Dissertations / Theses on the topic 'Erosion and mitigation measure'
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SHRESTHA, Badri Bhakta. "Study on Mitigation Measures against Debris Flow Disasters with Driftwood." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/85379.
Abstract:
Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第14913号
工博第3140号
新制||工||1471(附属図書館)
27351
UT51-2009-M827
京都大学大学院工学研究科社会基盤工学専攻
(主査)教授 中川 一, 教授 関口 秀雄, 教授 藤田 正治
学位規則第4条第1項該当
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Chun, Wang. "Erosion-corrosion mitigation using chemicals." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/747/.
Abstract:
The presence of entrained sand in oil and gas production is becoming increasingly prevalent as wells age and this is leading to erosion-corrosion in C02-saturated conditions becoming a major mechanism of material attack. Its understanding, prediction and control are key challenges to sound facilities design. The use of carbon steel in conjunction with corrosion inhibitors in preventing erosioncorrosion has been observed as an economically viable solution for oil and gas piping systems. In order to produce highly effective corrosion inhibitors, it is important to understand how inhibitors act on each of the components of erosion-corrosion. Although research into corrosion inhibition has been extensively conducted, there is less documentation of inhibitors in retarding erosion-corrosion. This thesis has attempted to construct a quantitative structure relationship between erosion, corrosion and their synergistic effects to investigate erosion-corrosion and inhibition mechanisms with four fully formulated CO2 inhibitors (CGO, CRO, CRW8 and CRW9) along with some mechanistic studies involving single components from inhibitor formulations. Two experimental set-ups were used: a rotating cylinder electrode (RCE) and a submerged impinging jet (SIJ). In both experimental methodologies, gravimetric measurement, cathodic polarisation, Linear Polarisation and AC impedance techniques were used to ascertain the extent of corrosion as a function of conditions and inhibitor dosing/type. Both RCE and SIJ test samples were studied using surface analysis techniques such as scanning electron microscope (SEM), Light microscope, Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). In this thesis, through integration of electrochemical analysis and gravimetric measurements the damage has been identified as being associated with mechanical erosion, electrochemical corrosion or interactive electrochemical/mechanical processes. The role that inhibitors can play in reducing damage in addition to that caused by corrosion, namely by erosion and their synergistic action has been shown. Under both configurations. erosion-corrosion interactions play a major role in damage with corrosion being a controlling parameter. The thesis has made substantial advances in the understanding of the extent to which corrosion inhibitors could be used to control erosion-corrosion damage and in understanding the mechanisms of how this can be achieved.
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Song, Layheang. "Usage des terres, ruissellement de surface, érosion des sols : analyse multi-échelles de l'impact des plantations de teck dans un agro-écosystème montagneux tropical humide." Electronic Thesis or Diss., Toulouse 3, 2021. http://www.theses.fr/2021TOU30188.
Abstract:
L'érosion des sols est pourtant connue comme l'un des problèmes environnementaux les plus préoccupants au monde. L'érosion des sols est particulièrement et de plus en plus entraînée par les activités anthropiques dans le cadre du changement climatique. En RDP lao, un pays tropical, l'érosion des sols est due de manière significative à une gestion inappropriée des terres sur les terrains en pente. Le Houay Pano, un bassin versant cultivé du nord de la RDP lao, est exposé à l'érosion des sols, en particulier après la conversion de la culture itinérante en plantation de teck. La mauvaise gestion des terres en défrichant le sous couvert végétal sous la plantation de teck est considérée comme une cause sous-jacente du coefficient de ruissellement (Rc) plus élevé et de l'érosion des sols. Certaines mesures d'atténuation telles que le sous couvert végétal et la végétation rivulaire sont suggérées pour atténuer l'érosion des sols. Cependant, la mesure d'atténuation de l'érosion des sols et l'effet de la gestion de l'utilisation des terres sur le ruissellement de surface (SR) et la perte en sols/rendement de sédiments (Sl) à plusieurs échelles dans la plantation de teck ne sont pas entièrement évalués. Dans ce contexte, nous émettons l'hypothèse que le sous couvert végétal et l'herbe rivulaire atténuent l'érosion du sol dans la plantation d'arbres à teck et que les plantations d'arbres à teck ont ??des impacts sur SR et Sl entraînés par des processus dominants (l'érosion en nappe, l'érosion linéaire et le dépôt de sédiment) sur diverses échelles spatiales. Par conséquent, les objectifs fixés pour ce travail sont : (1) d'évaluer l'effet de la gestion du sous couvert végétal sur le ruissellement de surface et la perte en sols dans la plantation de teck à l'échelle de la micro-parcelle ; (2) d'évaluer la capacité des zones tampons d'herbes rivulaires à atténuer SR et Sl, et d'évaluer leur efficacité de piégeage de l'eau et des sédiments dans les plantations de teck sans sous couvert végétal à l'échelle du versant ; et (3) d'évaluer l'effet de la plantation de teck sur SR et Sl à diverses échelles spatiales (échelles de micro-parcelle, de versant incluant micro-bassin versant, et de bassin versant) dans un bassin versant tropical montagneux à utilisations mixtes de terre. Dans cette étude, le village de Ban Kokngew et le bassin versant d'Houay Pano ont été sélectionnés comme zones d'étude expérimentale pendant la saison des pluies. Des micro-parcelles, des pièges Gerlach et des déversoirs ont été utilisés pour estimer SR et Sl à chaque échelle. Nous avons suivi le modèle TEST développé pour l'érosion en nappe, qui nécessite quelques paramètres, pour évaluer Sl sur la micro-parcelle et le mettre en hautes échelles spatiales pour prédire Sl à l'échelle du versant et du bassin versant. Dans une étude réalisée en 2017 dans les plantations de teck de Ban Kokngew à l'échelle micro-parcelle, nous avons montré que Rc et Sl (23%, 381 Mg·km-2, respectivement) sous teck avec sous couvert végétal étaient inférieurs à ceux sous teck sans sous couvert végétal (60 % et 5455 Mg·km-2, respectivement). Par conséquent, l'atténuation de l'érosion des sols par le maintien du sous couvert végétal sous la plantation de teck réduit Sl de 14 fois. [...]Soil erosion is yet known as one of the most concerning problems of the environment in the world. Soil erosion is particularly and increasingly driven by anthropogenic activities under the changing climate. In Lao PDR, a tropical country, soil erosion is significantly due to inappropriate land management on the sloping land. The Houay Pano, a cultivated catchment of the northern Lao PDR, is prone to soil erosion, particularly after the conversion from shifting cultivation to teak tree plantation. Land mismanagement by clearing the understory under the teak tree plantation is considered as an underlying cause of higher runoff coefficient (Rc) and soil erosion. Some mitigations such as understory and riparian vegetation are suggested for alleviating soil erosion. However, the mitigation measure of soil erosion and the effect of land use management on surface runoff (SR) and soil loss/sediment yield (Sl) on multiple scales in the teak tree plantation are not fully assessed. In this context, we hypothesize that understory and riparian grass mitigate the soil erosion in the teak tree plantation and that teak tree plantation impacts on SR and Sl driven by dominant processes (inter rill erosion, linear erosion, and deposition) on various spatial scales. Therefore, the objectives set out for this work are: (1) to assess the effect of understory management on SR and Sl in the teak tree plantation on the microplot scale; (2) to assess the ability of riparian grass buffers to mitigate SR and Sl, and to assess their water and sediment trapping efficiencies in the teak tree plantations with no understory on the hillslope scale; and (3) to assess the effect of teak tree plantation on SR and Sl on various spatial scales (microplot, hillslope including micro-catchment, and catchment scales) in a mixed land uses mountainous tropical catchment. In this study, Ban Kokngew village and Houay Pano catchment were selected as experimental study areas during the rainy season. Microplots, Gerlach traps, and weirs were used to estimate SR and Sl on each scale. We followed the TEST model developed for inter rill erosion, which requires a few parameters, to assess Sl on the microplot and upscale it to predict Sl on the hillslope and catchment scale. In a study performed in 2017 in the teak tree plantations of Ban Kokngew on the microplot scale, we showed that Rc and Sl (23%, 381 Mg·km-2, respectively) under teak tree with understory were less than those under teak tree with no understory (60% and 5455 Mg·km-2, respectively). Hence, soil erosion mitigation by keeping the understory under teak tree plantation reduces Sl by 14 times. In a study performed in 2014 in the teak tree plantations of Houay Pano on both the microplot and the hillslope scales, we showed that leaving the riparian grass buffer of at least 6 m could limit SR and Sl discharging downstream during small storms (24-hour rainfall < 54.8 mm) with the trapping efficiency up to 88%. Lastly, in a study performed in 2014 in the teak tree plantations of Houay Pano on various scales, we showed that SR and Sl were significantly higher (p-value < 0.05) in the teak-dominated micro-catchment than in the mixed-land-use micro-catchment. SR and Sl decreased from the microplot (122 - 196 mm, 275 - 1065 Mg·km-2, respectively) to the micro-catchment (24 - 188 mm, 95 - 3635 Mg·km-2, respectively) and catchment scale (33 mm, 236 Mg·km-2, respectively), except that Sl in teak tree plantation increased from the microplot (1065 Mg·km-2) to the micro-catchment scale (3635 Mg·km-2). [...]
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Cnossen, Peter D. "Streambank erosion: mechanisms and mitigation techniques." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/101370.
Abstract:
This report presents a study of the various mechanisms that may cause erosion of streambanks and the corresponding mitigation techniques used to combat them. The determination of each may depend upon a number of considerations. The source of the information comes from a variety of reports and papers, which are referenced in the text.
Of all the mitigation techniques available to prevent streambank erosion, fabrics will generally offer the most cost effective method. Fabrics have had a good service record since their inception approximately 20 years ago. Further, as the technology continues to advance, it seems likely that fabric applications in this area will only increase. However, there are some concerns that need to be addressed. These include, assessment of geotextile performance in long term use under the different forces it will be subjected to, clogging potential of fabrics for various soil distributions, and the type of fabrics, woven or nonwoven, used in these applications. These factors should become more clearly defined as long term case study data becomes available.M. Eng.
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Alegre, Sergio Prats. "Soil erosion mitigation following forest wildfires." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11925.
Abstract:
Doutoramento em Ciências do Mar e do Ambiente - Planeamento e Gestão AmbientalThis study aims to measure the effectiveness of four post-fire emergency techniques for reducing overland flow and soil erosion on the central-Portugal typical forest. The selection and development of these techniques was based on the review of the scientific background, but specially after checking throughout field rainfall simulation experiments which factors were the key for runoff and soil erosion on the specific case of high repellent soils. The forest residue mulch, a new treatment never tested before, was highly effective in reducing runoff and soil erosion in recently burnt eucalypt forest. The logging slash mulch had no obvious effect, but it was attributed to the small amounts of runoff and sediments that the untreated plots produced due to the extensive needle cast following a low severity fire. The hydromulch, a mixture of water, organic fibres, seeds, nutrients and a surfactant used in cutted slopes rehabilitation was also highly successful and was specially indicated for especially sensible areas. The utilization of polyacrylamides, a chemical agent with good performance in agricultural erosion, was not successful in post-fire runoff and soil erosion control, once that did not alter the most important key factor for soil erosion: the ground cover. The development of a new fibre optic turbidity sensor was a successful development on the soil erosion determination methodology, and its patent is being processed in the mean time.
O presente trabalho centra-se na avaliação da efetividade de quatro técnicas de controlo da escorrência e da erosão após incêndios florestais, adaptadas para o caso de povoamentos florestais no centro norte de Portugal. A seleção e desenvolvimento das técnicas foi efetuada após revisão bibliográfica alargada, mas sobre tudo após a comprovação no campo, efetuando simulações de chuva, de quais os fatores determinantes da erosão nos solos típicos do centro norte do País, caracterizados por serem altamente repelentes ainda antes dos incêndios. O “mulch” com restos de casca de eucalipto triturada foi um tratamento pioneiro nunca antes testado e deu bons resultados no controlo da escorrência e da erosão em eucaliptais ardidos. O “mulch” com restos florestais não triturados (ramos, paus e folhas) aplicados em um pinhal recentemente ardido não pode ser bem testado devido à protecção natural que forneceram as agulhas do pinheiro que caíram das árvores. No entanto, a sua alta taxa de aplicação desaconselham a sua utilização. O “hidromulch”, uma variante do “mulch” composto por água, fibras orgânicas e sementes utilizadona restauração de taludes e pedreiras, também deu resultados altamente efetivos e foi indicado para o tratamento de áreas especialmente sensíveis. Por outro lado, a utilização de poliacrilamidas (PAM), um agente aglutinante com bastante êxito na redução da erosão em terrenos agrícolas e com alto potencial devido ao seu baixo custo, não obteve resultados satisfatórios, uma vez que não alterou o principal fator envolvido na geração da erosão: o coberto do solo. No decorrer destas experiências, foi ainda desenvolvido um sensor óptico de turvação que permite facilitar a determinação da concentração de sedimentos nas amostras de escorrência das parcelas de erosão. Atualmente, foi realizado o pedido de patente de um novo protótipo de sensor de turvação da água mais desenvolvido.
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Dubey, Anant Aishwarya. "Erosion Mitigation via Bio-Mediated Soil Improvement." Thesis, Curtin University, 2022. http://hdl.handle.net/20.500.11937/89779.
Abstract:
In the present study, the biocementation potent bacteria were isolated from the soil of the Brahmaputra River basin based on the hypothesis that soils are rich in microbial biodiversity. A novel biopolymer-biocement composite was also proposed. The efficacy of biocementation to mitigate soil erosion was studied via lab-scale simulation of aeolian, riverbank and coastal erosion. This study provides solid evidence for substantial improvement in soil erodibility resistance with biocementation.
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Gurhan, Ozkan. "A methodology to measure the metal erosion on recovered armatures." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA401404.
Abstract:
Thesis (M.S. in Physics) Naval Postgraduate School, Dec. 2001.Thesis advisors, William B. Maier II, Francis Stefani. "December 2001." Includes bibliographical references (p. 93). Also available in print.
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Petersen, Paul A. "Mitigation, Monitoring, and Geomorphology Related to Gully Erosion of Archaeological sites in Grand Canyon." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/6730.
Abstract:
Gully erosion has been damaging archaeological sites in Grand Canyon during the last several decades, and there is a need to protect these features through mitigation, monitoring, and better geomorphic understanding. The purpose of this study was to assess the effectiveness of erosion-control structures , determine the accuracy and utility of aerial photogrammetry for monitoring gullies , and understand the geomorphology of the erosion . We performed total-station surveys and other data collection during February and October , 2002, at nine study sites in eastern and western Grand Canyon.
Erosion-control structures are more prone to be damaged by flow when they are placed in reaches of very high local gradient. Treatments are generally successful in slowing erosion or causing deposition of sediment, but damaged erosion-control structures were shown to be less effective than intact structures, and actually increase local erosion in cases.
Aerial photogrammetry was performed on four eroding archaeological sites in western Grand Canyon in March and October 2002 in order to assess the accuracy and change-detection utility of this tool. Accuracy was assessed on several different levels by comparing photogrammetry data to ground-survey data, and mean absolute vertical error ranged from 6-10 cm.
Error of manual photogrammetry digital terrain models (DTMs) increased with topographic ruggedness and decreased with greater photogrammetric point density. Mean error reached a minimum of 5 cm for March and 6.5 cm for October when the ratio of point density to topographic ruggedness was ~40. Ground surveys and repeat photography indicated that two study gullies eroded or aggraded during the study period by 10-20 cm, but these changes were mostly undetected in the photogrammetry DTMs.
Repeat ground surveys showed that gullies erode most at knickpoints and in steep reaches , and that new knickpoints tend to form in relatively steep reaches of a given channel. An area-slope erosion threshold was identified for the study sites and applied in a GIS-based model at four sites to show areas that exceed the threshold and are sensitive to gully erosion . Overall results show an upcatchment control of gully erosion and suggest that baselevel changes due to Glen Canyon Dam operation are subordinate controls.
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Anderson, Dylan Rory. "A hybrid approach to beach erosion mitigation and amenity enhancement, St Francis Bay, South Africa." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/d1008192.
Abstract:
The St Francis Bay beach has experienced chronic erosion over the past three decades. This erosion can largely be attributed to the stabilisation of a large coastal dunefield which contributed +/- 80 percent of the sand supply to St Francis Bay. Stabilisation began in 1975 initially using plant cuttings and followed by the development of the Santareme holiday suburb resulting in complete stabilisation by 1985. Effects were felt from the late 1970‟s and since then the beach has retreated at between 0.5 - 3 m.yr-1. Erosion has encroached on beachfront properties since the early 1990‟s, leading to the placement of 3-4 m high unsightly rock revetments along much of the beach. Where properly maintained these structures have proved successful in protecting the properties behind, however exacerbated erosion of areas in front and adjacent to these structures is evident. Currently no dry beach is present at high tide for most of the year, leading to a significant reduction in beach amenity value. Several technical studies to investigate remediation of this beach erosion problem have been conducted since the early 1990‟s. This study includes investigations into the processes and dynamics of the existing environment and evaluation of the effectiveness and impacts of several elements of a hybrid approach to coastal protection and amenity enhancement for St Francis Bay beach. This proposal incorporated: Multi-Purpose Reefs (MPR‟s) offshore, for coastal protection and amenity enhancement in terms of surfing; beach nourishment with sand from the Kromme Estuary and dune rehabilitation with appropriate native sand binding species. Extensive fieldwork and data collection were conducted, this included: a series of bathymetric surveys; diving surveys and a helicopter flight; sediment sampling; beach profiling and deployment of a wave/current meter. Analysis of these data provided a greater understanding of the existing environment and dynamics of St Francis Bay and provided reliable inputs for numerical modelling. Numerical and physical modelling was conducted to assess the existing processes and conduct MPR design testing. In addition calibrated hydrodynamic modelling of the Kromme Estuary was conducted in order to assess the impacts of sand extraction from the large sand banks within the mouth of the Kromme Estuary for use as beach nourishment. Comparison of bathymetric survey data collected by the author in 2005/06 with survey data collected by the South African Navy Hydrographic Office (SANHO) in 1952 suggest a major loss of sand from the bay, with a volume difference of some 8.8 X 106 m3 calculated. Greater losses were measured between 10-15 m water depths, with shallow areas of +/- 5 m water depth, remaining more stable. This can be attributed to the presence of shallow reef and rocky substrate through much of the bay at this depth range. Monthly RTK GPS survey data from September 2006 to September 2007 indicates a total loss of 40 000 m3 over this period with the greatest losses measured along the northern part of the beach. The greatest losses were measured after large long period waves from a southerly to south-easterly direction occurred in conjunction with equinox tides in mid March 2007. Sediment sampling at over 100 locations within the bay indicated a high percentage of reef (26 percent) and fairly consistent grain size in the fine to medium size class throughout much of the beach, bay and large sand bank within the estuary. While the majority of the South African Coast is exposed to the predominant south westerly winds and waves, St Francis Bay‟s orientation means that waves from a south easterly to easterly direction dominate. The results of the detailed numerical modelling of the hydrodynamics agree with previous calculations and modelling results which concluded that strong unidirectional longshore currents occur along the headland due to the oblique angle of wave incidence and the close to parallel angle of wave incidence along the beach leads to weak longshore currents of variable direction. Erosion along St Francis Bay beach is a result of cross-shore erosion due to large waves from a southerly to easterly direction. Detached breakwaters are the most effective form of coastal protection in these environments and MPR‟s offer additional benefits over traditional breakwater structures. Results of empirical calculations and numerical modelling indicate that the MPR‟s will provide effective coastal protection through the processes of wave dissipation, wave rotation, salient formation and alteration of nearshore circulation. Physical modelling results allowed the MPR design to be assessed and refined in terms of surfing amenity enhancement and construction constraints. In addition numerical modelling results indicate that impacts due to the extraction of up to 600 000 m3 of sand from the lower Kromme Estuary result in highly localised velocity reduction, mainly limited to the extraction areas. The calculated rate of sediment influx into the lower Kromme Estuary indicates that limited extraction, in the order of 20 000 – 40 000 m3 per year, should be sustainable in the long term. Sedimentation of the lower estuary over recent years has had negative recreational and ecological impacts, through reduced navigability and water exchange respectively. Therefore both the estuary and beach systems prove to benefit from this approach. Although not investigated in detail as part of this study, evidence from numerous projects worldwide indicates that foredunes help to trap wind-blown sand on the beach and form a buffer to storm erosion, therefore dune rehabilitation with native sand-binding plant species was recommended as the third element of the proposed remediation of St Francis Bay beach.
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Shoemaker, Alexander Lee Zech Wesley C. "Evaluation of anionic polyacrylamide as an erosion control measure using intermediate-scale experimental procedures." Auburn, Ala, 2009. http://hdl.handle.net/10415/1725.
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RAFFAELE, LORENZO. "Windblown Sand Modelling and Mitigation for Civil Structures." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2729355.
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Cervone, Edmund. "An Engineering, Economic, and Political Approach to Beach Erosion Mitigation and Harbor Development: A Review of the Beach Communities of Camp Ellis, Maine, Wells, Maine, and Cape May, New Jersey." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/CervoneEJ2003.pdf.
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Nejad, Ghafar Ali. "An Experimental Study to Measure And Improve the Grout Penetrability." Licentiate thesis, KTH, Byggvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-184511.
Abstract:
An essential demand in any underground facility is to seal it against the water ingress to reduce the time and cost of the construction and the corresponding environmental hazards. To achieve this, obtaining sufficient grout spread is of great importance. Among the grouts, cement grouts with lower costs and environmental issues have been more reliable, whereas their main problem is filtration that restricts the grout spread. Several investigations have been therefore aimed to develop instruments to measure the grout penetrability as a fundamental means to improve the grout spread. Due to the difference in assumptions, limitations, and test conditions, and the deficiency in design their results are occasionally in contradiction. The question here is how to measure the grout penetrability more realistic? To answer this, two of the most frequently used instruments, Filter pump and Penetrability meter, were adjusted to approach the test conditions in Short slot. The results were discussed with respect to the origins of contradictions to better evaluate the reliability and functionality of the instruments. Among the influencing parameters on grout spread, applied pressure is a key element. The stepwise pressure increment is the method currently used to improve the grout spread in rock. Application of dynamic grouting has been studied as a solution to improve the grout spread for almost three decades. Despite some promising results, the method has not been yet industrialized due to the limited efficiency and issues in the type and frequency of the applied pressure, and the geometry of the test equipment. Therefore, finding a more efficient alternative of the applied pressure was the second goal of this study. A pneumatic pressure control system was consequently employed to examine the efficiency of the method in Short slot. The results conclusively revealed the effectiveness of the method and provided a strong basis for further development of the dynamic grouting.Ett viktigt krav när man bygger under mark är att konstruktionen blir tillräckligt tät, så att inläckage av grundvatten minimeras. Detta minskar både projektkostnaden och eventuell miljöpåverkan. För att skapa en tät konstruktion måste injekteringsbruket spridas tillräckligt i bergmassan. Kemiska injekteringsmedel har ofta bättre spridning i bergmassan än cementbaserade bruk, men cementbaserade bruk är både billigare och ger mindre miljöpåverkan. Det finns dock en del problem med cementbaserade bruk, nämligen att cementpartiklarna filtreras och att brukets reologiska egenskaper begränsar brukets utbredning. Ett antal studier har därför utförts för att studera dessa egenskaper hos cementbaserade bruk och utveckla metoder och instrument för att mäta brukets inträngningsförmåga. Detta i syfte att förbättra brukets utbredning. Dagens metoder och instrument ger nämligen ibland motsägelsefulla resultat på grund av de olika antaganden, begränsningar och förutsättningar som används i de olika testerna. Huvudfrågan är alltså hur man kan mäta brukets inträngningsförmåga på ett mer realistiskt sätt. För att undersöka detta modifierades två vanliga mätinstrument – filterpumpen och filterpressen – för att passa förhållandena i testanordningen Short slot. Resultaten diskuterades med avseende på olika typer av skillnader mellan metoderna i syfte att utröna dels vad som påverkar inträngningsförmågan, dels instrumentens tillförlitlighet och funktionalitet. Bland de parametrar som påverkar brukets spridning i bergmassan har injekteringstrycket en central roll. I dagsläget används stegvis tryckökning för att förbättra brukets spridning i sprickigt, hårt berg. Hur man kan använda dynamisk injektering för att förbättra brukets spridning har dock undersökts under snart tre decennier. Trots lovande resultat av denna metod ännu inte börjat användas i praktiken. Ett problem är svårigheten att ta försök på labb till fältmässiga förhållanden. Ett exempel är att man använde ett tryck som varierade med hög frekvens i en spricka som modellerades med två parallella skivor utan förträngningar, vilket är mycket annorlunda jämförelse med en riktig bergspricka. I modellen blir nämligen brukets spridning starkt beroende av brukets reologiska egenskaper, medan det snarare är filtrering som är problemet i en naturlig spricka på grund av förträngningarna. Dessutom fokuserade tidigare studier endast på sprickor med en sprickvidd större än 100 μm, trots att god spridning av bruket även i de smala sprickorna med mindre än 70 μm bredd är mycket viktigt när det är höga krav på anläggningens täthet. Ett annat mål med denna licentiatuppsats var därför att hitta nya sätt att förbättra brukets spridning i berget. Därför övervakades trycket med ett pneumatiskt kontrollsystem vid tester i Short slot för att studera hur effektiv denna metod är under mer realistiska förhållanden med förträngningar på mindre än 70 μm. Resultaten visade att metoden är effektiv, vilket utgör en bra bas för att fortsätta utveckla dynamisk injektering.
QC 20160413
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HORVAT, MARKO. "Computational Wind Engineering simulations for design of Sand Mitigation Measures and performance assessment." Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2872324.
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Vlčanová, Veronika. "Vliv změn faktoru erozní účinnosti deště na návrh ochranných opatření v povodí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372164.
Abstract:
The subject of the diploma thesis was the evaluation of erosion and drainage conditions in the cadastral area of Čejkovice in the Morava basin and the subsequent proposal of protective measures. The erosion analysis and the subsequent design of the protective measures were carried out in four variants depending on the increasing R factor. In conclusion, the scope of individual protective measures for each variant was evaluated.
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Mendes, Pablo Bettio. "Análise comparativa de elementos de bioengenharia no controle do processo erosivo de um talude de alta inclinação em um curto período de tempo." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/157282.
Abstract:
Submitted by Pablo Bettio Mendes (bettiomendes@hotmail.com) on 2018-10-10T15:48:29Z
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A erosão dos solos é fenômeno natural que ocorre tanto em áreas rurais como urbanas, atuando através da remoção e arraste de material, tendo consequências muito sérias ocasionando diversas perdas financeiras e até de vidas humanas. A necessidade de conter ou controlar esse processo de degradação inspirou o desenvolvimento de várias tecnologias ligadas à área de bioengenharia. Duas delas, biomanta e hidrossemeadura, são atualmente vendidas separadamente no mercado provavelmente por razões comerciais, mas possuem o potencial de ser trabalhadas de maneira integrada. O objetivo do presente trabalho foi testar a eficácia do uso integrado de duas técnicas de controle de erosão causada pela água em encostas e taludes: biomanta e hidrossemeadura. O trabalho foi realizado no município de Sorocaba em um talude com forte pendente disponibilizado dentro do Campus da Faculdade de Tecnologia (FATEC). Foram usados materiais de baixo custo, além do uso de rejeitos de material proveniente de cortes de vegetação de baixo porte que muitas vezes não tem um destino adequado. Para tanto foram construídas oito parcelas retangulares de aproximadamente seis metros de extensão por um metro de largura. Duas destas parcelas foram mantidas continuamente descobertas (condição controle de terreno natural) e as outras seis foram cobertas / protegidas com mantas biodegradáveis, sementes ou sistema integrado de palha e sementes. Ao todo foram construídos quatro pares, cada um deles com uma técnica diferente de combate a erosão. Durante a pesquisa, foram avaliadas e quantificadas as mudas das espécies que germinaram, também foi medido o volume de chuva durante o período. Sem prejuízo, fez-se, também, a quantificação do volume do material erodido (sedimento) em cada tipo de recobrimento após cada evento de chuva.
Soil erosion is a natural phenomenon that occurs in rural and urban areas, acting through the removal and dragging of material, with very serious consequences causing several losses including human lifes. The need to contain or control this degradation process has inspired the development of several technological alternatives linked to the area of bioengineering. Two of them are currently sold separately on the market, probably for commercial reasons, but have the potential to be worked on in an integrated fashion. The aim of the present work is to test the effectiveness of two techniques integrated to avoid erosion caused by water on slopes used together: bio-blanket and hydroseeding. The work was carried out in Sorocaba in a slope with strong inclination made available within the Campus of the Faculdade de Tecnologia (FATEC). For the work, low cost materials were used as the litter usually coming from the tailings, vegetation cuts that often did not have an adequate destination. For this, eight rectangular plots of approximately six meters in length by a meter of width each were constructed. Two of these plots were kept continuously discovered (natural land control condition) and the other six were covered / protected with biodegradable blanket, seeds or integrated straw and seed system. Altogether there are four pairs compared, each with a different solution from the each other. During the research, the seedlings of the species that germinated were evaluated and quantified. The volume of rain was quantified and also the volume of the eroded material (sediment) in each type of cover were also measured right after every rain event
17
Chowdhooree, Imon. "Impacts of structural mitigation measures on perceptions of community flood resilience: Experiences from Haor communities of Bangladesh." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/117767/1/Imon_Chowdhooree_Thesis.pdf.
Abstract:
This research explores perceptions of community flood resilience among adults from isolated settlements in Bangladesh’s Haor region from a perspective of change in the surrounding environment, with structural mitigation measures as outcomes of development planning activities. This research explains perceived resilience as the freedom of choice. This is achieved through eliminating all factors of vulnerability. Through discovering the reason for communities' dependency on external supports, this research proves the necessity of practicing community participation at a meaningful level and prioritizing community concerns and demands in the planning process.
18
Poole, Richard. "The use of tax incentive measure in conjunction with carbon taxes to reduce greenhouse gas emissions and achieve economic growth: a comparative study with lessons for South Africa." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001607.
Abstract:
In 1997 industrialized nations, the Third Conference of the Parties to the United Nations Framework Convention on Climate Change, met in Kyoto, Japan to sign a treaty (the “Kyoto Protocol”) in terms of which industrialized nations would be required to reduce their greenhouse gas emission by at least five percent below 1990 levels by the end of the “first commitment period” 2008-2012. South Africa is not regarded as an industrialized nation, but nonetheless acceded to the Kyoto Protocol in 2002. The literature reviewed in the present research reveals that, although idealistic, the Kyoto Protocol has been problematic. Fourteen meetings of the Conference of Parties to the Kyoto Protocol between 1997 and 2011 have achieved little more than to repeatedly defer and redefine Kyoto obligations. This research was undertaken to document the existing environmental taxation policies employed in selected international jurisdictions with a view to providing a framework for environmental tax policy formation in South Africa to assist this country in meeting its “greenhouse gas” emission targets, while at the same time promoting economic growth. A doctrinal research methodology was adopted in this study as it mainly analysed and interpreted legislation and policy documents and therefore the approach was qualitative in nature. An extensive literature survey was performed to document the various environmental policies that have been legislated in the selected jurisdictions. Comparisons were drawn with proposed tax policy measures for South Africa. The literature indicates that in the selected international jurisdictions carbon taxes achieved less-than-optimal results, largely due to political and industry-competitive agendas. With South Africa planning to introduce a carbon tax, it is submitted that the implementation of a carbon tax regime in isolation will be counter-productive, given South Africa’s economic profile. On the basis of the literature reviewed, it was concluded that South Africa should consider “recycling” carbon tax revenues within the economy to fund a broad-based tax incentive regime that will stimulate the change to non-carbon energy whilst promoting growth through sustainable development
19
Eriksson, Elin. "Initial nutrient retention capacity in a constructed wetland : Evaluating the effectiveness of a newly constructed wetland to reduce eutrophication symptoms in a Baltic Sea bay in northern Sweden." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184268.
Abstract:
Since the turn of the last century, a substantial increase in nutrient load to the Baltic Sea is apparent. Adding the ongoing environmental change with raising temperatures and increased precipitation, this will continue to have a prominent environmental impact on our coastal ecosystems, especially in northern latitudes. Constructed wetlands are becoming more important as a mitigation measure to retain nutrients, however, they are until this day not well studied in northern latitudes. In this paper, nutrient retention in a newly constructed wetland is studied during its first month after activation, as well as potential downstream effects in associated sea bay. An additional literature study compiles information about the current knowledge, use and functionality of wetlands surrounding the Baltic Sea. This is done to widen knowledge regarding effectiveness of wetlands as nutrient traps in general, as well as to compare with the studied wetland. A net retention of 30 % for dissolved organic carbon (DOC) and total phosphorus (TP) was found, as well as 27 % for total nitrogen (TN), 25 % for phosphate (PO43-) and 21 % for nitrate (NO3-). TP was found to be within range of expected retention capacity, when comparing with wetlands included in the synthesis. TN retention, however, seemed to be somewhat greater than in other wetland studies. Furthermore, the retention varied and seemed to be highest during an increased discharge, in the beginning and end of March. This was partly reflected by greater inlet concentrations and transports in most of the parameters during the initial time period. Decreasing temporal trends was seen in concentrations of DOC, total nutrients and NO3- concentrations in the sea bay, indicating an immediate downstream effect of the wetland installation. Findings from the synthesis indicate that there are very few studies in, and thus little knowledge about, wetlands in northern climate. Overall, the results from the pioneer northern wetland in Sörleviken suggest that net retention is possible during its first month post-activation.
20
Piton, Guillaume. "Sediment transport control by check dams and open check dams in Alpine torrents." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU041/document.
Abstract:
Barrages de corrections torrentielles et plages de dépôts jouent un rôle clés dans la protection contre les crues des torrents. Leurs gestionnaires ont pour mission de réduire les risques d'inondations, mais doivent désormais aussi minimiser les impacts environnementaux liés aux ouvrages de protection. Ceci nécessite une meilleure compréhension des effets des barrages de corrections torrentielles et des plages de dépôts sur le transport sédimentaire des torrents. Cette thèse s'inscrit dans cet objectif et se décompose en deux parties. Sa section sur l'état de l'art présente: i) les différents effets des barrages de correction torrentielle sur la production et le transfert sédimentaire; ii) des descriptions des processus hydrauliques et de sédimentation ayant lieu dans les plages de dépôts; et iii) les processus liés à la production et au transfert de bois d'embâcle. Une nouvelle méthode de quantification de la production sédimentaire des torrents complète cet état de l’art.La seconde partie de cette thèse présente le travail réalisé en banc d’essai expérimental. Une première série d’expérience a permis de mettre en évidence un transport par charriage plus régulier lorsque des barrages de correction torrentielle sont ajoutés à un bief alluvial. Une seconde série d’essais a été réalisée sur un modèle générique de plage de dépôt dans l’objectif d’en caractériser les écoulements. Pour cela, une nouvelle procédure de mesure et de reconstruction par approche inverse a été développée. Il en résulte une description des caractéristiques d’un écoulement proche du régime critique, ainsi que des mécanismes de rétrocontrôle entre morphologie et hydraulique pendant la phase de dépôtCheck dams and open check dams are key structures in torrent hazard protection. Their managers must mitigate flood hazards, but now must also minimize the environmental impacts of these protection structures. This requires to improve the knowledge on the effects of check dams and open check dams on the sediment transport, and this thesis forms a contribution towards this end.The section on the current state of research reviews i) the diverse effects of check dams on sediment production and transfer; ii) descriptions of the hydraulics and sedimentation processes occurring in open check dams; and iii) woody debris production and trapping processes. This state of the art is completed with proposition of new bedload transport estimation methods, specifically developed for paved streams experiencing external supply or armour breaking.Experimental results are then provided. Firstly, flume experiments highlight the emergence of a more regular bedload transport when check dams are built in alluvial reaches. In a second stage, experiments were performed on a generic Froude scale model of an open check dam basin in order to capture the features of laterally-unconstrained, highly mobile flows. A new flow measurement and inverse-reconstruction procedure has been developed. A preliminary analysis of the results describes flows that tend toward a critical regime and the occurrence of feedback mechanisms between geomorphology and hydraulics during massive bedload deposition
21
Englund, Sofia. "Optimizing the design of two-stage ditches to improve nutrient and sediment retention." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415420.
Abstract:
Negative effects on water quality are created by eutrophication of the world’s water resources. Mitigation measures have been implemented, but poor improvements in water quality have been observed. Two-stage ditches have the possibility to increase nutrient and sediment retention to reduce eutrophication in receiving water bodies. A two-stage ditch has floodplain terraces on each side of the ordinary main channel. The terraces are available for flooding during high water flows and enables decreases in flow velocities. However, more knowledge is needed about the two-stage ditch and its effect in Swedish landscapes. The aim of the project was to study the two-stage ditch design with focus on water retention. Optimization of the two-stage ditch design was made by modeling and simulating design parameters and vegetation in the software Hydrologic Engineering Center’s River Analysis System (HEC-RAS). An existing two-stage ditch in Sweden was used as base and comparison to the theoretical model. In addition, a climate change scenario was studied to evaluate the impact of increased storm events in a two-stage ditch. Results showed that increased retention time of water, nutrients, and sediments theoretically can be given by designing two-stage ditches with maximum terrace width and minimum terrace height, and with terraces angled away from the main channel. Vegetation should also be kept on both terraces and in the main channel of the two-stage ditch to increase retention time. The study also showed that the two-stage ditch design has the possibility to decrease peak water levels during storm events, which can be expected to increase in the future. The impact on transport of nutrients and sediments from more future extreme hydrological events needs further studies.Negativa effekter i vattenkvalitet skapas av övergödning i världens vattenresurser. Åtgärder för att begränsa övergödningen har genomförts, men svaga förbättringar i vattenkvalitet har noterats. Tvåstegsdiken har möjligheten att öka retentionen av näringsämnen och sediment för att minska övergödning. Ett tvåstegsdike har terrasser på vardera sida om den vanliga mittfåran. Terrasserna är tillgängliga för översvämning vid höga vattenflöden, vilket möjliggör minskning av flödeshastigheter. Dock krävs mer kunskap för tvåstegsdiken och dess effekt i svenska landskap. Syftet med projektet var att studera designen av tvåstegsdiken med fokus på retention av vattenflöde. Optimering av tvåstegsdikens design genomfördes via modellering och simulering av designparametrar och vegetation i programvaran Hydrologic Engineering Center’s River Analysis System (HEC-RAS). Ett befintligt tvåstegsdike i Sverige användes som bas och jämförelse mot den teoretiska modellen. Ett scenario för klimatförändring studerades även för att utvärdera effekten i ett tvåstegsdike då fler stormevent sker. Resultaten visade att ökad retentionstid for vatten, näringsämnen, och sediment teoretiskt kan ges genom att designa tvåstegsdiken med maximal terrassbredd och minimal terrasshöjd, samt med terrasser vinklade bort från mittfåran. Vegetation bör även behållas på terrasser och i mittfåran av tvåstegsdiket för att öka retentionstiden. Studien visade även att tvåstegs- dikets design har möjligheten att minska toppflöden vid stormevent, vilka kan förväntas öka i framtiden. Påverkan på transport av näringsämnen och sediment från fler framtida extrema hydrologiska event kräver ytterligare studier.
22
Qiu, Bo. "Numerical study on vibration isolation by wave barrier and protection of existing tunnel under explosions." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0011/document.
Abstract:
Les vibrations du sol induites par les activités humaines telles que, les activités industrielles, la circulation des camions et voitures, les explosions dues aux constructions ou l’exploitation de la déconstruction, atteignent souvent la limite de gêne pour les usagers et parfois la limite de nocivité. Dans les régions urbaines à forte densité et pour les bâtiments abritant des équipements sensibles, les vibrations du sol doivent être strictement contrôlées. Jusqu'à présent, de nombreuses méthodes de réduction de vibration ont été proposées, dont l'une est l'installation d'une barrière d'ondes entre les sources et les structures à protéger. Au cours des dernières décennies, l'efficacité de l'isolation des vibrations à l’aide de barrière d'ondes a été étudiée. Toutefois, il y a peu de travaux consacrés à l’influence mutuelle des paramètres du système sol-barrière sur l'efficacité de l'isolation de la barrière d'ondes, et l'optimisation de la barrière d'onde est également rare. D'autre part, l'influence des vibrations du sol, générées par les explosions durant la construction d’un nouveau tunnel, sur un tunnel avoisinant, interpelle en raison des dommages qui peuvent être produits. Jusqu'à présent, il existe peu de mesures d'atténuation globale proposées par les chercheurs et les ingénieurs concernant la réduction de vibrations dans les tunnels lors des explosions. Pour répondre à ces insuffisances, cette thèse porte sur l'étude de l'influence des différents paramètres du système sol-barrière et qualifie l'efficacité de l'isolation de la barrière d'ondes. Les paramètres clés sont identifiés, leur rôle respectif quantifié. Plus important encore, une méthode de conception d'optimisation est mise au point, dans le but de proposer la barrière qui est capable de réduire au minimum la vibration du sol en site protégé. Enfin, le comportement dynamique du tunnel existant sous les sollicitations des explosions proches est examiné. Les paramètres qui influent considérablement sur la réponse du tunnel sont mis en évidence. Deux mesures d'atténuation pratiques, concernant l'installation d'une couche de protection le long de la paroi du tunnel d’une part et des explosions à retardement (plutôt que des explosions instantanées) d’autre part, sont présentées en détails. Les recherches menées dans le cadre de cette thèse sont en mesure de fournir des éléments pour la conception optimisée de la barrière d'ondes afin de réduire les vibrations du sol en site protégé et pour la conception de mesures d'atténuation concrètes afin de protéger un tunnel existant par des explosions à proximitéGround vibration induced by human activity such as industrial activities, car or truck traffic, or pilling and blasting in construction or deconstruction operation, generally reaches the troublesome limit for men and occasionally attains the harmful limit. In the densely populated urban regions and buildings housing sensitive equipments, ground vibration has to be strictly controlled. Up to now, many vibration reduction methods have been proposed, one of which is the installation of wave barrier between the dynamic sources and the protected structures. Over the past decades, the vibration isolation effectiveness of wave barrier has been extensively studied. However, to the best of the writer’s knowledge, there is little study about the mutual influence of the parameters of soil-barrier system on the barrier screening efficiency, and the optimization design for wave barrier is rare as well. On the other hand, the influence of ground vibration generated by explosions on the nearby existing tunnel has attracted more and more attention due to the recent damage or even failure of tunnels. Up to now, there are few mitigation measures comprehensively proposed by researchers and engineers for the tunnel vibration reduction during explosions. To overcome those drawbacks, this dissertation focuses on the investigation of the influence of various parameters of soil-barrier system on the barrier isolation efficiency. Key parameters are identified. More importantly, an optimization design method is developed, aiming to find out the desirable barrier that is able to minimize the ground vibration in protected site. Besides, the dynamic behavior of existing tunnel under nearby explosions is examined. Parameters that significantly affect the response of tunnel are pointed out. Furthermore, two practical mitigation measures: the installation of a protective layer along the tunnel lining and time-delayed explosions (rather than instantaneous explosions), are presented with details. The research in this dissertation is able to provide a good reference for the optimization design of wave barrier in reducing ground vibration in protected site and for the design of practical mitigation measures to protect existing tunnel from nearby explosions
23
Lopes, Ana Rita Brás. "Evaluation of two measures for soil erosion mitigation after wildfire." Master's thesis, 2017. http://hdl.handle.net/10773/24055.
Abstract:
Wildfires contribute for soil degradation and acceleration of erosion processes. Emergency measures applied after wildfire can be decisive in mitigating soil loss and preserving fertility. In this study, which was held in Semide in a area burned in August 2015, two measures were evaluated: ploughing and mulching. Both selected by the stakeholders during a participatory process developed under the RECARE European project. Ploughing is a recurrent practice of forestland management following a wildfire in order to prepare soil for planting and / or seedling. Ploughing was implemented in July 2016 and consisted on the analysis of two contiguous areas, with ploughed plots and control, respectively. Soil and organic matter losses were monitored at two scales: MP (0.25m2) and SF plots (16m2). Soil losses in the SF plots were quite similar between the both treatments. In the MP soil losses were three times higher in the ploughed plots. At the level of the SF plots the efficiency of the treatment was positive, with a more relevance in the mitigation of organic matter loss (61%). In the MP ploughing was inefficient in losses mitigation. Losses decreased over the study time. The ploughed plots revealed, at both scales, a higher cover of the soil surface by stones and less vegetation, when
compared to the control. However, results obtained from the ploughing experience are considered inconclusive given the short period of experimental monitoring (7 months) and the fact that soils were ploughed 11 months after the wildfire. The second year of data monitoring of the mulching experience aimed to evaluate the efficiency of the treatments on soil protection against the direct impact of the raindrops. The treatments consisted in the application of the mulch at two rates: the standardized rate in the literature as efficient in soil
protection (8 Mg ha-1) and the innovative low rate (2.6 Mg ha-1). The treatments were applied in three replicate SF plots, one per block. It was also monitored 6 MP, 2 for each block, where in addition to soil and organic matter was also evaluated the surface runoff. The SF plots with the application of the high mulch rate revealed lower losses of soil than the plots treated with the low mulch rate. The highest losses were obtained in the control SF plots. The efficiency of the treatments in soil and organic matter loss mitigation was 94% and 90%, respectively, in the SF plots with the high rate mulch, and 68% and 62%, respectively, in the SF plots with the lowest rate application. In the three treatments the soils losses area considered in the literature as tolerable (1 Mg ha-1 year -1). The development of new vegetation was higher in the control SF plots than in the treated ones. The MP revealed intolerable soil losses.Os incêndios florestais contribuem para a degradação do solo e aceleração dos processos de erosão. As medidas de emergência aplicadas após incêndio podem ser determinantes na mitigação da perda de solo e na preservação da fertilidade. Neste estudo, que decorreu em Semide, numa área ardida em Agosto de 2015, foram avaliadas duas medidas: lavragem e a aplicação de mulching. Ambas as medidas foram selecionadas pelos atores sociais interessados no decorrer do processo participativo desenvolvido no âmbito do projeto europeu RECARE. Considera-se a lavragem uma prática recorrente de gestão de terrenos florestais depois de um incêndio na preparação dos mesmos para plantação e/ou sementeira. A lavragem, implementada em Julho 2016, consistiu na análise de duas áreas contíguas, com parcelas lavradas e controlo. Foi monitorizada a perda de solo e matéria orgânica a duas escalas: MP (0.25m2) e parcelas SF (16 m2). As perdas de solo nas parcelas SF foram similares entre tratamentos. Nas MP as perdas de solo foram três vezes mais altas nas parcelas lavradas. Ao nível das parcelas SF a eficiência foi positiva, com maior relevância na mitigação de perda de matéria orgânica (61%). Nas MP a lavragem revelou-se ineficiente na mitigação de perdas. A perda de solo e de matéria orgânica foi diminuindo ao longo do tempo de estudo. As parcelas lavradas revelaram, em ambas as escalas, maior cobertura de solo com pedras e menos vegetação, relativamente ao controlo. Contudo os resultados obtidos foram considerados inconclusivos dado o curto período de monitorização experimental (7 meses) e ao facto da lavragem ter sido implementada 11 meses após o incêndio. A monitorização do segundo ano da experiência de mulching visou avaliar a eficiência na proteção do solo à ação da precipitação, tendo os tratamentos derivado da aplicação do material a duas taxas: a taxa estandardizada na literatura como eficiente (8 Mg ha-1), e a inovadora baixa aplicação (2.6 Mg ha-1). Estas taxas foram aplicadas em três parcelas SF replicadas por três blocos. Foram ainda monitorizadas 6 MP, 2 por cada bloco, onde, para além da avaliação das perdas de solo e matéria orgânica, foi analisada a escorrência superficial. As parcelas SF com a aplicação da taxa de mulch mais alta revelaram perdas mais baixas de solo e de matéria orgânica que as parcelas com a aplicação da taxa mais baixa. As perdas mais elevadas foram obtidas no controlo. A eficiência na mitigação de perda de solo e matéria orgânica foi de 94% e 90%, respectivamente, nas parcelas com taxa de mulch mais alta, e 68% e 62%, respectivamente, nas parcelas com a taxa mais baixa. Nos três tratamentos as perdas de solo consideradas pela literatura como toleráveis (1 Mg ha-1 ano-1). O desenvolvimento de nova vegetação foi mais elevado no controlo do que nas parcelas SF tratadas. As MP revelaram perdas intoleráveis de solo.
Tese desenvolvida no âmbito do projeto europeu RECARE – Preventing and Remediating degradation of soils in Europe through Land Care, financiado pelo 7º Programa-Quadro Europeu (FP7) direcionado para pesquisa e desenvolvimento tecnológico.
Mestrado em Gestão e Políticas Ambientais
24
Chuang, Li Sheng, and 莊禮盛. "The Mitigation of Erosion Phenomena for Butterfly Valves." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/45050112769858979283.
Abstract:
碩士國立成功大學
機械工程學系
86
In a piping system, butterfly valves are often used as a flow controller to either modulate the flow throttling range or control the flow's on/off positions. Because butterfly valves are usually light-weighted and low cost, they have a wide range in size selection and possess a small flow resistance, therefore, they are widely accepted in many industrial applications. After a certain period of service, a butterfly valve and its downstream pipe wall may be damaged by erosion. The elimination or mitigation of this kind of erosion problem is actually the most important issue for a valve user. An experiment setup is used in this study to investigate the erosion problem. The water tunnel is 3 inches in diameter and the pipes are made by transparent PE for the ease of flow visualization and photograph purpose. At certain key positions, the pressure and flow vibration level are also measured to support the observation of possible erosion phenomena. The results indicate the most serious erosion problem may occur when the valve open angle is between 20-40 degrees. In this paper, five different valve disks are used to perform the tests, the results shows the model 5 have the smallest vibration level both on the valve stick and its downstream pipe wall under the critical valve opening angle. These results implies that a suitable buffer attached on the back side of disk surface near the orifice side could mitigate the erosion phenomena.
25
Myint, Than. "Erosion mitigation practices for stream protection in the Eden woodchip area." Master's thesis, 1990. http://hdl.handle.net/1885/115481.
Abstract:
Field inspections to establish the frequency of occurrence and the length of sediment tongues
around the boundaries of drainage lines of logged coupes on the granite soils in the Eden Woodchip
Area, New South Wales showed that a sediment tongue occurs for every
0.5 km of drainage line but that sediment tongues penetrate to drainage lines on average once per
2.4 km of drainage line.
When the lengths of sediment tongues are compared with the provisions for buffer strip width, it is
concluded that, for slopes for up to 20*, a width of buffer strip of 20 metres is conservative.
Associated studies of the source of sediment in sediment tongues, using the isotopes Cs-137 and
Be-7, showed that the source of the sediment was almost entirely from the snig tracks. The methods
used are promising for the study of sediment tongues.
26
Lin, Ching-Jia, and 林慶家. "Application of UAV Photogrammetry to Measure Erosion in Mudstone Badland." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/38srx9.
Abstract:
碩士國立彰化師範大學
地理學系
107
Mudstone badland refers to the rugged and bare landscape, which is mainly resulted from weak rock, low cohesion, low water permeability, and high salinity concentration. When rainfall drops on the surface, the rapid erosion on the surface triggers gully erosion, mud-flow, and landslide hazards. Observations of the topography change and erosion rate in high spatial and temporal scale help clarify the mechanism of surface erosion and develop erosion susceptibility model. However, the traditional measurements of erosion pin and erosion plot can only provide erosion rates at a specific site or region-averaged. This study used UAV photogrammetry to establish high spatial and time resolution Digital Surface Model (DSM). By comparing the multi-temporal DSMs, I determined the erosion rate and it correlation with rainfall and topography attributes. I firstly set up the ground control points (GCPs) and independent control points (IGCs) and used the UAV to take stereo-photos from 2016/3/18 to 2018/10/19. Then, I used Pix4DMappr software to establish the DSMs. After obtaining the DSMs, we then validated the accuracy of DSM, calculated the erosion rate of each event, and correlated the erosion rate with rainfall, slope, slope aspect, and curvature. The results show that the ground sampling distance of the DSMs are 0.005 m. The root mean square errors in vertical direction are 0.026 m and 0.130 m. The averaged surface erosion rate is 0.53 m from 2016/3/15 to 2018/10/19. The erosion rates positively correlated with slope gradient on the slope < 50°, but the erosion is consistent at the rates from 0.2 to 0.4 m on the slope ≥ 50°. The erosion rate is highest on the south aspect and decrease gradually to the northwestern aspect or on the convex slope. The analysis of rainfall factor and erosion rate show that maximum 48-hour rainfall has highest r-square with the erosion rates, which can be expressed by an empirical formula of y = 0.0003x - 0.0234 (R2 = 0.6106). Moreover, the erosion rate on the sandstone area is on 73.5% of the averaged rate, which means lithology is another controlling factor. This study shows that several erosion processes occurred during rainfall simultaneously, including the uniform erosion pattern cause by rainfall splash, erosion in the gullies by overland flow, and the rapid erosion by landsliding. The study also demonstrated that UAV photogrammetry is feasible to produce multi-temporal DSM and measure the surface erosion because of its high mobility, low cost, and high precision.
27
Sawatsky, Les, Wes Dick, Dave L. Cooper, and Marie Keys. "Design of a rainfall simulator to measure erosion of reclaimed surfaces." 1996. http://hdl.handle.net/2429/10787.
Abstract:
Rainfall simulation is a useful tool in the analysis of soil erosion. The use of rainfall simulators has become more widespread with the development of automated instrumentation and control systems which offer a physically based system of predicting soil erosion. A variety of simulator designs have been used. This paper describes a rainfall simulator designed for analysis of erosion on steep (2.5H: 1V) reclaimed sand slopes at two oil sand mines near Fort McMurray, Alberta. The rainfall simulator applies artificial rain on a 225 m² test site divided into two side-by-side
test plots.
Most rainfall simulators have used a constant intensity of rainfall throughout a given simulation event. The rainfall simulator designed for this project can vary the rainfall application rate in fifteen discrete rainfall intensity increments. Therefore, it is capable of simulating a variety of non-uniform rainfall hyetographs. The rainfall simulator consists of a system of seven nozzles on each of 27 vertical support pipes. A combination of nozzles was
used to simulate a desired uniform or non-uniform rainfall hyetograph with intensities ranging from 10 mm/h to
200 mm/h. The rainfall simulator also successfully simulated extreme historic and synthetic hyetographs.
28
Morris, Rowena Helen. "Managing post-fire soil erosion in the southern Mount Lofty Ranges." Thesis, 2013. http://hdl.handle.net/2440/83354.
Abstract:
Post-fire soil erosion is a great concern to land managers due to the potential adverse effects on water quality, the alteration to soil profiles and the detrimental impacts on human communities. To reduce the potential adverse effects of post-fire erosion mitigation actions have been instigated following severe wildfires. Various programs of prescribed burning have been initiated to reduce the risk of wildfires. In order to predict and manage post-fire erosion a clear understanding is needed of the influential environmental variables, associated processes and whether mitigation actions will be effective. In the Southern Mount Lofty Ranges there is a paucity of post-fire erosion data from which to generate evidence-based predictive models and management recommendations. This thesis has the overarching goal of developing evidence-based options for managing post-fire sediment movement in the Southern Mount Lofty Ranges. Evidence-based management of sediment movement from both prescribed fire and wildfire can reduce potential erosion and hence protect regional natural services such as soil profile formation, soil mineral health, the regulation of water quality and maintenance of local landscape character. A case study of the Southern Mount Lofty Ranges is used to produce evidence-based options for managing post-fire erosion in relation to a wildfire at Mount Bold and ten prescribed burns conducted within the Southern Mount Lofty Ranges. Field techniques included visual erosion assessments, erosion pins, terrestrial laser scanning, digital close range photogrammetry and sediment traps. Experiments were designed to incorporate the spatial differences within the topography. Regression modelling was used to analyse environmental variables that influence post-fire sediment movement. Erosion assessments indicated that after prescribed burning sediment movement occurred in 52% of the burnt areas compared to only 4% in the unburnt areas, however magnitude of movement was only minor. Fire severity was the most influential variable in generating sediment movement after prescribed burning. In contrast slope steepness was the most influential environmental variable in relation to the magnitude of erosion after the 2007 wildfire at Mount Bold. After a 1 in 5 year rainfall event hay-bale sediment barriers will reduce but not prevent post-fire charcoal-rich sediment and debris reaching water reservoirs. Managing soil erosion in the post-fire landscape requires an appreciation of the influencing environmental variables and the available mitigation options. This thesis highlights the importance of recognising the spatial variability of the topography when managing post-fire erosion. A suite of environmental variables including fire severity, rainfall, aspect, bioturbation, slope length, slope angle and cross-slope curvature need consideration when predicting the occurrence of sediment movement following prescribed fire. Mitigation actions to minimise the adverse effects of post-fire erosion need to take account of rainfall intensity, fire severity and topographical influences. Management of post-fire soil erosion in the Southern Mount Lofty Ranges also needs a recognition of the potential influence on regional natural services including soil profile formation, regulating water quality and maintaining local landscape character.Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2013
29
Nelson, Alison G. "Soil erosion risk and mitigation through crop rotation on organic and conventional cropping systems." 2005. http://hdl.handle.net/1993/20689.
30
Juan, Pardo María Elena [Verfasser]. "Characterisation and mitigation of chemical erosion of doped carbon materials / María Elena Juan Pardo." 2004. http://d-nb.info/973055421/34.
31
Thelberg, Hanna, and Birgitta Sjödell. "Impact of agroforestry on soil loss mitigation in the sloping land of Northwest Vietnam." Thesis, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-411180.
Abstract:
Soil erosion is one of the major threats to soil functions in many parts of the world. To- day’s challenge is to adapt agriculture practices in order to reduce soil erosion and at the same time consider local conditions. One solution that has been proposed for hilly regions is agroforestry, a land-use system in which woody perennials are grown on the same piece of land as agricultural crops and/or animals. This Master thesis was conducted in two sites in Northwest Vietnam, in Son La and Dien Bien province. Northwest Vietnam is characterized by a mountainous landscape and agri- culture is practiced in the hills, often as monoculture of sole crops. This type of land use in combination with seasonal large high-intensity rains aggravates soil erosion. In this study, agroforestry (AF) practices’ capacity for erosion control was evaluated, and compared to sole crops of the dominant species in the area. An Experimental Trial in form of replicated field plots of block design and a larger Exemplar Landscape were used. The Experimental Trials and the Exemplar Landscape had two treatments, one AF system and one control treatment with sole crops. The AF system included crops, fruit trees and grass strips with the aim to form terraces naturally. To evaluate the AF’s capacity for erosion control, average amount of lost soil was es- timated in the Experimental Trials by three methods; erosion traps, erosion pins (both field methods) and a WEPP model. Another function of the erosion pins was to evaluate the movement of soil along the hillside. Soil texture, structure, color and signs of bio- logical activity were analyzed from soil profiles. Soil samples were also taken for soil analyzes of parameters needed for calculations and the WEPP model. A method was also developed to assess the terrace formation over a longer a time scale. Results of this study showed that agroforestry in combination with grass strips perform well in decreasing soil loss in the Son La study site. The soil loss in Son La was found to be 43% less two years after establishment compared to the sole maize system figuring as the control. The results also showed that grass strips have the ability to start forming terraces already one year after establishment of the Experimental Trial in both study sites. The terraces showed further development several years after the establishment at land- scape level.
32
ŠLAPÁKOVÁ, Veronika. "Uplatnění meziplodin jako stabilizujícího prvku v protierozní ochraně v oblasti podhůří Šumavy." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-188519.
Abstract:
The aim of this thesis is to evaluate the possibility of applying the intercrop in the erosion control crop rotation and their effect on the system of the sustainable agriculture and assess the suitability of utalizition of the intercrop as an element of the erosion control for the environmentally friendly farming on the arable ground. Erosion phenomena will be evaluated in the selected location and in the cadastral Borovany. The outcome will be the evaluation of the washes of the conventional crop rotation and of the process which uses the intercrop using the USLE method.
33
Almeida, Hugo. "Erosão e Galgamentos na Costa Portuguesa." Master's thesis, 2019. http://hdl.handle.net/10400.26/31287.
Abstract:
Neste trabalho avaliaram-se os resultados da implementação dos instrumentos de gestão territorial na ocupação do espaço costeiro em Portugal, bem como a eficácia das medidas propostas e suas implementações ao longo dos últimos anos, nas alterações à exposição do risco de erosão e galgamentos costeiros. A opção de escolha deste estudo deveu-se, fundamentalmente, à importância na identificação, resolução e mitigação dos problemas da zona costeira portuguesa, nomeadamente no facto de esta assumir uma importante estratégia no que diz respeito à política de desenvolvimento sustentável do nosso país, e ao seu enquadramento numa gestão integrada e coordenada destas áreas. O trabalho consistiu, essencialmente, na avaliação do atual estado da arte no que diz respeito ao que tem vindo a ser feito, analisando a mais valia dos investimentos nas medidas implementadas nas últimas décadas, com especial incidência em dois casos de estudo, considerados dos mais representativos da atual realidade da nossa costa. Os estudos focados evidenciam essas fragilidades, associadas a um excesso de confiança nas defesas costeiras adotadas, bem como a vulnerabilidade a que as comunidades estão sujeitas. Torna-se, pois, urgente garantir a segurança de toda a costa de forma a mitigar o avanço do mar em direção a terra sendo, para isso, importante analisar e encontrar soluções que permitam alcançar um equilíbrio na dinâmica sedimentar. Assim, entende-se como prioritária a criação de um depósito maior de inertes nas zonas junto à costa permitindo, desta forma, o efeito de perda de energia das ondas na sua rebentação, resultando na redução do seu espraiamento pela costa. Através da utilização de novas técnicas entretanto desenvolvidas, em detrimento das técnicas de ripagem classicamente usadas, as quais consistem na utilização de um processo mecânico de Bypass – solução nunca testada em Portugal – usando sistemas de bombagem permanente, seria possível transportar areias submersas de locais de maior acumulação, para as zonas mais carenciadas, permitindo assim a sua reposição nas zonas costeiras que se encontram com um forte défice sedimentar.This work evaluated the results on the implementation of territorial management instruments in the occupation of coastal space in Portugal, as well as the effectiveness of the proposed measures and their implementations over the past few years, on changes in exposure to erosion risk and coastal gaps. The choice of this study was fundamentally due to the importance on identifying, solving and mitigating the problems of the Portuguese coastal zone, in particular the fact that it assumed an important strategy regarding our country's sustainable development policy, and its integrated and coordinated management of these areas. The work consisted mainly on evaluating the current state of the art on what has been already done, analysing the added value of investments in the measures implemented during the last decades, with a special focus on two case studies considered to be the most representative of the current reality of our coast. The focused studies highlighted these weaknesses, associated with overconfidence in the coastal defences adopted, as well as the vulnerability to which communities are subject. Therefore, it is urgent to ensure the safety of the whole coast in order to mitigate the sea progress towards the land and, for this reason, it is important to analyse and find solutions that allow a balance in the sedimentary dynamics. Thus, it is understood as a priority to create a larger deposit of aggregates in the areas near the coast, allowing the effect of energy loss of the waves in their surfacing, resulting in the reduction of their spreading by the coast. Through the use of new techniques recently developed, instead of those classical ripping techniques from the past, which consist of the use of a mechanical Bypass – a solution not yet tested in Portugal – using permanent pumping systems, it would be possible to transport submerged sands from greater accumulation, to the most deprived areas, thus allowing them to be replenished on the coastal zones that have a strong sedimentary deficit.
34
Putter, Henrike. "Analysing the South African General Anti-Avoidance Rule as a Pre-emptive Base Erosion and Profit Shifting (BEPS) Measure." Diss., 2016. http://hdl.handle.net/2263/58739.
35
ČERNOHORSKÁ, Veronika. "Uplatnění meziplodin jako stabilizujícího prvku v protierozní ochraně." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-317861.
Abstract:
By this diploma paper we are going to find out what influance intercrop included in sowing process has on soil wash off. In the first part of the diploma paper describes erosion, erosion control measures and intercrops. The other part deals with the calculation of erosive wash off. Erosive soil wash off is calculated according to Wischmeier - Smith equation and results of sowing processes are compared and evaluated. Erosive wash off is calculated on the selected location in the basin of Zdíkov brook in the foothills of the Šumava.
36
ROLNÍKOVÁ, Jitka. "Návrh plánu společných zařízení ve zvolené lokalitě." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-395261.
Abstract:
The diploma thesis is devoted to the elaboration of a plan of common facilities in the cadastral area Přídolí. The work focused on the methodological procedure in the implementation of ground adaptations, according to technical and metodical standards. The content of the first part is a literature review, which not only describes the field of land consolidation and its course, but also specifies the plan of common facilities together with the scope of work necessary for its elaboration. Everything important in this section is theoretically described. In the second practical part, attention is paid to the selection of the territory and the evaluation of its condition with the help of exploratory works. Further to the field research, the practical part is focused mainly on the proposal of individual proceedings concerning the protection of ZPF, elements of TSES, water management elements and ensuring access to lands. The results of surveys and draft measures are presented in both text and graphic form.
37
ANDREJKOVÁ, Michaela. "Zpracování plánu společných zařízení pro komplexní pozemkovou úpravu." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-395252.
Abstract:
This diploma thesis is focused on the elaboration of a plan of joint facilities for comprehensive land treatment in the selected cadastral territory of Dolní Třebonín, located in the South Bohemian Region. The purpose of the thesis is the characterization and evaluation of the cadastral area as part of the need to implement these joint facilities: anti-erosion measures for the protection of agricultural land resources, measures for access to land, measures for protection and creation of the environment and water management measures. The theoretical part of this work is literary research. This section explains basic concepts such as land treatment, forms of land treatment, exploration works and joint facilities. The practical part describes the characteristics of the selected area, the exploration work in the given area and the proposal of the common facilities. The results are processed in textual and graphical form using ArcMap 10.0.