Dissertations / Theses on the topic 'Hydrology not elsewhere classified'

A critical consequence of agriculturally managed lands is the transport of nutrients and sediment to fresh water systems, which is ultimately responsible for a range of adverse impacts on human and environmental health. In the U.S. alone, over half of streams and rivers are classified as impaired, with agriculture as the primary contributor. To address deterioration of water quality, there is a need for reliable tools and mathematical models to monitor and predict impacts to water quantity and quality. Soil water content is a key variable in representing environmental systems, linking and driving hydrologic, climate, and biogeochemical cycles; however, the influence of soil water simulations on model predictions is not well characterized, particularly for water quality. Moreover, while soil moisture estimation is the focus of multiple remote sensing missions, defining its potential for use in water quality models remains an open question. The goal of this research is to test whether updating model soil water process representation or model soil water estimates can provide better overall predictive confidence in estimates of both soil moisture and water quality. A widely-used ecohydrologic model, the Soil and Water Assessment Tool (SWAT), was used to evaluate four objectives: 1) investigate the potential of a gridded version of the SWAT model for use with similarly gridded, remote sensing data products, 2) determine the sensitivity of model predictions to changes in soil water content, 3) implement and test a more physically representative soil water percolation algorithm, and 4) perform practical data assimilation experiments using remote sensing data products, focusing on the effects of soil water updates on water quality predictions. With the exception of the first objective, model source code was modified to investigate the relative influence and effect of soil water on overall model predictions. Results suggested that use of the SWAT grid model was currently not viable given practical computational constraints. While the advantages provided by the gridded approach are likely useful for small scale watersheds (< 500 km2), the spatial resolution necessary to run the simulation was too coarse, such that many of the benefits of the gridded approach are negated. Sensitivity tests demonstrated a strong response of model predictions to perturbations in soil moisture. Effects were highly process dependent, where water quality was particularly sensitive to changes in both transport and transformation processes. Model response was reliant upon a default thresholding behavior that restricts subsurface flow and redistribution processes below field capacity. An alternative approach that removed this threshold and keyed processes to relative saturation showed improvement by allowing a more realistic range of soil moisture and a reduction of flushing behavior. This approach was further extended to test against baseline satellite data assimilation experiments; however, did not conclusively outperform the original model simulations. Nevertheless, overall, data assimilation experiments using a remote sensing surface soil moisture data product from the NASA Soil Moisture Active/Passive (SMAP) mission were able to correct for a dry bias in the model simulations and reduce error. Data assimilation updates significantly impacted flow predictions, generally by increasing the dominant contributing flow process. This led to substantial differences between two test sites, where landscape and seasonal characteristics moderated the impact of data assimilation updates to hydrologic, water quality, and crop yield predictions. While the findings illustrate the potential to improve predictions, continued future efforts to refine soil water process representation and optimize data assimilation with longer time series are needed. The dependence of ecohydrologic model predictions on soil moisture highlighted by this research underscores the importance and challenge of effectively representing a complex, physically-based process. As essential decision support systems rely on modeling analyses, improving prediction accuracy is vital.

Hyporheic exchange is key to buffer water quality and temperatures in streams and rivers, while also providing localized downwelling and upwelling microhabitats. In this research, the effect of geomorphological parameters on hyporheic exchange has been assessed from a physical standpoint: surface and subsurface flow fields, pressure distribution across the sediment/water interface and the residence time in the bed.

First, we conduct a series of numerical simulations to systematically explore how the fractal properties of bedforms are related to hyporheic exchange.We compared the average interfacial flux and residence time distribution in the hyporheic zone with respect to the magnitude of the power spectrum and the fractal dimension of riverbeds. The results show that the average interfacial flux increases logarithmically with respect to the maximum spectral density whereas it increases exponentially with respect to fractal dimension.

Second, we demonstrate how the Froude number affects the free-surface profile, total head over sediment bed and hyporheic flux. When the water surface is fixed,the vertical velocity profile from the bottom to the air-water interface follows the law of the wall so that the velocity at the air-water interface has the maximum value. On the contrary, in the free-surface case, the velocity at the interface no longer has the maximum value: the location having the maximum velocity moves closer to the sediment bed. This results in increasing velocity near the bed and larger head gradients, accordingly.

Third,we investigate how boulder spacing and embeddedness affect the near-bed hydrodynamics and the surface-subsurface water exchange.When the embeddedness is small, the recirculation vortex is observed in both closely-packed and loosely-packed cases, but the size of vortex was smaller and less coherent in the closely-packed case. For these dense clusters, the inverse relationship between embeddedness and flux no longer holds. As embeddedness increases, the subsurface flowpaths move in the lateral direction, as the streamwise route is hindered by the submerged boulder. The average residence time therefore decreases as the embeddedness increases.

Lastly, we propose a general artificial neural network for predicting the pressure field at the channel bottom using point velocities at different level. We constructed three different data-driven models with multivariate linear regression, local linear regression and artificial neural network. The input variable is velocity in x, y, and z directions and the target variable is pressure at the sediment bed. Our artificial neural network model produces consistent and accurate prediction performance under various conditions whereas other linear surrogate models such as linear multivariate regression and local linear multivariate regression significantly depend on input variable.

As restoring streams and rivers has moved from aesthetics and form to a more holistic approach that includes processes, we hope our study can inform designs that benefit both structural and functional outcomes. Our results could inform a number of critical processes, such as biological filtering for example. It is possible to use our approach to predict hyporheic exchange and thus constrain the associated biogeochemical processing under different topographies. As river restoration projects become more holistic, geomorphological, biogeochemical and hydro-ecological aspects should also be considered.

Disturbance regimes like freezing and thawing (FT) can have potentially significant impacts on nutrient release from soil and are predicted to increase with climate change. This is particularly important in biogeochemical hotspots like floodplains that can both remove and release nutrients to surface waters during flooding. Connection between the river and floodplain can improve water quality by reducing nutrient loads through microbial processes and sedimentation. However, conditions during flooding can also lead to phosphorus (P) release from pools that are not normally bioavailable. Disturbance events like FT can also lead to changes in bioavailable P due to microbial cell lysis. This study investigates differences in P chemistry and flux during flooding from intact soil cores that have undergone a FT cycle compared to soils that have not undergone freezing. Floodplain soils were collected from four sites along the Wabash and Tippecanoe Rivers in Indiana. We hypothesized that (i) the primary pools of P within the soil would change with freezing (ii) and flooding; (iii) frozen treatment cores would release more P during flood incubations than unfrozen control cores; and (iv) processes controlling P release during flood incubations would change after FT due to changes in the primary pools of P in the soil cores.

On average, soil cores that underwent FT released greater amounts of P than unfrozen cores over the course of the 3-week experimental flood incubation. Phosphorus release in both unfrozen control and FT treatment cores during flooding was explained in part by soil extractable Al and Fe and redox status; however, P release was influenced by soil Ca-P in the FT cores to a greater extent than unfrozen cores. Phosphorus release in FT cores occurred faster than in control cores with overlying water concentrations peaking 2 weeks after onset of flooding, followed by lower concentrations at 3 weeks. Whereas control cores had some release and uptake early on but then released P throughout the 3-week incubation—supporting the hypothesis that drivers of P release were different after FT. Interactive effects of FT and flooding suggest that concentration gradients between soil pore water and overlying surface water could have enhanced dissolution of the Ca-P pool, highlighting the importance of floodwater chemistry to P dynamics following FT. This study provides an important link between observed winter floodplain P loss and potential drivers of release and retention, which is critical to informing floodplain restoration design and management through all seasons.

Hydrological modeling has been a valuable tool to understand the processes governing water distribution, quantity, and quality of the planet Earth. Through models, one has been able to grasp processes such as runoff, soil moisture, soil erosion, subsurface drainage, plant growth, evapotranspiration, and effects of land use changes on hydrology at field and watershed scales. The number and diversity of water-related challenges are vast and expected to increase. As a result, current models need to be under continuous modifications to extend their application to more complex processes. Several models have been extensively developed in recent years. These models include the Soil and Water Assessment Tool (SWAT), Variable Infiltration Capacity (VIC) model, MIKE-SHE, and the Water Erosion Prediction Project (WEPP) model. The latter, although it is a well-validated model at field scales, the WEPP watershed model has been limited to small catchments, and almost no research has been introduced regarding water quality issues (only one study).

In this research, three objectives were proposed to improve the WEPP model in three areas where either the model has not been applied, or modifications can be performed to improve algorithms of the processes within the model (e.g. erosion, runoff, drainage). The enhancements impact the WEPP model by improving the current stochastic weather generation, extending its applicability to subsurface drainage estimation, and formulating a new routing model that allows future incorporation of transport of reactive solutes.

The first contribution was development of a stochastic storm generator based on 5-min time resolution and correlated non-normal Monte Carlo-based numerical simulation. The model considered the correlated and non-normal rainstorm characteristics such as time between storms, duration, and amount of precipitation, as well as the storm intensity structure. The model was tested using precipitation data from a randomly selected 5-min weather station in North Carolina. Results showed that the proposed storm generator captured the essential statistical features of rainstorms and their intensity patterns, preserving the first four moments of monthly storm events, good annual extreme event correspondence, and the correlation structure within each storm. Since the proposed model depends on statistical properties at a site, this may allow the use of synthetic storms in ungauged locations provided relevant information from a regional analysis is available.

A second development included the testing, improvement, and validation of the WEPP model to simulate subsurface flow discharges. The proposed model included the modification of the current subsurface drainage algorithm (Hooghoudt-based expression) and the WEPP model percolation routine. The modified WEPP model was tested and validated on an extensive dataset collected at four experimental sites managed by USDA-ARS within the Lake Erie Watershed. Predicted subsurface discharges show Nash-Sutcliffe Efficiency (NSE) values ranging from 0.50 to 0.70, and percent bias ranging from -30% to +15% at daily and monthly resolutions. Evidence suggests the WEPP model can be used to produce reliable estimates of subsurface flow with minimum calibration.

The last objective presented the theoretical framework for a new hillslope and channel-routing model for the Water Erosion Prediction Project (WEPP) model. The routing model (WEPP-CMT) is based on catchment geomorphology and mass transport theory for flow and transport of reactive solutes. The WEPP-CMT uses the unique functionality of WEPP to simulate hillslope responses under diverse land use and management conditions and a Lagrangian description of the carrier hydrologic runoff at hillslope and channel domains. An example of the model functionality was tested in a sub-catchment of the Upper Cedar River Watershed in the U.S. Pacific Northwest. Results showed that the proposed model provides an acceptable representation of flow at the outlet of the study catchment. Model efficiencies and percent bias for the calibration period and the validation period were NSE = 0.55 and 0.65, and PBIAS = -2.8% and 2.1%, respectively. The WEPP-CMT provides a suitable foundation for the transport of reactive solutes (e.g. nitrates) at basin scales.

 This thesis used a homogeneous sample of 116 professional nurses to empirically test the theoretical proposition that transactional coping and emotional intelligence are different constructs. Using that same sample, the research also empirically tested the theory that professional nurses' emotional work response behaviours require emotional intelligent ability (McQueen 2004; Molter 2001). Other research questions were related to testing relationships between emotional work, emotional intelligence, coping and the outcome variables of job satisfaction and health and well-being.  

A major problem that nurses face at the start of each shift is the amount of information they receive in relation to the patients allocated to their care. The patient may have been in the ward for many days and the nurse has abundant previous information about them. The patient may be a newly admitted and the only information nurses have is their name and that of the consultant. Not only is information needed at the start of the shift, but there are also ongoing needs throughout the shift. Therefore there is a constant process of giving and gathering information.
A qualitative approach using interviews and participant observation was chosen as the most appropriate form of investigation. Ten nurses were interviewed, then observed both at handover and for some hours afterwards. The collected data were analysed using a grounded theory approach. Because of data and time constraints only an initial conceptual framework could be developed and presented in this work.
It was found that nurses both actively seek and are passively given information, which they use for providing patient care. A continuum was found ranging from low to high for both the nurses' knowledge of the patient and the patient's condition, as well as the nurses' clinical knowledge and experience, that has an affect on these activities. This gathering of information can be likened to nurses "learning" about the patient much as one 'learns' the meaning of a picture. Initially one passively absorbs the scene but then the person looks more closely to fill in the details raised by questions they may have.
The process of gathering information needed for patient care is a complex intertwining of many factors relating both to the nurse and the situation. This has implications in the way information is communicated at each nursing change of shift if ongoing care is to be continued appropriately. 

 The use of open learning systems for the provision of higher education continues to grow and evolve around the world. The diversity of open learning systems that now exist reflects the ability to adapt this form of education to meet the higher education needs of individuals in a range of contexts including cultural, political, and economic contexts. 

This thesis examines the provision of open and distance education in Bangladesh which has a population of 120 million and where higher education has been mainly available through eleven conventional universities. Until recently these universities were only able to access 5% people of the country and were unable to cater to the growing needs for higher education of the increasing population, particularly those people not living in large cities. In order to overcome the low participation in higher education, the Bangladesh Open University (BOU) was established in 1992 to help to meet the country's increasing need for higher education and vocational training using open and distance teaching mode. 

The approach to materials design and course delivery by the BOU endeavours to accommodate the cultural, economic and student learning contexts that prevail in Bangladesh. This thesis describes this approach through an evaluation of the open and distance education materials used in one unit of the Bachelor of Education (BEd) program and one unit of the Diploma in Management (DIM) at the BOU. 

Three broad criteria for evaluating the selected BOU materials were: learner support structure, learning resources and learning systems. The criteria were derived from a comparative study of open and distance education that exists in developed and developing countries. Final conclusions were made after evaluating the selected materials from BOU using these criteria. 

The curriculum evaluation methodology by Stufflebeam (1985) and Dogan (1989) was used for assessing open and distance education materials. 

Findings indicate that the text materials of the BOU should be changed and be prepared according to the social, cultural, economic, and education contexts of Bangladesh. For instance, printed text materials should have pretest questions, concept maps, specific objectives, illustrations within the content, exercises and questions, assignments, quotations, footnotes, and references. At the same time, in addition to text materials, support services should be re -arranged in accordance with access issues and cultural perspectives.  

study, a home use testing (HUT) of instant tuwo and fura porridges in Niamey, Niger indicated that overall consumers’ acceptability was good. In a market test conducted in Niamey over 20 weeks, in collaboration with local cereal processors and distributors, showed repeat purchases with good frequency of sale of instant tuwo and fura porridges that have generated about 1/3 in total sales of 35 products related millet and cereal based foods in the period. In conclusion, the low-cost single screw extruder has the potential to catalyze and increase demand and diversification of uses of millet grains, to develop market-driven nutritious and healthy grain-based foods, to benefit smallholders’ farmers, and favor growth of small- and medium-scale entrepreneur processors in West Africa.