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  • 1.
    Bilal, Ahmed
    et al.
    College of Water Conservancy and Hydropower Engineering, Hohai University (HHU), Nanjing 210098, China.
    Xie, Qiancheng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Zhai, Yanyan
    Division of Fluid Mechanics, Coastal and Maritime Engineering, Technical University of Denmark (DTU), 2800 Kgs, 2800 Lyngby, Denmark .
    Flow, Sediment, and Morpho-Dynamics of River Confluence in Tidal and Non-Tidal Environments2020Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 8, nr 8, artikkel-id 591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    River confluences are the key features of the drainage basins, as their hydrological, geomorphological, and ecological nature strongly influences the downstream river characteristics. The river reaches near the coastal zones, which also makes them under the influence of tidal currents in addition to their runoff. This causes a bi-directional flow and makes the study of confluences more interesting and complex in these areas. There is a reciprocal adjustment of flow, sediment, and morphology at a confluence, and its behaviors, differ greatly in tidal and non-tidal environments. Existing studies of the river junctions provide a good account of information about the hydrodynamics and bed morphology of the confluent areas, especially the unidirectional ones. The main factors which affect the flow field include the angle of confluence, flow-related ratios (velocity, discharge, and momentum) of the merging streams, and bed discordance. Hydraulically, six notable zones are identified for unidirectional confluences. However, for bi-directional (tidal) junctions, hydrodynamic zones always remain in transition but repeat in a cycle and make four different arrangements of flow features. This study discusses the hydrodynamics, sediment transport, morphological changes, and the factors affecting these processes and reviews the recent research about the confluences for these issues. All of these studies provide insights into the morpho-dynamics in tidal and non-tidal confluent areas.

    Fulltekst (pdf)
    fulltext
  • 2.
    Dai, Wenhong
    et al.
    College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China.
    Ding, Wei
    College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China.
    Lu, Chuanteng
    State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China. Nanjing Hydraulic Research Institute, Nanjing 210029, China.
    Luo, Xiaofeng
    State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China. Nanjing Hydraulic Research Institute, Nanjing 210029, China.
    Xie, Qiancheng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Field Investigations of Underwater Mounds Formed by Hopper Dredge Discharges in a Coastal Environment2020Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 8, nr 6, artikkel-id 395Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a coastal environment, this paper investigated the formation process and the cumulative shape of subaqueous mounds formed by hopper dredged discharges. Hydrological observations and field tests were performed to examine the flow features and ultimately generated morphology characteristics. A high-precision digital elevation model (DEM) was established by multi-beam depth sweeping (MBDS) in the experiment. Particular attention was paid to the formation of the mounds, the three-dimensional shape and the influence factors. The field measurements showed that the mounds were roughly symmetrical in space, and the tidal current, though of weak strength, played a certain role in shaping the profiles. Cone and volcanic cone mound tops were observed, featuring the main top shapes. The height and covered area of the mounds were proportional to the amount of dumped sediment, and they were also affected a lot by the water depth. The results of superimposed tests showed that the second placement over the existing mound resulted in a similar overall shape, but there was pronounced movement around the mound; additional discharged volumes at the same location mainly increased the mound height. The field tests provided a reference for understanding the sediment dumping in other similar coastal areas.

    Fulltekst (pdf)
    fulltext
  • 3.
    Ding, Wei
    et al.
    Nanjing Hydraulic Research Institute, Nanjing 210029, China.
    Lu, Chuanteng
    Nanjing Hydraulic Research Institute, Nanjing 210029, China; State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China.
    Xie, Qiancheng
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Luo, Xiaofeng
    Nanjing Hydraulic Research Institute, Nanjing 210029, China; State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Nanjing 210098, China.
    Zhang, Gongjin
    Nanjing Hydraulic Research Institute, Nanjing 210029, China.
    Understanding the Settling Processes of Dredged Sediment Disposed in Open Waters through Experimental Tests and Numerical Simulations2022Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 10, nr 2, artikkel-id 220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During dredging for subsea tunnels and pipelines, the dredged soil is typically dumped in a designated area. Understanding the settling behaviors of the dumped particles is essential for an accurate prediction of the resulting morphology. This study dealt with the settling processes in the open-water column by means of experimental tests and numerical simulations. Both quiescent and ambient current conditions were taken into account. Particular attention was paid to the induced flow patterns, descent sediment movement features and the resulting topography. Regarding the diffusion width and settling velocity, three key effect factors, i.e., dumped volume, particle size and ambient flow strength, were considered. The results show that the dumped sediment in the water forms a particle cloud, and two vortices with opposite rotations occur on both sides of the cloud. During settlement, three stages corresponding to convective descent, dynamic collapse and passive diffusion are observed. Most of the descending sediment is incorporated in a spherical vortex, resembling an upside-down mushroom cloud, and some sediment is also contained in an irregular trailing stem. The dumped particles exhibit initial acceleration, and then they slow down to converge to a fixed value. Subjected to the ambient currents, the initial acceleration phase is prolonged, and the vortex is somewhat distorted; the particle cloud is also advected downstream with a velocity roughly equal to the ambient current.

    Fulltekst (pdf)
    fulltext
  • 4.
    Pedersen, Kristine B.
    et al.
    Akvaplan-niva AS, High North Research Centre for Climate and the Environment, 9007 Tromsø, Norway; Department of Chemistry, UiT—The Arctic University of Norway, 9037 Tromsø, Norway.
    Lejon, Tore
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. Department of Chemistry, UiT—The Arctic University of Norway, 9037 Tromsø, Norway.
    Evenset, Anita
    Akvaplan-niva AS, High North Research Centre for Climate and the Environment, 9007 Tromsø, Norway.
    Tailored Leaching Tests as a Tool for Environmental Management of Mine Tailings Disposal at Sea2022Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 10, nr 3, artikkel-id 405Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The expanding human activities in coastal areas increase the need for developing solutions to limit impacts on the marine environment. Sea disposal affects the marine environment, but despite the growing knowledge of potential impacts, there are still no standardized leaching tests for sea disposal. The aim of this study was to contribute to the development of leaching tests, exemplified using mine tailings, planned for submarine disposal in the Repparfjord, Norway. The mine tailings had elevated concentrations of Ba, Cr, Cu, Mn and Ni compared to background concentrations in the Repparfjord. Variables known to affect metal leaching in marine environments (DOC, pH, salinity, temperature, aerated/anoxic) were studied, as was the effect of flocculant (Magnafloc10), planned to be added prior to discharge. Stirred/non-stirred setups simulated the resuspension and disposal phases. Leaching of metals was below 2% in all experiments, with the highest rate observed for Cu and Mn. Multivariate analysis revealed a different variable importance for metals depending on their association with minerals. Higher leaching during resuspension than disposal, and lower leaching with the addition of Magnafloc10, especially for Cu and Mn, was observed. The leaching tests performed in this study are transferable to other materials for sea disposal. 

  • 5.
    Strack, Kurt
    et al.
    KMS Technologies, Houston, TX 77057, USA.
    Davydycheva, Sofia
    KMS Technologies, Houston, TX 77057, USA.
    Passalacqua, Herminio
    Red Tree Consulting, Houston, TX 77055, USA.
    Smirnov, Maxim
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik. KMS Technologies, Houston, TX 77057, USA.
    Xu, Xiayu
    KMS Technologies, Houston, TX 77057, USA.
    Using Cloud-Based Array Electromagnetics on the Path to Zero Carbon Footprint during the Energy Transition2021Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 9, nr 8, artikkel-id 906Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fluid imaging is one of the key geophysical technologies for the energy industry during energy transition to zero footprint. We propose better Cloud-based fluid distribution imaging to allow better, more optimized production, thus reducing carbon dioxide (CO2) footprint per barrel produced. For CO2 storage, the location knowledge of the stored fluids is mandatory. Electromagnetics is the preferred way to image reservoir fluids due to its strong coupling to the fluid resistivity. Unfortunately, acquiring and interpreting the data takes too long to contribute significantly to cost optimization of field operations. Using artificial intelligence and Cloud based data acquisition we can reduce the operational feedback to near real time and even, for the interpretation, to close to 24 h. This then opens new doors for the breakthrough of this technology from exploration to production and monitoring. It allows the application envelope to be enlarged to much noisier environments where real time acquisition can be optimized based on the acquired data. Once all components are commercialized, the full implementation could become a real game changer by providing near real time 3-dimensional subsurface images in support of the energy transition.

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