Ground-penetrating radar and trenching studies of a barrier spit on the north shore of Huangqihai Lake were made,that reveal important implications for the coastal washover barrier boundary hierarchy and interpretatio...Ground-penetrating radar and trenching studies of a barrier spit on the north shore of Huangqihai Lake were made,that reveal important implications for the coastal washover barrier boundary hierarchy and interpretations of this depositional record.A four-fold hierarchy bounding-surface model,representing different levels of impact and genesis,is defined.Each level of the hierarchy is enclosed by a distinct kind of surface characterized by different ground-penetrating radar reflection features,sedimentary characteristics(color,grain size,sorting,rounding and sedimentary structures) and origin.We suggest that this hierarchical model can be applied to any coastal washover barrier deposits.展开更多
The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a nar...The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods. The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.展开更多
研究以渤海湾为生态系统服务需求区,以渤海湾滨海地区为生态系统服务供给区,从生态系统服务供需的视角,以水资源、水环境、水生态为问题与目标维度构建了渤海湾滨海地区生态安全屏障功能评价体系。根据渤海湾生态问题,截污净化、产水量...研究以渤海湾为生态系统服务需求区,以渤海湾滨海地区为生态系统服务供给区,从生态系统服务供需的视角,以水资源、水环境、水生态为问题与目标维度构建了渤海湾滨海地区生态安全屏障功能评价体系。根据渤海湾生态问题,截污净化、产水量和生境质量3类指标被筛选为生态安全屏障功能的关键指标,并分别使用生态系统服务和权衡的综合评估模型(Integrated Valuation of Ecosystem Services and Trade-offs,InVEST)模型中的营养物迁移模型、产水量模型和生境质量模型进行评价。此外,对2000—2020年渤海湾滨海地区土地利用格局和截污净化、产水量、生境质量3类生态安全屏障功能指标的时空变化进行评价,并分析了生态安全屏障功能时空演变的驱动因素。研究的主要结果如下:(1)在20 a间渤海湾滨海地区,耕地、未利用地面积减少而建设用地和湿地面积增加,氮磷截留率和产水量增加,但生境质量下降。(2)渤海湾滨海地区综合生态安全屏障功能供给良好,但近年来呈下降趋势。(3)人类活动引起的土地利用变化是影响渤海湾滨海地区生态安全屏障功能时空演变的主要驱动力。研究对渤海湾滨海地区生态安全屏障功能评价方法及结果不仅可指导本区域生态建设,同时对其他区域的生态安全屏障功能评价具有借鉴意义。展开更多
The interactions between regular surface waves and a surface-pitching slotted barrier are investigated both analytically and experimentally. A quasi-linear theory is developed using the eigenfunction expansion method....The interactions between regular surface waves and a surface-pitching slotted barrier are investigated both analytically and experimentally. A quasi-linear theory is developed using the eigenfunction expansion method. The energy dissipation within the barriers is modeled by a quadratic friction factor, and an equivalent linear dissipation coefficient, which is depth-varying, wave-height dependent, is introduced to linearize the matching condition at the surface-pitching barrier. By comparing the theoretical results with laboratory experiments, it is shown that the present method can satisfactorily predict the variation of the reflection and transmission coefficients with wave height.展开更多
The Denglou Cape, southwest of the Leizhou Peninsula, is the most typical tropical coast in the continent of China.The coastal geomorphic development basics of the geology and Quaternary environment change are discus...The Denglou Cape, southwest of the Leizhou Peninsula, is the most typical tropical coast in the continent of China.The coastal geomorphic development basics of the geology and Quaternary environment change are discussed. Aerial photograph interpretation with fieldwork is applied to draw the outlines of geomorphic types. Based on the investigative data, the exogenic forces and marine organism conditions concerning tropical coast development in the area are expounded, and coastal dynamo-deposition geomorphic bodies are analysed, mainly with sea cliff-abrasion platform,barrier-lagoon system, modern beach, coral reef and mangrove tidal flat, and the general process of coastal evolution at this area, as well as coastline changes since middle Holocene transgression.展开更多
Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best...Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best Spartina (S.) species to ameliorate the coast. Using graph theory in the Geometer’s Sketch Pad program, progressive land loss from Isles Dernieres was determined from 1853 to 2005. This was accomplished using Pick’s Theorem (A = I + B/2 - 1), where A = total land area, I = interior intersections, and B = boundary intersections. The analysis indicated that there had been more than ninety percent land loss from 1853 to 2005. Additionally, four plants from each Spartina species (alterniflora, patens, and spartinae) were planted and flooded in four containers, respectively, filled with potting soil, and a non-vegetated control was included in this same manner. Dissolved oxygen was measured three times a week under three different temperature regimes, twenty-two, thirty, and ten degrees Celsius, respectively. This resulted in the control group diffusing the most oxygen at twenty-two degrees Celsius, the S. alterniflora diffusing the most oxygen at thirty degrees Celsius, and all the species diffusing statistically similar oxygen levels at ten degrees Celsius. After six months of flooded conditions, penetration and subsidence were measured. The vegetated soils required the greatest penetration forces and subsided the least. Oxygen diffusion is dependent on plant species and temperature. The penetration and subsidence results also support the conclusion that plants can reduce land loss and preserve the coastline.展开更多
The radial tidal current field accounts for the formation of the radial sand ridges in the South Yellow Sea. Understanding the formation and evolution of this radial tidal current field is vital to assessing the morph...The radial tidal current field accounts for the formation of the radial sand ridges in the South Yellow Sea. Understanding the formation and evolution of this radial tidal current field is vital to assessing the morphodynamic features in the area. A semi-enclosed rectangular basin with and without a coastal barrier was schematized from the topography of the Bohai Sea and Yellow Sea. The 2D tidal current field in this basin was simulated using the DELFT3D-FLOW model. The concept of tidal wave refraction, which highlights the effect of the sloped or stepped submarine topography on the propagation of the tidal waves, was introduced to explain the formation of the radial tidal current field. Under the effect of tidal wave refraction, co-phase lines of the counterclockwise rotating tidal wave and incident tidal wave are transformed into clockwise and counterclockwise deflections, respectively, leading to the convergence and divergence of the flow field. Regardless of whether a coastal barrier exists or not, the outer radial tidal current field might emerge over certain topography. The responses of the radial tidal current field in this basin to the environmental variations such as coastline changes and bottom erosions were discussed. Results show that local protrusion near the focal point of the radial tidal current field will have limited effects on the location of the tidal system. However, a remarkable shift of the amphidromic point toward the entrance and central axis of this basin and a movement of the focal point of the radial tidal current field toward the entrance could be caused by the significant seaward coastline advance and submarine slope erosion.展开更多
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20120022130002)the State Scholarship Fund from the China Scholarship Council(No.201406400030)
文摘Ground-penetrating radar and trenching studies of a barrier spit on the north shore of Huangqihai Lake were made,that reveal important implications for the coastal washover barrier boundary hierarchy and interpretations of this depositional record.A four-fold hierarchy bounding-surface model,representing different levels of impact and genesis,is defined.Each level of the hierarchy is enclosed by a distinct kind of surface characterized by different ground-penetrating radar reflection features,sedimentary characteristics(color,grain size,sorting,rounding and sedimentary structures) and origin.We suggest that this hierarchical model can be applied to any coastal washover barrier deposits.
文摘The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods. The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.
文摘研究以渤海湾为生态系统服务需求区,以渤海湾滨海地区为生态系统服务供给区,从生态系统服务供需的视角,以水资源、水环境、水生态为问题与目标维度构建了渤海湾滨海地区生态安全屏障功能评价体系。根据渤海湾生态问题,截污净化、产水量和生境质量3类指标被筛选为生态安全屏障功能的关键指标,并分别使用生态系统服务和权衡的综合评估模型(Integrated Valuation of Ecosystem Services and Trade-offs,InVEST)模型中的营养物迁移模型、产水量模型和生境质量模型进行评价。此外,对2000—2020年渤海湾滨海地区土地利用格局和截污净化、产水量、生境质量3类生态安全屏障功能指标的时空变化进行评价,并分析了生态安全屏障功能时空演变的驱动因素。研究的主要结果如下:(1)在20 a间渤海湾滨海地区,耕地、未利用地面积减少而建设用地和湿地面积增加,氮磷截留率和产水量增加,但生境质量下降。(2)渤海湾滨海地区综合生态安全屏障功能供给良好,但近年来呈下降趋势。(3)人类活动引起的土地利用变化是影响渤海湾滨海地区生态安全屏障功能时空演变的主要驱动力。研究对渤海湾滨海地区生态安全屏障功能评价方法及结果不仅可指导本区域生态建设,同时对其他区域的生态安全屏障功能评价具有借鉴意义。
文摘The interactions between regular surface waves and a surface-pitching slotted barrier are investigated both analytically and experimentally. A quasi-linear theory is developed using the eigenfunction expansion method. The energy dissipation within the barriers is modeled by a quadratic friction factor, and an equivalent linear dissipation coefficient, which is depth-varying, wave-height dependent, is introduced to linearize the matching condition at the surface-pitching barrier. By comparing the theoretical results with laboratory experiments, it is shown that the present method can satisfactorily predict the variation of the reflection and transmission coefficients with wave height.
文摘The Denglou Cape, southwest of the Leizhou Peninsula, is the most typical tropical coast in the continent of China.The coastal geomorphic development basics of the geology and Quaternary environment change are discussed. Aerial photograph interpretation with fieldwork is applied to draw the outlines of geomorphic types. Based on the investigative data, the exogenic forces and marine organism conditions concerning tropical coast development in the area are expounded, and coastal dynamo-deposition geomorphic bodies are analysed, mainly with sea cliff-abrasion platform,barrier-lagoon system, modern beach, coral reef and mangrove tidal flat, and the general process of coastal evolution at this area, as well as coastline changes since middle Holocene transgression.
文摘Coastal erosion, subsidence, salt water intrusion, and hypoxia are forces that impact Louisiana and beyond. The objective of this research was to determine the extent of land loss due to erosion and establish the best Spartina (S.) species to ameliorate the coast. Using graph theory in the Geometer’s Sketch Pad program, progressive land loss from Isles Dernieres was determined from 1853 to 2005. This was accomplished using Pick’s Theorem (A = I + B/2 - 1), where A = total land area, I = interior intersections, and B = boundary intersections. The analysis indicated that there had been more than ninety percent land loss from 1853 to 2005. Additionally, four plants from each Spartina species (alterniflora, patens, and spartinae) were planted and flooded in four containers, respectively, filled with potting soil, and a non-vegetated control was included in this same manner. Dissolved oxygen was measured three times a week under three different temperature regimes, twenty-two, thirty, and ten degrees Celsius, respectively. This resulted in the control group diffusing the most oxygen at twenty-two degrees Celsius, the S. alterniflora diffusing the most oxygen at thirty degrees Celsius, and all the species diffusing statistically similar oxygen levels at ten degrees Celsius. After six months of flooded conditions, penetration and subsidence were measured. The vegetated soils required the greatest penetration forces and subsided the least. Oxygen diffusion is dependent on plant species and temperature. The penetration and subsidence results also support the conclusion that plants can reduce land loss and preserve the coastline.
基金Supported by the National Natural Science Foundation of China(Nos.51179067,51379072)the Special Funds for Scientific Research on Public Welfare of Ministry of Water Resources of China(No.201201045)the College Graduate Research and Innovation Project of Jiangsu Province,China(No.CXZZ12_0254)
文摘The radial tidal current field accounts for the formation of the radial sand ridges in the South Yellow Sea. Understanding the formation and evolution of this radial tidal current field is vital to assessing the morphodynamic features in the area. A semi-enclosed rectangular basin with and without a coastal barrier was schematized from the topography of the Bohai Sea and Yellow Sea. The 2D tidal current field in this basin was simulated using the DELFT3D-FLOW model. The concept of tidal wave refraction, which highlights the effect of the sloped or stepped submarine topography on the propagation of the tidal waves, was introduced to explain the formation of the radial tidal current field. Under the effect of tidal wave refraction, co-phase lines of the counterclockwise rotating tidal wave and incident tidal wave are transformed into clockwise and counterclockwise deflections, respectively, leading to the convergence and divergence of the flow field. Regardless of whether a coastal barrier exists or not, the outer radial tidal current field might emerge over certain topography. The responses of the radial tidal current field in this basin to the environmental variations such as coastline changes and bottom erosions were discussed. Results show that local protrusion near the focal point of the radial tidal current field will have limited effects on the location of the tidal system. However, a remarkable shift of the amphidromic point toward the entrance and central axis of this basin and a movement of the focal point of the radial tidal current field toward the entrance could be caused by the significant seaward coastline advance and submarine slope erosion.
