The water stored in and flowing through the subsurface is fundamental for sustaining human activities and needs, feeding water and its constituents to surface water bodies and supporting the functioning of their ecosystems. Quantifying the changes that affect the subsurface water is crucial for our understanding of its dynamics and changes driven by climate change and other changes in the landscape, such as in land-use and water-use. It is inherently difficult to directly measure soil moisture and groundwater levels over large spatial scales and long times. Models are therefore needed to capture the soil moisture and groundwater level dynamics over such large spatiotemporal scales. This thesis develops a modeling framework that allows for long-term catchment-scale screening of soil moisture and groundwater level changes. The novelty in this development resides in an explicit link drawn between catchment-scale hydroclimatic and soil hydraulics conditions, using observed runoff data as an approximation of soil water flux and accounting for the effects of snow storage-melting dynamics on that flux. Both past and future relative changes can be assessed by use of this modeling framework, with future change projections based on common climate model outputs. By direct model-observation comparison, the thesis shows that the developed modeling framework can reproduce the temporal variability of large-scale changes in soil water storage, as obtained from the GRACE satellite product, for most of 25 large study catchments around the world. Also compared with locally measured soil water content and groundwater level in 10 U.S. catchments, the modeling approach can reasonably well reproduce relative seasonal fluctuations around long-term average values. The developed modeling framework is further used to project soil moisture changes due to expected future climate change for 81 catchments around the world. The future soil moisture changes depend on the considered radiative forcing scenario (RCP) but are overall large for the occurrence frequency of dry and wet events and the inter-annual variability of seasonal soil moisture. These changes tend to be higher for the dry events and the dry season, respectively, than for the corresponding wet quantities, indicating increased drought risk for some parts of the world.

The relevance, value and multi-dimensional application of soil moisture in many areas such as hydrological, meteorological and agricultural sciences have increased the focus on this important part of the ecosystem. However, due to its spatial and temporal variability, accurate soil moisture determination is an ongoing challenge. In the fall of 2013 and spring of 2014, the accuracy of five soil moisture instruments was tested in heavy clay soils and the Root Mean Squared Error (RMSE) values of the default calibration ranged from 0.027 and 0.129 m3 m-3. However, after calibration, the range was improved to 0.014 – 0.040 m3 m-3. The need for calibration has led to the development of generic calibration procedures such as soil texture-based calibrations. As a result of the differences in soil minerology, especially in clay soils, the texture-based calibrations often yield very high RMSE. A novel approach that uses the Cation Exchange Capacity (CEC) grouping was independently tested at three sites and out of seven different calibration equations tested; the CEC-based calibration was the second best behind in situ derived calibration. The high cost of installing and maintaining a network of soil moisture instruments to obtain measurements at limited points has influenced the development of models that can estimate soil moisture. The Versatile Soil Moisture Budget (VSMB) is one of such models and was used in this study. The comparison of the VSMB modelled output to the observed soil moisture data from a single, temporally continuous, in-field calibrated Hydra probe gave mean RMSE values of 0.052 m3 m-3 at the eight site-years in coarse textured soils and 0.059 m3 m-3 at the six site-years in fine textured soils. At field-scale level, the representativeness of an arbitrarily placed soil moisture station was compared to the mean of 48 data samples collected across the field. The single location underestimated soil moisture at 3 of 4 coarse textured fields with an average RMSE of 0.038 m3 m-3 and at only one of the four fine textured sites monitored with an average RMSE of 0.059 m3 m-3. / February 2017

Call number: LD2668 .T4 1958 H33 / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Silty soils are a common occurrence and can exhibit low strengths, and minimal bearing capacity, causing widespread construction and performance problems. These soils are highly moisture-sensitive and their stability is greatly influenced by the degree of densification achieved during compaction. The strength and stiffness of silty-subgrade soils is also greatly reduced when moisture infiltrates the compacted soil during post construction period. This investigation concentrated on further developing the description of the pumping problem for soils with high silt content and the development of guidelines for stabilization of problematic silts. Using documented field experiences of the DOTD districts, the study presents a testing program to investigate the nature of the problem, the character of the silt materials, and their performance with modifying/stabilizing agents. Seven representative silt soil samples were used in the laboratory program. The unique characteristics that identify a soil with a high potential to pump were determined with standard laboratory tests. The response and stability of the silts under compaction and loading with various moisture levels and compaction efforts was also tested. The susceptibility to pumping of the different samples was reviewed in terms of their physical characteristics. In addition to the silt content percentage, the plasticity character was noted as being significant. The potential for the modification/stabilization of the problem silt soils was also studied. The laboratory tests were selected with respect to construction needs and possible post construction conditions. A limited number of specific additives were proposed with consideration for their ability to dry the subgrade silts sufficiently to be compacted and with the strength to provide a "working table" for the construction of the base and pavement. The additives selected included hydrated lime, portland cement, and class c fly ash. A unitary set of guidelines for stabilizing problematic silts is proposed.

Sobre opiso desenvolvem-se todas as atividades a que se destina a edificação. Falhas Em sua execução, tais como, empenamentos, placas soltas, bolhas e manchas têm como conseqüências, desde o desconforto pessoal de andar em uma superfícieirregular, ao risco de acidentes de trabalho, contaminação de produtos por poeira, de salinhamento de equipamentos ou até mesmo a interferência no processo de produção, podendo provocar a paralisação parcial ou total da atividade produtiva da empresa.Tais problemas, muitas vezes são decorrentes do excesso de umidade do substrato de concreto, quando da aplicação do revestimento, por não ter tido o tempo de secagem adequado, de maneira a atingir o nível de umidade ideal. O excesso de água residual decorrente da umidade do substrato é uma das principais causas geradoras de patologias nos pisos de concreto quando utilizados revestimentos suscetíveis à presença de água. O comportamento da umidade do concreto é resultado de uma complexa ação entre a quantidade de água física e quimicamente ligada, durante a hidratação do cimento e a capacidade de transporte de água do sistema de poros do concreto. Neste contexto, o presente trabalho procura contribuir na sistematização do conhecimento sobre o assunto, descrevendo, inicialmente, o comportamento de bases de concreto frente à ação da água e os fatores que a influenciam: grau de hidratação, condições de equilíbrio e fluxo de umidade. É mostrado como ocorre a secagem do concreto e a influencia do tempo de cura, relação água/cimento do concreto e condições ambientes sobre o tempo necessário para que a umidade do concreto atinja o nível ideal para o início do revestimento do piso. São descritos os testes utilizados para a medição do nível de umidade do concreto, enfatizando os de caráter quantitativo, baseados na medição do teor de umidade, taxa de emissão de vapor de água e umidade relativa interna do concreto. Valores dos níveis ideais de umidade, em conformidade com o tipo de teste aplicado e materiais empregados, estabelecidos por entidades representativas de fabricantes de revestimentos para pisos de concreto, são apresentados como referências. O texto é finalizado com a apresentação das recomendações que visam facilitar a secagem do concreto e aspectos a serem observados quando da realização da medição do nível de umidade. / On the floor are developed all the activities the building is destined to. Faults in its execution, such as warping, loose plates, bubbles and stains, bring about from the personal discomfort of walking on an irregular surface, to the risk of workplace accidents, contamination of product due to dust, misalignment of equipment or even the interference in the production process, which may cause a partial or total stalling of the company productive activity. Such problems often derive from excess moisture in the concrete substrate, when the lining is applied, for not having been dried long enough, so as to attain the ideal moisture level. The excess residual water deriving from substrate moisture is one of the main causes generating pathologies on concrete floors when linings susceptible to the presence of water are used. The moisture behavior of concrete derives from a complex action between the amount of physical and chemically related water, during the hydration of the cement and the water transport capacity of the concrete pore system. In thisn context, the present work aims to contribute in systematizing the knowledge on the matter, initially describing the behavior of the concrete bases concerning the action of water and the factors influencing this: degree of hydration, balance conditions and humidity. The work shows how the drying of concrete occurs and the influence of the curing time flux, concrete water/cement ratio and ambient conditions on the time required for the concrete moisture to attain the ideal level to start the floor lining. The tests used to measure the concrete moisture level are described, emphasizing those of quantitative character, based on the measurement of the moisture content, water vapor emission rate and the concrete relative internal humidity. Values of the ideal levels of moisture, in accordance with the type of test applied and materials employed, established by representative manufacturer entities for concrete floors linings, are presented as references. The text concludes with the presentation of recommendations that aim to make the drying of concrete easier and aspects to be observed when the measurement of the moisture level is performed.

Photocopy of typescript. / Digitized by Kansas Correctional Industries

Barley is one of the important crops in many of the irrigated regions of the world. It is an important crop in Iran for both human consumption and livestock feed. In the United States and Europe it is used for livestock feed and beverages. The income from this crop is moderate in comparison to that from other major agricultural products. Barley production has a definite place in the economy of the region, because it requires only a small amount of care. It can be readily grown on poor lands. One of the factors contributing to the increased acreage of barley in many countries is the tolerance and adaptability of this plant to salt and poor or second class land. Yields have been increased materially in recent years with the development of new varieties superior to the standard varieties previously used. Better cultural practices are improving yields, but much remains to be done in this phase of the work.

When in commercial practice seed peas (Pisum sativum) are harvested, the vines are cut and windrowed or bunched and allowed to cure for a week or longer, depending upon the moisture content of the crop and weather conditions. The sooner the crop can be threshed, the less is the chance of loss caused by rain and the often-necessary attendant operation of turning the windrow or bunch to facilitate drying. In general, growers wait until the vines, pods, and seeds are quite dry. To what extent this is necessary is not known.

No description available.