Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"soil heterogeneity"”.
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Soil Heterogeneity in Arid Shrublands: Biotic and Abiotic Processes
This dissertation investigates the evolution of soil heterogeneity on arid alluvial fans. Soil formation begins when depositional or erosional processes cease and a geomorphic surface becomes stable. The transformation of sediment to soil (pedogenesis) affects a multitude of hydrologic processes …
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Soil Heterogeneity Changes During Forest Succession: Test of a Model Using Univariate and Geostatistics
… 80 years) to elucidate the temporal changes in soil spatial heterogeneity. Samples were collected from loblolly pine plantations representing reorganization through aggradation phases of succession, and from one set of oak-hickory stands to signify the steady-state phase of the model. These …
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Subsurface methane migration from natural gas distribution pipelines as affected by soil heterogeneity: field scale experimental and numerical study
… is how the environmental conditions (i.e. soil type and moisture, competing utilities, ground surface cover) affect gas migration behavior (including the migration rate and extent). To mitigate these concerns, an increased understanding of gas migration through soil is necessary to support …
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Impact of nutrient heterogeneity on plant response and competition in Coastal plain species
Relationships between nutrient heterogeneity, root foraging behavior and short-term competitive interactions were investigated for six species native to southeastern USA. Monoculture, two- and six-species garden plots were established and fertilized to create spatially homogeneous or heterogeneous …
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Farm-scale Water Management in Adaptation to Climate Change in Morocco
… of its catchment area, rainfall pattern, soil type, cost of construction, water price, as well as crops water requirements. Within reasonable assumptions, capacities close to the reservoir in Benguerir (4000 m³) are estimated. However, the results are sensitive to multiple partially …
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Understanding scale impacts of heterogeneity and topography on water and energy fluxes in mountain meadows using a fully-integrated hydrologic model
… Land cover, subsurface, and topographic heterogeneity have all been shown to control infiltration rates, subsurface flow, soil moisture, and energy flux distributions. Many hydrologic models operate at scales which do not capture the variability of these parameters, often because of …
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Variability Structure Estimation: The Role of Sample Support
The characterization of spatial variability in soil properties is a prerequisite to many activities, such as site specific management (i.e., precision farming), groundwater and solute transport modeling, groundwater pollution assessment and remediation, etc. Due to soil heterogeneity, statistical …
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Variability structure estimation: The role of sample support
The characterization of spatial variability in soil properties is a prerrequisite to many activities, such as site specific management (i.e., precision farming), groundwater and solute tranport modeling, groundwater pollution assessment and remediation, etc. Due to soil heterogeneity, statistical …
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An investigation of the influence of drought and other soil factors on the structure of a calcareous grassland.
… been given to the interaction of drought with soil heterogeneity and mineral nutrient stress. Efforts have been made to differentiate between mechanisms of drought tolerance and drought avoidance, and this has allowed some assessment of the contribution of diversity in morphology, life history …
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Parameter estimation for unsaturated flow models
The estimation of parameters in models for soil unsaturated hydraulic properties from transient flow experiments via inversion of the governing initial-boundary value problem is examined. Emphasis is on the estimation of parameters from in-situ experiments where available data are in the form of …
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Spatio-temporal patterns of soil resources following disturbance in a 40-year-old slash pine (pinus elliottii Engelm.) forest in the Coastal Plain of South Carolina
… in characterizing and interpreting ecological heterogeneity over space and time in the past two decades. This is mainly due to the renewed recognition of the significance of heterogeneity in ecological theories. However, studies that have combined both spatial and temporal aspects of …
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Ecophysiological effects of high concentrations of iron and other heavy metals on Eriophorum angustifolium Honck. and Phragmites australis (Cav.) Trin ex steudel.
… the study is based on the analysis of plants and soil samples collected from the field and relates heavy metal concentration in plant tissue to concentrations in soil/sediments. The second part of the study is based on laboratory work to determine individual factors influencing heavy metal uptake …
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The influence of redox dynamics on nitrogen cycling and nitrous oxide emissions from soils
Soils are a dominant source of nitrous oxide (N2O), a potent greenhouse gas. The complexity of drivers of N2O production and emissions has hindered our ability to predict the magnitude and spatial dynamics of N2O fluxes. Soil moisture can be considered a key driver because it influences oxygen …
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Meander migration with physically-based bank erosion
… floodplains, the effects of horizontal heterogeneity of floodplain soils on rates and shapes of meander migration are evaluated. It is shown that floodplain-soil complexity can greatly contribute to meander planform complexity. Using a stochastic approach, the parameters governing the …
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Quantitative multifactor analysis of planter settings and row unit design for corn stand establishment in precision agriculture
… among planter operational parameters, soil heterogeneity, and the design of mechanical components. Critical factors, including planting speed, hydraulic downforce application, and row unit arrangement, significantly influence the quality of seed-to-soil contact and the integrity of …
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Variability of physical, chemical and hydraulic parameters in soils of Mt. Kilimanjaro across different land uses
The heterogeneity of soils is a key to biological processes, carbon turnover and water storage. Climate change and anthropogenic land use changes often decrease important functioning of soil systems. In order to understand the soil complexity, sophisticated technologies to measure soil properties …
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Soil physical impacts and recovery rates following human-induced disturbances in the Ross Sea region of Antarctica
… of the impacts of human activities on Antarctic soil environments has become an important issue. The overall objective of this thesis was to investigate soil physical impacts, and soil recovery rates, following human disturbance in the Ross Sea region of Antarctica. Visually disturbed and nearby …
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Soil resource heterogeneity and site quality in Southern Appalachian hardwood forests: Impact of decomposing stumps, geology and salamander abundance
… Three interconnected research projects regarding soil resource heterogeneity were designed to increase our understanding of this ecosystem. The objective of these projects were as follows: 1) to examine and quantify the role of decaying stumps in regards to total carbon (C) and nitrogen (N) pools …
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Turning a problem into a solution: heterogeneities in soil hydrology
It is commonly recognized that soil moisture exhibits spatial heterogeneities occurring in a wide range of scales. These heterogeneities are caused by different factors ranging from soil structure at the plot scale to land use at the landscape scale. There is an urgent need for effi-cient …
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Studio del comportamento statico e dinamico dei sistemi galleria-terreno-strutture in elevazione in ambiente urbano
Al giorno d'oggi, è sempre più evidente la necessità di costruire strutture in sotterraneo per contrastare le problematiche relative alle reti di trasporto e all’inquinamento atmosferico. Così, negli ultimi cinquant'anni, grande attenzione è stata dedicata alla costruzione di strutture …