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.

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.

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

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.

There are only a few detailed measurements of the cross-shore variation in the net sediment transport and beach evolution for single or multiple swash events, and no data showing the influence of long waves and wave groups on swash zone morphology. Novel laboratory experiments and numerical modeling have been performed to study the influence of long waves and bichromatic wave groups on sediment transport and beach morphodynamics in the swash zone. Due to complex processes, difficulties in measuring, and very significant difficulties in isolating the morphodynamic processes induced by long waves and wave groups on natural beaches, a laboratory study was designed to measure in very high detail the bathymetric evolution of model sand beaches under monochromatic waves, long wave and short wave composites (free long waves), and bichromatic wave groups (forced long waves). Net sediment transport, Q(x), and beach morphology changes under the monochromatic waves were analyzed and compared to conditions with and without the free long waves, and then compared with the bichromatic wave groups. A range of wave conditions, e.g., high energy, moderate energy, and low energy waves, were used to obtain beach evolution ranging from accretionary to erosive, and including intermediate beach states. Hydrodynamics parameters, e.g., instantaneous water depths, wave amplitudes, run-up and rundown, were also measured to study and test a sediment transport model for the swash zone, based on modifying the energetic-bedload based sediment transport equations with suspended sediment. The experimental data clearly demonstrate that for the monochromatic wave conditions, beach evolution develops erosion for high steepness waves and accretion for lower steepness waves. The model beach profile evolutions are similar to natural beaches, and form and develop bars and berms over time. Adding a free long wave to the short wave in the composite wave results in changes to the overall trend of erosion/accretion of the beach profile, but the net transport pattern does not change significantly. The short wave strongly dominates beach behavior and the net transport rate, instead of the free long wave in the composite wave. The free long wave, however, carries more water and sediment onshore, leading to an increase in shoreline motion and wave run-up further landward. The long wave influences the structure and position of the swash bar/berm, which generally tends to move onshore and forms a larger swash bar/berm for higher long wave amplitudes. The free long wave also increases overall onshore sediment transport, and reduces offshore transport for erosive conditions. The long wave tends to protect the beach face and enhances onshore transport for accretive conditions, especially in the swash zone. In contrast, for bichromatic wave groups having the same mean energy flux as their corresponding monochromatic wave, the influence on sediment transports is generally offshore in both the surf and swash zone instead of onshore. The swash berm is, however, formed further landward compared with the berm of the corresponding monochromatic wave. The sediment transport patterns (erosion or accretion) generated by the bichromatic wave group or corresponding monochromatic wave are similar, but differ in magnitude. The numerical model, starting in the inner surf zone to reduce the effect of poor breaker description in the non-linear shallow water equations, can produce a good match between observed data and the modeled hydrodynamics parameters in the SZ. The sediment transport model shows the important role of suspended sediment in the swash zone. In contrast with the observed data, energetic-based bed-load models predict offshore sediment transport for most wave conditions because of negative skewness. The modified sediment transport model, with added suspended sediment terms and optimized coefficients, produces a good match between model results and observed data for each wave condition, especially for low frequency monochromatic waves. The optimized coefficient set corresponding to particular monochromatic wave conditions can be used to predict the net sediment transport quite well for some composite wave conditions. Overall, the same optimized coefficient sets can be applied to predict the correct overall trend of net transport for most composite wave conditions. However, the predicted net transport for the bichromatic wave groups does not match well with the overall net transport patterns. There is no set of single transport coefficients that can be used to predict sediment transport for all wave conditions. This suggests that the present sediment transport models cannot predict evolution correctly, even for conditions which represent only perturbation from those for which they were calibrated.

There are only a few detailed measurements of the cross-shore variation in the net sediment transport and beach evolution for single or multiple swash events, and no data showing the influence of long waves and wave groups on swash zone morphology. Novel laboratory experiments and numerical modeling have been performed to study the influence of long waves and bichromatic wave groups on sediment transport and beach morphodynamics in the swash zone. Due to complex processes, difficulties in measuring, and very significant difficulties in isolating the morphodynamic processes induced by long waves and wave groups on natural beaches, a laboratory study was designed to measure in very high detail the bathymetric evolution of model sand beaches under monochromatic waves, long wave and short wave composites (free long waves), and bichromatic wave groups (forced long waves). Net sediment transport, Q(x), and beach morphology changes under the monochromatic waves were analyzed and compared to conditions with and without the free long waves, and then compared with the bichromatic wave groups. A range of wave conditions, e.g., high energy, moderate energy, and low energy waves, were used to obtain beach evolution ranging from accretionary to erosive, and including intermediate beach states. Hydrodynamics parameters, e.g., instantaneous water depths, wave amplitudes, run-up and rundown, were also measured to study and test a sediment transport model for the swash zone, based on modifying the energetic-bedload based sediment transport equations with suspended sediment. The experimental data clearly demonstrate that for the monochromatic wave conditions, beach evolution develops erosion for high steepness waves and accretion for lower steepness waves. The model beach profile evolutions are similar to natural beaches, and form and develop bars and berms over time. Adding a free long wave to the short wave in the composite wave results in changes to the overall trend of erosion/accretion of the beach profile, but the net transport pattern does not change significantly. The short wave strongly dominates beach behavior and the net transport rate, instead of the free long wave in the composite wave. The free long wave, however, carries more water and sediment onshore, leading to an increase in shoreline motion and wave run-up further landward. The long wave influences the structure and position of the swash bar/berm, which generally tends to move onshore and forms a larger swash bar/berm for higher long wave amplitudes. The free long wave also increases overall onshore sediment transport, and reduces offshore transport for erosive conditions. The long wave tends to protect the beach face and enhances onshore transport for accretive conditions, especially in the swash zone. In contrast, for bichromatic wave groups having the same mean energy flux as their corresponding monochromatic wave, the influence on sediment transports is generally offshore in both the surf and swash zone instead of onshore. The swash berm is, however, formed further landward compared with the berm of the corresponding monochromatic wave. The sediment transport patterns (erosion or accretion) generated by the bichromatic wave group or corresponding monochromatic wave are similar, but differ in magnitude. The numerical model, starting in the inner surf zone to reduce the effect of poor breaker description in the non-linear shallow water equations, can produce a good match between observed data and the modeled hydrodynamics parameters in the SZ. The sediment transport model shows the important role of suspended sediment in the swash zone. In contrast with the observed data, energetic-based bed-load models predict offshore sediment transport for most wave conditions because of negative skewness. The modified sediment transport model, with added suspended sediment terms and optimized coefficients, produces a good match between model results and observed data for each wave condition, especially for low frequency monochromatic waves. The optimized coefficient set corresponding to particular monochromatic wave conditions can be used to predict the net sediment transport quite well for some composite wave conditions. Overall, the same optimized coefficient sets can be applied to predict the correct overall trend of net transport for most composite wave conditions. However, the predicted net transport for the bichromatic wave groups does not match well with the overall net transport patterns. There is no set of single transport coefficients that can be used to predict sediment transport for all wave conditions. This suggests that the present sediment transport models cannot predict evolution correctly, even for conditions which represent only perturbation from those for which they were calibrated.