The deltas serve as the primary interactive zone where terrestrial and marine environments converge,playing a pivotal role in the coastal deposition.In the Holocene,climate changes and sea level fluctuation are the pr...The deltas serve as the primary interactive zone where terrestrial and marine environments converge,playing a pivotal role in the coastal deposition.In the Holocene,climate changes and sea level fluctuation are the principal driving factors in the evolution of deltas.However,human activities such as the construction of dams and reservoirs in the Anthropocene have significantly altered sediment transport in rivers,leading to depositional pattern variation during deltaic evolution.In this study,we have conducted a comparative analysis of the morphological variations(1986-2021)in the barrier system of the Hanjiang River Delta(HRD)using satellite remote sensing(SRS)method.Additionally,we have examined the lithological changes and facies alterations observed in eight boreholes on the present barrier spit.Our findings indicate that the intensification of anthropogenic activities led to a significant reduction in the sediment flux of the Hanjiang River(HR),resulting in depocenter landward migration at the estuary.SRS analysis reveals their periodical morphological characteristics and spatial variations of estuarine sandbars(1986-1992),barrier islands-lagoons(1993-2009),and barrier spits(2010-2021)during 1986 to 2021.The stratigraphy of boreholes demonstrates a south-to-north facies transition from lagoon to lagoon-barrier spit and barrier spit in vertical lithology.Therefore,the depositional evolution of the HRD barrier system is categorized into three phases:estuarine sandbar-barrier island phase(1986-1998);barrier island-lagoon phase(1999-2009);and barrier spit phase(2010-2021).During the estuarine sandbar-barrier island phase,fluvial processes played a predominate role in the deposition.Consequently,with a significant decrease in river sediment load,the dominant factors driving depositional processes shifted towards wave action and alongshore current.Based on the conceptual model in the Holocene,we propose a modified depositional model of wave-dominated deltas during Anthropocene that encompasses three evolutionary phases:estuarine sandbars and delta front platforms,barrier island-lagoon formation and landward migration of barrier spits.This pattern highlights that human-induced reduction in river sediment flux has led to a seaward deltaic progradation driven by barrier landward migration.展开更多
基金The Guangdong Basic and Applied Basic Research Foundation under contract Nos 2024A1515012628the National Natural Science Foundation of China under contract Nos 41876059 and 42372213+4 种基金the Open Research Fund Program of Zhoushan Field Scientific Observation and Research Station for Marine Geo-hazards,China Geological Survey under contract No.ZSORS-22-5the Shantou University Scientific Research Foundation for Talents under contract No.NTF20028China-Association of Southeast Asian Nations(ASEAN)Maritime Cooperation Fund Project under contract No.12120100500017001China Geological Survey Projects under contract Nos DD20211553,DD20221710,and DD20230415the Science and Technology Innovation Fund of Command Center of Integrated Natural Resources Survey Center under contract No.KC20230017.
文摘The deltas serve as the primary interactive zone where terrestrial and marine environments converge,playing a pivotal role in the coastal deposition.In the Holocene,climate changes and sea level fluctuation are the principal driving factors in the evolution of deltas.However,human activities such as the construction of dams and reservoirs in the Anthropocene have significantly altered sediment transport in rivers,leading to depositional pattern variation during deltaic evolution.In this study,we have conducted a comparative analysis of the morphological variations(1986-2021)in the barrier system of the Hanjiang River Delta(HRD)using satellite remote sensing(SRS)method.Additionally,we have examined the lithological changes and facies alterations observed in eight boreholes on the present barrier spit.Our findings indicate that the intensification of anthropogenic activities led to a significant reduction in the sediment flux of the Hanjiang River(HR),resulting in depocenter landward migration at the estuary.SRS analysis reveals their periodical morphological characteristics and spatial variations of estuarine sandbars(1986-1992),barrier islands-lagoons(1993-2009),and barrier spits(2010-2021)during 1986 to 2021.The stratigraphy of boreholes demonstrates a south-to-north facies transition from lagoon to lagoon-barrier spit and barrier spit in vertical lithology.Therefore,the depositional evolution of the HRD barrier system is categorized into three phases:estuarine sandbar-barrier island phase(1986-1998);barrier island-lagoon phase(1999-2009);and barrier spit phase(2010-2021).During the estuarine sandbar-barrier island phase,fluvial processes played a predominate role in the deposition.Consequently,with a significant decrease in river sediment load,the dominant factors driving depositional processes shifted towards wave action and alongshore current.Based on the conceptual model in the Holocene,we propose a modified depositional model of wave-dominated deltas during Anthropocene that encompasses three evolutionary phases:estuarine sandbars and delta front platforms,barrier island-lagoon formation and landward migration of barrier spits.This pattern highlights that human-induced reduction in river sediment flux has led to a seaward deltaic progradation driven by barrier landward migration.
