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Muller, Eugene 1951. "In situ measurement of the cohesion of a cemented alluvial soil." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277090.
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A modified plate load (MPL) test was developed to measure the in situ cohesion of a carbonate or caliche cemented soil. The MPL test was performed on the crest of a vertical cut in alluvial soil with a steel plate loaded until the soil failed. A three-dimensional slope stability analysis was then used to back calculate soil cohesion. In situ test results were used in conjunction with laboratory testing of deaggregated soils samples to completely define the Mohr-Coulomb strength parameters of the in situ soil. In order to check the result of the in situ test procedure, the field test conditions were modeled for use in a two-dimensional slope stability analysis using the computer program CSLIP1. A comparison of the results shows reasonable values of soil cohesion were obtained using the MPL test method.
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Marriott, Susan B. "Floodplain processes, palaeosols and alluvial architecture : modelling and field studies." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321271.
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Vanbuskirk, Stephanie. "Alluvial stratigraphy and soil formation at Cox Ranch Pueblo, New Mexico." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Fall2004/s%5Fvanbuskirk%5F120904.pdf.
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Al-Hawas, Ibrahim A. M. "Clay mineralogy and soil classification of alluvial and upland soils associated with Blackwater and Nottoway rivers in southeastern Virginia." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44104.
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Because the Coastal Plain of southeastern Virginia has not been extensively studied, thirty random samples associated with Blackwater and Nottoway rivers were collected in the spring of 1987 from Surry, Sussex, and Southampton counties. Soil classification as well as mineralogical, chemical, and physical analysis were conducted for all samples.
The purposes of this investigation were to: (1)classify the soils in this area, (2) determine the distribution of sand and clay minerals, (3) examine the weathering effect on clay minerals on different position of the landscape for different parent material sources.
The soils examined classified as follow: Aquic Hapludults 43% > Typic Hapludults 26.6% > Ultic Hapludalfs 10% > Humic Hapludults 3% = Typic Rhodudlts 3% = Aquic Hapludalfs 3% = Typic Udipsamment 3% = Typic Quartzpsamment 3% = Psammentic Hapludalfs. Qualitative analysis of clay minerals revealed that kaolinite and hydroxy interlayer vermiculite were the dominant clay minerals; that montmorillonite, mica, gibbsite quartz, and vermiculite were of lesser quantities; that chlorite, feldspar and interstratified minerals were of trace amounts. Kaolinite represents about 21-70%, HlV 11-60%, montmorillonite 0-20%, mica 0-16%, gibbsite 0-13%, quartz 1-12%, and vermiculite 0-10%. The presence of these minerals were mainly related to the acid reaction of the soil media, which was essentially attributed to Al and H ions in soil solution. From the past history and geological composition of the Piedmont it is assumed that kaolinitic minerals were transported and sedimented in the Coastal Plain. Hydroxy-interlayer vermiculite minerals was weathering from vermiculite because most of the Al was adsorbed by vermiculite to form HIV. Therfore, gibbsite was not precipitated. Montmorillonite was assumed to have formed from mica minerals. That was substantiated by statistical analysis which showed a high negative correlation between gibbsite and vermiculite (r=0.46, n=30) and between montmorillonite and mica (r=-0.6, n=10).
Master of Science
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CHADWICK, OLIVER AUSTIN. "INCIPIENT SILICA CEMENTATION IN CENTRAL NEVADA ALLUVIAL SOILS INFLUENCED BY TEPHRA (DURIPAN, TAXONOMY, OPAL-CT, GENESIS)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/187945.
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Silica cemented pedogenic horizons known as duripans occur on relict landforms in climates having limited leaching potential. Under the influence of tephra, incipient silica cementation may also occur in late Quaternary soils. The source of silica for cementation in Holocene soils is rapidly weatherable volcanic glass. In response to wetting and drying cycles volcanic glass weathers to form sand-size composite particles composed of silt, clay and redeposited silica. A portion of the hydrolyzed silica is eluviated as monosilicic acid which accumulates as the wetting front evaporates. Illuvial silica augments existing composite particles eventually forming a continuously cemented duripan. In actively forming late Quaternary soils, the cementation process is a complex interaction between illuvial silica, clay and calcium carbonate and the soil matrix. Surface reactions between monosilicic acid and illuvial clay or soil matrix particles provide nucleation sites for polymerization of silica concentrated by evaporation. The resulting opaline silica bonds adjacent soil grains without necessarily plugging intervening pore spaces. In contrast, calcium carbonate preferentially precipitates in large pores and interped voids. Cementation occurs by the plugging of progressively smaller pores with relatively pure calcite rather than by heterogeneous bonding of mineral grains. In illuvial zones containing both silica and calcium carbonate, cementation may occur rapidly because the former holds small soil particles in place while the latter plugs large pores. The mineralogy of silica cement is determined by identification of varying amounts of crystal order using X-ray diffraction. Opal-A is recently polymerized, noncrystalline, highly hydrated silica gel. The more prevalent, partly crystalline opal-CT forms where surface reaction with clays create crystal orientation, where silica gel dehydrates or when silica precipitates from soil solutions having high concentrations.
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Perez, Waldo Flores, Jorge Chavez Cerdena, Gary Duran Ramirez, and Maggie Martinelli Montoya. "Correlation of dynamic probing light (DPL) and standard penetration test (SPT) for sandy soil of alluvial origin." Institute of Electrical and Electronics Engineers Inc, 2020. http://hdl.handle.net/10757/656568.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.In geotechnical studies, the dynamic probing light (DPL) turns out to be an alternative method to the Standard Penetration test (SPT) for the determination of soil parameters. The requirement of various regulations for correlating both tests in the same field and not establishing a methodology to carry it out, limits the practical scope of dynamic probing light. Thus, this research presents a correlation methodology between the dynamic probing light (DPL) and the Standard Penetration test (SPT) specifically for sandy soils (SP and SP-SM) located in an area of Chilca, located in Cañete. - Lima Peru. For the analysis, more than 400 data pairs were used, obtaining two linear correlations between the count blow of Standard Penetration-NSPT test and the dynamic probing light method-N10, which presented an adjustment correlation between 84% and 87 %.
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Mayer, James H. "Late Quaternary Landscape Evolution, Environmental Change, and Paleoindian Geoarchaeology in Middle Park, Colorado." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193994.
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Stratigraphic records in Middle Park in north-central Colorado provide evidence for the late Quaternary geomorphic and environmental history of a non-glaciated Southern Rocky Mountain basin. Episodes of geomorphic instability apparent in the stratigraphic record coincide with changes in paleoenvironmental records from above 2750 m in north-central Colorado, suggesting that the western Middle Park landscape was sensitive to environmental changes affecting the region over the last ~14,000 years. Tributaries were incised prior to 14.0 ka, but deposits older than 12.0 ka are rare. Upland erosion and incision followed by rapid aggradation in alluvial settings between 12.0 and 11.0 ka coincide with evidence for regional temperatures at or above present, and is interpreted to signal the onset of Holocene summer-wet precipitation. A widespread soil-stratigraphic marker represents a long period of landscape stability between <11.0 and 6.0 ka in upland and alluvial settings. Pedologic evidence from upland settings indicates the expansion of grass and forest cover to lower elevations that today are characterized by sagebrush steppe, probably during a period of increased summer precipitation relative to present. During the late Holocene, episodes of aggradation in alluvial valleys at 6.0-1.0 ka and 0.6-0.2 ka and soil formation in uplands at 5.0-3.5 ka and 2.5-1.0 ka overlap with evidence for cooling at higher elevations. Incision of valley floors documented at 1.0-0.6 ka and during the last few centuries and episodes of erosion in uplands at 3.5-2.5 ka, after 1.0 ka, and within the last few centuries, are roughly synchronous with evidence for warming. Upland and alluvial stratigraphic records are interpreted to indicate that during cool intervals summer precipitation was diminished, resulting in relative hillslope stability and gradual valley bottom aggradation, while pulses in summer precipitation accompanying warmer episodes caused basin-wide geomorphic instability. The recent increasing frequency of geomorphic instability appears to correspond with an increase in sagebrush steppe at the expense of forest and grass cover, interpreted to represent progressive drying during the late Holocene. It stands to reason that future warming, if accompanied by similar patterns in precipitation, will result in continued erosion on a landscape already at a threshold of geomorphic instability.
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Avsar, Ulas. "Evaluation Of Alluvial Deposits In Gemlik Basin In Terms Of Earthquake Odes." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607247/index.pdf.
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Gemlik County is located in the Marmara Region (NW Turkey), which has been affected by destructive earthquakes sourced from North Anatolian Fault System throughout its history. The bulk of the settlement rests on alluvial deposits of the Gemlik pull-apart basin. So, it is vital to investigate the foundation soils in this basin and the response of them to earthquakes. Many earthquake codes were established by the authorities in different countries of the world to estimate the possible ground shaking and seismic loads which may act on buildings. In this study, Turkish Earthquake Code (TEC-1998) and Eurocode-8 (EN-1998) have been utilized. The analyses showed that EN-1998 results in more conservative estimates relative to TEC-1998, in terms of spectral ordinates. The source of difference between TEC-1998 and EN-1998 has been investigated and three possible reasons have been identified. The variation is probably due to the different seismic characteristics of Turkey and Europe, different soil amplification levels defined by the codes, and different soil classification procedures of the codes.
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Nasermoaddeli, Mohammad Hassan [Verfasser], and Erik [Akademischer Betreuer] Pasche. "Bank erosion in alluvial rivers with non-cohesive soil in unsteady flow / Mohammad Hassan Nasermoaddeli. Betreuer: Erik Pasche." Hamburg-Harburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2012. http://d-nb.info/1048542378/34.
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Kross, Jennifer. "Conservation of Waste Rice and Estimates of Moist-soil Seed Abundance for Wintering Waterfowl in the Mississippi Alluvial Valley." MSSTATE, 2006. http://sun.library.msstate.edu/ETD-db/theses/available/etd-01112006-164423/.
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Waste rice in harvested fields and natural seeds in moist-soil wetlands are important foods for waterfowl in the Mississippi Alluvial Valley (MAV). Waste rice declines significantly between harvest and late autumn. I conducted experiments in 19 rice fields in Arkansas and Mississippi during autumns 2003 and 2004 to evaluate the ability of common post-harvest practices to conserve waste rice between harvest and late autumn. Greatest mean abundance of waste rice in late autumn occurred in standing stubble (x&95 = 105 kg/ha; CL = 72.84, 150.16 kg/ha) followed by burned (x&95 = 72 kg/ha; 49.57, 105.81 kg/ha), mowed (x&95 = 67 kg/ha; 46.65, 97.42 kg/ha), rolled (x&95 = 51 kg/ha; 35.54, 73.076 kg/ha), and disked stubble (x&95 = 48 kg/ha; 33.26, 68.41 kg/ha). I recommend leaving stubble or burning fields to create interspersion of stubble and water after flooding. Additionally, I estimated abundance of moist-soil seed in 72 management units on public lands throughout the MAV for autumns 2002-2004. Mean seed abundance was 496 kg/ha (SE = 62). I recommend increased active management of moist-soil wetlands to mitigate decreased availability of waste rice in the MAV.
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Ounaïes, Sana. "Modélisation du transfert hydrique dans l'aquifère alluvial du polder d'Erstein (Bas Rhin)." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAH011/document.
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Les aménagements hydrauliques du Rhin ont fortement modifié le fonctionnement hydrologique des zones alluviales et provoqué la déconnexion de la plupart des bras du Rhin et des forêts alluviales. Des opérations de ré-inondation des secteurs déconnectés du fleuve ont été menées dans un objectif à la fois de rétention de crue et de submersion écologique qui devraient permettre à ces zones de retrouver tout ou partie de leur fonctionnalité. Le polder d’Erstein est un secteur forestier expérimental pour le suivi de l’impact des ré-inondations des zones alluviales. Les inondations du polder par les eaux de Rhin sont susceptibles d’en modifier le fonctionnement hydrologique (écoulements de surface, échanges nappe-rivière, recharge de la nappe …). L’objectif général de ces recherches est l’analyse et la quantification des transferts hydriques dans un aquifère poreux dans un contexte de ré-inondation. Pour ce faire nous avons réalisé des simulations numériques de l’écoulement à l’aide du code de calcul Feflow (Finite element subsurface flow system), qui ont été validées par les données hydrogéologiques mesurées in situ. Ce travail est organisé en cinq volets. Le point de départ est un état de l’art du fonctionnement, de la structure des zones alluviales et des mécanismes du transfert hydrique dans ces zones. La deuxième partie, fournit une présentation détaillée du site expérimental sur lequel une mission de suivi scientifique a débuté en 2003 et ainsi fourni une importante base de données hydrologiques (eaux de surface et eaux souterraines). Ces données ont servi à caractériser les écoulements d’eau en zone non saturée. La troisième partie est consacrée à la construction du modèle hydrodynamique. Compte tenu de l’importance du réseau des anciens bras du Rhin alimentées par la nappe existant à l’intérieur du polder, la question des échanges cours d’eau-nappe a été abordée. Hormis la recharge de la nappe par les cours d’eau, une part importante de l’infiltration d’eau depuis la surface du sol lors des inondations contribue à la recharge. Pour quantifier cette part, nous avons développé une approche pédologique originale afin de caractériser les hétérogénéités des sols par des paramètres hydrodynamiques. Ces hétérogénéités qui varient spatialement sur le polder ont une influence significative sur les flux verticaux et les temps de résidence de l’eau dans la zone non saturée. Les résultats obtenus en 1D ont ensuite été appliqués à toute la superficie du polder d’Erstein avec l’objectif de quantifier l’ensemble des écoulements à cette échelle. Différents scénarios d’hétérogénéité proposés se fondent sur une complexification de la structure de l’aquifère poreux, afin d’évaluer l’impact des hétérogénéités du sol sur le transfert hydrique dans le polder d’ErsteinThe hydraulic management of the Rhine has drastically modified the hydrological functioning of alluvial zones and caused the disconnection of most side-channels of the Rhine and alluvial forests. The re-flooding restoration works of the disconnected sectors are planned with objective of both the retention of flood and of ecological flooding which should allow these zones to recover all or part of their functionality.The Erstein polder is a forested experimental area for monitoring the impact of the alluvial zones re-flooding. The flooding of the Rhine plain may modify its hydrological functioning in terms of runoff, groundwater-river exchanges and groundwater recharge. Our general objective is to analyze and quantify water flux in an unsaturated porous aquifer. Therefore, based on the given hydraulic and hydrogeological conditions of the study site, we performed numerical flow simulations using the finite element model Feflow 5.3.This work is structured in five chapters. The starting point is a state of the art about the functioning and the structure of alluvial zones and the mechanisms of water flux in these areas. The second chapter presents the experimental site. A scientific monitoring mission has been implemented on the polder site and an extensive data base of hydrological measurements (surface and groundwater) was created. This data base was used to characterize the water flux in the unsaturated zone. The third chapter is devoted to the construction of the hydrodynamic model. Given the importance of the side channels network supplied by the existing groundwater inside the polder, the water exchange between surface water and groundwater was discussed. Apart from the groundwater recharge by streams, a significant infiltration of water from the soil surface during flooding contributes to groundwater recharge. To quantify this part, we developed an original approach in order to characterize the heterogeneities of soils using hydrodynamic model parameters. These heterogeneities that vary spatially on the polder have a significant influence on the vertical flow and the residence time of water from the ground surface to the groundwater. The results obtained in 1D were then used to model the influence of soil heterogeneities of the entire area of the study site on water infiltration during inundation event and groundwater recharge. Different scenarios of heterogeneity were used to render the structure of the porous aquifer progressively more complex in order to evaluate the impact of the heterogeneities on water flux in the vadose zone of the Erstein polder
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MONTEIRO, Adriano Luiz Normandia. "Avaliação de lavagem incompleta de sais em neossolo flúvico utilizando modelagem computacional." Universidade Federal Rural de Pernambuco, 2007. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4909.
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This study has been developed in two locations which are typical of communal agriculture in the Northeast semi-arid, in alluvial valleys: Nossa Senhora do Rosário Farm, municipal district of Pesqueira, in the “agreste” area of Pernambuco State and another in the municipal district of Belo Jardim-PE. The objective was to evaluate a computational model to simulate scenarios involving salinization in alluvial soils in the semi-arid Northeast and to simulate the reduction effect on soil salinity in drainage leaching lisimeters and the precipitation as an element to reduce salt content. Based on numeric simulations with finite elements, using the model HYDRUS-1D, it was evaluated flow and transport of salts. For model calibration, of the model field data of water content and soil water pressure head, electric conductivity of soil solution, in adition to soil water characteristic parameters. Using measured actual evapotranspiration of the crop separated: potential evaporation (Ep) and potential transpiration (Tp), and precipitation, besides irrigation with different leaching depths, it was verified that the model is a satisfactory tool to simulate flow and transport in the studied situations. The leach should be used as handling for reduction of the salinity in the root zone since effective precipitations can drain in the winter periods. Incomplete leaching can be an effective alternative to reduce salinity in the root zone, when rainfall might occur.
O presente estudo foi desenvolvido em duas localidades que são modelos típicos de pequena agricultura familiar no semi-árido do Nordeste, em vales aluviais: a Fazenda Nossa Senhora do Rosário, localizada do município de Pesqueira-PE, região Agreste do Estado de Pernambuco, e em lotes irrigados na zona de rural do município de Belo Jardim, região Agreste do Estado de Pernambuco. O objetivo foi calibrar e validar modelo computacional para simular cenários que envolvam o transporte de sais em solos aluviais no semi-árido nordestino, e prever o efeito de lâminas de lixiviação e da precipitação no controle da salinidade do solo em lisímetros de drenagem. Com base em simulações numéricas, utilizando o modelo HYDRUS-1D, avaliou-se o fluxo e o transporte de sais. Para calibração do modelo foram utilizados dados do potencial matricial da água no solo, condutividade elétrica da solução do solo, além de dados da curva característica de retenção de água no solo. Usando medidas de campo de evapotranspiração potencial, e precipitação, foi possível inferir que o modelo apresentou-se como ferramenta adequada nas simulações realizadas, para diferentes cenários de lâminas de lixiviação. Verificou-se experimentalmente e numericamente que a lixiviação incompleta pode ser utilizada como alternativa de manejo para redução da salinidade na zona radicular, desde que precipitações efetivas possam complementar as lavagens.
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Nascimento, Alexandre Ferreira do. "Relações pedologia-geomorfologia-sedimentologia no Pantanal Norte." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-06072012-103745/.
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As relações entre os solos, material de origem e feições geomórficas são importantes para a compreensão da distribuição dos solos na paisagem e o entendimento de sua variabilidade espacial, sobretudo em ambientes úmidos (wetlands) de natureza sedimentar complexa. Procurou-se descrever e caracterizar os ambientes deposicionais de uma área de estudo, a Reserva Particular do Patrimônio Natural (RPPN) SESC Pantanal, buscando na sedimentologia e na geomorfologia que sistemas deposicionais e/ou erosivos formaram a paisagem e dessa forma interpretar as alterações ocorridas no relevo e nos sedimentos responsáveis pela gênese dos solos nesta parte do Pantanal Norte. Primeiramente foram realizados os estudos geomorfológicos com auxílio de ferramentas de sensoriamento remoto, expedições ao campo e sobrevoo da área. Nos compartimentos identificados foram realizadas tradagens mecanizadas profundas para se observar a arquitetura e a distribuição dos sedimentos. Os solos de 3 transeções representativas da área foram descritos, coletados e analisados, de forma a se determinar a configuração lateral e vertical dos horizontes e camadas, assim como a classificação pedológica e as evidências de processos pedogenéticos e sedimentares. A paisagem da RPPN SESC Pantanal foi modelada desde o Pleistoceno superior pela atividade de sistemas deposicionais distributários dominados por rios, caracterizados pela sucessiva construção e abandono de lóbulos deposicionais. O leque aluvial do rio São Lourenço é responsável pela maior parte dos depósitos e das formas do relevo observadas na área de estudo, enquanto que a planície do rio Cuiabá tem menor contribuição e se restringe à parte oeste. De maneira geral, os solos de canais antigos são Neossolos Quartzarênicos, de planície aluvial são Gleissolos, Plintossolos ou Neossolos/Cambissolos flúvicos, de diques e Murundus são Planossolos. Os nódulos de ferro e manganês podem ocorrer nos solos das porções elevadas e baixas (canais, diques e planícies antigas). Os mosqueados são mais contrastantes nas porções baixas (planícies antigas) e progressivamente se tornam menos evidentes à medida que se caminha para as porções elevadas (diques). Os contrastes e gradientes texturais são observados em todos os solos que possuem textura média ou mais fina, independente da porção do relevo, resultado da combinação de processos pedogenéticos e sedimentares. A argiluviação é evidente em todos os solos, porém com intensidade variável. A elevada porcentagem de sódio trocável ocorre com maior frequência nos solos das porções elevadas que não sofrem inundação (diques e murundus), contudo, é observado também em locais com ligeira influência de lâmina dágua. Dessa forma, por meio da abordagem solo x paisagem é possível identificar o controle geológico na distribuição e formação dos solos, como é o caso da presença de Neossolos Quartzarênicos nos canais antigos e a formação de contrastes texturais, e o controle pedogenético condicionado pelo relevo, como vem a ser o acúmulo de sódio. A abordagem integradora entre geomorfologia, sedimentologia e pedologia é indispensável para o entendimento da distribuição, variabilidade espacial e gênese de solos no Pantanal. Fora dessa ótica se torna difícil entender e estabelecer o papel efetivo da geogênese e da pedogênese nesse ambiente.Relationships between soils, parent material and geomorphic features are important to understand the distribution of soils in the landscape. This approach gains more importance when the landscape in study is too complex, e.g., wetlands constructed by depositional systems. Hence, the goal of this work was describe and characterize depositional environments of an unit of fauna and flora preservation (RPPN SESC Pantanal - nonprofits), searching for sedimentary and geomorphology evidences to know which depositional and/or erosional systems have shaped the landscape and then, to set up its relationship with weathering and changes in the system due to pedogenesis. Preliminary geomorphologic studies were developed using remote sensorial tools, fieldworks and flights over the studied area. In each Geomorphic features identified were done drilling procedures to assess the architecture and distribution of their sediments. Three representative soil sequences were described, sampled and analyzed to determine the lateral and vertical boundaries of horizons and layers, as well to find evidences of pedologic and sedimentological processes. Since late Pleistocene the landscape of the RPPN SESC Pantanal has been shaped by distributaries fluvial systems in which rivers were actives. The alluvial fan of the São Lourenço River was responsible by the most shapes and sediments observed in the studied area, while floodplain of the Cuiabá River had minor contribution and it is restricted to western part. Overall, the soils in the paleochannels are Arenosols; in paleofloodplains are Gleysols, Plinthosols or Fluvisols; in paleolevee and Murundus are Planosols. The mottles are common in the low portion of the relief (paleo-foodplain) and become progressively less apparent in the higher portions (paleo-levees). The textural horizons and vertical textural contrasts are observed in the soils of all geomorphic features that have loamy or finer textures, formed by pedogenic and geological processes. The clay illuviation is present in all those soils with textural horizons but in different intensities. The high levels of exchangeable sodium are observed in the soils located in the relief nonflooded (paleo-levee and murundus features). However, it can be also found in places with low flood. Therefore, the approach soil-landscape allows understanding the geological processes controlling the soil genesis and its distribution, as Arenosols in the paleochannels and the formation of textural contrasts. Moreover, it is possible to assess factors of soil formation (relief and whether) controlling the sodium accumulation. Thus the integration of geormorphology, sedimentology and pedology is needful to understand the distribution, spatial variability and genesis of soils in the Pantanal. Without this approach it seems hard to understand and establish the role of pedogenic and geological processes in this environment.
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Levine, Steven Joel. "Genesis of typic paleorthids and petrocalcic paleargids on the same fan terrace in the Avra Valley near Tucson, Arizona." Thesis, The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_414_sip1_w.pdf&type=application/pdf.
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DELARMELINDA, Elaine Almeida. "Solos desenvolvidos nas bacias sedimentares do Acre e do Solimões, Amazônia Sul-Ocidental." Universidade Federal Rural de Pernambuco, 2015. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5400.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
There are large areas of soils in the Southwestern Amazon originated of sediments from the Acre and Solimões sedimentary basins. In Acre basin arises sediments of Solimões Formation of lacustrine and alluvial origin, composed of mudstones, siltstones and sandstones. However, the Solimões basin has extensive area covered by alluvial sediments, especially in the region of Eastern Wood, south of Amazonas state. This work aimed to study soil in two geological framework of southwestern Amazon: a litosequence in the alluvial sediments of the Middle Madeira River, Solimões Basin, in order to determine the morphological, chemical, physical and mineralogical properties, and to study the processes of genesis occurring in these soils. The second geological context is the two strata of Solimões Formation in Acre Basin, consisting the Lower Solimões Formation (LSF) and Higher Solimões Formation (HSF), and aimed to identify changes in morphological, chemical, physical and mineralogical soil propoerties originated from this geological unit. In addition, was also an objective of the study to identify variations which occur in the soil properties along two toposequences in the Solimões Formation. The investigation comprising the regions of Humaitá city, Amazonas state; Nova Califórnia district, Rondônia state; Sena Madureira and Tarauacá cities, Acre state. It was studied nine soil profiles, including morphological characterization, chemical analysis (pH, exchangeable cations, available phosphorus, exchangeable aluminum, potential acidity, organic carbon); and physical (particle size, bulk and particle densisty, water dispersible clay and flocculation), sulfuric extraction and selective extractions with DCB and ammonium oxalate; analysis by x-ray fluorescence to total chemical; mineralogical analysis by x-rays diffraction using clay samples with saturation and thermal treatments, and not oriented powder of silt and clay. Additionally, analysis were performed by SEM and TEM coupled with EDS, and modeling for interstratified study. In general, we observed variations in relation to soil properties in the alluvial sediments of the Madeira River, and that fluctuation of the water table and poor drainage restricts process of leaching, also occurs mica, vermiculite, HIV, pyrophyllite, quartz and kaolinite in the clay fraction. The soils were Argissolo Amarelo Alumínico plintossólico and Cambissolo Flúvico Alumínico típico. In the Solimões Formation was observed Cambissolo Háplico Ta Eutrófico vertissólico in LSF, Nitossolo Háplico Alítico típico and Argissolo Vermelho Alítico nitossólico in the USF, a predominance of smectite, illite, kaolinite and silica in the clay fraction, and Latossolo Vermelho-Amarelo Distrófico típico, the latter probably associated with Debris-Lateritic a predominance of kaolinite, quartz and gibbsite. In relation to changes in soils in different landscape positions, it was observed in the LSF there is no one variation in soil properties in upper and lower position, probablt because of the high restriction on the drainage. In USF variations are related to the values of exchangeable bases that tend to increase in the lower parts of the relief, while the exchangeable aluminum values decreases. In these soils, the mineralogy is very similar in the A and B horizons, while in depth occurs variations related to the deposition of other mineral materials.
Na Amazônia Sul-Ocidental ocorrem extensas áreas de solos originados de sedimentos localizados nas bacias sedimentares do Acre e do Solimões. Na bacia do Acre afloram principalmente sedimentos da Formação Solimões, de origem lacustre e fluvial, composta de argilitos, siltitos e arenitos. Por sua vez, a bacia do Solimões tem vasta área recoberta por sedimentos aluviais, especialmente na região do Médio Madeira, sul do estado do Amazonas. Nesse trabalho objetivou-se estudar solos em dois contextos geológicos da Amazônia Sul-Ocidental: uma litossequência nos sedimentos aluviais do Médio Madeira, Bacia do Solimões, no intuito de determinar as propriedades morfológicas, químicas, físicas e mineralógicas, bem como verificar os processos de gênese que ocorrem nesses solos. O segundo contexto geológico abrange os estratos da Formação Solimões Inferior (FSI) e Superior (FSS), e objetivou-se identificar variações nas propriedades morfológicas, químicas, físicas e mineralógicas dos solos originados nessa unidade geológica; ainda no contexto da Formação Solimões, também foi objetivo do estudo identificar quais variações ocorrem nos atributos dos solos ao longo de duas topossequências. Para isso foram estudados 9 perfis de solos compreendendo as regiões de Humaitá, AM; Nova Califórnia, RO; Sena Madureira e Tarauacá, AC. Foi realizada caracterização morfológica, química (pH, cátions trocáveis, fósforo disponível, alumínio trocável, acidez potencial, carbono orgânico); e física (granulometria, densidade do solo e de partículas, argila dispersa em água e grau de floculação), extração sulfúrica e extrações seletivas com DCB e oxalato de amônio; análise por fluorescência de raios-x da composição química total; análises mineralógicas por difração de raios-x utilizando amostras de argila com tratamentos de saturação e térmico, e pó não orientado da fração silte e argila. Adicionalmente foram realizadas análises por MEV e MET com EDS acoplado, e modelagem para estudo de interestratificados. De forma geral, foi observado variações em relação às propriedades dos solos nos sedimentos aluviais do Médio Madeira, e que a flutuação do lençol freático e a má drenagem restringe processos de perda de elementos, além disso ocorre mica, vermiculita, VHE, pirofilita, quartzo e caulinita na fração argila desses solos, nesse local foram observados Argissolo Amarelo Alumínico plintossólico e Cambissolos Flúvico Alumínico típico. Na Formação Solimões foram observados Cambissolos Háplicos Ta Eutrófico vertissólico na FSI, Nitossolo Háplico alítico típico e Argissolo Vermelho Alítico nitossólico na FSS, com predomínio de esmectita, ilita, caulinita e quartzo na fração argila, e Latossolo Vermelho-Amarelo Distrófico típico, este último provavelmente associado a coberturas Detrito-Lateríticas com predomínio de caulinita, quartzo e gibbsita. Em relação às variações dos solos nas diferentes posições da paisagem, observa-se que na FSI não há variação nas propriedades dos solos em posição de terço superior e inferior, ocasionado pela alta restrição à drenagem desses solos. Na FSS as variações ocorrem em relação aos teores de bases trocáveis que tendem a aumentar nas partes mais baixas do relevo, enquanto os valores de alumínio trocável diminuem. Nesses solos, a mineralogia é muito semelhante nos horizontes A e B, enquanto em profundidade ocorrem variações que parecem estar relacionadas à deposição de outros materiais minerais.
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Chen, Daqin 1958. "Geotechnical characterization of an alluvial fanglomerate." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276713.
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The Department of Energy (DOE) has recently announced that the Superconducting Super Collider (SSC) will soon be built somewhere in the United States. Preliminary geophysical studies indicate that the Sierrita site 35 miles southwest of Tucson has geological conditions that would facilitate construction of the SSC. The Maricopa site southwest of Phoenix is also one of the two potential sites in Arizona. However, several additional geotechnical investigations were required to convincingly demonstrate the suitability of these two locations. The present research program identified the geotechnical properties of the soils at the two sites through various levels of laboratory and field testing. The significance of these results are discussed and recommendations are given.
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Abbott, James T. "Late Quaternary alluviation and soil erosion in Southern Italy /." Digital version accessible at:, 1997. http://wwwlib.umi.com/cr/utexas/main.
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Okae-Anti, Daniel Theophilus Akwa. "Spatial variability studies in relation to pedogenic processes in alluvial soils." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239027.
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Ogg, Charles Morgan. "Pedogenesis and geomorphic implications of soils developed on Blue Ridge alluvial fans, Virginia." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08272007-163709/.
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Nofal, Salah. "Étude du fonctionnement hydrodynamique de la nappe alluviale d'Avignon : impact de l'usage du sol sur les mécanisme de recharge." Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0051/document.
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La nappe superficielle de la plaine d’Avignon, située entre le Rhône et la Durance, présente les caractéristiques d’une nappe péri urbaine, avec un secteur agricole étendu, mais dont la surface se réduit rapidement sous l’effet de l’extension urbaine et du développement économique. Peu profonde et proche de la surface, cette nappe est directement sous l’influence des eaux de surface. En particulier, l’eau de la Durance participe fortement à la recharge soit directement soit indirectement via les nombreux canaux d’irrigation et donc localement de manière décalée par rapport au régime hydrologique méditerranéen. L’occupation des sols, et en particulier l’urbanisation, joue donc un rôle important sur le fonctionnement hydrodynamique. En particulier le recul des terres agricoles et la diminution parallèle des volumes d’irrigation tendent à réduire la recharge de la nappe.Pour essayer d’anticiper les conséquences de cette évolution, la présente étude vise à proposer un modèle de fonctionnement hydrogéologique de la zone intégrant le rôle du sol et de son usage. Il fallait pour cela compléter les connaissances sur le fonctionnement de la nappe préciser les conditions aux limites et établir un bilan en eau au pas de temps mensuel. Ce travail repose sur une démarche multi-approches utilisant, en particulier, la complémentarité entre le suivi piézométrique et la technique du traçage naturel de l'eau (traceurs chimiques et isotopiques). Les différentes approches ont permis de localiser et de quantifier les trois principales composantes de la recharge : la Durance ou la recharge latérale, l’irrigation et la pluie ou la recharge verticale. Cette dernière est contrôlée surtout par la nature et l’usage du sol. Très clairement, la majeure partie de cette recharge se trouve dans des zones encore irriguées qui apportent un volume moyen annuel de 19 Mm3. Avec une moyenne annuelle de 135 mm, la recharge par la pluie joue un rôle secondaire. Son impact sur la nappe est visible en dehors des zones irriguées en particulier en amont de la plaine sur les versants des collines qui bordent la plaine à l’Est. Cet apport de la pluie n’est plus visible dans la partie médiane, fortement diluée par les eaux d’irrigation. Plus à l’ouest en zone urbaine, l’effet de la pluie est réduit et discontinu à cause des surfaces imperméabilisées ; il subit en outre une dilution par l’apport des eaux de la Durance. L’importance de la recharge par la Durance a été confirmée par une modélisation hydrodynamique et du transfert du signal isotopique. Elle constitue l’entrée principale du système avec un volume moyen de 70 Mm3/an. Les résultats de différents scénarios du modèle numérique valident les ordres de grandeur de différentes composantes et les caractéristiques de l’écoulement (direction, vitesse…) et montrent que dans le cas d’un abandon de l’irrigation, la baisse piézométrique serait de l’ordre de 3 m sous les périmètres irrigués. La nappe retrouverait alors les fluctuations piézométriques naturelles sous la dépendance de la pluie d’une part et de la Durance d’autre part. En fonction de son régime futur, l’alimentation par la Durance pourrait augmenter et compenser une partie de la baisse vers l’intérieur de la plaineThe groundwater system of the alluvial plain of Avignon, located between the Rhone and the Durance rivers, is characterized by an expanded agricultural area, whose surface is rapidly shrinking due to urban sprawl and economic development. This shallow aquifer is directly under the influence of surface water. In particular, the Durance water is heavily involved in the recharge process either directly or indirectly via the numerous irrigation canals and therefore with a time shift according to the Mediterranean hydrological regime. Land use, particularly urbanization, plays an important role on the hydrodynamic occurrence. In particular, the loss of agricultural land and accordingly the reduction in irrigation volumes tend to reduce groundwater recharge. To anticipate the consequences of these developments, this study aimed at proposing a hydrogeological model of the area including the role of land use. First of all, This required a better understanding of the aquifer system, namely specify boundary conditions and establish a monthly water balance An experimental investigation was carried out using different approaches including water level monitoring and environmental tracing of water (chemical and isotopic tracers). This work enabled us locating and quantifying the three main components of recharge: Durance or lateral recharge, irrigation and rainfall or vertical recharge. This recharge proved to be controlled primarily by the soil nature and land use. Clearly, much of this recharge occur in irrigated areas which provide an average annual volume of 19 millions m3. With an annual average of 135 mm, recharge by the rainfall plays a secondary role. Its impact on the groundwater was observed out of the irrigated lands especially, on the eastern boundaries of the plain. This contribution of rainfall was no longer detected downwards, where irrigation water was getting predominant in the recharge process. In urban areas down west, the effect of rainfall drops owing to the increase of impervious surfaces and the rising of Durance influence.. The importance of the recharge from the Durance was confirmed by hydrodynamic and isotope transfer modeling. It is the main input to the system with an average volume of 70 millions m3 / year
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Webb, Laura D. "Historical changes in the geomorphology of the Ottawa River (NW Ohio, U.S.A.) due to urbanization and land clearance." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1276534992.
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Carrión, Carmona Miguel Ángel. "The effects of the structure on the mechanical behaviour of young Holocene alluvial materials from the Bormida River (Italy) and Turia River (Spain)." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/63470.
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[EN] The understanding of the mechanical behaviour of natural intact soils is central to engineers when designing new structures. The research carried in this thesis focused on investigating the effects of the naturally occurring in-situ structure on the mechanical behaviour of two shallow recently deposited Holocene alluvial materials, the Bormida River silts (BRS) from Italy and the Valencia silty soils (VSS) from the alluvial plains of the Turia River, Spain. These types of deposits are frequently characterised by highly heterogeneous in-situ structures.
A large range of soils with different size distributions from sands to silty clays were investigated. Oedometer and triaxial tests were carried out on intact, slurry and compacted samples. The first step was to characterise the behaviour of the materials at their reconstituted state to define the reference framework for investigating the effect of the in-situ structure of the intact specimens. The effects of the sample preparation technique on the mechanical behaviour were examined, in particular its influence on the uniqueness of the normal compression line and critical state line. The initial structure created during the preparation of the specimens was totally removed after compression and shearing regardless of the sample preparation method. Only one soil displayed a clear effect of the sample preparation technique, the oedometer compression lines of which remained parallel to each other even at a very high stress levels for the case of the slurry samples. This result showed that contrary to what is stated in the literature the sample preparation technique can created very robust initial structures resulting in a transitional behaviour.
Clears effects of the in-situ structure of the intact samples of the BRS and VSS were observed on the oedometer compression behaviour even at very high stress levels with stress sensitivity values still larger than unity at the end of the tests. It appeared that the effects were more noticeable as the degree of heterogeneity inside the specimens increased at a meso-structure level as it was the case of some samples of the VSS materials which exhibited a certain layering. Small effects of the in-situ structure were seen at large shearing strains and only on the wet side of the critical state.[ES] El conocimiento del comportamiento mecánico de los suelos en su estado natural es de importancia capital para los ingenieros a la hora de diseñar nuevas obras. La investigación desarrollada en esta Tesis se centra en descubrir los efectos que tiene la estructura del suelo en su estado natural en la respuesta mecánica de dos suelos aluviales holocenos, depositados superficialmente: los limos del río Bormida (BRS) en Italia y los suelos limosos provenientes de la llanura aluvial del río Turia (VSS) en España. Este tipo de suelos se caracterizan frecuentemente por una estructura inicial altamente heterogénea. Se ha ensayado una gran variedad de muestras con diferentes granulometrías, desde arenas a arcillas limosas en las que se han realizado ensayos edométricos y triaxiales en muestras intactas, compactadas y en muestras reconstituidas (slurry). En una primera etapa de la investigación se caracterizó la respuesta del material en su estado reconstituido para definir un marco de referencia con el que poder comparar la respuesta de las muestras intactas tomadas in situ y que preservan su estructura natural (inalteradas). Se ha analizado la influencia del modo de preparación de las muestras en su comportamiento mecánico, y, en particular, en la unicidad de las curvas de compresión noval y de estado critico. Se ha comprobado que la estructura inicial inducida durante el proceso de preparación desaparece completamente tras someter la muestra a compresión y corte, independientemente del método de preparación utilizado. Únicamente un suelo mostró, de un modo nítido, el efecto de la técnica de preparación, de modo que las líneas de compresión edométrica se mantuvieron paralelas incluso a niveles de tensión elevados en el caso de muestras reconstituidas (slurry). Este resultado demostró, contrariamente a la opinión aceptada en la bibliografía, que el sistema de preparación de la muestra puede crear una potente estructura inicial dando lugar a un comportamiento de tipo transicional. En los ensayos de compresión edométrica se ha podido comprobar un claro efecto positivo de la estructura inicial de las muestras intactas, incluso a niveles altos de tensión, observándose índices de sensitividad tensional superiores a uno al final de los ensayos, de modo que para igualdad de índice de huecos, la tensión efectiva vertical de la muestra intacta es superior a la correspondiente en la muestra reconstituida. Aparentemente, este efecto es tanto más significativo cuanto mayor es el grado de heterogeneidad interno de la muestra a nivel de meso-estructura, como se pudo observar en algunas muestras de los suelos (VSS) que presentaban niveles de laminación horizontal. En los ensayos de corte la influencia de la estructura intacta fue relativamente pequeña y únicamente en el lado húmedo del estado critico.
[CAT] Conèixer el comportament mecànic dels sòls en el seu estat natural és d'importància capital per als enginyers a l'hora de dissenyar noves obres. La investigació desenvolupada en aquesta Tesi se centra a descobrir els efectes de l'estructura del sòl en el seu estat natural en la resposta mecànica de dos sòls al¿luvials holocens, dipositats superficialment: els llims del riu Bormida (BRS) a Itàlia i els sòls llimosos provinents de la plana al¿luvial del riu Túria (VSS) a Espanya. Aquests tipus de sòls es caracteritzen sovint per una estructura inicial altament heterogènia. S'ha assajat una gran varietat de mostres amb diferents granulometries, des d'arenes fins a argiles llimoses amb les quals s'han realitzat assajos edomètrics i triaxials en mostres intactes, compactades i en mostres reconstituïdes (slurry). En una primera etapa de la investigació es va caracteritzar la resposta del material en el seu estat reconstituït per a definir un marc de referència amb el qual poder comparar la resposta de les mostres intactes preses in situ i que preserven la seua estructura natural (inalterades). S'ha analitzat la influència del mètode de preparació de les mostres en el seu comportament mecànic i en particular, en la unicitat de les corbes de compressió noval i d'estat crític. S'ha comprovat que l'estructura inicial induïda al llarg del procés de preparació desapareix completament després de sotmetre la mostra a compressió i tall, independentment del mètode de preparació utilitzat. Únicament un sòl va mostrar clarament l'efecte de la tècnica de preparació, de manera que les línies de compressió edomètrica es van mantenir paral¿leles fins i tot a nivells de tensió elevats en el cas de mostres reconstituïdes (slurry). Aquest resultat va demostrar, contràriament a l'opinió acceptada en la bibliografia, que el sistema de preparació de la mostra pot crear una potent estructura inicial donant lloc a un comportament de tipus transicional. Als assajos de compressió edomètrica s'ha pogut comprovar un clar efecte positiu de l'estructura inicial de les mostres intactes, inclús a nivells alts de tensió, observant-se índexs de sensitivitat tensional superiors a la unitat al final dels assajos, de manera que per a igualtat d'índex de buits, la tensió efectiva vertical de la mostra intacta és superior a la corresponent en la mostra reconstituïda. Aparentment, aquest efecte és més significatiu quant major és el grau d'heterogeneïtat intern de la mostra a nivell de meso-estructura, com es va poder observar en algunes mostres dels sòls (VSS) que presentaven nivells de laminació horitzontal. Als assajos de tall la influència de l'estructura intacta va ser relativament petita i únicament en el costat humit de l'estat crític."
Carrión Carmona, MÁ. (2016). The effects of the structure on the mechanical behaviour of young Holocene alluvial materials from the Bormida River (Italy) and Turia River (Spain) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63470
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Ng, Chi Hong. "Comparative study of soil constitutive models on simulation of a diaphragm walled excavation in Macao alluvium." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2099643.
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Pickles, A. R. "The application of critical state soil mechanics to predict ground deformations below an embankment constructed on soft alluvium." Thesis, City University London, 1989. http://openaccess.city.ac.uk/7404/.
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An embankment has been constructed to a maximum height of approximately twelve metres at Beckton, east London. The embankment is underlain by up to eight metres of alluvium and made ground. The embankment was monitored during construction. Centreline settlements of the order of O.6m and horizontal movements at the embankment toe of up to O.1Sm were measured. The excess pore pressures generated during construction were found to dissipate rapidly. Soil samples recovered from the site have been tested at city University. The alluvial clay is shown to have extremely variable compression characteristics and it is not possible to determine a single set of critical state soil parameters from the "undisturbed" soil samples. The use in design of parameters derived from reconstituted soil samples is investigated. Laboratory test results indicate that a small quantity'of organic matter in the soil has a large effect on the engineering properties of the alluvial clay. The importance of not dry~ng soils which contain organic matter is highlighted. It is shown that, despite the effects of the organic matter, critical state concepts and in particular the modified Cam clay soil model can be used to predict the behaviour of the alluvial clay in a wide variety of laboratory tests. standard methods of determining the yield stress or preconsolidation pressure are shown to be inadequate when used to analyse the results of compression tests performed at a constant rate of loading. An alternative method, the Lambda construction, is proposed and this is shown to be both reliable and objective. Two distinct testing methods have been used to probe the state boundary surface of the reconstituted alluvial clay samples. The results of these tests appear to indicate the existence of a single state boundary surface for both Ko and isotropically compressed samples. This surface has a shape similar to that predicted by the modified Cam clay soil model. This result conflicts with the findings of many other investigators. Finite element modelling of the embankment construction has been carried out. A single set of soil parameters derived from tests on the reconstituted clay were used to represent the alluvial stratum. The construction of the embankment was modelled as a drained event. The results are shown to compare favourably with the actual field data.
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Mubamu, Makady Elvis. "Large herbivore stocking rate effects on plant palatability, forage preference and soil properties in an Alluvium Fynbos-Renosterveld mosaic." Thesis, Stellenbosch : Stellenbosch University, 2009. http://hdl.handle.net/10019.1/4043.
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Thesis (MSc (Conservation Ecology and Entomology))--Stellenbosch University, 2009.ENGLISH ABSTRACT: An understanding of the interactions of herbivores, plant nutrients and soil properties is crucial for grazing management. Of particular interest are plant palatability and herbivore grazing preferences. These aspects, the focus of this thesis, were studied in a Swartland Shale Renosterveld and Swartland Alluvium Fynbos mosaic in the Western Cape of South Africa. This vegetation is classified as critically endangered due to the transformation of its landscape in favour of agricultural production and urban settlement. Pre-colonial herbivore vertebrates were hunted out by 1700, leading to a sparse knowledge of the early dynamics of the vegetation. However, currently game farmers and landowners are re-introducing selected species into the area. Thus, managers require knowledge on how to implement practical guidelines for best-practice grazing management. This study investigates, firstly, the relationship between plants and animals. This included seasonal assessment of seed germination from dung of bontebok and eland; the effect of stocking rates on plant palatability (crude protein, crude fibre, crude fat, moisture, tannin and mineral) of herbage was studied with the aim to understand how palatability influences herbivore forage decisions. Secondly, this study looked at how stocking rates influence soil nutrients (nitrogen, phosphorus), and others soil properties such as pH and soil moisture. The distribution of alien grasses was facilitated by grazers. About 58 % of grasses germinated from the dung of eland and Bontebok were alien species. Additionally, there was significant variation in palatability related to grazing pressure and plant maturity between sites and over seasons. Grasses on the high grazing site had higher carbohydrate (3%-5% higher) and protein content (1%-5% higher) than at the least grazed site. Mature grasses contained less water (10%-20%), but no obvious variation in tannin concentration than immature grasses. However, species such as Ficinia sp. showed variations with grazing pressure and maturity. Ficinia sp. on the high grazing site had higher tannin concentration (5mg/ml-22mg/ml) and crude protein (4%-9%) than at the least grazed site. When the plant ages, tannin concentration increase (ranging from 15% to19% higher). Two types of plant were recoreded according to their chemical response following grazing pressure. These types are 1) plants that are grazing tolerant and which produce more carbohydrate when grazed and 2) plants that are grazing intolerant under high grazing pressure and which produce chemical defence compounds such as tannin to deter herbivores attacks. The results indicate that in fynbos and renosterveld, the relationship between preference and plant chemical compounds is not consistent since no IV patterns emerged to explain what compounds drive preference. A combination of chemical compounds may be the reason for the selection by the grazers; alternatively, other compounds not included in the study may influence the forage selection by an herbivore. The second part of the study showed that stocking rates appeared to have a significant effect on soil properties investigated. Soil moisture was significantly affected by the stocking rate in autumn. The high grazing intensity site had the lowest soil moisture especially in autumn (10% lower than the control site), likely due to heavy trampling and soil compaction. pH was the lowest at the high grazing intensity site in all seasons compared to the control site. Likely reasons were the high deposition of nitrogen through dung and urine deposition, high removal of basic cations and animal exportation through hunting activities. Lastly, grazing maintains inorganic nitrogen at stable levels regardless of seasonal changes and increases the concentration of phosphorus especially under high grazing pressure compare to less grazed sites. The grazing dynamics of Swartland Shale Renosterveld - Swartland Alluvium Fynbos mosaic system are complex and multifaceted. Farmers need to pay attention to the nutritional status of plant species grazed to know whether they meet the nutritional requirements of the game in the area. Overstocking should be avoided in this system as it triggers the production of tanniferous compounds that could decrease the survivorship of herbivores. Moderate grazing 0.09 LAU/ha pressure provides the best stocking rates for effective grazing management.
AFRIKAANSE OPSOMMING: Vir suksesvolle weidingsbestuur is dit noodsaaklik om die interaksie tussen herbivore, plantvoedingstowwe en grondeienskappe te verstaan. Van besondere belang is plantsmaaklikheid en herbivore se weidingsvoorkeure. Hierdie aspekte, wat die fokus van hierdie tesis is, is bestudeer in ‘n Swartland Shale Renosterveld en Swartland Alluvium Fynbos-mosaïek in die Wes-Kaap Provinsie van Suid-Afrika. Hierdie plantegroei word as kritiek bedreigd geklassifiseer weens die transformering van sy landskap ten gunste van landbou-aktiwiteite en stedelike vestiging. Pre-koloniale herbivoor vertebrata is teen 1700 deur jagters uitgeroei, wat gelei het tot min kennis oor die vroeë dinamiek van die plantegroei. Wildsboere en grondeienaars is egter besig om geselekteerde spesies in die area te hervestig. Bestuurders moet dus weet hoe om praktiese riglyne vir beste-praktyk weidingsbestuur te implementeer. Hierdie studie ondersoek eerstens die verhouding tussen plante en diere. Dit sluit seisoenale evaluering van saadontkieming uit die mis van bontebokke en elande in; die effek van veegetalle op plantsmaaklikheid (ruproteïen, ruvesel, ru-vet, vogpeil, tannien en minerale) van die weiveld is bestudeer om vas te stel hoe plantsmaaklikheid herbivore se weidingsbesluite beïnvloed. Tweedens het die studie die invloed van veegetalle op grondvoedingstowwe (stikstof, fosfor) ondersoek, asook ander grondeienskappe soos pH en grondvogpeile. Die verspreiding van uitheemse grasse is deur weidende diere gefassiliteer. Ongeveer 58% van alle grasse wat uit die mis van elande en bontebokke ontkiem het, was uitheemse spesies. Verder was daar beduidende variasie in plantsmaaklikheid verwant aan beweidingsdruk en plantvolwassenheid tussen verskillende persele en oor seisoene. Grasse op die hoogs beweide persele het 3%-5% hoër koolhidraatinhoude en 1%-5% hoër proteïeninhoude gehad as die minder beweide persele. Volwasse grasse het 10%-20% minder water bevat as onvolwasse grasse, maar het nie in terme van tannienkonsentrasie van die onvolwasse grasse verskil nie. Spesies soos Ficinia sp. het variasies getoon met beweidingsdruk en volwassenheid. Ficinia sp. het op die hoog-beweide perseel ‘n hoër tannienkonsentrasie (5mg/ml-22mg/ml) en meer ruproteïen (4%-9%) gehad as op die minste beweide perseel. Wanneer die plant verouder, verhoog die toename in tannienkonsentrasie (met tussen 15% en 19%). Twee tipes plante is aangeteken volgens hul chemiese response ná beweidingsdruk. Hierdie tipes is 1) plante wat beweidingstolerant is en wat meer koolhidrate produseer wanneer hulle as weiding dien en 2) plante wat onder hoë beweidingsdruk beweidingsintolerant is en wat chemiese verbindings VI soos tannien produseer om herbivooraanvalle af te weer. Die resultate dui aan dat die verhouding tussen voorkeur en plante se chemiese verbindings nie konstant bly in fynbos en renosterveld nie, aangesien geen patrone na vore getree het wat kon verklaar watter verbindings bepalend is vir voorkeur nie. ‘n Kombinasie van chemiese verbindings mag die rede wees waarom die herbivore sekere plante verkies; alternatiewelik mag ‘n herbivoor se plantseleksie beïnvloed word deur chemiese verbindings anders as dié wat in hierdie studie ondersoek is. Die tweede deel van die studie het aangetoon dat veegetalle blyk ‘n beduidende invloed te hê op die grondeienskappe wat ondersoek is. Grondvogpeile is in die herfs beduidend beïnvloed deur die veegetalle. Die perseel met die hoë beweidingsintensiteit het die laagste grondvogpeil gehad, veral in die winter (10% laer as dié van die kontrole-perseel), waarskynlik weens erge getrappel en grondkompaktering. Vergeleke met die kontrole-perseel was pH die laagste op die perseel met die hoë beweidingsintensiteit, in alle seisoene. Waarskynlike redes hiervoor is die hoë neeerslag van stikstof deur mis- en uriene-neerslae, hoë verwydering van basiese katione en dierevervoer wat deur jagaktiwiteite teweeg gebring word. Laatstens behou weiding anorganiese stikstof teen stabiele vlakke ongeag van seisoenale veranderinge en toenames in die konsentrasie van fosfor, veral onder hoë beweidingsdruk vergeleke met minder beweide persele. Die weidingsdinamiek van die Swartland Shale Renosterveld - Swartland Alluvium Fynbosmosaïeksisteem is kompleks en veelvlakkig. Boere behoort aandag te skenk aan die voedingstofstatus van die plantspesies wat as weiding dien, sodat hulle kan weet of die voedingsbehoeftes van die wild in die omgewing bevredig word. Die aanhou van te veel vee in hierdie sisteem behoort vermy te word aangesien dit as sneller dien vir die produksie van tannienbevattende verbindings wat die oorlewingsvermoë van herbivore kan verlaag. Matige beweidingsdruk (0.09 LAU/ha) bied vir effektiewe weidingsbestuur die beste veegetalle.
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Silva, Rafael Cipriano da. "GÃnese e classificaÃÃo de solos em ambientes de planÃcies da regiÃo Nordeste do Brasil." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8512.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoCoordenaÃÃo de AperfeiÃoamento de NÃvel Superior
Solos formados por sedimentos em ambientes de planÃcie apresentam caracterÃsticas genÃticas distintas quanto ao material de origem, podendo ser compostos basicamente por sedimentos minerais e orgÃnicos. O primeiro à formado a partir do intemperismo das rochas, e as propriedades quÃmicas, fÃsicas e mineralÃgicas sÃo herdadas do material que lhe deram origem. Jà os sedimentos orgÃnicos sÃo influenciados pelo tipo de vegetaÃÃo predominante na paisagem, e o aporte de material orgÃnico em condiÃÃo de saturaÃÃo de Ãgua, que favorece o acÃmulo e o espessamento das camadas de sedimentos orgÃnicos, podendo levar à gÃnese dos solos orgÃnicos. Este estudo teve por objetivo avaliar as caracterÃsticas morfolÃgicas, fÃsicas e quÃmicas de seis perfis de solos orgÃnicos desenvolvidos na regiÃo litorÃnea dos Estados do CearÃ, Rio Grande do Norte e ParaÃba; e avaliar os mesmos atributos e as caracterÃsticas mineralÃgicas e micromorfolÃgicas de quatro perfis de solos originados de sedimentos aluviais do baixo curso da Bacia do rio Acaraà - CE. Foram avaliadas propriedades tais como: cor, densidade, textura, teores de fibras, grau de decomposiÃÃo da matÃria orgÃnica, teores de C, matÃria orgÃnica, N, P e micronutrientes, soma de bases, valor T e V, fraÃÃes hÃmicas, grau de repelÃncia à Ãgua, condutividade elÃtrica, sais solÃveis, difratometria de raio-X, dentre outras. Para os Organossolos, foi verificado que os teores de C estabeleceram correlaÃÃes positivas com a densidade do solo, com a subsidÃncia, acidez potencial, com os teores de N e com a hidrofobicidade, alÃm de influenciar na CTC e no teor de H+ proveniente dos Ãcidos orgÃnicos. Os diferentes mÃtodos para a determinaÃÃo dos teores de carbono orgÃnico apresentaram correlaÃÃo positiva entre si. Os teores de C da fraÃÃo humina foram mais elevados devido à presenÃa de fibras nesta fraÃÃo, enquanto que os teores de Ãcidos fÃlvicos foram os menores em relaÃÃo aos teores de Ãcidos hÃmicos, indicando maior estabilidade dos compostos orgÃnicos presentes nestes solos. Com relaÃÃo aos solos de sedimentos aluviais, foram observados elevados teores de sais solÃveis, conferindo-lhes carÃter salino e sÃdico. Isso se deve à influÃncia marinha e do lenÃol freÃtico elevado, alÃm da presenÃa de minerais intemperizÃveis. Na descriÃÃo micromorfolÃgica foram verificados alguns aspectos relacionados à gÃnese desses solos, tais como a iluviaÃÃo de argila em profundidade, a origem alÃctone do material de origem e a alteraÃÃo in situ desses sedimentos aluviais. A geomorfologia foi o principal fator na maior expressÃo dos processos pedogenÃticos na paisagem, e a posiÃÃo em que os solos se encontram à um forte indicativo de sua fragilidade ambiental.
Soils formed by sediments in lowland environments have distinct genetic characteristics according to the parent material, which can be basically composed of mineral and organic sediments. The first is formed from the weathering of rocks, and the chemical, physical and mineralogical properties are inherited from the source material. The organic sediments are influenced by the type of vegetation dominant in the landscape, and the addition of organic material under water saturation conditions, that favors the accumulation and thickening of organic sediment layers, which can lead to the genesis of organic soils. This study aimed to evaluate the morphological, physical and chemical properties of six organic soil profiles developed in the coastal region of the States of CearÃ, Rio Grande do Norte and ParaÃba; besides these attributes and the mineralogical and micromorphological characteristics of four soil profiles from alluvial sediments in the lower course of Acaraà river Basin - CE. The properties evaluated were: color, density, texture, fiber content, degree of decomposition of organic matter, C content, organic matter, N, P and micronutrients, sum of bases, T and V value, humic fractions, degree of water repellency, electrical conductivity, soluble salts, X-ray diffraction, among others. For the Histosols, it was found a positive correlation of the C levels with the soil density, with subsidence, potential acidity, N content and hydrophobicity; as well as influencing the CTC and the content of H+ from the organic acids. The different methods for measuring organic carbon were positively correlated with each other. The C content of humin fraction were higher due to the presence of fibers in this fraction, while the fulvic acid contents were lower compared to the humic acids, indicating increased stability of organic compounds present in these soils. With respect to the soils from alluvial sediments, there were observed high levels of soluble salts, conferring them the saline and sodic characters. This is due to the marine influence and the high water table, besides the presence of weatherable minerals. The micromorphological description showed some aspects related to the soil genesis, such as clay illuviation in depth, the allochthonous origin of the parent material and in situ alteration of the alluvial sediments. The geomorphology was the main factor in the greatest expression of pedogenetic processes in the landscape, and the position where the soils are located is a strong indicator of their environmental fragility.
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Decosterd, Marie-Christine. "Pollution diffuse de la nappe alluviale de l'Ariège : étude de la contribution de cultures céréalières." Toulouse 3, 1985. http://www.theses.fr/1985TOU33266.
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Suite au constat d'une importante pollution azotee de la nappe phreatique de la plaine de l'ariege, un suivi du devenir des engrais azotes en periode de culture a ete mene sur deux sites ecxperimentaux. La methode mise en oeuvre pour cette etude fait appel au tracage isotopique de l'azote 15. A partir de l'ensemble des donnees acquises sur le terrain, un bilan sol plante est etabli, quelques informations relatives au cycle interne in situ de l'azote sont apportees et l'on estime les risques de pollution, de la nappe en fonction du type de sol rencontre
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Boigné, Audrey. "Restauration écologique de prairies humides à vocation agricole suite au comblement d'une ballastière en basse vallée de Seine : incidence du type de sol recréé sur les fonctions pédologiques associées et sur la dynamique de colonisation végétale." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR008/document.
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Dans un contexte de destruction des zones humides à l’échelle mondiale, conséquence des activités d’origine anthropique, la restauration écologique de ces milieux et de leurs fonctions est devenue un enjeu écologique et sociétal. L’objectif de ce projet est de recréer des prairies humides à vocation agricole aux caractéristiques pédologiques et floristiques aussi proches que possible de celles des prairies totalement détruites par l’exploitation de matériaux alluvionnaires. L’étude présentée ici se focalise sur l’incidence des matériaux pédologiques utilisés pour la recréation de quatre sols sur les fonctions du sol et les cortèges floristiques associés. L’hypothèse principale est que la recréation d’un sol morphologiquement proche de celui détruit devrait permettre d’orienter la restauration écologique.L’hypothèse sous-jacente est qu’en utilisant différents matériaux pédologiques locaux, on hérite de leurs caractéristiques physico-chimiques et biologiques ce qui permettait de conserver les fonctions pédologiques qui leur sont associées et favorisait le retour d’un cortège floristique compatible avec un usage agricole. La première partie est consacrée à l’étude de deux fonctions remplies par les sols de zones humides à savoir le stockage du carbone organique et la dénitrification. Deux années et demi après la fin des travaux de comblement de ballastières, ces deux fonctions sont conservées au sein des quatre types de sols recréés. Les principaux résultats montrent un niveau d’efficience des matériaux pédologiques testés, fonction de leur sol origine et de leurs caractéristiques physico-chimiques. La deuxième partie est consacrée à l’étude des mécanismes de structuration des communautés végétales. Le suivi de la colonisation spontanée de la végétation a permis d’appréhender la forte contribution de la banque de graines issue des matériaux pédologiques locaux. Malgré la mise en évidence d’un début de trajectoires dynamiques au sein des quatre sols recréés, la similarité entre les communautés obtenues et les communautés cibles des prairies de référence n’excède pas 50 %. Les productions de biomasses aériennes associées à ces communautés sont comparables en quantité à celles des prairies de référence mais pas en qualité. La mise en place d’une gestion par semis associée à une fauche montre dès la première année une production de biomasses de qualité se rapprochant de celles des prairies locales.La dernière partie de ce manuscrit est consacrée à l’effet de trois niveaux d’engorgement des sols sur le processus de dénitrification et sur les traits de réponse d’une espèce prairiale, Holcus lanatus. Placer les quatre matériaux pédologiques dans des conditions identiques d’engorgement permet de souligner l’importance de l’héritage des communautés bactériennes dénitrifiantes sur le processus de dénitrification. Parallèlement, ces conditions expérimentales permettent de mettre en évidence les traits de réponses morphologiques et fonctionnels de l’espèce considérée. À l’issue de ces suivis, le meilleur compromis de restauration alliant sol, végétation et coûts économiques doit prendre en considération l’origine et l’histoire (i.e. gestion) des matériaux utilisés lors de la recréation écologiqueIn a worldwide context of wetland destruction, a consequence of anthropic activities, ecological restoration of such habitats and their functions has become a societal and ecological issue. The objective of this project is to recreate agriculture-oriented wet grasslands with pedological and floristical properties as similar as possible to typical grasslands destroyed by alluvial materials extraction. The study presented here focuses on the impact of pedological materials, used in the re-creation of four soils, on soil functions and associated floristic processions. The main hypothesis is that re-creation of a soil morphologically similar to the previously destroyed one should drive ecological restoration. The underlying hypothesis is that different local pedological materials inherit their previous physicochemical and biological properties. This should conserve associated pedological functions and favor the return of a floristic procession compatible with agricultural exploitation. The first part is dedicated to the study of carbon storage and denitrification, two wetlands soils functions. These two functions are retained within the four re-created soils two and a half year after gravel-pit filling. Main results highlight functional efficiency levels of tested pedological material inherited from their respective initial topsoil physico-chemical properties. The second part is devoted to the study of mechanisms structuring plant communities. The high contribution of local pedological materials seed bank during the colonization process and its impact on aforementioned mechanisms was highlighted from our monitoring. Despite demonstration of the start of a dynamic trajectory in the four created soils similarity between obtained and target communities never exceeds 50%. Aerial biomass production associated to these communities is comparable to the production in reference wet grasslands in terms of quantity, but not quality. Implementation of management (sowing and mowing) shows biomass production of comparable quality to reference grassland from the first year onwards. The last part focuses on the effect of three soil waterlogging levels on the denitrification process and the response traits of Holcus lanatus, a meadow species. Pedological materials placement in identical waterlogging conditions highlights the importance of denitrifying bacteria communities inheritance on the denitrification process. These experimental conditions also enabled us to highlight the considered species morphological and functional response traits. To conclude and following our monitoring the best compromise for concurrent restoration of soil and vegetation while considering cost-effectiveness needs to account for topsoils origin and history (i.e. management)
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Ettinger, Susanne. "Geomorphological impact of lahars on the southwestern flank of Cotopaxi volcano, Ecuador : drainage system and alluvial fan." Thesis, Clermont-Ferrand 2, 2012. http://www.theses.fr/2012CLF20017.
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Pendant une éruption volcanique sur des sommets englacés, des coulées de débris syn-eruptifs,dénommées lahars, peuvent être générées par la fonte partiale de glaciers. Ce phénomène estbien connu sur le volcan Cotopaxi, Equateur. La présente étude concerne trois vallées et un cônede déjection sur le flanc sud-ouest de ce volcan. Une première analyse a été conduite par relevésde formes géomorphologiques dans ces vallées qui témoignent des processus d’érosion et desédimentation lors du passage de lahars dans le passé, notamment ceux du dernier événementéruptif datant de 1877 AD. Bien que les types des formes géomorphologiques déterminées sontles mêmes, leur distribution spatiale varie d’une vallée à l’autre en fonction d’une interaction deparamètres morphologiques locaux. Les conditions environnementales individuelles déterminentégalement le volume de l’écoulement, paramètre crucial dans la délimitation de zones de risques delahars dans les plaines adjacentes. Pour cela, une deuxième étude a été menée à grande échelle surle cône de déjection à l’exutoire de la vallée la plus au Sud des trois. Une analyse intégrale de la morphologiede surface et des affleurements naturels a été complétée par des données stratigraphiquesde subsurface obtenues via un sondage avec un Géoradar. Reconstituer l’architecture sédimentairede ce cône permet de visualiser la distribution spatiale de formes érosives et de dépôts. L’étude àrévélé que différentes parties du cône sont actives à des moments distincts et les épaisseurs dedépôts de lahars sont variables en fonction du type d’écoulement et de son volume. Ceci permetde relier les dynamiques géomorphologiques des plaines alluviales aux zones d’initiation de laharssur les flancs du volcan. Enfin, cette étude a débouché sur la mise en place d’une nouvelle fonctiondans le logiciel de modélisation de lahars LAHARZ prenant en compte l’incorporation progressive desédiment dans un contexte érosif dans les vallées, ce qui permet une meilleure délimitation de zonesde risque de lahars sur le côneDuring a volcanic eruption at ice capped volcanoes, syn-eruptive volcanic debris flows, lahars, canbe triggered through the partial melting of the glaciers. This phenomenon is well known to have happenedat Cotopaxi volcano, Ecuador, where the present study has been realized. The latter concernsthree drainages on the southwestern flank of the volcano and one alluvial fan. A first analysis hasbeen conducted assessing geomorphologic features in the drainages testifying from erosional anddepositional processes during past lahars, in particular of those generated during the last eruptiveevent dating back to 1877 AD. Although the types of determined geomorphologic features are thesame, their spatial distribution varies among the three valleys as a function of an interplay of localmorphologic parameters. The individual environmental conditions determine also the flow volumeof such lahars, a critical parameter when to delineating hazard zones in the adjacent lowlands. Thesecond analysis has therefore be performed at large scale on the alluvial fan forming at the mouthof the southernmost of the three drainages. An integral study of the surface morphology and naturalexposures was enriched with subsurface stratigraphic information obtained through a ground penetratingradar survey. The sediment architecture of the fan provides valuable insights on the distributionof erosional features and deposits. Different fan parts appear to be active at different times andlahar deposit thicknesses are highly variable as a function of flow type and volume. This allows torelate floodplain dynamics to the initiation zone of lahars on the upper flanks of the volcano. At last,this research led to integrate a new bulking function acknowledging for erosional processes in thevalleys into the lahar-modeling software LAHARZ allowing to better delineate lahar hazard zones onthe fan
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Santucci, Jay N. "Hydrogeologic conditions controlling contaminant migration from storage tanks overlying Mississippi River Alluvium a case study /." Master's thesis, Mississippi State : Mississippi State University, 2006. http://library.msstate.edu/etd/show.asp?etd=etd-07072006-161425.
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Gury, Michel. "Genèse et fonctionnement actuel des pseudogleys podzoliques sur terrasses alluviales, dans l'est de la France." Nancy 1, 1990. http://www.theses.fr/1990NAN10507.
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L'étude porte sur les sols les plus différenciés et les plus engorgés par l'eau, dans une séquence évolutive lessivage hydromorphie temporaire. Le lessivage d'argile a permis l'installation de nappes perchées et l'apparition de processus d'oxydo-réduction. Le fonctionnement actuel est dominé par une podzolisation modérée, localisée dans les horizons supérieurs : en conditions acides et organiques, les phyllites ferromagnésiennes s'altèrent et les éléments solubilisés sont redistribués dans le profil et dans le paysage par l'intermédiaire des solutions et des nappes, sans qu'il y ait constitution de véritables horizons spodiques
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Salloum, Nancy. "Evaluation de la variabilité spatiale des paramètres géotechnique du sol à partir de mesures géophysiques : application à la plaine alluviale de Nahr-Beyrouth (Liban)." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAU014/document.
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La variabilité spatiale des formations géologiques rend difficile la détermination des paramètres géotechniques nécessaires pour l'évaluation des aléas naturels (sismiques et gravitaires). Les méthodes d'imagerie géophysique, non-destructives et rapides, sont de plus en plus utilisées pour la reconnaissance de telles structures hétérogènes. Une campagne d'essais géophysiques et géotechniques a été réalisée dans la plaine alluviale de Beyrouth (Liban), ville soumise à un fort risque sismique, en vue de caractériser la variabilité des couches alluviales. Les résultats combinés ont permis de caractériser la structure 3D du site et de détecter la présence d'une couche d'argile molle, peu profonde et d'épaisseur variable. Cette couche de faible compacité, qui a rendu complexe l'interprétation des courbes de dispersion des ondes de surface, a une influence importante sur la réponse sismique du site. Les incertitudes reliées à la variabilité spatiale des propriétés géotechnique (N60) et géophysiques (Vs, ρ) ont pu être quantifiées au sein des couches rencontrées et les fonctions de distribution de ces paramètres ont été déterminées dans chaque couche à partir de ces essais, à la fois verticalement et horizontalement. Les valeurs de distance d'autocorrélation verticale (Vs, N60) et horizontale (ρ) obtenues ainsi que les valeurs de coefficient de variation se situent dans la gamme de valeurs trouvées dans la littérature. La réponse dynamique (amplification spectrale) de la plaine alluviale de Beyrouth a été simulée avec des modèles probabilistes unidimensionnels, et l'effet des trois paramètres statistiques (loi d'autocorrélation, distance d'autocorrélation et coefficient de variation) décrivant les variabilités des propriétés élastiques du sol (Vs) a été quantifié. Pour obtenir des réponses sismiques réalistes, un critère de sélection des profils Vs générés de façon probabiliste a été introduit afin de ne retenir que les profils compatibles (dans une gamme d'incertitude) avec la courbe de dispersion établie. Les modélisations probabilistes ont montré des différences significatives par rapport aux modélisations déterministes. Le principal paramètre probabiliste contrôlant l'amplification spectrale est le coefficient de variation, suivi de la distance d'autocorrélation, alors que le type de loi a peu d'influence. Enfin, nous avons vu que l'activité humaine peut avoir une influence significative sur l'application des méthodes géophysiques en site urbain. La compréhension d'un milieu complexe dans ce contexte nécessite de combiner toutes les méthodes géotechniques et géophysiques d'investigation afin d'obtenir un modèle robuste 2D/3D de la structure du solThe spatial variability of geological formations makes it difficult to determine the geotechnical parameters necessary for the evaluation of natural hazards (seismic and gravity). The geophysical imaging methods, non-destructive and fast, are now increasingly used for heterogeneous structures of sub-surface recognition. Geophysical and geotechnical tests were carried out in the alluvial plain of Beirut (Lebanon), city with high seismic risk, to characterize the variability in the alluvial layers. Analyses of these tests were used to characterize the 3D structure of the site and to detect the presence of a shallow soft clay layer of variable thickness. This layer of low compactness, which made the interpretation of dispersion curves of surface waves complex, could be of prime importance for seismic response of the site. Using all the collected data, the uncertainties related to the spatial variability of geotechnical (N60) and geophysical (Vs, ρ) properties of soil were quantified in the layers encountered and the distribution functions of these parameters were determined in each layer, in both directions (vertical and horizontal). The autocorrelation distance in the vertical (Vs, N60) and horizontal (ρ) directions and the coefficient of variation are within the range of values founded in the literature. The dynamic response (spectral amplification) of the alluvial plain of Beirut was modeled by one dimensional probabilistic model and we quantified the effect of the three statistical parameters (autocorrelation function, autocorrelation distance and coefficient of variation) describing the elastic variability properties of soil (Vs). To obtain realistic seismic responses, we proposed a probabilistic (Vs) profile selection criteria in order to retain only compatible profiles (in a range of uncertainty) with the obtained dispersion curve. Probabilistic modeling showed significant differences from the deterministic modeling. It appeared that the main factor controlling probabilistic spectral amplification is the coefficient of variation (COVVs) followed by the autocorrelation distance, while the type of autocorrelation function has little influence. Finally, Human activity was also found to have a significant influence on the application of geophysical prospecting at this urban site. This case illustrates the need of combining investigation methods in order to understand the geophysical measurements in a complex medium and to reach a robust 2D/3D model
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Pottier, Nathalie. "L'Utilisation des outils juridiques de prévention des risques d'inondation : évaluation des effets sur l'homme et l'occupation des sols dans les plaines alluviales (application à la Saône et à la Marne)." Marne-la-vallée, ENPC, 1998. http://www.theses.fr/1998ENPC9825.
Full textAbstract:
La politique de prévention des risques naturels privilégie aujourd'hui les mesures non structurelles, spécialement les outils juridiques de contrôle de l'occupation des sols, plutôt que les mesures structurelles (digues, barrages, etc. ) qui entrainent un déséquilibre souvent irréversible des milieux naturels. Cette recherche pose la question de l'adéquation de ces outils pour répondre efficacement à la gestion des inondations dans une perspective de développement durable des plaines alluviales. Elle s'attache à évaluer les effets liés à la mise en place des outils règlementaires de prévention des inondations sur les sites auxquels ils s'appliquent (efficacité et impacts sur l'occupation des sols et sur la société locale). La première partie de la thèse analyse l'évolution des problématiques de gestion des inondations dans les plaines des grandes vallées françaises. Elle met en évidence les spécificités géographiques des crues puis des relations entre les sociétés et les plaines alluviales. La deuxième partie réalise une analyse conceptuelle des méthodes utilisées pour l'évaluation des politiques publiques et des moyens de gestion des zones inondables. à partir de cette analyse, une méthodologie d'évaluation globale est élaborée puis appliquée sur deux sites regroupant six communes soumises à des crues de plaine et règlementées par un plan d'exposition au risque d'inondation (PERI). La troisième partie présente les résultats de l'évaluation qui s'appuie sur une base de données constituée par enquête auprès de 800 occupants des zones inondables, sur des entretiens, sur une cartographie de l'évolution de l'usage des sols et sur l'étude des autorisations d'occupation des sols sur plusieurs décennies. L’analyse statistique de ces données met en évidence les facteurs déterminants lies a la prise en compte du risque d'inondation et de la règlementation par les pouvoirs publics locaux, d'une part et a l'échelle individuelle d'autre part.
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Biggs, Thomas. "Fire Frequency, Nutrient Concentrations and Distributions, and δ13C of Soil Organic Matter and Plants in Southeastern Arizona Grassland." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/244085.
Full textAbstract:
Over the past century, woody plants and shrubs have increased in abundance at the expense of grasslands in many semiarid regions. The availability and concentrations of nutrients influence the relative success of plants, but the effects of fire frequency on soil nutrients is unknown for semiarid grasslands. On the gunnery ranges of Fort Huachuca in southeastern Arizona, study sites were established to examine the effects of fire frequency on soil biogeochemistry, plant biochemistry, and δ¹³C values in soil organic matter (SOM). The sites were on homogeneous granitic alluvium where wildfire frequency history is known from 1973 to present and no cattle grazing has occurred in recent decades. Subplots represent fire frequencies of no burns, 3 fires per decade, and 5 fires per decade. The "no burn" plot has abundant C₃ Prosopis veleruina (mesquite) trees, whereas the burned plots are open C₄-dominated grasslands with scattered mesquite trees. Prosopis trees have altered SOM pools by the concentration of plant nutrients and the addition of isotopically light shrub litter. Frequent fires have altered the basic geochemistry and nutrient availabilities of the soil, and the changes appear to be significant enough to affect plant growth. Soil pH increases with burning frequency, and TOC, total nitrogen, and plant -available phosphorus show significant increases on the infrequently burned plot. Burning is advantageous for preservation or restoration of grasslands, as total living grass biomass is greater on the two burned plots. Root biomass is significantly lower on the "frequently burned" plot. Concentrations of the key nutrients nitrogen and phosphorus are reduced in plants on the burned sites compared to plants on the unburned site. Fires help re-distribute nutrients but evidence of nutrient concentrations and δ¹³C values are retained in SOM for many decades. Estimates of bulk carbon turnover rates range from 112 to 504 years. Evidence for modern C₃ shrub expansion is found in the shift of SOM δ¹³C values from values characteristic of C₄ grasses to C₃ shrubs in surface soil layers. δ¹³C(SOM) values indicate that the Holocene and Late Pleistocene were dominated by C₄ grasslands, and the pre-Late Pleistocene vegetation was a C₄-grass savanna with abundant C₃ plants.
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Heitz, Jean-François. "Propagation d'ondes en milieu non linéaire : applications à la reconnaissance des sols et au génie parasismique." Grenoble 1, 1992. http://www.theses.fr/1992GRE10120.
Full textAbstract:
La propagation d'ondes en milieu non lineaire est etudiee sur les plans theorique, experimental et numerique. Des applications touchant les domaines du genie parasismique et de la reconnaissance in situ des sols sont proposes. Apres un etat des connaissances acquises a ce jour sur le comportement du sol sous sollicitation dynamique, un modele de comportement viscoelastique non lineaire est introduit dans l'equation fondamentale de la dynamique. L'equation du mouvement du sol obtenue exhibe au second membre un terme de source contenant l'ensemble des termes caracteristiques lies a la non-linearite du sol. Une analyse dans l'espace des frequences montre que le comportement non lineaire deviatoire du sol est a l'origine de modifications du contenu spectral au cours de la propagation par rapport au contenu frequentiel de la sollicitation. Une methode iterative de resolution de l'equation du mouvement est utilisee. A chaque iteration, la solution est obtenue explicitement par l'utilisation de transformations fonctionnelles integrales appropriees. Deux essais dynamiques in situ en surface et en puits avec excitation harmonique sont interpretes sur la base de l'approche theorique precedente. Le premier essai a permis essentiellement de mettre en evidence in situ le comportement non lineaire du sol sous sollicitation sinusoidale. Pour le second essai, des calculs simulent la reponse du sol a distance du puits et une methode d'identification de parametres caracteristiques du comportement non lineaire du sol est proposee. Une autre application de l'approche theorique proposee permet d'etudier les effets de site unidimensionnels caracteristiques du comportement non lineaire d'un horizon de sol reposant sur un demi-espace et subissant une sollicitation transitoire de type sismiques. Une extension du calcul en configuration bidimensionnelle est ensuite proposee
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Andrieux, Patrick. "Influence de la variabilité spatiale des caractéristiques physiques des sols sur le bilan hydrologique : l'exemple d'un système de sols sur barre prélittorale (Guyane française)." Montpellier 2, 1990. http://www.theses.fr/1990MON20157.
Full textAbstract:
Cette these aborde l'etude des determinants du fonctionnement hydrologique d'un interfluve sedimentaire (barre prelittorale) en guyane francaise. L'accent est mis sur les relations existant entre la variabilite spatiale de la recharge de la nappe, des conductivites hydrauliques a saturation et des traits geomorphologiques et pedologiques de la barre etudiee. Dans une premiere etape, des releves des hauteurs piezometriques de la nappe et des mesures de la teneur en eau volumique sont effectuees. L'analyse de la variabilite spatiale des conductivites hydrauliques a saturation montre une forte variance. Dans une seconde etape, on identifie la variabilite spatiale de la recharge de la nappe, a l'aide d'un modele d'ecoulements en zone saturee, des hauteurs piezometriques et des conductivites hydrauliques a saturation mesurees. La modelisation confirme l'hypothese d'isolement hydraulique de la barre et met en evidence le role important de la variabilite spatiale des conductivites sur le regime hydrologique. Etant donne qu'une faible part de la pluie contribue a la recharge de la nappe, l'existence d'un ruissellement important est supposee. Un schema precisant les principaux types de ruissellement sur la barre est propose
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Mozaffari, Morteza. "Potassium supplying power of an alluvial soil in Massachusetts /." 1990. https://scholarworks.umass.edu/theses/3418.
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Wu, Chi-Chen, and 吳季蓁. "Mobility of nickel in alluvial soils of western Taiwan and its relation to soil properties." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/44989104657789322091.
Full textAbstract:
碩士國立屏東科技大學
環境工程與科學系所
104
In order to understand the environmental factor affecting Ni mobility in the alluvial soil at western Taiwan, the soil of agricultural land in the alluvial soil area of Taoyuan city, Changhua County and Tainan city were used as research targets to conduct basic property analysis of the soil (soil texture, pH value, EC, CEC, OC), 0.1N HCl, 0.005M DTPA, 0.05M EDTA extraction and Aqua regia digestion Ni total content concentration analysis were also conducted. Meanwhile, the ratios between three extraction methods and Ni total content concentration were used respectively to calculate coefficient of distribution (Kd) to be used as the index of mobility of In in the soil. Finally, correlation and regression statistical methods were used to investigate the correlation and linear relationship between Physicochemical Characteristic and Ni mobility of soil. From the research results, it is clear that significant negative correlation exists between Ni concentration and clay content for three extraction methods, but Ni concentration shows significant positive correlation with EC and OC; moreover, three Kd values show significant negative correlation with clay content, but significant positive correlation with OC. Through regression analysis, the following result can be obtained: Kd_HCl = 0.004 OC +0.028 (R2=0.298, P<0.001) Kd_DTPA = -0.001 Clay -0.005 pH +0.001 OC +0.001 CEC +0.069 (R2=0.444, P<0.001) Kd_EDTA = -0.001 Clay +0.014 pH +0.002 OC -0.011 (R2=0.391, P<0.001) Under different extraction methods, Ni mobility was affected differently by Physicochemical Characteristic.
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Kelley, John Phillip. "Influence of alluvial sedimentation rate on floodplain soil development and vegetation." 2006. http://digital.library.okstate.edu/etd/umi-okstate-1995.pdf.
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Pham, Van Quang. "Soil Degradation of Raised-beds on Orchards in the Mekong Delta Field and Laboratory Methods." Doctoral thesis, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127802.
Full textAbstract:
Soil degradation is a complex process which may occur anywhere and at any time. It directly affects the physical, chemical and biological processes within the soil profile. Soil degradation can either be as a result of natural hazards or due to manmade actions, such as mismanagement on cropping patterns, soil preparation and cultivation practices. Regardless of how it is caused, soil degradation has strong negative effects on plant and soil productivity. Soil degradation can accelerate a series of processes such as erosion, compaction, loss of organic matter, loss of whole soil biota, surface sealing and contamination. This thesis presents the assessment of soil properties to improve our understanding of soil degradation on raised-bed orchards in the Vietnamese Mekong delta (MD). Measurements were made on 10 citrus plantations which had been established during a range of years from 1970 to 1998 at Hau Giang province. Soil sampling was made in the dry season of 2010 at two soil depths for each raised-bed to determine soil chemical and physical properties. The soil penetration resistance (PR) was periodically measured once a week together with soil sampling for moisture measurements during a period of 5 months. Analysis indicated the pH value of the soil was tending to decrease, nutrient imbalance and deficiency was developing, and the soil structure was deteriorating during the age since the raised-beds were originally constructed. Preventive and restorative measures need to be considered for restoring and retaining the quality of the soil and the ground water. These measures should consist of (1) neutralizing of excess acidity, (2) balancing of nutrients, (3) maintaining of soil organic matter, and (4) application of appropriate irrigation schedules.Suy thoái đất là một tiến trình phức tạp xuất hiện ở mọi nơi, mọi lúc làm tác động trực tiếpđến các quá trình lý, hóa và sinh học trong phẫu diện đất. Nó có thể là kết quả của các hoạtđộng do tự nhiên hoặc do con người như sử dụng sai hoặc thực hành quản lý đất đai bất hợplý. Cho dù nguyên nhân thế nào chăng nữa, suy thoái đất cũng gây ra các ảnh hưởng bất lợinặng nề lên cây trồng và sức sản suất của đất. Suy thoái đất có thể thúc đẩy hàng loạt cácquá trình như là xói mòn, nén dẽ, mất vật liệu hữu cơ và sinh vật đất, đóng váng bề mặt vàô nhiễm. Luận văn này trình bày sự đánh giá về các đặc tính của đất để mở mang sự hiểubiết về suy thoái đất trên các vườn cây ăn trái ở đồng bằng sông Cửu Long. Thí nghiệmthực hiện trên 10 vườn cam quít với khoảng thời gian thành lập vườn từ 1970 đến 1998 tạitỉnh Hậu Giang. Mẫu đất được lấy vào mùa khô năm 2010 ở hai độ sâu cho mỗi vườn đểphân tích các chỉ tiêu lý hóa đất. Sức kháng xuyên của đất được đo định kỳ mỗi tuần kếthợp với lấy mẫu để xác định ẩm độ đất trong suốt khoảng thời gian 5 tháng. Kết quả phântích cho thấy pH đất có khuynh hướng giảm, sự thiếu và mất cân bằng dinh dưỡng đất ngàycàng lộ rõ, và cấu trúc đất đang xấu đi theo độ tuổi của vườn. Các biện pháp phòng ngừa vàphục hồi cần được quan tâm đối với việc phục hồi và duy trì chất lượng của đất và nướcngầm. Các biện pháp nên bao gồm (1) trung hòa độ chua đất, (2) cân bằng dinh dưỡng, (3)duy trì vật liệu hữu cơ trong đất, và (4) áp dụng chế độ tưới thích hợp.
QC 20130909
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Chen, Chih-Chieh, and 陳志杰. "Studies on Depression and Afforestation Using Circulating Fluidized Bed Ash Mixed with Alluvial Soil." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/37193611895279710422.
Full textAbstract:
碩士朝陽科技大學
環境工程與管理系碩士班
101
The characteristics of soil in Taiwan are different due to different locations, which can provide different elements to plants. Instead of using chemical fertilizers, we may think if we can take good advantage of materials which can provide elements needed by plants and also save costs. Formosa Petrochemical Plant uses petroleum coke as fuel through circulation fluidized-bed (CFB) steam generator which generates byproduct ash containing high level of CaSO4 and CaO with high pH value. If this byproduct ash can be mixed with soil in proper ratio, it should be able to achieve the purposes of improving pH value and providing essential elements needed by plants. In this experiment, we use alluvial soil along with sea sand, in equal weight, mixed with the byproduct ash and use Taiwan Short-leaf Pine for pot experiment and Silvery Messerdhmidia and Norkfolk Island Pine for on-site experiment along the sea shore. As results from pot experiment, the Taiwan Short-leaf Pine with mixed soil shows obvious improvements in both growing speed and plant height, especially for the ratio 0.7:0.7:0.6. Moreover, the best ratio becomes 0.5:0.5:1.0 based on results of plant essential elements analysis. This could be due to different stage of plants needs different essential elements and adjustment for essential elements for different stages might be necessary. For the on-site experiment, we use Silvery Messerdhmidia and Norkfolk Island Pine for the first trial but the condition of Norkfold Island Pine was severe. On the contrary, the Silvery Messerdhmidia was growing well instead. Finally, the initial results from Silvery Messerdhmidia was consistent with results from pot experiment and it was obvious that this byproduct ash can improve the growth of plants effectively.
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Jones, Geraint Alan. "Development of sounding equipment for the assessment of the time- settlement characteristics of recent alluvial deposits when subjected to embankment loads." Thesis, 1992. http://hdl.handle.net/10413/10534.
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The whole of this thesis is my work unless specifically indicated to the contrary in the text,
and has not been submitted in part or in whole to any other University.
Some thirty years ago the author operated a deep sounding machine, one of the first in
the country, on a misty lake in Ireland and marvelled at the way subsoil information could
be garnered. The magic of the moment never entirely passed and when the opportunity
arose to use the technique in Natal the die was cast.
The development of the national road system surged in the early 1970's and since many
of these roads on the Natal coastal routes crossed extensive recent alluvial deposits, the
geotechnical problems of instability and settlement became major factors in the road
design. Traditional methods of investigation consisted of boreholes with sampling and
laboratory testing. Whilst these were satisfactory, provided they were of adequate quality,
they were relatively expensive if sufficiently detailed models of the subsoil were to be
obtained for design purposes.
Cone penetration testing provided a potential a solution and this led to research work
conducted over a period of twenty five years which continues today. The initial
development of ideas for improvements to the mechanical equipment took place whilst the
author was carrying out preliminary investigations for freeway routes over the coastal
alluvial deposits. This was followed by a period devoted largely to cone penetration testing
research and deVelopment and to embankment design methods at the National Institute
for Transport and Road Research, and to the initial registration for a Master's degree
under the supervision of Professor K Knight in 1975. This research programme was
completed as originally envisaged, but not submitted because during its course the author
conceived the idea of the piezometer cone. This proved to be such an exciting prospect
that the research and development continued for a number of years until piezometer cone
testing has now become almost routine for geotechnical investigations on alluvial deposits.
In 1983, due to Professor Knight's retirement from the University, Mr Phillip Everitt was
appointed as the supervisor.
At that stage piezometer testing was becoming accepted internationally and new aspects
and information frequently appeared. It was apparent, however, that the essential proof
of the system for the prediction of embankment performance was to use it at
embankments where the performance had been monitored. Eventually grants were
provided by the Department of Transport for this, which enabled two research projects to
be conducted during 1989 - 1990 and 1991 - 1992. After completion of the first of these
a presentation of the author's work on cone penetration testing since the mid 1960's was
made to the Faculty of Engineering at the University of Natal. The Executive Committee
of the University Senate subsequently approved, in August 1991, that the registration be
upgraded to doctoral status.
Mr Everitt's encouragement during this extended period has been a vital factor in ensuring
an outcome for this task and the author wishes to express his gratitude for this.Thesis (Ph.D.)-University of Natal, Durban, 1992.
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WANG, YA-HSUAN, and 王雅萱. "Applying Indicator Kriging to Estimate Spatial Distributions of Highly and Lowly Permeable Soil Texture Ratios of Aquifers in the Choshui River Alluvial Fan." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/s98h6w.
Full textAbstract:
碩士國立臺北科技大學
土木工程系土木與防災碩士班
107
Groundwater is one of major water resources in Taiwan. Continuously over-pumping has resulted in social and economic disasters, such as soil salinization, seawater intrusion, and land subsidence in this country. Rational use of groundwater resources has become a crucial issue for environmental protection and sustainable economic development. Therefore, it’s necessary to establish an integral hydrogeological stratification structure applied for accurate evaluation of the groundwater budget in aquifers.Considering the soil permeability plays an important role in groundwater recharge and pollution transport in vadose zone, the indicator kriging (IK) was applied to estimate spatial distributions of highly and lowly permeable soil texture ratios of aquifers in the Choshui River Alluvial Fan. First, the borehole data reported by the Central Geological Survey were statistically analyzed to establish multiple thresholds. The multi-threshold IK was then used to probabilistically estimate occurrence probabilities of highly and lowly permeable soil texture ratios of aquifers and determine the conditional cumulative distribution function (CCDF) at each cell. Finally, quartiles obtained from CCDF were adopted to determine the estimates of highly and lowly permeable soil texture ratios of aquifers and the interquartile range was employed to explore the estimate uncertainty. The research results reveal that the highly permeable soil texture ratios of aquifers are mainly located in the proximal-fan and partial area of mid-fan (Changhua and Yunlin). The lowly permeable soil texture ratios of aquifers are primarily situated in the distal-fan and the partial mid-fan (Chiayi). In addition, the results also prove that the IK approach with multiple thresholds can reduce the smoothing effect presented in OK estimation and characterize a reliable hydrogeological pattern in vadose soils. In the future, the effects of soil layer distribution and texture on the soil water retention characteristics, deep seepage and pollution transport in groundwater can be further explored based on the study results. Moreover, comprehensive groundwater management strategies can be formulated according to the revised hydrogeological pattern with more detailed highly and lowly permeable soil textures.
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MILLER, Zbyněk. "Výskyt rtuti v nivních půdch horního toku řeky Ohře." Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-53004.
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The aim of this study was to summarize information about the behavior of mercury in soils, particularly the assessment of its mobility and bioavailability, and to verify the extent of contamination of alluvial soils under the reservoir Skalka. This research was aimed to evaluate the contamination of mercury floodplain soils with mercury belong the upper river Ohře near the town of Chvoječná, near 230th river kilometer. River sediments of the upper river Ohře and the surrounding alluvial soils in floodplains contain high mercury levels. The site has been sampled for mercury analysis of soil samples taken from farmed areas, which are expected enrichment of mercury deposits of the inserted river Ohře. There were two main types of land-use, permanent grassland and arable land. The observed results can be concluded that the river floodplain sediments enrich the soil with mercury. Analytical method (atomic absorption spectrometry, CV-AAS) showed that almost all surface soil samples from the flooded area exceeds the maximum allowed value (for light soils 0.6 mg.kg-1 and other land 0.8 mg.kg-1 ) that are designated for agricultural land. Indicative of mercury was determined by mobility, which was up to 2.18%. Levels of organic forms of mercury were also measured in the soils that reached the area of grassland 2 maximum 0.147 mg.kg-1; the subsidiary surface S1 had the relative distribution of organic mercury 10.98% at a depth of 101-140 cm.
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Cosio, Sergio Javier. "Infiltration into stratified alluvium a comparison between simulated values and field measurements /." 1988. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1988_113_sip1_w.pdf&type=application/pdf.
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CHANG, YEN-CHUN, and 張硯鈞. "Estimation of Compression Parameters of Soils and Prediction of Ground Subsidence in Alluvial Deposits Using Genetic Algorithms." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/01298305902545489196.
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碩士國立雲林科技大學
營建工程系
104
ABSTRACT Agriculture is thriving in the southwestern plains of Taiwan and farmers usually need a lot of groundwater for irrigation. Due to the uneven distribution of rainfall and insufficient capacity of the existing reservoirs for irrigation, water pumping is often seen in this area. Consequently, the extraction of groundwater has become the primary cause of ground subsidence in this area over time. In this study, we examined the data of ground subsidence at Tuku Junior High School (TJHS) because TJHS is located at southeastern part of the convergence of Taiwan Expressway No.78 and Taiwan High Speed Rail, which is also on the eastern rim of the serious area of land subsidence. As the ground subsidence problem has imposed great danger on the safety of the two main traffic arteries, it is extremely important to evaluate and predict the amount and rates of ground subsidence patterns in this area. However, for existing studies, the prediction of ground subsidence is based on in-situ sampling, laboratory testing and the consolidation theory and this is more costly and time-consuming. Another approach adopts previous monitoring data and uses various prediction theories to analyze and predict ground subsidence, which is more economical and efficient. Consequently, the second approach was adopted in this study. The aim of this study was to predict the long-term trend of ground subsidence and provide the results for future prevention of ground subsidence in this region. To achieve this goal, based on the previous in-situ data of the TJHS Monitoring Station and 1D Terzaghi Consolidation Theory with taking into account decompression and swelling behavior, secondary compression, and maximum past pressure, we used genetic algorithm to obtain an optimized ground compression index and establish an analysis model. As the results of the analysis of the generation and population of genetic algorithm suggested that there is not a trend of convergence when the population (P) is 30 and the generation (G) is 100, the two values were adopted in this study. With the two values, the optimized parameters from the four cases (Case-A, Case-B, Case-C, Case-D) were obtained to make sensitivity analysis graphs. Among the graphs, Case-D (T4-P4) showed the lowest value of the optimized error. After using the data from the previous one to four years respectively to train the best parameters in layer and predict the settlement from 2004 to 2011, the results showed the lowest RMS (root mean square) and most accurate result in Case-D when the data of four years was used to train the parameter and predict the settlement of the previous eight years, followed by three years, two years and one year. Keywords：ground subsidence, genetic algorithm, consolidation theory, soil compression index , Chouswei River Alluvial Fan
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楊雅真. "The establishment of electromagnetic physics auxiliary indices:the rapid assessment of the trasport of heavy metal in alluvial soils." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/98265261962740341837.
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Jhang, Jhe-Hao, and 張哲豪. "Investigation of Compressibility Characteristics and Creep Behavior of Soils in Chuoshui River Alluvial Fan through In-situ Monitoring and Laboratory Testing." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/45787879713220299472.
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碩士國立雲林科技大學
營建工程系
103
Chuoshui River Alluvial Fan (CRAF), formed by Chuoshui River, is the largest alluvial fan in Taiwan. The deposit of the fan consists of inter-bedded layers of unconsolidated sandy and clayey soils with relatively high potential of compressibility. Based on survey data by Water Resources Agency, Ministry of Economic Affairs (WRA/MOEA), the CRAF, including Changhua and Yunlin Counties, is currently the most serious ground subsidence area in the island. In recent decades, the ground subsidence center in the CRAF has been gradually moving from the coastline to inlands. In accordance, the safety of Taiwan High Rail (THR) which passes through the center of CRAF becomes a serious concern as the ground subsidence approaches the design limit of vertical gradient of the rail alignment. Based on the studies by WRA/MOEA and Industrial Technology Research Institute (ITRI), the major compressive layers in central CRAF are located at the depth range of 170~300m in recent decades. We have selected the intersection area of THR and the Expressway 78 as our study site. The coring samples from this site were tested in the laboratory for soil classification and material layer identification purposes. Furthermore, we performed a series of 1D consolidation and creep tests on the undisturbed samples collected at depths of 205m and 220m from the site, in order to understand the compressibility characteristics of the materials and their relations to the observed ground subsidence. Based on our in-situ monitoring data, the ground subsidence is intimately related to the fluctuation of ground water levels at the site. It was found that the ground water levels of the aquifers in CRAF appeared synchronizing, in which the 2nd and 3rd aquifers the ground water levels fluctuated most dramatically. We notice compressions occurred approximately in all soil layers within the 300m monitoring depth during our study period. It appeared, however, the sandy soil layers exhibit relatively more compressions than other types of soil layer. Results of soil classification and material layer identification show that the deposit of CRAF consists of more sandy soils inter-bedded with less clayey and silty soils. The undisturbed samples for 1D consolidation and creep testing are classified as clayey sand (SC) and silty sand (SM), for the sample collection depths of 205m and 220m, respectively. Results on these undisturbed samples indicate that the volumetric compression coefficients, mv, are of medium to very low types; the compression indices, Cc, are of slight to low types; and the consolidation coefficients, Cv, are belong to those of the low plasticity clay and silt. For the short-term loading case (24hrs), major compressions would occur in SC soils due to primary consolidation and secondary compression. In the SM soils, however, major compression would occur due to the primary consolidation. For the long-term loading case (7days), major compressions in both SC and SM soils would due to primary consolidation and secondary compression as well. By applying the creep potential evaluation technique proposed by Singh and Mitchell (1969), we found that the m-values for the SM soils in this study are less than 1, indicating a high creep potential. Alternatively, the m-values for the SC soils are greater than 1, indicating a low creep potential. Based on results of this study, we conclude the ground subsidence in CRAF should consider the compressibility of both sandy and clayey soils that exist at the site. In addition, the long-term creep behavior of the sandy soils should be taken into account as part of the ground subsidence in this area.