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| 《国际泥沙研究》2021年第三期 |
| 发布时间： 2021-01-22 |
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Papers Published in the International Journal of Sediment Research Volume 36, No.3, 2021 Pages 335-448 (June 2021)
1. Experimental study on the effect of bottomless structure in front of a bottom outlet on a sediment flushing cone 2. Experimental investigation on scour topography around high-rise structure foundations 3. A grain-size correction for metal pollution indexes in river sediments 4. Study of water renewal and sedimentation of a square harbor encapsulated in a coastal front with seawalls due to wind-induced hydrodynamic circulation 5. Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary, Noakhali coast, Bangladesh 6. Mineral composition and particle size distribution of river sediment and loess in the middle and lower Yellow River 7. Comparison of Pb(II) and Cd(II) micro-interfacial adsorption on fine sediment in the Pearl River Basin, China 8. How can stream bank erosion be predicted on small water courses? Verification of BANCS model on the Kubrica watershed 9. Amplification of flood discharge caused by the cascading failure of landslide dams 10. Assessing morphological changes in a human-impacted alluvial system using hydro-sediment modeling and remote sensing
1. Experimental study on the effect of bottomless structure in front of a bottom outlet on a sediment flushing cone Abstract: One of the main problems in reservoirs is sedimentation which reduces the operating life of dams if a proper plan and analysis method are not in place. The techniques to manage sediment in reservoirs include several sustainable management techniques that route sediment through or around the reservoir. One of the main economical methods in arid and semi-arid regions is pressurized flushing using moderate drawdown of the water level of the reservoir to evacuate sediment deposited behind dams. In the current study, the effect of a new structure called a dendritic bottomless extended (DBE) outlet structure at three angles of 30°, 45°, and 60° on pressurized flushing efficiency was investigated. Consequently, 45 experiments were designed for three discharge rates (Qo), three sediment levels (Hs), four types of structure, and a no-structure condition (reference test). The results indicated that the DBE structure with a 30° angle between the branches, a sedimentary dimensionless index of Hs/Do=4.59, and a flow dimensionless index of
2. Experimental investigation on scour topography around high-rise structure foundations Abstract: The current study aims to investigate the characteristics of scour topography around High-Rise Structure Foundations (HRSFs) via physical modeling tests. Clear-water scour tests with a uniform non-cohesive bed are modeled under the action of unidirectional steady flows. Time variations of the erosion and deposition topography are measured. The results show that deposition downstream of the first dune behind the HRSF is not located on the centerline of the wake. The deposition pattern indicates that a long steady wake region exists behind the permeable foundation. The scour depth around an HRSF is much less than that around a monopile because of the structural permeability, which gives rise to the bleed flow and a weakened down flow and horseshoe vortex. Additionally, the asymmetry of the HRSF affects the scour rate but not the final equilibrium scour depth. The average scour slope decreases along the direction of the flow. On the contrary, the scour radial distance increases along the direction of the flow, with the average value changing from 1.36De to 2.35De (where De is the equivalent diameter of the foundation). Furthermore, the scour hole around the HRSF is serrated rather than smooth owing to the presence of multiple piles. Empirical formulae are suggested for estimating the evolution of scour depth and volume. These laboratory experiments provide reference information for relevant numerical modeling studies and can be applied to guide engineering designs in an ocean area.
3. A grain-size correction for metal pollution indexes in river sediments Abstract: According to the List of Hazardous Substances of the Agency of the Toxic Substances and Disease Registry (ATSDR 2017), some metallic elements such as Pb or Cd are still considered as the most polluting elements in the world. These elements accumulate in sediments, and there are various methods available that differentiate lithogenic sources from anthropogenic sources. For that, the natural geochemical background is required, however, its definition is far from unanimous: it can be a global or local value, single or statistically estimated value, depending on the studies. Our study is focused on the Subaé River in the state of Bahia, Northeastern Brazil, which was historically contaminated by lead metallurgy. The river sediments were sampled at 21 locations: one at the discharge point of the plant's rainwater basin, ten upstream, and ten downstream. The total contents of Fe, Ti, Mn, Pb, Zn, Cu, Cr, particle-size distribution, and organic matter were analyzed. The conventional geochemical indexes, i.e., the pollution degree (mCd), pollution load index, and enrichment factor indicated contamination by Zn, Pb, Cr, and Cu. Then, a new enrichment factor is introduced, assuming that the sediments come from erosion of soils in the watershed. After obtaining the natural concentrations of metals in the clay, silt, and sand fractions of uncontaminated reference soils, we corrected the pollution indexes by calculating a new individual background in each sediment sample, according to its grain size distribution. This new approach provided more precise indexes in the assessment of sediment pollution, by highlighting higher contamination of Zn and Pb (around 50%) and at the same time the absence of Cr and Cu contamination, two metals not involved with the metallurgical activity.
4. Study of water renewal and sedimentation of a square harbor encapsulated in a coastal front with seawalls due to wind-induced hydrodynamic circulation Abstract: In the current study in the middle of a coastal zone, a harbor basin in the form of a square area recessed to the front is considered. A breakwater of variable length and position offers protection from waves. The water renewal time and the self-purification capacity of the harbor under the influence of alongshore currents due to wind-induced water circulation of varying intensities were examined. Furthermore, the transport of particulate matter released from the upstream side of the coastal zone and the possible influence (via sedimentation) on the lateral basin was investigated. The current study was based on the use of a two-dimensional depth-averaged hydrodynamic model and a quasi-three-, dimensional transport model while the effect of partial closing of the harbor's entrance was examined. The (1) adjustment and (2) validation of the reliability of the numerical model at a laboratory level were done using a recent research based on the use of a particle image velocimetry (PIV) measurements ensuring very good agreement between numerical and experimental results. The current study showed that the partial closing of the opening between the harbor basin and the extended coastal zone, with a breakwater of length equal to 1/3 of the opening, seems to be the most acceptable technical solution.
5. Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary, Noakhali coast, Bangladesh Abstract: Sediment samples were collected from ten selected sites of the lower Meghna River estuary, and six heavy metals were analyzed with Atomic Absorption Spectrophotometry (AAS) to assess the contamination level and the metals’ association with sediment grain size. The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron (Fe) (1.29 × 103 mg/kg) > zinc(Zn) (42.41 mg/kg) > lead (Pb) (12.48 mg/kg) > chromium (Cr) (10.59 mg/kg) > copper (Cu) (6.22 mg/kg) > cadmium (Cd) (0.28 mg/kg). The geo-accumulation, contamination, and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe, Zn, Pb, Cr, and Cu. The mean size of the sediment ranged from 28.92 to 126.2 μm, and the Pearson correlation coefficient showed a significant association between Fe and Pb (coefficient of determination, r2 = 0.836; p < 0.05), and no significant correlation was found between individual metals and grain size, indicating no or low influence on the metals distribution.
6. Mineral composition and particle size distribution of river sediment and loess in the middle and lower Yellow River Abstract: Hyper concentrated flows often occur in the middle and lower Yellow River (MLYR) and its tributaries, within which the main sediment source originates from the Loess Plateau of China due to serious water erosion. Little is known about the properties of river sediment that is transported by hyper concentrated flows, particularly with respect to the mineral composition and size distribution. Samples of sediment and loess were collected in the northern, middle, and southern Loess Plateau and the mainstream and tributaries of the MLYR. A total of 18 loess samples and 24 river sediment samples were analyzed to determine their sediment size distribution and mineral composition. The bottom loess samples reflected the original sedimentary features of the Loess Plateau, and the median particle size reduced, and the clay content increased from the north to the south of the study region. The surface loess has been weathered under the action of wind and rainfall, and the clay particle content in the surface loess samples was higher than that in the undisturbed bottom loess. Erosion of the surface soil due to rainfall and surface runoff means that fine particles (mostly clay) have been washed away. The median diameter of surface loess particles was a little larger than that of the bottom loess particles where water erosion dominates. The particle size became coarser with increasing distance from the estuary in the MLYR, which reflects depositional sorting in the river channel. Significant logarithmic relations were found between the median diameter of the sediment particles and the i) non-clay mineral content and ii) clay mineral content. Thus, clay and non-clay mineral compositions can be conveniently estimated from the particle size distribution.
7. Comparison of Pb(II) and Cd(II) micro-interfacial adsorption on fine sediment in the Pearl River Basin, China Abstract: The complex micro-interfacial interaction theories of heavy metal ions such as Pb(II) and Cd(II) adsorption on fine sediment in aqueous solution were not systematically investigated. The aim of this work was to reflect the micro-interfacial adsorption characteristics. Sediment samples were collected from an estuary. The Isothermal and kinetics adsorption experiment were done to acquire the data. Isothermal, kinetics, film diffusion and intraparticle diffusion models were adopted to fit the adsorption experimental data. The results indicated that the Langmuir, Freundlich and Temkin models were suitable for analyzing the isothermal experimental data. The maximum adsorption capacities of Pb(II) and Cd(II) on the sediment were 1.1377 and 0.9821 mg·g?1, respectively. The qm and KL of the Langmuir model, Kf and nF of the Freundlich model, and b and A of the Temkin model all exhibited a power function relationship with the initial adsorbate concentration. The pseudo-second-order model provided a better fit for the experimental kinetics data compared with the fit of the pseudo-first-order and Elovich models. The pseudo-second-order parameters k2 and qe of Pb(II) and qe of Cd(II) both had a power function relationship with adsorption time, additionally, the k2 of Cd(II) had an exponential function relationship with adsorption time. The liquid-film diffusion parameters kfd of Pb(II) and Cd(II) were 0.0569 and 0.1806 min?1, respectively. The intraparticle diffusion parameter kid values of Pb(II) and Cd(II) were 0.0055 mg·g?1·min1/2 and 0.0049 mg·g?1·min1/2, respectively. The physical significance of the model parameters showed that Pb(II) adsorption on sediment was stronger than Cd(II). The results of this study provided a theoretical reference for the micro-interfacial mechanism of heavy metal ion adsorption on sediment.
8. How can stream bank erosion be predicted on small water courses? Verification of BANCS model on the Kubrica watershed Abstract: The current paper deals with the evaluation of the BANCS erosion prediction model and its two components–the Bank Erosion Hazard Index (BEHI) and Near-Bank Stress (NBS) indices. To construct the erosion prediction curves, 18 experimental sections were established on the Kubrica Stream, district of Tren?ín, Slovakia. Each section was assessed through the NBS index and BEHI index and real annual bank erosion was measured using erosion toe pins. Subsequently, the relations between the BEHI and real annual bank erosion was assessed through regression and correlation analyses. The relation proved to be moderately strong, with the correlation coefficient (R) reaching 0.47. Further, the relation between the NBS index and real annual bank erosion was evaluated, which was also moderately strong, with R = 0.65. Based on the measured data, two erosion prediction curves were constructed, the first for moderate BEHI, with R = 0.69 and coefficient of determination (R2) of 0.47 and the second for high BEHI with R = 0.74 and R2 = 0.55. The prediction curves were based on data from one year of measurements and can, therefore, be used only for discharges that occurred within that year and in the region where the model was developed. In the current case, according to runoff Curve Numbers (CN), the real culmination discharge was Q = 1.88 m3/s, which is roughly equivalent to 1.5-year recurrence interval flow (Q1.5).
9. Amplification of flood discharge caused by the cascading failure of landslide dams Abstract: The cascading failure of multiple landslide dams can trigger a larger peak flood discharge than that caused by a single dam failure. Therefore, for an accurate numerical simulation, it is essential to elucidate the primary factors affecting the peak discharge of the flood caused by a cascading failure, which is the purpose of the current study. First, flume experiments were done on the cascading failure of two landslide dams under different upstream dam heights, downstream dam heights, and initial downstream reservoir water volumes. Then, the experimental results were reproduced using a numerical simulation model representing landslide dam erosion resulting from overtopping flow. Finally, the factors influencing the peak flood discharge caused by the cascading failure were analyzed using the numerical simulation model. Experimental results indicated that the inflow discharge into the downstream dam at the time when the downstream dam height began to rapidly erode was the main factor responsible for a cascading failure generating a larger peak flood discharge than that generated by a single dam failure. Furthermore, the results of a sensitivity analysis suggested that the upstream and downstream dam heights, initial water volume in the reservoir of the downstream dam, upstream and downstream dam crest lengths, and distance between two dams were among the most important factors in predicting the flood discharge caused by the cascading failure of multiple landslide dams.
10. Assessing morphological changes in a human-impacted alluvial system using hydro-sediment modeling and remote sensing Abstract: Construction of managed aquifer recharge structures (MARS) to store flood water is a common strategy for storing depleted groundwater resources in arid and semi-arid regions, as part of integrated water resources management (IWRM). MARS divert surface water to groundwater, but this can affect downstream fluvial processes. The impact of MARS on fluvial processes was investigated in this study by combining remote sensing techniques with hydro-sediment modeling for the case of the Kaboutar-Ali-Chay aquifer, northwestern Iran. The impact of MARS on groundwater dynamics was assessed, sedimentation across the MARS was modeled using a 2D hydrodynamic model, and morphological changes were quantified in the human-impacted alluvial fan using Landsat time series data and statistical methods. Changes were detected by comparing data for the periods before (1985–1996) and after (1997–2018) MARS construction. The results showed that the rate of groundwater depletion decreased from 2.14 m/yr before to 0.86 m/yr after MARS construction. Hydro-sediment modeling revealed that MARS ponds slowed water outflow, resulting in a severe decrease in sediment load which lead to a change from sediment deposition to sediment erosion in the alluvial fan. Morphometric analyses revealed decreasing alluvial fan area and indicated significant differences (p < 0.01) between pre- and post-impact periods for different morphometric parameters analyzed. The rate of change in area of the Kaboutar-Ali-Chay alluvial fan changed from -0.228 to -0.115 km2/year between pre- and post-impact periods. |
