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 16 of 16 for “"Near-surface soil"”.
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Long-Term Effects of Rice Rotation, Tillage, and Fertility on Near-Surface Soil Carbon and Nitrogen Cycling
… the year) conditions can influence the rate of soil organic matter (SOM) decomposition, which can greatly influence carbon (C) and nitrogen (N) storage and sequestration in the soil over time. Therefore, a study was conducted on a silt-loam soil (fine, smectitic, thermic, Typic Albaqualf) at the …
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Switchgrass Cultivar, Harvest Frequency, Fertilizer Source, and Irrigation Effects on Near-Surface Soil Properties in West-Central Arkansas
… differing switchgrass management combinations on near-surface soil properties. The objective of this research was to determine the residual near-surface soil property effects of three years (2008 to 2011) of consistent management combinations to maximize switchgrass biomass production, including …
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Estimating Soil Moisture and Energy Fluxes Using Assimilation of Remotely Sensed Land Surface State Variables
Soil moisture plays a critical role in the land-atmosphere interactions. Given the approximate model physics representation in the land surface models predicting these fluxes, better predictions can be obtained by assimilating hydrologically relevant remotely sensed data into the predictive models. …
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Deep-Layer Terrestrial Hydrologic Memory and Mechanisms of Its Influence on the Eco-Climatology of the Biosphere
… of the terrestrial memory is limited to the near-surface soil, and the role of deep-soil reservoir is unknown or has simply been neglected. Observational evidence shows the existence of plant roots much deeper in the soil/rock profile than the depth usually incorporated in existing land …
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Effect of tree mortality on biogeochemical response after mountain pine beetle forest infestation, The
… and geochemical parameters within three near-surface soil horizons were contrasted between healthy and deceased lodgepole pines (Pinus contorta) surrounded by varying extents of tree mortality. Bark beetle impact altered N cycling, as an increased proportion of the total N pool was …
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Correlation Analyses among Soil, Plant, and Environmental Variables and Greenhouse Gas Emissions from Furrow-irrigated Rice on a Silt-loam Soil
… to relate greenhouse gas (GHG) production to soil and plant properties or environmental factors under furrow-irrigated rice. The objective of this field study was to evaluate correlations between methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) fluxes and emissions and global …
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Hydrological and Hydrochemical Responses From Thawing Permafrost in the Canadian Arctic
… (2) what the short and long-term changes are to surface water chemistry in watersheds impacted by thermal and physical permafrost disturbances, (3) which key factors control permafrost chemistry and runoff solute loads, and (4) where in the Canadian Arctic are changes to surface water chemistry …
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Spatio-Temporal Analysis of Observed Soil Moisture from Nebraska
<p>Soil moisture is a measure of the water content in a soil that is dependent upon precipitation, evapotranspiration, runoff, drainage, and irrigation. Nebraska is one of the few states that measures soil moisture in an extensive network that records weather variables on a daily basis. Daily soil …
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Impact of Cascadia Subduction Zone Earthquakes on Coastal Bridges in Washington State
… velocity model of the region and assuming a surface shear wave velocity of 600 m/s. This research uses the simulated ground motions as input into regional-scale bridge damage analyses. To account for the variation of near-surface soil conditions across the Pacific Northwest, amplification …
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Investigation of Parameters Influencing Reverse Fault Rupture Propagation to the Ground Surface
<p>Surface fault rupture poses a serious threat to infrastructure in many seismically active regions, but knowledge about the factors which control the likelihood of surface displacement is limited. Current probabilistic frameworks rely only on fault mechanism and moment magnitude to predict the …
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Improving seismic site response analysis for non-standard sites
… waves will be affected by travelling through soil deposits near the surface. In fact, these near-surface layers act as a filter modifying (amplify/de-amplify) the input motion and leading to modified ground motions at the ground surface. Hence, the study of the effect of these near-surface …
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Soil moisture dynamics and soil moisture controlled runoff processes at different spatial scales : from observation to modelling
Soil moisture is a key state variable that controls runoff formation, infiltration and partitioning of radiation into latent and sensible heat. However, the experimental characterisation of near surface soil moisture patterns and their controls on runoff formation remains a challenge. This subject …
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Cadmium accumulation in agricultural soils
Cadmium (Cd) has accumulated in New Zealand (NZ) soils as a result of phosphate fertiliser application. Cadmium is a biotoxic heavy metal and can be adsorbed by soil and enter the human food chain. Three objectives were investigated in this thesis: 1. Determine if the distribution of Cd varies …
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From groundwater to the atmosphere: using RELAMPAGO observations and modeling to understand changes in the hydrologic cycle of southeastern South America
… climate variability and extreme events impact surface hydrology, the land surface of the region influences evapotranspiration, groundwater table depth, near-surface soil moisture and surface runoff. These surface conditions in turn affect the overlying atmosphere and precipitation. …
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Development of mechanistic energy balance models for grassland
… determinants of grassland productivity include near-surface soil and air temperatures and plant water use. Therefore it is important to understand how grasslands partition the energy they receive into heat and vapour fluxes, and soil heat flux which regulates the underlying soil temperatures. …
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Impacts of model-data uncertainties on biogeophysical-biogeochemical interactions in a land surface model (with an emphasis on the northern high-latitude regions)
… To achieve this objective, I applied a land surface model, specifically the Integrated Science Assessment Model (ISAM), at spatial scales ranging from flux tower sites to the global land surface in order to explore how the modeling uncertainties translate from site to regional to global …