Influence of alluvial slope on avulsion in river deltas
<p>Changing hydrological regimes, sea-level rise, and accelerated subsidence are all putting river deltas at risk across the globe. One mechanism by which deltas may respond to these stressors is that of avulsion. Decades of delta avulsion studies have resulted in conflicting hypotheses as to...
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Copernicus Publications
2025-05-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://esurf.copernicus.org/articles/13/349/2025/esurf-13-349-2025.pdf |
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| author | O. A. Prasojo O. A. Prasojo T. B. Hoey A. Owen R. D. Williams |
| author_facet | O. A. Prasojo O. A. Prasojo T. B. Hoey A. Owen R. D. Williams |
| author_sort | O. A. Prasojo |
| collection | DOAJ |
| description | <p>Changing hydrological regimes, sea-level rise, and accelerated subsidence are all putting river deltas at risk across the globe. One mechanism by which deltas may respond to these stressors is that of avulsion. Decades of delta avulsion studies have resulted in conflicting hypotheses as to whether avulsion timing and location are primarily controlled by upstream (water and sediment discharge) or downstream (backwater and sea-level rise) drivers. Here we use Delft3D morphodynamic simulations to test the upstream-influence hypothesis by varying the initial alluvial slopes upstream of a self-formed delta plain within a range (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.13</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">4</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="23cd809342d9b21ff9dea0c7b3617a7f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-13-349-2025-ie00001.svg" width="57pt" height="14pt" src="esurf-13-349-2025-ie00001.png"/></svg:svg></span></span> to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">3.04</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="0a4c4aac753810e21f8c7b0b07ac7c7f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-13-349-2025-ie00002.svg" width="57pt" height="14pt" src="esurf-13-349-2025-ie00002.png"/></svg:svg></span></span> m m<span class="inline-formula"><sup>−1</sup></span>) that is representative of global deltas, while leaving all other parameters constant. Avulsion timing and location were recorded in six scenarios modelled over a 400-year period. We measured independent morphometric variables including avulsion length, delta lobe width, bankfull depth, channel width at avulsion, delta topset slope, and sediment load and compare these to natural and laboratory deltas. We find that larger deltas take more time to avulse, as avulsion timing scales with avulsion length, delta lobe width, and bankfull depth. More importantly, we find strong negative correlations between sediment load avulsion timescale and sediment load initial alluvial slope. Sediment load is directly dependent on the upstream alluvial slope, and increases in this slope raise transport capacity and introduce more sediment into a delta plain, leading to higher aggradation rates and, consequently, more frequent avulsions. These results introduce further debate over the role of downstream controls on delta avulsion.</p> |
| format | Article |
| id | doaj-art-4330313ba30342eb9516bc0982bbff7d |
| institution | DOAJ |
| issn | 2196-6311 2196-632X |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Copernicus Publications |
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| series | Earth Surface Dynamics |
| spelling | doaj-art-4330313ba30342eb9516bc0982bbff7d2025-08-20T02:58:32ZengCopernicus PublicationsEarth Surface Dynamics2196-63112196-632X2025-05-011334936310.5194/esurf-13-349-2025Influence of alluvial slope on avulsion in river deltasO. A. Prasojo0O. A. Prasojo1T. B. Hoey2A. Owen3R. D. Williams4School of Geographical and Earth Sciences, University of Glasgow, University Avenue, Glasgow, G12 8QQ, United KingdomGeoscience Study Program, Faculty of Mathematics and Natural Sciences (FMIPA), Universitas Indonesia, Depok 16424, IndonesiaDepartment of Civil and Environmental Engineering, Brunel University London, Uxbridge, UB8 3PH, United KingdomSchool of Geographical and Earth Sciences, University of Glasgow, University Avenue, Glasgow, G12 8QQ, United KingdomSchool of Geographical and Earth Sciences, University of Glasgow, University Avenue, Glasgow, G12 8QQ, United Kingdom<p>Changing hydrological regimes, sea-level rise, and accelerated subsidence are all putting river deltas at risk across the globe. One mechanism by which deltas may respond to these stressors is that of avulsion. Decades of delta avulsion studies have resulted in conflicting hypotheses as to whether avulsion timing and location are primarily controlled by upstream (water and sediment discharge) or downstream (backwater and sea-level rise) drivers. Here we use Delft3D morphodynamic simulations to test the upstream-influence hypothesis by varying the initial alluvial slopes upstream of a self-formed delta plain within a range (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.13</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">4</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="23cd809342d9b21ff9dea0c7b3617a7f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-13-349-2025-ie00001.svg" width="57pt" height="14pt" src="esurf-13-349-2025-ie00001.png"/></svg:svg></span></span> to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">3.04</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="0a4c4aac753810e21f8c7b0b07ac7c7f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-13-349-2025-ie00002.svg" width="57pt" height="14pt" src="esurf-13-349-2025-ie00002.png"/></svg:svg></span></span> m m<span class="inline-formula"><sup>−1</sup></span>) that is representative of global deltas, while leaving all other parameters constant. Avulsion timing and location were recorded in six scenarios modelled over a 400-year period. We measured independent morphometric variables including avulsion length, delta lobe width, bankfull depth, channel width at avulsion, delta topset slope, and sediment load and compare these to natural and laboratory deltas. We find that larger deltas take more time to avulse, as avulsion timing scales with avulsion length, delta lobe width, and bankfull depth. More importantly, we find strong negative correlations between sediment load avulsion timescale and sediment load initial alluvial slope. Sediment load is directly dependent on the upstream alluvial slope, and increases in this slope raise transport capacity and introduce more sediment into a delta plain, leading to higher aggradation rates and, consequently, more frequent avulsions. These results introduce further debate over the role of downstream controls on delta avulsion.</p>https://esurf.copernicus.org/articles/13/349/2025/esurf-13-349-2025.pdf |
| spellingShingle | O. A. Prasojo O. A. Prasojo T. B. Hoey A. Owen R. D. Williams Influence of alluvial slope on avulsion in river deltas Earth Surface Dynamics |
| title | Influence of alluvial slope on avulsion in river deltas |
| title_full | Influence of alluvial slope on avulsion in river deltas |
| title_fullStr | Influence of alluvial slope on avulsion in river deltas |
| title_full_unstemmed | Influence of alluvial slope on avulsion in river deltas |
| title_short | Influence of alluvial slope on avulsion in river deltas |
| title_sort | influence of alluvial slope on avulsion in river deltas |
| url | https://esurf.copernicus.org/articles/13/349/2025/esurf-13-349-2025.pdf |
| work_keys_str_mv | AT oaprasojo influenceofalluvialslopeonavulsioninriverdeltas AT oaprasojo influenceofalluvialslopeonavulsioninriverdeltas AT tbhoey influenceofalluvialslopeonavulsioninriverdeltas AT aowen influenceofalluvialslopeonavulsioninriverdeltas AT rdwilliams influenceofalluvialslopeonavulsioninriverdeltas |