{"title":"海冰对北极三角洲演变的影响:阿拉斯加科尔维尔河三角洲模型研究","authors":"Caroline Cooper, Emily Eidam, Harvey Seim, Jaap Nienhuis","doi":"10.1029/2024JF007742","DOIUrl":null,"url":null,"abstract":"<p>Seasonal sea ice impacts Arctic delta morphology by limiting wave and river influences and altering river-to-ocean sediment pathways. However, the long-term effects of sea ice on delta morphology remain poorly known. To address this gap, 1D morphologic and hydrodynamic simulations were set up in Delft3D to study the 1500-year development of Arctic deltas during the most energetic Arctic seasons: spring break-up/freshet, summer open-water, and autumn freeze-up. The model focused on the deltaic clinoform (i.e., the vertical cross-sectional view of a delta) and used a floating barge structure to mimic the effects of sea ice on nearshore waters. From the simulations we find that ice-affected deltas form a compound clinoform morphology, that is, a coupled subaerial and subaqueous delta separated by a subaqueous platform that resembles the shallow platform observed offshore of Arctic deltas. Nearshore sea ice affects river dynamics and promotes sediment bypassing during sea ice break-up, forming an offshore depocenter and building a subaqueous platform. A second depocenter forms closer to shore during the open-water season at the subaerial foreset that aids in outbuilding the subaerial delta and assists in developing the compound clinoform morphology. Simulations of increased wave activity and reduced sea-ice, likely futures under a warming Arctic climate, show that deltas may lose their shallow platform on centennial timescales by (a) sediment infill and/or (b) wave erosion. This study highlights the importance of sea ice on Arctic delta morphology and the potential morphologic transitions these high-latitude deltas may experience as the Arctic continues to warm.</p>","PeriodicalId":15887,"journal":{"name":"Journal of Geophysical Research: Earth Surface","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JF007742","citationCount":"0","resultStr":"{\"title\":\"Effects of Sea Ice on Arctic Delta Evolution: A Modeling Study of the Colville River Delta, Alaska\",\"authors\":\"Caroline Cooper, Emily Eidam, Harvey Seim, Jaap Nienhuis\",\"doi\":\"10.1029/2024JF007742\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Seasonal sea ice impacts Arctic delta morphology by limiting wave and river influences and altering river-to-ocean sediment pathways. However, the long-term effects of sea ice on delta morphology remain poorly known. To address this gap, 1D morphologic and hydrodynamic simulations were set up in Delft3D to study the 1500-year development of Arctic deltas during the most energetic Arctic seasons: spring break-up/freshet, summer open-water, and autumn freeze-up. The model focused on the deltaic clinoform (i.e., the vertical cross-sectional view of a delta) and used a floating barge structure to mimic the effects of sea ice on nearshore waters. From the simulations we find that ice-affected deltas form a compound clinoform morphology, that is, a coupled subaerial and subaqueous delta separated by a subaqueous platform that resembles the shallow platform observed offshore of Arctic deltas. Nearshore sea ice affects river dynamics and promotes sediment bypassing during sea ice break-up, forming an offshore depocenter and building a subaqueous platform. A second depocenter forms closer to shore during the open-water season at the subaerial foreset that aids in outbuilding the subaerial delta and assists in developing the compound clinoform morphology. Simulations of increased wave activity and reduced sea-ice, likely futures under a warming Arctic climate, show that deltas may lose their shallow platform on centennial timescales by (a) sediment infill and/or (b) wave erosion. This study highlights the importance of sea ice on Arctic delta morphology and the potential morphologic transitions these high-latitude deltas may experience as the Arctic continues to warm.</p>\",\"PeriodicalId\":15887,\"journal\":{\"name\":\"Journal of Geophysical Research: Earth Surface\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2024-09-05\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JF007742\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Geophysical Research: Earth Surface\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1029/2024JF007742\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Earth Surface","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2024JF007742","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Effects of Sea Ice on Arctic Delta Evolution: A Modeling Study of the Colville River Delta, Alaska
Seasonal sea ice impacts Arctic delta morphology by limiting wave and river influences and altering river-to-ocean sediment pathways. However, the long-term effects of sea ice on delta morphology remain poorly known. To address this gap, 1D morphologic and hydrodynamic simulations were set up in Delft3D to study the 1500-year development of Arctic deltas during the most energetic Arctic seasons: spring break-up/freshet, summer open-water, and autumn freeze-up. The model focused on the deltaic clinoform (i.e., the vertical cross-sectional view of a delta) and used a floating barge structure to mimic the effects of sea ice on nearshore waters. From the simulations we find that ice-affected deltas form a compound clinoform morphology, that is, a coupled subaerial and subaqueous delta separated by a subaqueous platform that resembles the shallow platform observed offshore of Arctic deltas. Nearshore sea ice affects river dynamics and promotes sediment bypassing during sea ice break-up, forming an offshore depocenter and building a subaqueous platform. A second depocenter forms closer to shore during the open-water season at the subaerial foreset that aids in outbuilding the subaerial delta and assists in developing the compound clinoform morphology. Simulations of increased wave activity and reduced sea-ice, likely futures under a warming Arctic climate, show that deltas may lose their shallow platform on centennial timescales by (a) sediment infill and/or (b) wave erosion. This study highlights the importance of sea ice on Arctic delta morphology and the potential morphologic transitions these high-latitude deltas may experience as the Arctic continues to warm.