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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Hydroclimatic influences on suspended sediment delivery in a small, High Arctic catchment

McDonald, Dana Marie 27 September 2007 (has links)
A study of suspended sediment transport dynamics was undertaken in the West River at Cape Bounty, Melville Island, Nunavut. Hydrometerological conditions and sediment transport were measured over three seasons in order to characterize suspended sediment transport and grain size characteristics in relation to catchment and channel snowpack. Catchment snow water equivalence was measured at the beginning of the season, and discharge, suspended sediment concentration (SSC) and grain size were measured at high temporal resolution through the runoff period to evaluate diurnal-, event- and seasonal-scale discharge-suspended sediment and grain size hysteresis. In addition, two models of a time-integrated suspended sediment trap, modified from Philips et al. (2000), were deployed in both streams to assess the representativeness of the captured sediment. The West stream discharge was dominated by the snowmelt peak in all three seasons. From 54-96% of suspended sediment was transported during this short period, although hysteresis relationships indicate that delivery of sediment and water were not synchronous and interannual relationships suggest disproportionate increases in sediment discharge with increased catchment snowpack. Clockwise and counter-clockwise suspended sediment hysteresis relationships were apparent and associated with lesser and greater snowpack, respectively. Additionally, grain size hysteresis suggested variable sediment sources during the season. Assessment of the time-integrated suspended sediment trap in the East and West streams illustrated that the captured material was not representative of the ambient stream conditions. Captured mass was typically two orders of magnitude less than expected iii capture rates (<1%) and that the captured sediment was significantly coarser than the ambient stream suspended sediment load. Investigations of suspended sediment transfer in this small, High Arctic catchment reveal that sediment transport increased with increased catchment snowpack, but delivery of water and sediment were not synchronous during the nival discharge event suggesting changing sediment accessibility during the season. An attempt to collect a time-integrated suspended sediment sample that would incorporate variability in the character and magnitude of sediment delivery provided an unrepresentative sample, but results indicate that a detailed examination of hydraulic relationships between the trap and ambient conditions could ultimately lead to the development of a more representative trap. / Thesis (Master, Geography) -- Queen's University, 2007-09-16 10:03:25.925
2

Modelling of river corridors : modelling urban particulate transport processes

Headey, Jonathan Mark January 2002 (has links)
No description available.
3

Downstream Patterns and Catchment Controls on Suspended Sediment Transport in a High Arctic River

Favaro, ELENA 26 September 2013 (has links)
A study of downstream suspended sediment transport dynamics in the West River at Cape Bounty, Melville Island, Nunavut, was undertaken in 2012. The first component of the research quantified the sediment mobilized in the West River during the 2012 season. A nival bed-contact survey was undertaken to identify areas of the river in which stream flow was isolated from the bed, and was combined with a reach-based sediment budget approach to assess sediment entrainment and downstream movement. This analysis revealed the propensity of the West River to store suspended sediment through much of the season. Permafrost disturbances in 2007 inundated the West River with fine sediments, the majority of which are progressing from the headwaters as a sediment slug that is subject to substantial downstream storage. Diurnal and event hysteresis analysis from 2004-2012 demonstrate the change in sediment delivery inter-annually, transitioning from a system characterized by clockwise hysteresis prior to the 2007 disturbances, to counter-clockwise hysteresis post 2007. The latter is reflective of the important contribution of the headwater sediment slug from disturbance to downstream sediment transport and common net sediment storage in the lower reaches of the river. The second project studied the delivery of suspended sediment following late season major rainfall events (MRE) and the control antecedent catchment conditions prior to rainfall exert on the magnitude of stream runoff and suspended sediment transport. Two MREs on July 9 and July 23, totalling 35.4 and 10.6 mm, respectively, resulted in exceptionally low discharge response and sediment mobilization. Analysis of synoptic level pressure patterns and catchment soil moisture revealed low volumetric water content preceding both MREs, a result of sustained exceptional early summer warmth under stable regional high pressure. Compared to similar MREs in 2007-2009, the soil in 2012 did not become saturated, and substantial runoff did not occur. These studies contribute to an understanding of the processes of sediment transport in response to disturbances, rainfall, and antecedent catchment conditions, all of which are becoming important components of the Arctic fluvial systems but have had limited study due to the emphasis on snow melt processes and hydrological fluxes. / Thesis (Master, Geography) -- Queen's University, 2013-09-25 11:36:58.882
4

Estimation of Velocity Distribution and Suspended Sediment Discharge in Open Channels Using Entropy

Cui, Huijuan 2011 May 1900 (has links)
In hydraulics, velocity distribution is needed to determine flow characteristics, like discharge, sediment discharge, head loss, energy coefficient, moment coefficient, and scour. However, the complicated interaction between water and sediment causes great difficulties in the measurement of flow and sediment discharge. Thus, the development of a method which can simulate the velocity distribution and sediment discharge in open channels is designable. Traditional methods for the estimation of velocity distribution, such as the Prandtl-von Karman logarithmic velocity and of sediment concentration distribution, such as the Rouse equation, are generally invalid at or near the channel bed and are inaccurate at the water surface. Considering the limitations of traditional methods, entropy based models have been applied, yet the assumption on the cumulative distribution function made in these methods limits their application. The objective of this research is to develop an efficient method to estimate velocity distribution and suspended sediment discharge in open channels using the Tsallis entropy. This research focuses on a better-organized hypothesis on the cumulative probability distribution function under more applicable coordinates, which should be transformable in different dimensions. Velocity distribution and sediment distribution are derived using the Tsallis entropy under the hypothesis that the cumulative probability distribution follows a non-linear function, in which the value of the exponent is shown to be related to the width-depth ratio of channel cross-section. Three different combinations of entropy and empirical methods for velocity and sediment concentration distribution are applied to compute suspended sediment discharge. Then advantages and disadvantages of each method are discussed. The velocity distribution derived using the Tsallis entropy is expected to be easy to apply and valid throughout the whole cross-section of the open channel. This research contributes to the application of entropy theory and shows its advantages in hydraulic engineering.
5

SUSPENDED SEDIMENT AND PATHOGEN TRANSPORT IN TWO INNER BLUEGRASS KARST GROUND-WATER BASINS, WOODFORD COUNTY, KENTUCKY

Reed, Thomas M. 01 January 2006 (has links)
Multiple parameters were monitored during an 18-month period in two karst groundwater basins in Woodford County, Kentucky, in order to assess the effects of land use on water quality. Blue Hole Spring drains a primarily urban area, whereas spring SP-2 drains an agricultural area. Water-quality parameters were monitored manually weekly or biweekly, as well as more frequently during storms. Discharge (Q), temperature (T), specific conductance (SC), and turbidity were continuously monitored and logged at 15-minute intervals. It is hypothesized that pathogen and sediment concentrations would be lower at SP-2 than at Blue Hole Spring due to differences in land use between basins. Average Q was greater at Blue Hole than at SP-2, and SC values were greater at Blue Hole than at SP-2 for 70 of 71 sample sets. During two monitored storms, as Q increased, SC decreased and turbidity increased. Biweekly Blue Hole fecal coliform (FC), total coliform (TC), and atypical colonies (AC) values averaged 160, 3,600, and 40,000 cfu/100 mL, respectively, and fluctuated more than at SP-2. Biweekly SP-2 FC, TC, and AC values averaged 130, 2,000, and 8,300 cfu/100 mL, respectively. Biweekly values for AC/TC averaged 14.29 at Blue Hole and 6.27 at SP-2. AC/TC ratios were greater at Blue Hole than at SP-2 for 29 of 31 biweekly sample sets. There is a statistically significant difference between the biweekly data sets from the two sites, as well as between data collected under WET and NORMAL flow conditions at each site. Male-specific coliphage (MSP) was detected in most samples collected from Blue Hole, but was never detected at SP-2. Given the proximity of the basins, differences in water quality appear to reflect differences in land use, as hypothesized. Results were similar to other studies in the Inner Bluegrass region. For both Blue Hole and SP-2, wet weather was associated with changes in certain parameters. This study has also shown that the AC/TC ratio appears to be a valid tool for determining the source of contamination within karst ground-water systems as well as in surface water.
6

Investigation of the sediment transport capacity in vegetated open channel flow

Huai, W.-X., Wang, X., Guo, Yakun, Sun, Z.H. 22 March 2022 (has links)
No / The suspended sediment transport capacity is important for estimating the suspended load concentration and the ecological environment of the river. So far, few studies have been conducted to investigate the suspended sediment transport capacity in the vegetated sediment-laden flow. In this study, a new formula is derived to predict the sediment transport capacity in a vegetated flow by considering the absolute value of the energy loss between the sediment-laden flow and the clear water flow. Finally, the formula is expressed in a practical form by using the logarithmic matching method.
7

Analysis of Suspended Particulate Matter Concentrations in Weeks Bay, Alabama Using Landsat Imagery

Flickinger, Devon Lee 06 May 2017 (has links)
Estuaries are valuable ecosystems that are easily affected by human activities within the watershed. One determinant of water quality for in an estuary is the presence of suspended sediments. The use of satellite sensors to remotely sense visible and near-infrared reflectance allows for suspended particulate matter (SPM) and suspended particulate inorganic matter (SPIM) concentrations to be monitored on a repetitive synoptic scale. Previously presented algorithms for relating remote sensing reflectance (Rrs) and SPM/SPIM concentrations were evaluated for the Weeks Bay estuary in Alabama. Additionally, numerous potential SPM/SPIM concentration retrieval algorithms using the Landsat-8 satellite were determined through regression analysis, as well as through the consideration of the inherent optical properties of the water body. The most robust empirical algorithm produced an RMSE of 12.50% and utilized the band combination of Ln(Band4)/Ln(Band3), while the most robust semi-analytical algorithm produced an RMSE of 16.34% and utilized the band combination of Band4/Band3.
8

Variability of Suspended-Sediment Concentration in the Connecticut River Estuary

Cuttler, Michael Vincent William January 2012 (has links)
Thesis advisor: Gail Kineke / Turbidity maxima are areas of elevated suspended-sediment concentration commonly found at the head of the salt intrusion in partially-mixed estuaries. The suspended-sediment distribution in the Connecticut River estuary was examined to determine where turbidity maxima exist and how they form. Areas of enhanced suspended-sediment concentration were found to exist at all phases of the tide near the head of the salt intrusion as well as downstream of this point in deeper parts of the estuarine channel. These areas are locations where peaks in the longitudinal salinity gradient exist, suggesting the presence of a front, or zone of flow convergence. During flood conditions there is a layer of landward-flowing water in the middle of the water column that decelerates upon entering deep parts of the estuary; thus enhancing particle settling. During ebb conditions, stratification and therefore settling from surface waters is enhanced. The combination of processes acting throughout the tidal cycle focuses and, potentially, traps sediment in the deeper parts of the Connecticut River estuary. / Thesis (BS) — Boston College, 2012. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: College Honors Program. / Discipline: Geology & Geophysics Honors Program. / Discipline: Earth and Environmental Sciences.
9

The spatial and temporal variability and budget of suspended sediment in Taiwan major rivers

Chueh, Sheng-An 17 July 2012 (has links)
¡@¡@Sediment loads of Taiwan rivers have increased in recent years because of frequently recurring typhoons. In addition to the dry and wet seasons causing sever erosion and deposition of the riverbed, the long-term records from 1967 to 2009 of suspended sediment concentration and daily discharge observed by the Water Resource Agency in Taiwan Rivers were used in this study. ¡@¡@To understand the sediment deposition or erosion in the rivers, we need to find how the discharge and sediment load interact with each other under the natural and human influences. The hydrological data we used in this study were from Water Resources Agency¡¦s annual reports, including the Danshui River, the Lanyang River, the Zhuoshui River, the Beinan River, and the Gaoping River. ¡@¡@High turbidity happen when sediment concentration exceeds 40 g/L. Judging by this threshold, taking upstream stations of the Zhuoshui River for example, the Nei-Mao-Pu Station (1973-2009) reached this threshold 6 times, Bao-Shih Bridge Station (2004-2009) 19 times, and Yun-Feng Bridge Station (1995-2009) 19 times. But Yen-Ping Bridge Station (2004-2009), which is at the middle part of Zhuoshui River, has never reached the threshold, became the erosion rate and sedimentation rate are balanced here. Chi-Chou Bridge Station (2000-2009) at the downstream reached the threshold for 11 times too. ¡@¡@According to the river graded profile, in the Danshui River, obvious erosion occurred at the Liu-Kwei Bridge Station in 2000, the Po Bridge Station in 2001, and San-Hsia (2) Station in 2004 and 2007. In the Zhuoshui River, significant deposition took place at the Yun-Feng Bridge Station in 2006 and 2010. In the Gaoping River, deposition occurred at the A-Chyi-Ba Bridge Station in 2000, while erosion occurred at Liu-Kwei Station in 2001 and at the A-Chyi-Ba Bridge Station in 2007 and 2008. ¡@¡@Above results show that the major sediments are deposited upstream, forming a temporary sediment storage source region, such as at Li-Lin Bridge Station, Liu-Kwei Station, and Yun-Feng Bridge Station at the Gaoping River, all of which have reached the threshold when a typhoon comes. Investigating daily rainfall data from Taichung Weather Station in 2005, we find that besides typhoon influences, when the rainfall is exceeding 200 mm High turbidity events would occur in the Jhoushuei River. ¡@¡@According to our study, we find that most sediment deposits at the upper reaches, forming temporary sediment storages, so when a typhoon comes, we can see the sediment downstream is often mixed with the sediment coming from upstream storages. That is because the slope in the upper reaches is steeper, and heavy rain makes the temporary deposit easy to erode. On the contrary, the slope in the lower reaches is more gentle so it is easier for sediment to deposit, which is the reason why the stations at downstream often reach the threshold. When the extreme weather occurs, the temporary sediment storages along the entire river course become the source regions to release the sediment out to the sea.
10

The Combined Influence of Tides and Waves on the Benthic Boundary Layer

Li, Chia-na 13 July 2005 (has links)
Continental shelves connect land and the ocean and also play a major role through time in the storage and re-distribution of terrigenous sediments to the ocean. Most of the sediments which origin in land and very shallow waters are deposited on the continental shelf. Sediment entrainment and movement in the coastal ocean are dominated by the combined effect of waves and currents within the benthic boundary layer. Our study intends to examine the relation between currents, waves and acoustic echo intensity in a wave-current boundary layer. The site of the study was located southeast off Kaohsiung Harbor entrance in southern Taiwan on the inner shelf. Between April 16 and May 1, 2004, a tetrapod was deployed with an upward-looking ADCP (Aquadopp Profiler), a CTD with an OBS (XR-420). Another downward-looking ADCP was mounted at 2 m above bed (mab). The interval of the data collection was one hour. Water samples were pumped in seven time-segments (4 in the neap tide, 3 in the spring tide) through the experimental period at 1 and 0.5 mab, respectively for suspended sediment concentration (SSC) analysis in the laboratory. Aquadopp Profiler not only records 3-D current data but also measures the echo intensity (EI). The echo intensity is proportional to the amount of backscattering particles in the water column. The acoustic intensity could be a useful reference for the total concentration of the suspended particles. Our preliminary findings indicate strong tidal control on the dynamics of suspended particles in the benthic boundary layer. The wave field is also modified by the tidal. The form number of the observed tides is 1.87, which indicates mixed tides with a predominantly diurnal component. The data were analyzed using empirical orthogonal (eigen) function (EOF) analysis. The results indicate that the tidal current dominated the alongshore current. Its period is 24.67 hours. The echo intensity are dominated by the current shear velocity. The observations show that the maximum thickness of wave boundary layer and wave-current boundary layer at the experiment site is about 0.9 cm and 1.24 cm respectively. Cross-correlation analysis results among the roughness length, the thickness of wave boundary layer, and the thickness of wave-current boundary layer show that the roughness length correlates negatively to the thickness of both boundary layer. The data were analyzed by spectrum analysis. The results indicate that wave boundary layer were dominated by the low frequency current. The wave-current boundary layer and the roughness length were dominated by the semidiurnal tides.

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