Many methods and equations have been developed to predict bed load transport rates, most of which use some comparison between shear stress and critical shear stress. The critical shear stress is determined by the point of incipient motion. Researchers have attempted to predict bed load transport both deterministically with mean parameters and stochastically attempting to take into account the fluctuations of velocity at points near threshold. This work attempts to show that more than simple force balances are needed to determine the point at which a particle will move. Turbulent fluctuations in velocity seem to have an effect of particle entrainment. The fluctuations in velocity can be several times greater than their time averaged counterparts. These short durations of high velocity often result in particle movement even though the mean flow may be less than or very near critical conditions. Through experiments of a single spherical particle on a simple bed geometry in air without the effects of water, it is shown that time duration of force has an effect on entrainment. This shows that there may be a constant force-time combination, or impulse, required to entrain sediment. / Master of Science

Headwater streams drain the majority of the landscape, yet little is known about their form and function in comparison to lowland rivers. Better understanding of their morphology and sediment transport processes will improve understanding of landscape evolution and promote a more complete view of fluvial systems. Therefore, the goal of my project was to determine controls on headwater channel form and function in the humid, moderate-relief drainage basins of the Valley and Ridge and Blue Ridge provinces in the southern Appalachian Mountains. I surveyed nine headwater (0.33 - 2 km2 drainage area) streams in a variety of bedrock, climate, base level, and land use conditions and produced a high-resolution dataset on their longitudinal and cross sectional form. This data was analyzed empirically to determine controls on channel form, and used in hydrologic modeling to determine the ability of the channels to erode their beds during regularly recurring flows as well as the recurrence interval of bankfull flows. Field survey results demonstrate that the channels are dominantly alluvial and vary greatly between and within channels in their overall longitudinal form, channel slope values, and grain size. These variations are due to differences in bedrock resistance at the formation level as well as at short wavelengths. Bedrock also controls channel form through its influence on local and regional base level, channel initiation processes, and log jam abundance. Hydraulic geometry, steam competence and bankfull flow recurrence also vary greatly between and within channels. This variation is due to the high sensitivity of the streams to hillslope influences such as bedrock resistance, boulder influx, and soil profile development. Increases in bedrock resistance within a channel create knickpoints that lower stream competence and slow hilllslope erosion. Stream competence is generally higher in channels with erodable bedrock and lower in channels with resistant bedrock, but most channels could entrain the majority of the grains on their bed at 2-year stormflows. Bankfull is a larger, less frequent flow than the 2-year storm at very small drainage areas (<0.4 km2), but is approximately a 2-year recurrence flow at larger drainage areas. Bankfull occurs less frequently in North Carolina Blue Ridge streams, due to deep soils that form on metamorphic bedrock under an more intense precipitation regime and have high rainfall storage capacity. Results indicate that variability is a fundamental feature of headwater streams and that they do not follow channel slope, hydraulic geometry, and bankfull relations developed in lowland river systems. / Master of Science

No

Tsunami is one of the most dangerous natural hazards in the coastal zone worldwide. Large tsunamis are relatively infrequent. Deposits are the only concrete evidence in the geological record with which we can determine both tsunami frequency and magnitude. Numerical modeling of sediment transport during a tsunami is important interdisciplinary research to estimate the frequency and magnitude of past events and quantitative prediction of future events. The goal of this dissertation is to develop robust, accurate, and computationally efficient models for sediment transport during a tsunami. There are two different modeling approaches (forward and inverse) to investigate sediment transport. A forward model consists of tsunami source, hydrodynamics, and sediment transport model. In this dissertation, we present one state-of-the-art forward model for Sediment TRansport In Coastal Hazard Events (STRICHE), which couples with GeoClaw and is referred to as GeoClaw-STRICHE. In an inverse model, deposit characteristics, such as grain-size distribution and thickness, are inputs to the model, and flow characteristics are outputs. We also depict one trial-and-error inverse model (TSUFLIND) and one data assimilation inverse model (TSUFLIND-EnKF) in this dissertation. All three models were validated and verified against several theoretical, experimental, and field cases. / Ph. D. / Population living close to coastlines is increasing, which creates higher risks due to coastal hazards, such as tsunami. Tsunamis are a series of long waves triggered by earthquakes, volcanic eruptions, landslides, and meteorite impacts. Deposits are the only concrete evidence in geological records that can be used to determine both tsunami frequency and magnitude. The numerical modeling of sediment transport in coastal hazard events is an important interdisciplinary research area to estimate the magnitude their magnitude. The goal of this dissertation is to develop several robust, accurate, and computationally efficient forward and inverse models for tsunami sediment transport. In Chapter one, a general literature review is given. Chapter two will discuss a new model for TSUunami FLow INversion from Deposits (TSUFLIND). TSUFLIND incorporates three models and adds new modules to simulate tsunami deposit formation and calculate flow condition. In Chapter three, we present an inverse model based on ensemble Kalman filtering (TSUFLIND-EnKF) to infer tsunami characteristics from deposits. This model is the first model that forms a system state to include both observable variables and unknown parameters. In Chapter four, we present a new forward model for simulating Sediment TRansport in Coastal Hazard Events, which combines with GeoClaw (GeoClaw-STRICHE). In Chapter five, we discuss the future works for TSUFLIND, TSUFLIND-EnKF, GeoClaw-STRICHE and forward-inverse framework.

Yes / Within river systems, the process of bed-forming is intricate, dynamic and is shaped by different factors. Hydraulic forces exerted by water flow play a crucial role, forming the bed substrate over time. Additionally, the presence of vegetation within the riverbed and along its banks introduces further complexity, as the interaction between plants and hydrodynamics can alter sediment transport patterns and riverbed morphology. The movement of both suspended particles and bedload materials within the water column contributes to the ongoing riverbed landscape evolution. The primary aim of this editorial collection is to assemble an extensive range of research methodologies aimed to inform engineering practices pertinent to river management. Through an exhaustive exploration of various topics, including water quality indexing, erosion and sedimentation patterns, influence of vegetation, hydrological modelling for understanding flow dynamics, and identification of critical hydraulic parameters with the utilisation of both analytical and experimental modelling techniques, this paper endeavours to provide valuable insights derived from rigorous research efforts. By synthesising and presenting these findings, we offer a resource that can effectively guide future endeavours in river engineering and related disciplines.

No / In the search for sustainable city solutions, engineers face a bottleneck situation in balancing development and the intensified environmental challenges induced by scaled-up flooding, over-grown river vegetation, sediment transport, bridge and coastal scouring, and excessive pollution. The coupling impacts of uncontrolled flood and sediment to a city has caused difficulty in its management. Various numerical, theoretical, and experimental approaches have been proposed to reproduce flow and sediment transport conditions in real-world urban rivers, in order to perfect management strategies for them. This reprint, which is built from a well-planned journal’s Special Issue, aims to construct a collection of state-of-the-art studies and technologies to give insights to the related environmental, river, and sustainable city research and engineering communities. It is related and, hence, useful for environmental, river, and hydraulic engineers, authorities, and researchers to understand the current state-of-the-art practices in urbanized flow modelling, as well as vegetation- and sediment-related management. It also serves as a good knowledge source for research, post- or undergraduate students, in terms of knowledge about the most up-to-date topical advances.

by Tse Sui-fai, Peter. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 161-169). / ABSTRACT --- p.ii / ACKNOWLEDGEMENT --- p.iv / TABLE OF CONTENTS --- p.vi / LIST OF TABLES --- p.ix / LIST OF FIGURES --- p.x / LIST OF PLATES --- p.xi / Chapter CHAPTER I --- INTRODUCTION / Chapter 1.1 --- Scope of the problem --- p.1 / Chapter 1.2 --- Occurrence of urban sediments in an urban setting --- p.6 / Chapter 1.3 --- Nature of urban sediments --- p.9 / Chapter 1.4 --- Importance of studying urban sediment --- p.9 / Chapter 1.5 --- Objectives of this research --- p.10 / Chapter 1.6 --- Structure of this research --- p.10 / Chapter CHAPTER II --- LITERATURE REVIEW / Chapter 2.1 --- Hydrological problems related to urbanisation --- p.13 / Chapter 2.2 --- Importance of the urban sediment on the environment --- p.15 / Chapter 2.2.1 --- Road surface sediments --- p.20 / Chapter 2.2.2 --- Gully pot or catchment sediments --- p.22 / Chapter 2.2.3 --- Sewer sediments --- p.24 / Chapter 2.3 --- Studies on the characteristics of urban sediments --- p.25 / Chapter 2.3.1 --- Particle size and volatile content --- p.26 / Chapter 2.3.2 --- Surface features identification by using the SEM --- p.27 / Chapter 2.3.3 --- Studies in sub-tropical humid areas --- p.28 / Chapter 2.4 --- Problems raised from the previous studies and directions --- p.29 / Chapter CHAPTER III --- STUDY AREA - FO TAN CATCHMENT / Chapter 3.1 --- Introduction --- p.31 / Chapter 3.1.1 --- Hong Kong --- p.32 / Chapter 3.2 --- Fo Tan Catchment --- p.38 / Chapter 3.2.1 --- Geology --- p.44 / Chapter 3.2.2 --- Landuse --- p.48 / Chapter 3.2.3 --- Road surface and traffic characteristics --- p.49 / Chapter 3.2.4 --- Stormwater drainage network --- p.54 / Chapter 3.2.5 --- A unique hydrological year --- p.55 / Chapter 3.3 --- Conclusion --- p.59 / Chapter CHAPTER IV --- METHODOLOGY / Chapter 4.1 --- Rationale for the research method --- p.60 / Chapter 4.1.1 --- Introduction --- p.60 / Chapter 4.1.2 --- Operationalisation of the concept --- p.62 / Chapter 4.1.2.1 --- Street surface sediments --- p.62 / Chapter 4.1.2.2 --- Gully pot sediments --- p.63 / Chapter 4.1.2.3 --- Sewer sediments --- p.63 / Chapter 4.1.2.4 --- Channel deposits --- p.64 / Chapter 4.1.3 --- Study area---Fo Tan --- p.64 / Chapter 4.2 --- Empirical data and their collection --- p.64 / Chapter 4.2.1 --- Sampling sites --- p.64 / Chapter 4.2.2 --- Sample collection --- p.65 / Chapter 4.2.2.1 --- Street surface sediments --- p.66 / Chapter 4.2.2.2 --- Gully pot sediments --- p.66 / Chapter 4.2.2.3 --- Channel deposits --- p.67 / Chapter 4.2.3 --- Sample treatment --- p.67 / Chapter 4.3 --- Analyses of samples --- p.68 / Chapter 4.3.1 --- Particle size distribution --- p.68 / Chapter 4.3.1.1 --- Dry sieving analysis --- p.69 / Chapter 4.3.2 --- Volatile solids --- p.69 / Chapter 4.3.3 --- Surface characteristics of sediment grains --- p.70 / Chapter 4.3.3.1 --- The use of scanning electron microscope (SEM) --- p.70 / Chapter 4.3.3.2 --- Preparation of samples --- p.71 / Chapter 4.3.4 --- Data analysis and presentation --- p.73 / Chapter 4.4 --- Conclusion --- p.74 / Chapter CHAPTER V --- PHYSICAL CHARACTERISTICS OF URBAN SEDIMENTS / Chapter 5.1 --- Introduction --- p.75 / Chapter 5.2 --- Results --- p.76 / Chapter 5.2.1 --- Composition of the street surface sediments --- p.76 / Chapter 5.2.2 --- Street surface sediment loading --- p.79 / Chapter 5.2.3 --- Loading rate with slope factor --- p.86 / Chapter 5.2.4 --- Street sediment loads in different landuse areas --- p.86 / Chapter 5.2.5 --- Particle size distribution of the sediments --- p.88 / Chapter 5.2.5.1 --- Particle sizing for different sites in the same environment --- p.88 / Chapter 5.2.5.2 --- Particle size distribution for different sampling dates --- p.89 / Chapter 5.2.5.3 --- Particle size distribution in different environments --- p.89 / Chapter 5.2.5.5 --- Phi study --- p.91 / Chapter 5.2.6 --- Bivariate scattergram analysis --- p.96 / Chapter 5.3 --- Discussion --- p.100 / Chapter CHAPTER VI --- VOLATILE SOLIDS ANALYSIS / Chapter 6.1 --- Introduction --- p.105 / Chapter 6.2 --- Results --- p.108 / Chapter 6.2.1 --- The mean volatile solids in different environments --- p.108 / Chapter 6.2.2 --- The relationship between phi median and volatile solids content --- p.109 / Chapter 6.2.3 --- Particle size distribution on the volatile solids content --- p.110 / Chapter 6.3 --- Discussion --- p.111 / Chapter 6.3.1 --- Effects of road surface characteristics --- p.111 / Chapter 6.3.2 --- Effects of traffic flow --- p.112 / Chapter 6.3.3 --- Effects of landuse pattern --- p.114 / Chapter 6.4 --- Particle size and volatile solids: a synthesis --- p.114 / Chapter 6.5 --- Conclusion --- p.119 / Chapter CHAPTER VII --- SCANNING ELECTRON MICROSCOPIC STUDY / Chapter 7.1 --- Introduction --- p.120 / Chapter 7.2 --- Results --- p.125 / Chapter 7.2.1 --- Quantitative analysis of the surface features on grains from different depositional environments --- p.125 / Chapter 7.2.2 --- Description of the texture of the samples --- p.130 / Chapter 7.2.3 --- Texture interpretation --- p.142 / Chapter 7.3 --- Discussions --- p.143 / Chapter 7.3.1 --- Surface texture description and its relationship to landuse pattern --- p.143 / Chapter 7.3.2 --- Sediment transport in an urban setting: a synthesis --- p.146 / Chapter CHAPTER VIII --- CONCLUSION / Chapter 8.1 --- Findings of this research --- p.152 / Chapter 8.2 --- Future directions --- p.157 / Chapter 8.2.1 --- Equipment used in reducing urban sediments --- p.157 / Chapter 8.2.2 --- Sweeping practices of the street surface --- p.158 / Chapter 8.2.3 --- The use of SEM in urban sediments --- p.159 / Chapter 8.3 --- Conclusions --- p.160 / REFERENCES --- p.161 / APPENDICES --- p.170

by Wan Yuk-ching. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 146-152). / Abstracts in English and Chinese. / List of Tables --- p.i / List of Figures --- p.iii / List of Plates --- p.v / Chapter CHAPTER I --- INTRODUCTION / Chapter 1.1 --- Scope of the Problem --- p.1 / Chapter 1.2 --- Importance of the Urban Sediments on the Environment --- p.8 / Chapter 1.3 --- Hydrological and Sedimentological Problems Related to Urbanization -a Storm Event Basis --- p.13 / Chapter 1.4 --- Studies in Sub-tropical Humid Areas --- p.17 / Chapter 1.5 --- Objectives of this Research --- p.18 / Chapter CHAPTER II --- CHARACTERISTICS OF URBAN SEDIMENTS / Chapter 2.1 --- Sediments Transportation Pattern of Storm Events --- p.19 / Chapter 2.2 --- Particle Size Parameter --- p.29 / Chapter 2.3 --- Volatile and Chemical Parameters of Total Sediment Loading --- p.33 / Chapter 2.4 --- Problems Arisen from the Review of Previous Studies and Directions --- p.36 / Chapter CHAPTER III --- METHODOLOGY / Chapter 3.1 --- Experimental Design --- p.37 / Chapter 3.1.1 --- Catchment Approach --- p.38 / Chapter 3.1.2 --- Storm base Approach --- p.39 / Chapter 3.2 --- Study Area --- p.41 / Chapter 3.2.1 --- Rainfall Pattern --- p.41 / Chapter 3.3 --- Nature of the Study Areas --- p.44 / Chapter 3.3.1 --- Location --- p.45 / Chapter 3.3.2 --- Relief and Geology --- p.47 / Chapter 3.3.3 --- Landuse Pattern --- p.49 / Chapter 3.3.4 --- Climatic Condition --- p.57 / Chapter 3.3.5 --- Streamflow Measurement --- p.59 / Chapter 3.4 --- Suspended Sediment Concentration --- p.61 / Chapter 3.4.1 --- Sample Collection --- p.61 / Chapter 3.4.2 --- Laboratory Procedures --- p.62 / Chapter 3.4.3 --- Instantaneous Sediment Concentration --- p.63 / Chapter 3.5 --- Volatile and Mineral Solids --- p.63 / Chapter 3.6 --- Particle Size Measurement --- p.65 / Chapter CHAPTER IV --- TRANSPORTATION PATTERN OF STORM SEDIMENTS IN URBAN CATCHMENTS / Chapter 4.1 --- Introduction --- p.66 / Chapter 4.2 --- Suspended Sediment Transport Patterns During Storm Events --- p.70 / Chapter 4.3 --- The Relationship Between Discharge and Instantaneous Sediment Concentration --- p.81 / Chapter 4.4 --- Additional Factors Affecting Instantaneous Sediment Concentrations During Storm Events --- p.87 / Chapter 4.4.1 --- University Campus --- p.88 / Chapter 4.4.2 --- Fo Tan --- p.91 / Chapter 4.5 --- Discussion --- p.93 / Chapter CHAPTER V --- SEDIMENT CHARACTERISTICS / Chapter 5.1 --- Introduction --- p.97 / Chapter 5.2 --- Characterization of Sediments --- p.98 / Chapter 5.3 --- Variations in Sediment Size --- p.101 / Chapter 5.3.1 --- Between-Storm Variations in Particle Size --- p.103 / Chapter 5.3.1.1 --- Size Distribution Curves --- p.103 / Chapter 5.3.1.2 --- Median Particle Size --- p.107 / Chapter 5.3.2 --- Within-Storm Variations in Particle Size --- p.108 / Chapter 5.3.3 --- Factors Affecting the Between Storm Variations in Sediment Particle Size --- p.120 / Chapter 5.4 --- Variations in the Sediment Volatile Content --- p.123 / Chapter 5.4.1 --- Differences in Sediment Volatile Content Between the Two Catchments --- p.123 / Chapter 5.4.2 --- Variations in Volatile Content Between and Within Storms --- p.124 / Chapter 5.4.3 --- Timing of the Volatile Content Peaks --- p.128 / Chapter 5.4.4 --- Factors Affecting the Volatile Content --- p.131 / Chapter 5.4.5 --- Some General Observations on Sediment Volatile Content --- p.133 / Chapter 5.5 --- Summary and Discussion --- p.133 / Chapter CHAPTER VI --- CONCLUSION / Chapter 6.1 --- Summary of Findings --- p.137 / Chapter 6.2 --- Implications of the Research Findings --- p.141 / Chapter 6.3 --- Limitations of this Study and Suggestions for Future Work --- p.143

An alongshore sediment transport and shoreline change analysis on Galveston Island in the period of 1990-2001 is conducted in this study using the Generalized Model for Simulating Shoreline Change (GENESIS). The study is divided into three main parts: 1. Assessment of the numerical accuracy of GENESIS, 2. Assessment of the alongshore sediment transport and shoreline change on the Galveston coast in the period of 1990-2001, and 3. Assessment of several erosion control practices on the Galveston coast for the period of 2001-2011. The first assessment shows that GENESIS has a numerical error which tends to be large for low energy wave (small breaking wave height) and large breaking wave angle. This numerical inaccuracy cannot be neglected and needs to be compensated for. This can be done, for instance, by adjusting the transport parameter K1. In the second assessment, good agreement between the calculated and measured transport/shoreline is achieved, particularly on the West Beach. Comparison between the potential alongshore sediment transport and sediment budget-inferred alongshore transport provides a systematic way of selecting the proper wave data set for the alongshore and shoreline change calculation. The third assessment proves that beach nourishment is the best alternative to overcome/reduce the erosion problem on the Galveston coast. Constructing coastal structure (groins, offshore breakwater) on the West Beach does not resolve the problem of erosion, but instead shifts it further west.

Thesis (M. Phil.)--University of Hong Kong, 1978.