erosion and deposition
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CATENA ◽  
2022 ◽  
Vol 209 ◽  
pp. 105805
Author(s):  
Weibo Kong ◽  
Fuyuan Su ◽  
Qian Zhang ◽  
Satoshi Ishii ◽  
Michael J. Sadowsky ◽  
...  

2021 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
Paran Pourteimouri ◽  
Geert H. P. Campmans ◽  
Kathelijne M. Wijnberg ◽  
Suzanne J. M. H. Hulscher

The attractiveness of beaches to people has led, in many places, to the construction of buildings at the beach–dune interface. Buildings change the local airflow patterns which, in turn, alter the sediment transport pathways and magnitudes. This induces erosion and deposition patterns around the structures. In this study, a numerical model is developed using the open-source computational fluid dynamics solver OpenFOAM. First, the model is used to predict the airflow patterns around a single rectangular building. The model predictions are validated with wind-tunnel data, which show good agreements. Second, a reference beach building is introduced and then the building dimensions are increased in length, width and height, each up to three times the reference building dimension. The impact of each dimensional extent on the near-surface airflow patterns is investigated. The results show that the near-surface airflow patterns are least dependent on the length of the building in the wind direction and they depend most on the width of the building perpendicular to the wind direction. Third, the convergence of the third-order horizontal near-surface velocity field is calculated to interpret the impact of changes in airflow patterns on potential erosion and deposition patterns around the building. The numerical predictions are compared with the observed erosion and sedimentation patterns around scale models in the field. The comparisons show satisfactory agreements between numerical results and field measurements.


2021 ◽  
Author(s):  
Alina Eksaeva ◽  
Andreas Kirschner ◽  
Juri Romazanov ◽  
Sebastijan Brezinsek ◽  
Christian Linsmeier ◽  
...  

Abstract Erosion and deposition is modelled with ERO2.0 for a hypothetical full-tungsten ITER for an ELM-free H-Mode baseline deuterium discharge. A parameter study considering seeding impurities (Ne, Ar, Kr, Xe) at constant percentages (0.05% to 1.0%) of the deuterium ion flux is done while neglecting their radiation cooling and core plasma compatibility. With pure deuterium plasma, tungsten main wall erosion is only due to charge exchange deuterium atoms and self-sputtering and there is only minor tungsten divertor sputtering. With a beryllium main wall, beryllium erosion is due to deuterium ions, charge exchange deuterium neutrals and self-sputtering. For this case, tungsten in the divertor is eroded by beryllium ions and self-sputtering. The simulations for full-tungsten device including seeded impurities leads to significant tungsten erosion in the divertor. In general, tungsten erosion, self-sputtering and deposition increase by factors larger than 50 at the main wall and 5000 in the divertor compared to pure deuterium plasma


2021 ◽  
Vol 3 (1) ◽  
pp. 59-66
Author(s):  
Uddipta Ranjan Boruah

The obsession with inter-state territorial borders and the associated paraphernalia of border management and security makes borders and their management a primarily human-centric discourse. This paper makes an attempt at introducing the agency of rivers as non-human actors—or rather as actants—in shaping and managing international borders. The paper looks specifically at the riverine sector of the Indo-Bangladesh border, where the international boundary has been re-negotiated each year by the transnational rivers, primarily the Brahmaputra (also the Gangadhar), through flooding, erosion, and deposition of sediment. By interrogating the role of rivers in shaping the border and border management strategies, the paper argues that humans, despite persisting as the primary agents in border management, are not the only actors. Drawing on Actor Network Theory (ANT), a case is made to appreciate the general symmetry between humans and non-humans as a-priori equal. Incorporating both in an actor-network may provide insights into border management in complex borderlands. 


2021 ◽  
Author(s):  
Madison M. Douglas ◽  
Gen K. Li ◽  
Woodward W. Fischer ◽  
Joel C. Rowland ◽  
Preston C. Kemeny ◽  
...  

Abstract. Arctic river systems erode permafrost in their banks and mobilize particulate organic carbon (OC). Meandering rivers can entrain particulate OC from permafrost many meters below the depth of annual thaw, potentially enabling OC oxidation and the production of greenhouse gases. However, the amount and fate of permafrost OC that is mobilized by river erosion is uncertain. To constrain OC fluxes due to riverbank erosion and deposition, we collected riverbank and floodplain sediment samples along the Koyukuk River, which meanders through discontinuous permafrost in central Alaska. We measured sediment total OC (TOC), radiocarbon content, water content, bulk density, grain size, and floodplain stratigraphy. Radiocarbon abundance and TOC were higher in samples dominated by silt as compared to sand, which we used to map OC content onto floodplain stratigraphy and estimate carbon fluxes due to river meandering. Results showed that sediment being eroded from cutbanks and deposited as point bars had similar OC stocks (mean ± 1SD of 125.3 ± 13.1 kgOC m−2 in cutbanks versus 114.0 ± 15.7 kgOC m−2 in point bars) whether or not the banks contained permafrost. We also observed radiocarbon-depleted biospheric OC in both cutbanks and permafrost-free point bars. These results indicate that a significant fraction of aged biospheric OC that is liberated from floodplains by bank erosion is subsequently re-deposited in point bars, rather than being oxidized. The process of aging, erosion, and re-deposition of floodplain organic material may be intrinsic to river-floodplain dynamics, regardless of permafrost content.


2021 ◽  
Vol 13 (21) ◽  
pp. 4364
Author(s):  
Berta M. Carro ◽  
Alejandro Reyes ◽  
Juan A. Morales ◽  
José Borrego

For more than 40 years, the industrial complex which developed near Huelva (in SW Spain) produced a huge amount of phosphogypsum as a waste product of manufacturing fertilizers. This waste was stockpiled in a stack 25 m high, covering 1200 ha of what was once a salt marsh. The weight of that enormous amount of waste produced active subsidence in the underlying sediment. Part of the sediment was injected into the marginal areas, where the load pressure is minor, causing significant vertical movement in the floor of the estuarine channel. This manuscript describes several surficial features using multibeam echosound. A crest formed by cones and a bulge area could be interpreted as injection structures. The evolution of the topographic position of the floor was also analyzed by comparing different records of the estuarine bed in the margins of the stockpile. The data in this work document the changes in the dynamics of the estuary in relation to these vertical movements. These changes in dynamicsled to erosion and deposition in various areas of the bed.


2021 ◽  
pp. jgs2021-052
Author(s):  
Daniel Paul Le Heron ◽  
Christoph Kettler ◽  
Bethan J. Davies ◽  
Lars Scharfenberg ◽  
Lukas Eder ◽  
...  

The Gepatsch Glacier in Tirol (Austria) is a rapidly retreating valley glacier whose host valley and forefield reveal subglacial, proglacial, and reworked sediment-landform assemblages. Structures include roches moutonées develop on gneiss, compound bedrock-sediment bedforms (crag and tail structures), flutes, and small diamicton ridges. The glacial sediments and landforms are undergoing incision and terrace development by meltwater streams. Glacial geomorphological and surface geological maps maps, in concert with elevation models of difference between July 2019 and July 2020 highlight considerable changes to the forefield over a 12-month time period. Till exposed within the last 20 years has undergone substantial mass wasting and re-deposition as subaerial mass flows, or reworked into stream deposits. The lee sides of many roches moutonées completely lack subglacial sediment, and instead contain a sand and gravel deposit interpreted to result from glaciofluvial deposition. Thus, insights into the rates of erosion and deposition in a complex, proglacial setting, allow some of these processes to be quantified for the first time. Repeated monitoring of glacier forefields is expected to yield a better understanding of the preservation potential of proglacial sedimentary facies, and hence their preservation potential in Earth's sedimentary record.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5664299


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