Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models
<p>Submarine channels conveying sediment gravity flows are often topographically confined, but the effect of confinement width on channel morphodynamics is incompletely understood. We use physical experiments and a reduced-complexity model to investigate the effects of confinement width (<s...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-07-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/11/615/2023/esurf-11-615-2023.pdf |
| _version_ | 1797777263830237184 |
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| author | S. Y. J. Huang S. Y. J. Lai A. B. Limaye B. Z. Foreman C. Paola |
| author_facet | S. Y. J. Huang S. Y. J. Lai A. B. Limaye B. Z. Foreman C. Paola |
| author_sort | S. Y. J. Huang |
| collection | DOAJ |
| description | <p>Submarine channels conveying sediment gravity flows are often topographically confined, but the effect of confinement width on channel morphodynamics is incompletely understood. We use physical experiments and a reduced-complexity model to investigate the effects of confinement width (<span class="inline-formula"><i>B</i></span>) and the inflow-to-sediment discharge ratio (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi>Q</mi><mi mathvariant="normal">in</mi></msub><mo>/</mo><msub><mi>Q</mi><mi mathvariant="normal">s</mi></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="35pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="63688a98a9dd472fc30ffe3a24a7d426"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00001.svg" width="35pt" height="14pt" src="esurf-11-615-2023-ie00001.png"/></svg:svg></span></span>) on the evolution of submarine braided channels. The results show that a larger confinement width results in increased active braiding intensity (<span class="inline-formula">BI<sub>A</sub></span>) and that <span class="inline-formula">BI<sub>A</sub></span> takes longer to stabilize (i.e., a longer critical time; <span class="inline-formula"><i>t</i><sub>c</sub></span>). At a fixed confinement width, a higher <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi>Q</mi><mi mathvariant="normal">in</mi></msub><mo>/</mo><msub><mi>Q</mi><mi mathvariant="normal">s</mi></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="35pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c5aa0a408bb1d94d48fe1bd36040e54b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00002.svg" width="35pt" height="14pt" src="esurf-11-615-2023-ie00002.png"/></svg:svg></span></span> slightly decreases the <span class="inline-formula">BI<sub>A</sub></span>. Digital elevation models of difference (DoD) of the experiments allow measurement of the morphological active width (<span class="inline-formula"><i>W</i><sub>a</sub></span>) of the submarine channels and the bulk morphological change (<span class="inline-formula"><i>V</i><sub>bulk</sub></span>) within an experiment, defined as the sum
of total erosion and deposition. We find that <span class="inline-formula"><i>W</i><sub>a</sub></span> and <span class="inline-formula"><i>V</i><sub>bulk</sub></span> are proportional to <span class="inline-formula"><i>B</i></span>. We further confirm that <span class="inline-formula">BI<sub>A</sub></span> is proportional to both dimensionless sediment–stream power (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi mathvariant="italic">ω</mi><mrow><mo>*</mo><mo>*</mo></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="31e92eb3770034a7041cc4785b5e7e3e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00003.svg" width="18pt" height="11pt" src="esurf-11-615-2023-ie00003.png"/></svg:svg></span></span>) and dimensionless stream power (<span class="inline-formula"><i>ω</i><sup>*</sup></span>). These trends are consistent for submarine braided channels both with and without confinement width effects. Furthermore, we built a reduced-complexity model (RCM) that can simulate flow bifurcation and confluence of submarine braided channels. The simulated flow distribution provides reliable predictions of flow depth and sediment transport rate in the experiments. Using kernel density estimation (KDE) to forecast the probability and trends of cross-sectional flow distribution and corresponding <span class="inline-formula">BI<sub>A</sub></span> under extreme events, we find that
skewness of the flow distribution decreases as discharge increases. The
development of braided submarine channels, shown here to extend to
conditions of topographic confinement, suggests that factors not modeled
here (e.g., fine sediment) may be necessary to explain the abundance of
single-thread submarine channels in nature.</p> |
| first_indexed | 2024-03-12T23:01:39Z |
| format | Article |
| id | doaj.art-4d22081098a24cef88e84ba09d126745 |
| institution | Directory Open Access Journal |
| issn | 2196-6311 2196-632X |
| language | English |
| last_indexed | 2024-03-12T23:01:39Z |
| publishDate | 2023-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Earth Surface Dynamics |
| spelling | doaj.art-4d22081098a24cef88e84ba09d1267452023-07-19T10:10:09ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2023-07-011161563210.5194/esurf-11-615-2023Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity modelsS. Y. J. Huang0S. Y. J. Lai1A. B. Limaye2B. Z. Foreman3C. Paola4Department of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan, TaiwanDepartment of Hydraulic and Ocean Engineering, National Cheng Kung University, Tainan, TaiwanDepartment of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USADepartment of Geology, Western Washington University, Bellingham, WA 98225, USADepartment of Earth Sciences, University of Minnesota, Minneapolis, MN 55455, USA<p>Submarine channels conveying sediment gravity flows are often topographically confined, but the effect of confinement width on channel morphodynamics is incompletely understood. We use physical experiments and a reduced-complexity model to investigate the effects of confinement width (<span class="inline-formula"><i>B</i></span>) and the inflow-to-sediment discharge ratio (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi>Q</mi><mi mathvariant="normal">in</mi></msub><mo>/</mo><msub><mi>Q</mi><mi mathvariant="normal">s</mi></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="35pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="63688a98a9dd472fc30ffe3a24a7d426"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00001.svg" width="35pt" height="14pt" src="esurf-11-615-2023-ie00001.png"/></svg:svg></span></span>) on the evolution of submarine braided channels. The results show that a larger confinement width results in increased active braiding intensity (<span class="inline-formula">BI<sub>A</sub></span>) and that <span class="inline-formula">BI<sub>A</sub></span> takes longer to stabilize (i.e., a longer critical time; <span class="inline-formula"><i>t</i><sub>c</sub></span>). At a fixed confinement width, a higher <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi>Q</mi><mi mathvariant="normal">in</mi></msub><mo>/</mo><msub><mi>Q</mi><mi mathvariant="normal">s</mi></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="35pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c5aa0a408bb1d94d48fe1bd36040e54b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00002.svg" width="35pt" height="14pt" src="esurf-11-615-2023-ie00002.png"/></svg:svg></span></span> slightly decreases the <span class="inline-formula">BI<sub>A</sub></span>. Digital elevation models of difference (DoD) of the experiments allow measurement of the morphological active width (<span class="inline-formula"><i>W</i><sub>a</sub></span>) of the submarine channels and the bulk morphological change (<span class="inline-formula"><i>V</i><sub>bulk</sub></span>) within an experiment, defined as the sum of total erosion and deposition. We find that <span class="inline-formula"><i>W</i><sub>a</sub></span> and <span class="inline-formula"><i>V</i><sub>bulk</sub></span> are proportional to <span class="inline-formula"><i>B</i></span>. We further confirm that <span class="inline-formula">BI<sub>A</sub></span> is proportional to both dimensionless sediment–stream power (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi mathvariant="italic">ω</mi><mrow><mo>*</mo><mo>*</mo></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="31e92eb3770034a7041cc4785b5e7e3e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-11-615-2023-ie00003.svg" width="18pt" height="11pt" src="esurf-11-615-2023-ie00003.png"/></svg:svg></span></span>) and dimensionless stream power (<span class="inline-formula"><i>ω</i><sup>*</sup></span>). These trends are consistent for submarine braided channels both with and without confinement width effects. Furthermore, we built a reduced-complexity model (RCM) that can simulate flow bifurcation and confluence of submarine braided channels. The simulated flow distribution provides reliable predictions of flow depth and sediment transport rate in the experiments. Using kernel density estimation (KDE) to forecast the probability and trends of cross-sectional flow distribution and corresponding <span class="inline-formula">BI<sub>A</sub></span> under extreme events, we find that skewness of the flow distribution decreases as discharge increases. The development of braided submarine channels, shown here to extend to conditions of topographic confinement, suggests that factors not modeled here (e.g., fine sediment) may be necessary to explain the abundance of single-thread submarine channels in nature.</p>https://esurf.copernicus.org/articles/11/615/2023/esurf-11-615-2023.pdf |
| spellingShingle | S. Y. J. Huang S. Y. J. Lai A. B. Limaye B. Z. Foreman C. Paola Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models Earth Surface Dynamics |
| title | Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models |
| title_full | Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models |
| title_fullStr | Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models |
| title_full_unstemmed | Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models |
| title_short | Confinement width and inflow-to-sediment discharge ratio control the morphology and braiding intensity of submarine channels: insights from physical experiments and reduced-complexity models |
| title_sort | confinement width and inflow to sediment discharge ratio control the morphology and braiding intensity of submarine channels insights from physical experiments and reduced complexity models |
| url | https://esurf.copernicus.org/articles/11/615/2023/esurf-11-615-2023.pdf |
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