estimate emissions from a bed of particles containing a bimodal size distribution. The experimental results were also used to validate the modeling, including the global emitted mass and the final characteristics of the bed surface. A good agreement was found between experimental and modeled results for the global emissions and the bed eroded depth. The erosion model was extended for application in stockpiles. In this case, the erodibility of the particles is more complex as the friction velocity and the threshold conditions are not spatially homogeneous. The idea of the model was to subdivide the pile in isosurfaces in which the threshold conditions and the friction velocity are constant and then treat each one of these areas as a different source where the emission model can be applied. Wind tunnel experiments were carried out in order to estimate emissions from a sand pile containing a bimodal size distribution. The modeled and the experimental results were compared for the configuration of an isolated stockpile and a good agreement was found between the estimated and the measured emitted mass. The impact of the presence of a building and a successive parallel stockpiles on the overall particles emission was also evaluated. Wind tunnel experiments and numerical simulations were carried out for several configurations evaluating the effects of: (i) main wind flow orientation, (ii) wind flow velocity, (iii) gap between the obstacle and (iv) amount of non-erodible particles. It was found that the flow interferences between the obstacles increase emissions. Therefore, all wind perturbations have a significant impact and have to be accounted in dust emission estimation and modeling
O processo de erosão eólica pode levar a várias consequências ambientais: desertificação, degradação da terra, poluição do ar, etc. Esta última está relacionada com as emissões de partículas provenientes de materiais granulares comumente encontrados em indústrias, como minério e carvão. A distribuição granulométrica destes materiais normalmente consiste em uma mistura com uma ampla gama de tamanhos, incluindo partículas maiores que não são erodíveis mesmo com fortes rajadas de vento. As partículas não erodíveis desempenham um papel protetor para as partículas erodíveis, pavimentando a superfície e reduzindo as emissões. O objetivo principal desta tese é estimar com maior acurácia as emissões devidas à erosão eólica considerando a influência da pavimentação causada pelas partículas não-erodíveis. Um modelo analítico foi proposto para quantificar as emissões de leitos de partículas e pilhas com ampla distribuição granulométrica. Os efeitos do processo da pavimentação são incorporados no modelo por meio da diminuição da velocidade de fricção média na superfície erodível à medida que as partículas nãoerodíveis se acumulam. Trabalhos anteriores definiram uma relação matemática entre a evolução da velocidade de fricção na superfície erodível e a geometria dos elementos rugosos. No entanto, a formulação é válida apenas para limitadas taxas de cobertura de partículas não-erodíveis (< 12%). Simulações numéricas foram realizadas neste trabalho para estender a formulação de modo a incluir outros casos encontrados em situações reais (com maiores quantidades de partículas nãoerodíveis). O modelo de emissão proposto descreve a relação entre o valor mínimo da velocidade de fricção (para qual as emissões cessam), utilizando os resultados numéricos, e a profundidade final erodida do leito, que, por sua vez, fornece a massa emitida. Experimentos em túnel de vento foram realizados para melhor compreender o fenômeno da pavimentação e estimar as emissões de um leito de partículas contendo uma distribuição granulométrica bimodal. Os resultados experimentais foram também utilizados para validar a modelagem, incluindo a massa global emitida e as características finais da superfície do leito. Uma boa concordância foi encontrada entre os resultados experimentais e modelados para as emissões globais e a profundidade erodida do leito. O modelo de erosão foi estendido para aplicação em pilhas de estocagem. Neste caso, a erodibilidade das partículas é mais complexa, uma vez que a velocidade de fricção e as condições de limiar não são espacialmente homogêneas. A ideia do modelo é subdividir a pilha em isosuperfícies em que as condições de limiar e a velocidade de fricção são constantes e, em seguida, tratar cada uma dessas áreas como uma fonte diferente onde o modelo de emissão pode ser aplicado. Foram realizados ensaios experimentais em túnel de vento para estimar as emissões de uma pilha de areia contendo uma distribuição de tamanho bimodal. Os resultados experimentais e modelados foram comparados para a configuração de uma pilha isolada (orientada 60 e 90° em relação a direção do escoamento) e uma boa concordância foi encontrada entre a massa estimada e a emitida. O impacto na emissão da presença de um edifício e de uma pilha de estocagem sucessiva também foi avaliado. Experimentos em túnel de vento e simulações numéricas foram realizados para várias configurações avaliando os efeitos de: (i) orientação do vento, (ii) velocidade do vento, (iii) espaçamento entre os obstáculos e (iv) quantidade de partículas não erodíveis. Verificou-se que as interferências do escoamento entre os obstáculos aumentam as emissões. Portanto, todas as perturbações no escoamento têm um impacto significativo e devem ser contabilizadas na estimativa e modelagem de emissões de partículas
Barchyn, Thomas Edward, i University of Lethbridge Faculty of Arts and Science. "Field-based aeolian sediment transport threshold measurement : sensors, calculation methods, and standards as a strategy for improving inter-study comparison". Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, 2010, 2010. http://hdl.handle.net/10133/2616.
Pełny tekst źródłaxi, 108 leaves : ill. ; 29 cm
Van, Jaarsveld Francis. "Characterising and mapping of wind transported sediment associated with opencast gypsum mining". Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2352.
Pełny tekst źródłaThis study aims to provide a practical tool for the prediction and management of dust generated by the activities of an opencast mining operation. The study was conducted on opencast gypsum mines in the semi-arid environment of the Bushmanland, 90 km north of Loeriesfontein in the Northern Cape Province from April 2000 to October 2007. The vertical and horizontal components of wind transported sediment were sampled and a dust settling model was designed to predict the settling pattern of dust generated by opencast mining operations. The model was applied to soil samples collected from an area surrounding a mine. The influence sphere of the mining operation was predicted by the application of the model and then mapped. Once the influence sphere is mapped, the dust influence can be managed with the aid of an onsite weather station. By further applying the predictions based on climatic data, the influence sphere can be modelled. The model is not only applicable to the planning phase of an opencast mine to plan the position of dust sensitive areas like the living quarters, office buildings and workshops etc., but also to indicate the historical impact that a mining operation had once a quarry on an active mine is worked out and rehabilitated or a mine is closed. The model application can also aid with the explanation and visual or graphic representation of the predicted impact of planned mining operations on communities or neighbouring activities to them and thus avoid later penalties.
Venier, Chiara. "Evaluation of sediment properties using wind and turbidity observation and experimental investigation of the impact of macroalgal mats on sediment stability and flow dynamics in shallow tidal areas". Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3425340.
Pełny tekst źródłaLa risospensione e la deposizione dei sedimenti sono processi chiave nel governo della morfodinamica a marea e sono influenzate in modo cruciale sia da fattori fisici che biologici. La presente tesi affronta due importanti aspetti dei processi di trasporto dei sedimenti negli ambienti a marea. Il primo argomento riguarda l’analisi quantitativa della concentrazione del sedimento in sospensione e della forzante vento per produrre delle stime delle proprietà del sedimento, quali la velocità di sedimentazione e lo sforzo tangenziale critico per l’erosione, a scale spaziali rilevanti per la generale dinamica morfologica del sistema. La prima parte della tesi pertanto sviluppa e descrive un metodo per valutare le proprietà del sedimento sulla base della soluzione di una equazione di conservazione del sedimento nella colonna d’acqua che tiene conto degli effetti dello sforzo tangenziale al fondo dovuto al vento e alle correnti di marea. Il metodo è applicato utilizzando osservazioni da una rete di sensori nella laguna di Venezia e produce stime in buon accordo con osservazioni puntuali negli stessi siti e allineate con i valori attesi per sedimenti sabbiosi- limosi. L’analisi è stata effettuata attraverso serie temporali relative a intensità del vento, fornite da stazioni anemometriche, a misure di torbidità, fornite da sensori torbidimetrici ed a serie temporali relative a livelli di marea acquisite dalla rete telemareografica; tutte le stazioni operano simultaneamente, sono dis- poste in prossimit`a l’un l’altra e ricoprono grossomodo l’intera area lagunare. Per calcolare gli sforzi dovuti all’azione del moto ondoso è stato implementato un modello puntuale forzato dal vento sotto l’ipotesi di fetch illimitato, in cui gli sforzi sono stati calcolati in funzione del coefficiente di attrito, della densità dell’acqua e della velocità orbitale massima al fondo. La velocità orbitale massima al fondo è stata espressa in funzione dell’altezza d’onda ed il periodo d’onda che è stato calcolato in funzione di parametri adimensionalizzati e seguendo la legge di potenza i cui parametri di fitting sono stati adattati alle osservazioni in laguna. L’altezza d’onda è stata calcolata secondo un bilancio energetico in cui si è trascurata la componente advettiva dell’energia dell’onda. Con il modello forzato dalla marea si sono calcolati gli sforzi in funzione del coefficiente di attrito, della densità dell’acqua e della velocità della corrente di marea. Una volta calcolati gli sforzi tangenziali al fondo è stata implementata l’equazione di conservazione della massa di sedimenti assumendo concentrazione dei sedimenti spazialmente uniforme (divergenza del flusso nulla e continuità della massa d’acqua), in cui la variazione nel tempo del prodotto tra il tirante e la concentrazione (la concentrazione viene espressa come differenza tra la concentrazione effettivamente acquisita dai torbidimetri ed una concentrazione residua che rimane sempre in sospensione in laguna) è data dalla somma tra il flusso di erosione ed il flusso di sedimentazione. Nel caso di processo di sedimentazione, il flusso erosivo è stato trascurato, ed i parametri ws (velocità di settling) e Co (concentrazione residua) sono stati calcolati risolvendo un fitting lineare. Una volta calcolati i valori di velocità di deposizione compresi tra 2.7 · 10-4 e 6.3 · 10−4 m/s e la concentrazione residua compresa tra 6.7 e 16.2 mg/l, si sono successivamente calcolati la velocità di erosione, sulla base della quale si è risolto l’algoritmo del simplesso per ottenere la curva di regressione dei valori medi di velocità di erosione. Dalla regressione si sono ottenuti i valori dello sforzo critico di erosione compresi tra 0.1 e 0.5 Pa e del parametro di erosione compresi tra 2 · 10−6 e 3 · 10−4 kg/sm2. E’ stata compiuta inoltre un’analisi stagionale dopo aver suddiviso le serie temporale in stagioni secondo la suddivisione astronomica. I risultati si sono dimostrati in generale in soddisfacente accordo con i valori misurati in situ attraverso le tradizionali strumentazioni, Sea Carousel e Mini Flume. La metodologia implementata ha il vantaggio di stimare i parametri dei sedimenti senza interferire con gli effetti di bio-stabilizzazione operati dai microrganismi e di fornire una stima parzialmente integrata delle soglie di erosione e della velocità di sedimentazione. Si può in definitiva concludere che il metodo di stima proposto è diretto e quantitativo, non interferisce con lo stato fisico e biologico locale del sistema e si presta ad attività di monitoraggio delle proprietà dei sedimenti su base stagionale e per lunghi periodi, con limitato sforzo operativo. Il secondo, correlato, argomento riguarda lo studio di laboratorio dell’impatto della macroalga Ulva intestinalis, sulla stabilità del sedimento e sul campo di velocità in aree a marea. Le macroalghe, infatti, esercitano un controllo importante sulla distribuzione della velocità e sul trasporto di sedimenti, poichè inibiscono l’erosione del sedimento dovuta a onde o correnti e promuovono la sedimentazione. Larghe estensioni di macroalghe sono sempre più frequenti in molti habitat intertidali estuarini e costieri ed è dunque importante caratterizzare quantitativamente il loro impatto sul campo di moto e la stabilità del sedimento, per una migliore comprensione dell’attuale degrado di lagune costiere e per sviluppare adatte misure di mitigazione e ricostruzione ambientale. La seconda parte della tesi, dunque, descrive e analizza una serie di esperimenti condotti in una canaletta di grandi dimensioni (il Total Environment Simulator - TES- presso l’Università di Hull, UK), con sedimento costituito da sabbia fine, parzialmente coperto da individui di U. intestinalis. L’attività sperimentale è stata indirizzata a quantificare l’effetto delle macroalghe sulla dinamica della struttura del campo di moto indotto da correnti e moto ondoso. L’apparato strumentale utilizzato è costituito da una canaletta di 11 metri di lunghezza e 2 di larghezza, su cui è disposto uno strato di sedimenti artificiali non coesivi (sabbia fine: 135μm di diametro). L’apparato è fornito di generatore di flusso ed onde. Attraverso una completa strumentazione costituita da ADV (Acoustic Doppler Profiler), PIV (Particle Image Velocimetry), ABS (Acoustic BackScat- ter) si sono fornite informazioni su: andamento temporale del vettore velocità, evoluzione temporale della superficie del fondo, andamento temporale della concentrazione dei sedimenti sospesi. Si sono infine utilizzate trappole di sedimento posizionate all’uscita del flusso di corrente dalla canaletta per fornire l’integrale della massa solida trasportata. Sono stati compiuti 12 test simulando diverse condizioni idrodinamiche: corrente ed onde per diversi livelli di tirante (0.21 m; 0.31 m; 0.25 m) dapprima in presenza di macroalghe e successivamente su fondo nudo. Le alghe dopo essere state prelevate presso la Riserva Naturale Nazionale di Budle Bay, sulla costa nord-orientale dell’Inghilterra, sono state ripiantate nello strato di sedimenti della canaletta in modo da seguire una disposizione su linee trasversali sfalsate ricoprendo tutta la superficie della canaletta con una densità di circa 12 unità /m2. Con l’obiettivo di quantificare le osservazioni raccolte durante ciascun test ed in particolare al fine di determinare l’intervallo di tempo entro cui calcolare il valor medio delle velocità turbolente, si è inizialmente calcolata la funzione di autocorrelazione della componente longitudinale della velocità di fluttuazione. Dalla funzione di autocorrelazione si sono calcolate la microscala e la macroscala temporale per i diversi esperimenti. Al fine di calcolare la velocità di attrito ed il parametro di scabrezza di Nikuradse, si è implementata la legge universale logaritmica delle velocità media per paretri scabre. Per ottenere questi parametri, si è realizzato il fitting lineare dei dati sperimentali: dalla stima della pendenza ed intercetta si sono ottenuti la velocità di attrito ed il parametro di scabrezza. Al fine di determinare l’esistenza di una relazione statisticamente significativa tra le rette di regressione (fitting lineare per i quattro ADV nelle 4 posizioni in cui sono stati disposti gli strumenti), si è calcolato l’errore standard per la pendenza e l’intercetta da cui si sono de- terminati i relativi intervalli di confidenza al 95 %. Sia la velocità di attrito sia il parametro di scabrezza sono risultati maggiori nei test con macroalghe piuttosto che nei test senza macroalghe, confermando quanto riscontrato in letteratura sul ruolo bio-stabilizzatore delle macroalghe. Sulla base degli sforzi di Reynolds e del gradiente di velocità media si è poi calcolato il profilo verticale degli sforzi tangenziali, i quali hanno dimostrato comportamenti differenti tra i test con e senza macroalghe. Nel primo caso gli sforzi aumentano dal fondo fino ai primi centimetri per poi diminuire quasi linearmente fino alla superficie, mentre nel secondo caso diminuiscono linearmente dal fondo alla superficie. Infine con l’obiettivo di studiare la struttura della turbolenza, si è calcolato lo spettro monodimensionale dell’energia nel tempo, caratterizzato principalmente dalla presenza di vortici di piccole dimensioni corrispondenti alle alte frequenze. Per visualizzare il trend decrescente della densità di energia è stato calcolato il valor medio dell’energia (binning) nell’intervallo inerziale. Si è calcolato il fitting lineare da cui si è ottenuto il valore della pendenza. Dal confronto delle pendenze per i diversi test, si sono ottenuti valori minori per i test con macroalghe che per i test senza macroalghe, poichè si ritiene che queste ultime agiscano interferendo sulla struttura della turbolenza del campo di energia. Attraverso l’ipotesi di Taylor si è calcolata la macroscala spaziale sulla base delle fluttuazioni temporali precedentemente calcolate, in modo da produrre lo spetto monodimensionale dell’energia nello spazio. Anche in questo caso la pendenza nel test con macroalghe è risultata minore rispetto alla pendenza nei test senza macroalghe. Dall’osservazione diretta compiuta durante gli esperimenti e dai risultati ottenuti dall’elaborazione dei dati di velocità acquisiti dagli ADV, si conferma quanto riscontrato in letteratura riguardo al ruolo bio-stabilizzatore delle macroalghe, a cui si associa riduzione del campo di moto in prossimità del fondo, forme di fondo di dimensioni inferiori, minor quantità di materiale solido trasportato sia di fondo sia in sospensione.
Sauter, Sabine Christina Anna [Verfasser], i Ewald [Akademischer Betreuer] Frie. "Dust Bowls Down Under : An Environmental History of Wind Erosion in the South-East of Australia, 1929–1945/46 / Sabine Christina Anna Sauter ; Betreuer: Ewald Frie". Tübingen : Universitätsbibliothek Tübingen, 2017. http://d-nb.info/1167311329/34.
Pełny tekst źródłaMeeks, Jeremy C. "Fugitive dust emissions from off-road vehicle maneuvers on military training lands". Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/15607.
Pełny tekst źródłaDepartment of Biological and Agricultural Engineering
Ronaldo G. Maghirang
Military installations in the United States may be large sources of fugitive dust emissions. Off-road vehicle training can contribute to air quality degradation resulting from increased wind erosion events as a result of soil disruption; however, limited information exists regarding the impacts of off-road vehicle maneuvering. This study was conducted to determine the effects of soil texture and intensity of training with off-road vehicles on fugitive dust emission potential due to wind erosion at military training installations. Multi-pass trafficking experiments, involving wheeled and tracked military vehicles (i.e., M1A1 Abrams tank, M925A1 water tanker and various HMMWV models), were conducted at three military training facilities with different climate and soil texture (i.e., Fort Riley, KS; Fort Benning, GA; and Yakima Training Center, WA). Dust emissions were measured on site using a Portable In-Situ Wind Erosion Laboratory (PI-SWERL) coupled with a DustTrak™ dust monitor. In addition, a top layer of soil was collected in trays and tested in a laboratory wind tunnel for dust emission potential. In wind tunnel testing, the amount of emitted dust was measured using glass-fiber filters through high-volume samplers. Also, the particle size distribution and concentration of the emitted dust were measured using a GRIMM aerosol spectrometer. Comparison of the PI-SWERL (with DustTrak™ dust monitor) and wind tunnel test (with GRIMM aerosol spectrometer) results showed significant difference and little correlation. Also, comparison of the filter and GRIMM aerosol spectrometer data showed significant difference but high correlation. The dust emission potential (as measured with the GRIMM spectrometer) was significantly influenced by soil texture, vehicle type and number of passes. For the light-wheeled vehicle, total dust emissions increased from 66 mg m-2 for undisturbed soil to 304 mg m-2 (357%) and 643 mg m-2 (868%) for 10 and 50 passes, respectively. For the tracked vehicle, an average increase in total dust emission of 569% was observed between undisturbed conditions and 1 pass, with no significant increase in emissions potential beyond 1 pass. For the heavy-wheeled vehicle, emissions increased from 75 mg m-2 for undisturbed soil to 1,652 mg m-2 (1,369%) and 4,023 mg m-2 (5,276%) for 10 and 20 passes, respectively. Soil texture also played an important role in dust emission potential. For all treatment effects, there was a 1,369% difference in emissions between silty clay loam soil and loamy sand soil.
Xu, Youjie. "Dust emissions from undisturbed and disturbed soils: effects of off-road military vehicles". Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18726.
Pełny tekst źródłaDepartment of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Military training lands can be significant sources of fugitive dust emissions due to wind erosion. This study was conducted to determine dust emission potential of soils due to wind erosion as affected by off-road military vehicle disturbance. Multi-pass traffic experiments using two types of vehicles (i.e., wheeled and tracked) were conducted on six soil textures at four military training facilities: Fort Riley, KS; Fort Benning, GA; Yakima Training Center, WA; and White Sands Missile Range (WSMR), NM. Prior to and after the preselected number of vehicle passes, soil samples at three locations were collected with minimum disturbance into trays. Adjacent to the location where tray samples were collected, a Portable In-Situ Wind Erosion Lab (PI-SWERL) was used to measure dust emission potential. The tray samples were tested in a laboratory wind tunnel (with sand abrader) for dust emission potential using a GRIMM aerosol spectrometer and gravimetric method with filters. Comparison of the PI-SWERL (with DustTrak™ dust monitor) and wind tunnel (with GRIMM aerosol spectrometer) measurement results showed significant difference in measured values but high correlation, particularly for soils with high sand content. Wind tunnel tests results showed that sampling locations significantly affected dust emissions for the tracked vehicles but not for the light-wheeled and heavy-wheeled vehicles. Also, soil texture, number of vehicle passes, and vehicle type significantly affected dust emissions. For the light-wheeled vehicles, dust emissions increased as the number of vehicle passes increased. From undisturbed conditions to 10 vehicle passes, there was a significant (P<0.05) increase in dust emissions (297%) on average for all light-wheeled vehicle tests. From 10 to 25 passes and 25 to 50 passes, an additional 52% and 62% increments were observed. For the tracked vehicle, for the straight section sampling location, dust emission increased as the number of vehicle passes increased. However, for the curve section, dust emissions at any level of pass were significantly higher than initial condition; beyond the first pass, no significant increase was observed.
Miljan, Velojić. "Kvantifikacija procesa eolske erozije na Deliblatskoj peščari". Phd thesis, Univerzitet u Novom Sadu, Poljoprivredni fakultet u Novom Sadu, 2016. https://www.cris.uns.ac.rs/record.jsf?recordId=101274&source=NDLTD&language=en.
Pełny tekst źródłaErosion is a very complex physical process which, under the impact of atmospheric forces, creates destructive changes on the soil surface layer. In case the primary agent of particle movement is wind, we talk about wind or aeolian erosion. Aeolian erosion is a specific process which occurs in extremely complex situations of mutual interaction of numerous natural and anthropogenic factors of mainly stochastic properties making its research a complex scientific-research problem.The main goal of conducted research was to monitor the process of aeolian erosion at the chosen localities of Deliblato Sands, the largest and the most important area of the kind in Europe. In other words, the goal is to determine the quantities of aeolian sediment – sediment transport by direct systematic measurements in field conditions, determine dominant direction of sediment transport, define its annual distribution and determine the effect of vegetation on reducing the intensity of aeolian erosion. During a four-year period, for the first time in this area, i.e. at the same locality, a comparative research of aeolian erosion have been conducted using the mechanical sediment trap and activities based on 137Cs radioisotope tracing technique for estimating soil losses using special theoretical models.The monitoring of aeolian erosion processes was conducted during the period 2006 – 2009 at Cvijićev vis which was chosen as a typical locality since it was, apart from the central position on Deliblato Sands, a cultivated surface without any wind protection. Alongside with these measurements, at Dragićev hat – nursery garden, the monitoring of aeolian erosion was conducted on two measurement points during the period May 2006 – April 2007 in areas with the protective vegetative covers and/or vegetative belts. Aeolian erosion intensity measurement was performed by static sediment traps of the type “deflametre” (dimension of entry opening 10 x 10 cm) oriented on certain directions (N, NE, E, SE, S, SW, W, NW) in order to define the aeolian erosion processes in vector terms. The quantification of aeolian sediment using static traps constantly facing certain wind blowing directions enabled to log and differentiate “summary” yield of aeolian sediment (arithmetic sum of all sediment quantities from all traps) and “resulting” quantity of aeolian sediment (vector sum), since those quantities determine not only the entire amount of transported aeolian sediment (sediment yield) but also the sediment transported outside the areas of erosion field (soil loss), bur also the general direction of its transport.Aeolian erosion measurement on Cvijićev vis for the period 2006 – 2009 indicated thesignificant aeolian erosion processes which were defined by medium annual edimenttransport of 4.48 kg m-1. It has been determined that the total quantities of movedsediment were 25.94, 20.92, 52.98 and 43.47 kg m-1 year-1, and sediment transport 3.24, 2.61, 6.62 and 5.43 kg m-1 year-1 in 2006, 2007, 2008 and 2009 respectively.Sediment transport for the period May 2006 – April 2007 showed that on Cvijićev vis which is characterized by bareness and openness there was the biggest aeolian erosion – four times bigger compared to Dragićev hat – nursery garden I characterized by bareness and protectiveness and 30.2 times bigger compared to Dragićev hat – nursery garden II characterized by overgrown condition and protectiveness of erosive field. At the locality Dragićev hat – nursery garden I the aeolian erosion was recorded 7.5 times bigger compared to the one recorded on Dragićev hat – nursery garden II.Soil loses expressed through the resulting monthly sediment transport (vector sum)equalled 5.13, 2.04, 4.31 and 11.94 kg m-1 in 2006, 2007, 2008 and 2009 respectively, and the percentage share of annual soil losses compared to total sediment yield (arithmetical sum) varied between 8.1% and 27.5%. The resulting aeolian sediment movement direction was SE-NW under the influence of the dominant southeast wind “Koshava”.Even though the most reliable determination of aeolian erosion and its effects is based on direct systematic measurements in real time conditions in the field, starting from the end of the last century the methods of tracking radionuclide from radioactive precipitation, especially 137Cs, for the purposes of estimating the soil loss and spatial distribution of aeolian sediment, have been used increasingly.The total number of samples taken for the method of monitoring the quantity of 137Cs was 149, 9 of which were initial samples (3 profiles with 3 samples each), 14 main samples (2 profiles with 7 samples each), 32 remaining samples (8 profiles with 4 samples each), 36 reference samples (9 profiles with 4 samples each) and 58 samples taken radially on certain directions (N, NE, E, SE, S, SW, W, NW).The main sample taken from the uncultivated land with the detected quantity of 137Cs of 10,603.57 Bq m-2 represents the comparative value, i.e. local precipitation input of 137Cs for the models of 137Cs quantities conversion into the quantities of lost soil. This sample depicts the area where the research was conducted and represents the comparative value which can properly define the aeolian erosion processes.For converting the measured quantities of 137Cs into the quantities of lost soil using Walling model the simplest proportional model (PM) for cultivated land was used and the most appropriate profile distribution model (PDM) for uncultivated soil with the newest version of PC compatible software package in Microsoft Excel Add-Ins. Using the profile distribution model (PDM) on all samples taken from the experimental area the quantities of average soil loss obtained were 207.06 t ha-1 year-1 and 2.10 cm. Basher & Webb model gave the average soil loss of 212.18 t ha-1 year-1 and 2.09 cm. Soil loss calculated using the conversion of 137Cs quantities into the soil loss quantities indicate the significant aeolian processes defined by strong and excessive aeolian erosion.For 58 soil samples taken from areas radially distributed on certain directions (N, NE, E, SE, S, SW, W, NW), apart from 137Cs and 210Pbex concentrations and quantities, spatial coordinates X and Y were determined as well as the altitude of taken samples. Spatial distribution of 137Cs and 210Pbex quantities are represented by isolines, and also 3D demonstrations were created showing the percentage of deviation of 137Cs and 210Pbex from the local precipitation input of 137Cs and 210Pbex. In both cases, the dominant direction SENW was noticeable, i.e. the southeast wind “Koshava”.The comparative analysis of these methods indicated the validity in the quantification of aeolian erosion process and the possibility of its application in the future and the obtained results of aeolian sediment yield and soil loss contributed to determining the state of soil degradation and vulnerability of Deliblato Sands.
Abdourhamane, Touré Amadou. "Erosion en milieu sableux cultivé au Niger : dynamique actuelle et passée en liaison avec la pression anthropique et les changements climatiques". Phd thesis, Université de Bourgogne, 2011. http://tel.archives-ouvertes.fr/tel-00833028.
Pełny tekst źródłaBouzaida, Dalel. "Caractérisation et suivi des états de surfaces éolisés en Tunisie pré-saharienne : approches stationnelle et spatiale". Thesis, Lyon 2, 2012. http://www.theses.fr/2012LYO20016.
Pełny tekst źródłaUnder the effect of climate change, new landscapes reflecting the interactions between natural processes and human inappropriate activities appeared in Southern Tunisia. Wind erosion is one of the most important events. In this thesis, operational and validated methodology (the permanent transect method) has been developed for the characterization of Surfaces States and quantification of the sediment balance of a 500 m length transect over a period of two years. On spatial scale, mapping of the Aeolian units of deflation, transit and sand deposit was developed. Radiometric characterization of sand accumulations was then tried for the detection of changes that occurred within more than 35 years.At the site level, the permanent transect method enabeled the diachronic sedimentary balance calculation and the comparison of the Surface states changes. The single observation of these areas is insufficient to determine the real eolian process of a region ; moreover it induces to errors of interpretation on the sedimentary process.At the spatial scale, maps of the Aeolian units enabeled to determine the vulnerability of the environment to the process of deflation, transport and deposition. In addition, the characterization of sand accumulations by radiometric indices is not obvious within 30 m resolution images. The statistical analyses have shown that Color Index is the most indicated for this type of study. The calculation of the rates of change between two successive dates images allows to estimate the sandy spaces evolution and their spatial distribution for more than 35 years
Prata, Alessandra Rodrigues. "Impacto da altura de edifícios nas condições de ventilação natural do meio urbano". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/16/16131/tde-20012010-113103/.
Pełny tekst źródłaThe objective of this research is to verify alterations of the wind pattern in the study area, stemming from changes to the grids natural ventilation, and evaluate the impact to the pedestrians comfort conditions. The verification of natural ventilation conditions in cities, with the study of models, aids in the creation of architectural or planning - designs, enabling an analysis of the influence of the effects of wind in certain points of the area in study. This thesis object of study is the relation between changes to the framework (building height) and changes to the natural ventilation in urban environments in the area between Canal 1 and 2 (Bairro Pompéia), in the city of Santos/SP. The hypothesis is that natural ventilation in urban areas depends on the height of buildings, direction and velocity of winds. The study involved an experimental method, with wind-tunnel simulation of the urban grid, in loco measurements of the climate conditions, simulation with CFD software and application of a thermal neutrality index. This thesis is experimental and exploratory in its character, and the methods used proved applicable to the understanding of the natural ventilation conditions in an urban environment.