Incipient motion criterion in sediment transport is very important, as it defines the flow condition that initiates sediment motion, and is also frequently employed in models to predict the sediment transport at higher flow conditions as well. In turbulent flows, even a reasonably accurate definition of incipient motion condition becomes very difficult due to the random nature of the turbulent process, which is responsible for sediment motion under incipient conditions. This work investigates two aspects, both of which apply to incipient sediment transport conditions. The first one deals with the role of turbulence in initiating sediment motion. The second part deals with the nature of sediment-fluid interaction for more general and complex flows where the number of sediment particles that form the rough surface is varied. The first part of this work that investigates the role of turbulence in initiating sediment motion, uses a video camera to simultaneously monitor and record the sediment (glass ball) motion and corresponding fluid velocity events measured by a three-component laser Doppler Velocimeter (LDV). The results of the single ball experiment revealed that the number of LDV flow measurements increase dramatically (more than four folds) just prior to the ball motion. The fluid mean velocity and its root-mean-square (rms) values also are significantly higher than the values that correspond to the flow conditions that yield no ball motion. The second part of the work, investigation of the fluid-sediment interaction, includes five tests with varying number of sediment particles. In order to understand the nature and extent of fluid-solid interaction, velocity profile measurements using the 3-D laser system were carried out at three locations for each of these five cases. Plots of mean velocities, rms quantities located the universal layer at about 1.5 ball diameters above the porous bed. However, at higher sediment particle concentrations, this distance reduced and the beginning of the universal layer approached the top of the porous bed. / Ph. D.

Le système fluvial Saigon-Dong Nai (SG- DN) est la plus importante source d'eau pour les douze villes et provinces du sud du Vietnam. Il est aujourd'hui gravement pollué par les activités humaines, agricoles, industrielles et domestiques, constituant une menace pour la vie de millions de personnes. Le ministère vietnamien des Ressources naturelles et de l'environnement a rapporté que les rivières ont reçu environ 1,54 milliard de litres d'eaux usées provenant de 70 parcs industriels par jour, dont 35% de déchets médicaux non traités, et que des tests effectués depuis 2006 ont montré des niveaux élevés de pollution, en particulier de substances toxiques organiques. Jusqu'à présent, il n'y a pas de données sur la diversité microbienne dans le système fluvial SG-DN, en particulier dans les sédiments, où la plus grande partie de la biomasse microbienne est généralement localisée. Les échantillons de sédiments ont été recueillis, réseau hydrographique national SG-DN, à 13 endroits dans les rivières représentant des emplacements pollués. Afin de caractériser les populations microbiennes présentes sur nos sites choisis, l'ADN total des échantillons environnementaux a été extrait et amplifié dans les régions V3 à V1 de l'ADNr 16S. L'étude a révélé que la population microbienne changeait de l'amont vers l'aval au niveau du phylum, du genre et de l'OTU après avoir traversé la zone de population industrielle et dense. De plus, les canaux du bassin versant SG-DN sont fortement pollués par de fortes concentrations de composés organiques (PAH) et possèdent différentes communautés bactériennes par rapport aux échantillons des rivières. / The SaiGon-DongNai (SG-DN)river system is the most important major water source for all twelve Southern Vietnam cities and provinces and is now dramatically polluted by industrial and living activities, giving “a threat” to the lives of millions people sharing this water source. The Ministry of Natural Resources and Environment of Vietnam reported that the rivers received around 1.54 billion liters of waste water from 70 industrial parks per day, including 35 percent of untreated medical waste, and tests since 2006 have found pollution in this river has increased to “serious levels”, an especially high concentration of organic toxic substances. Until now, there is no data on the microbial diversity in SG-DN river system especially in the sediments, where most of the microbial biomass is generally located. The sediment samples were collected in 13 locations across the rivers representing warning polluted locations done by Mr. Nguyen Thanh Hung of the National Water Qualifying in SG-DN river system. In order to characterize the microbial populations present at our chosen sites, the total DNA from the environmental samples were extracted and amplified at the V3 to V1 regions of the 16S rDNA. The study revealed that microbial population changed from upstream to downstream at the phylum, genus and OTUs levels after running through the industrial and dense population zone. Moreover, the canals of the SG-DN river catchment are heavily polluted with high concentrations of organic compounds (PAHs) and possessed different bacterial communities compared to the samples from the rivers.

The effect of particle size distribution of suspended sediment vii upon a turbidity reading at a known concentration has been relatively quantified for stream bank materials on the Moccasin Basin - North Fork Fish Creek (MB-NFFC) Watershed, located in northwestern Wyoming. As expected, an increase in the median particle size in suspension results in a decrease of turbidity at a given concentration. The relationship derived correlates the particle size distribution of a chemically dispersed stream-bank material sample, with the Coefficient of Fineness for a mechanically dispersed portion of the sample.

Wind erosion is a global issue and affecting millions of people in drylands by causing environmental issues (acceleration of snow melting), public health concerns (respiratory diseases), and socioeconomic problems (costs of damages and cleaning public properties after dust storms). Disturbances in drylands can be irreversible, thus leading to natural disasters such as the 1930s Dust Bowl. With increasing attention on aeolian studies, many studies have been conducted using ground-based measurements or wind tunnel studies. Ground-based measurements are important for validating model predictions and testing the effect and interactions of different factors known to affect wind erosion. Here, a machine-learning model (random forest) was used to describe sediment flux as a function of wind speed, soil moisture, precipitation, soil roughness, soil crusts, and soil texture. Model performance was compared to previous results before analyzing four new years of sediment flux data and including estimates of soil moisture to the model. The random forest model provided a better result than a regression tree with a higher variance explained (7.5% improvement). With additional soil moisture data, the model performance increased by 13.13%. With full dataset, the model provided an increase of 30.50% in total performance compared to the previous study. This research was one of the rare studies which represented a large-scale network of BSNEs and a long time series of data to quantify seasonal sediment flux under different soil covers in southern Utah. The results will also be helpful to the managers for controlling the effects on wind erosion, scientists to choose variables for further modeling or local people to increase the public awareness about the effects of wind erosion.

The goal of this study is to develop a model using GIS to estimate the source and quantity of accumulated sediment in the Emory & Henry College (EHC) duck pond.  Located in the Highlands of Southwest Virginia, the 1,194 acre duck pond watershed consists primarily of agricultural, forested, and low density urban land uses. The Revised Universal Soil Loss Equation (RUSLE) and the Sediment Distributed Delivery (SEDD) prediction models were used to determine the quantity of eroded sediment and the sediment yield at the duck pond, respectively.  These models require numerous computations, which were performed at the watershed scale with the aid of ArcGIS software.  In ArcGIS the watershed was broken into a raster grid of approximately 5,200 discrete 100 foot by 100 foot grid cells. The resulting watershed erosion model identified two main sources of sediment: a cluster of farms relatively close to and east of the duck pond, and a harvested timber site north of the duck pond.  The model predicted that 1,076 tons of sediment are delivered into the duck pond annually. The estimated sediment yield was then compared to the estimated amount deposited between October 2011 and September 2012, as measured by a topographic survey.  The model prediction was found to be within a factor of 6.3x of the measured value.  The predicted and measured sediment yields as well as identified erosion sources can be used to develop a water quality improvement plan and to help alleviate the need for periodic dredging. / Master of Science

A common view in today’s society is that natural background conditions is found just prior to the start of the industrialization. By employing this view in environmental work, it neglects the human impact attributed to historical site-specific activities such as metallurgy. These activities have been widespread throughout Sweden, reaching far back into history. It is therefore necessary to determine the site-specific background conditions in order to assess the impact these activities have had. This study investigates the start of the blast furnace Alntorpshyttan in Bergslagen by conducting geochemical analyzes using sediment profiles in Norasjön as a natural archive. This was coupled with an indirect dating method based on the immigration spruce (Picea abies) and the historical atmospheric lead (Pb) pollution. The earliest sign of human activities takes place at 1800 BP, possibly due to farming activities. Based on the increases in iron coupled with increases in other ore-related elements (e.g., Magnesium and copper) I placed the start of Alntorpshyttan in the early/late 13th century. This is consistent with the rapid expansion of blast furnaces throughout Bergslagen. Based on these results, I conclude that historical small-scale metallurgical activities have had a significant impact on local lake systems and potentially a cumulative effect further downstream.

Indiana University-Purdue University Indianapolis (IUPUI) / The outwash deposits of the Eel River paleo meltwater channel in DeKalb and Allen Counties, Indiana predominantly originated from the Erie Lobe of the Laurentide Ice Sheet, but do contain some sediment from the Saginaw Lobe. This determination helps clarify the ice dynamics and Last Glacial Maximum sediment depostional history in northeastern Indiana, which is complicated because of the interactions between the Erie and Saginaw Lobes. Outwash deposits were analyzed from IGS core SC0802 in the Eel River paleo meltwater channel, which intersects the previously identified Huntertown Formation. The core includes 29.2 m of deposits underlain by the hard glacial till of the Trafalgar formation. Mean grain size, sediment skewness, lithology, magnetic susceptibility, and quantitative X-ray diffraction were used to evaluate the provenance of the outwash deposits. Representative samples of Erie Lobe and Saginaw Lobe deposits were analyzed to develop end member provenance signatures. A weight of evidence approach was developed and revealed that deposits from 8.0-13.8 m are of mixed origin from the Erie and Saginaw Lobes, whereas the 0-8.0 and 13.8-29.2 m deposits are Erie Lobe in origin. Cluster analysis and discriminant function analysis supported the findings of this approach. These findings suggests that the Eel River paleo meltwater channel was formed as an outwash channel, and that the adjacent Huntertown Formation does not appear to have been directly deposited by the Saginaw Lobe. The sediments of Saginaw origin from ~8-14 m in the Eel River paleo meltwater channel were likely transported from an upgradient source. The sediments from this zone have a larger mean grain size indicating deposition occurred during higher meltwater discharge, such as the release of meltwater from the drainage of proglacial or subglacial lake(s) associated with the disintegration of the Saginaw Lobe, thus resulting in the mixing of Saginaw Lobe deposits with Erie Lobe deposits. However, the majority of the sediment in the Eel River paleo channel near SC0802 is Erie Lobe in origin. Based on the provenance and depositional sequence at SC0802, the Saginaw Lobe disintegrated prior to the Erie Lobe retreat from the Wabash moraine around 16-17 cal ka.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17881号 / 工博第3790号 / 新制||工||1580(附属図書館) / 30701 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 田中 宏明, 教授 清水 芳久 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19293号 / 工博第4090号 / 新制||工||1630(附属図書館) / 32295 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 教授 藤田 正治, 准教授 竹門 康弘 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Student Number : 9700136A - PhD thesis - School of Civil and Environmental Engineering - Faculty of Engineering and the Built Environment / A sediment budget model in which each steady discharge scours sediment along a trajectory towards ultimate target storage or deposits sediment towards the same ultimate target storage has been conceptualized and developed. The method is aimed at routing sediment in morphologically diverse bedrock-controlled channels in which sediment transport and storage is not a continuous process in space and time and mostly occurs in response to discrete discharges. The relative value of the ultimate stable scour depth (Huss) for each steady discharge with respect to the current scour depth after adding sediment supply determines the potential to scour or store sediment. Scour depths measured at discrete locations along the longitudinal profile of a laboratory pool at discrete times until changes in scour were not discernible for each steady discharge and sediment size have been integrated to provide the Huss and storage depletion curve. The experimentally established dependence of scour depth on critical flow depth, settling velocity and sediment supply formed the basis of generating dimensionless Huss and storage depletion curve from these parameters using the Buckingham π theorem. The optimization of experimental results to generate the storage depletion curve gave the exponent of time (φ) and the exponential decay factor (k) as 0.5 and 0.0040207 respectively. Regression fit of dimensionless Huss and critical flow intensity gave a linear relationship with a gradient of 0.90214, y-intercept of –1.4766 and R2 of 96%. The suitability of the model for budgeting sediment dynamics in a series of connected storage units, the validity of using the relative values of Huss and the current scour depth after adding sediment supply to determine scour potential and the existence of active storage associated with sediment supply for each steady discharge have been confirmed experimentally. Modelling with equivalent steady discharges computed from unit stream power principles on the rising and the falling limbs of the hydrograph resulted in scour on the rising limb of magnitude dependent on the magnitude and sequence of the flood event, and less or no scour on recession. The modelling concepts and approach have thus been validated and the potential to reasonably simulate sediment storage changes in bedrock-controlled rivers demonstrated.