Based on the data from gauging stations,the changes in water discharge and sediment load of the Huanghe (Yellow)River were analyzed by using the empirical mode decomposition(EMD)method.The results show that the period...Based on the data from gauging stations,the changes in water discharge and sediment load of the Huanghe (Yellow)River were analyzed by using the empirical mode decomposition(EMD)method.The results show that the periodic oscillation of water discharge and sediment load of the Huanghe River occurs at the interannual,decadal,and multi-decadal scales,caused by the periodic oscillations of precipitation,and El Nio/Southern Oscillation(ENSO)affects water discharge by influencing precipitation distribution and contributes to periodic varations in precipitation and water discharge at interannual timescale.The water discharge and sediment load of the Huanghe River have decreased since the 1960s under the influence of precipitation and huamn activities,and human activities attribute more than precipitation to the reduction in the water discharge and sediment load,furthermore,water abstraction and water-soil conservation practices are the main causes of the decrease in water discharge and sediment load,respectively.The reduction in sediment load has directly impacted on the lower reaches of the Huanghe River and the river delta, causing considerable erosion of the river channel in the lower reaches since the 1970s along with River Delta changing siltation into erosion around 2000.展开更多
Patterns of grain-size distributions of suspended sediment in relation to resuspension, settling, and tidal processes are investigated, based on in situ measurements over the Dafeng intertidal flat, on the Jiangsu coa...Patterns of grain-size distributions of suspended sediment in relation to resuspension, settling, and tidal processes are investigated, based on in situ measurements over the Dafeng intertidal flat, on the Jiangsu coast, in the summer of 2002 and 2003. The suspended sediment here is dominated by fine and very fine silt, with a mean grain-size of 7 - 13 μm. The patterns of the grainsize distributions of suspended sediment during a tidal cycle are characterized by two types： one stable type representing insignificant spatial and temperal variations; and the other bimedal type with significant variations. The main factors influencing the grainsize distributions include resnspension, settling, suspended sediment imported into intertidal flats during the flood phase, and the grain-size distribution of seabed sediment. Resuspension increases the coarse particle content, enhances the mean grain-size of suspended sediment, and results in grain-size distributions for the suspended sediment similar to those of seabed sediment; the settling process has opposite effects on the suspended sediment. When resuspension occurs, the gain-size distributions of suspended sediment in the lower part of water column respond significantly to the current velocity. Where the influence of resuspension and settling processes is weak, the grain-size distributions of suspended sediment appear to be stable and almost identical for the various parts of intertidal flats during different measurement periods. Such distributions are referred to the background grain-size distribution, for which the mean grain-size over the Dafeng intertidal flat is around 7 μm.展开更多
The delta evolution and erosion process of the abandoned Yellow River Delta （AYRD） have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less...The delta evolution and erosion process of the abandoned Yellow River Delta （AYRD） have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model, In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance （De） with the average range value （Ao） of grain size parameter. Filtering method （removing data that not at a sampling station） is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta （AS） is better than that in the northern part of the abandoned Yellow River Delta （AN）. Sediment in the area is found to be anisotropy at the northeast-southeast direc- tion. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Do, Ao, sediment transport and delta evolution shows a close link between Do and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.展开更多
基金Under the auspices of Major State Basic Research Development Program of China(No.2010CB951202)Ocean Public Welfare Scientific Research Project,State Oceanic Administration of the People's Republic of China(No.200805063)
文摘Based on the data from gauging stations,the changes in water discharge and sediment load of the Huanghe (Yellow)River were analyzed by using the empirical mode decomposition(EMD)method.The results show that the periodic oscillation of water discharge and sediment load of the Huanghe River occurs at the interannual,decadal,and multi-decadal scales,caused by the periodic oscillations of precipitation,and El Nio/Southern Oscillation(ENSO)affects water discharge by influencing precipitation distribution and contributes to periodic varations in precipitation and water discharge at interannual timescale.The water discharge and sediment load of the Huanghe River have decreased since the 1960s under the influence of precipitation and huamn activities,and human activities attribute more than precipitation to the reduction in the water discharge and sediment load,furthermore,water abstraction and water-soil conservation practices are the main causes of the decrease in water discharge and sediment load,respectively.The reduction in sediment load has directly impacted on the lower reaches of the Huanghe River and the river delta, causing considerable erosion of the river channel in the lower reaches since the 1970s along with River Delta changing siltation into erosion around 2000.
基金The study was supported by the National Natural Science Foundation of China under contract Nos 40231010 and 2002CB412408by the Post-doctoral Research Foundation of Shanghai under contract No.05R214119.
文摘Patterns of grain-size distributions of suspended sediment in relation to resuspension, settling, and tidal processes are investigated, based on in situ measurements over the Dafeng intertidal flat, on the Jiangsu coast, in the summer of 2002 and 2003. The suspended sediment here is dominated by fine and very fine silt, with a mean grain-size of 7 - 13 μm. The patterns of the grainsize distributions of suspended sediment during a tidal cycle are characterized by two types： one stable type representing insignificant spatial and temperal variations; and the other bimedal type with significant variations. The main factors influencing the grainsize distributions include resnspension, settling, suspended sediment imported into intertidal flats during the flood phase, and the grain-size distribution of seabed sediment. Resuspension increases the coarse particle content, enhances the mean grain-size of suspended sediment, and results in grain-size distributions for the suspended sediment similar to those of seabed sediment; the settling process has opposite effects on the suspended sediment. When resuspension occurs, the gain-size distributions of suspended sediment in the lower part of water column respond significantly to the current velocity. Where the influence of resuspension and settling processes is weak, the grain-size distributions of suspended sediment appear to be stable and almost identical for the various parts of intertidal flats during different measurement periods. Such distributions are referred to the background grain-size distribution, for which the mean grain-size over the Dafeng intertidal flat is around 7 μm.
基金Special Funding of Global Change Research Major Scientific Research Plan Project,No.2010CB951202State Key Laboratory of Estuarine and Coastal Research,ECNU,No.SKLEC-2012KYYW06
文摘The delta evolution and erosion process of the abandoned Yellow River Delta （AYRD） have been extensively studied. However, the variation of sediment at a large littoral scale along the north coast of Jiangsu is less understood. In this study, the data of surface sediment samples obtained in the littoral area of the Yellow River Delta in 2006 and 2012 is used to study the sediment variability and sediment transport trends by using the geostatistics analysis tool and the grain size trend analysis model, In order to ensure the applicability of the model, the geostatistics method is used to determine the characteristic distance （De） with the average range value （Ao） of grain size parameter. Filtering method （removing data that not at a sampling station） is used to improve accuracy of data selection. The results show that sedimentary spatial correlation in Lianyun Port area and southern part of the abandoned Yellow River Delta （AS） is better than that in the northern part of the abandoned Yellow River Delta （AN）. Sediment in the area is found to be anisotropy at the northeast-southeast direc- tion. The grain size trend analysis reveals that the sediment trend is towards bayhead and southerly in the Haizhou Bay, southeasterly along the shoreline in the south Lianyun Port, northwesterly in AN and easterly-southeasterly in AS respectively. The investigation of possible relationships between Do, Ao, sediment transport and delta evolution shows a close link between Do and Ao of one sediment combination. It is also found that sediment transport trends could reasonably represent the delta evolution to a certain degree.
基金Thanks are due to Profs. Zhen Du and Li Xiaowen of the Chinese Academy of Sciences （CAS） for their instructions and encouragement. Special thanks to Profs. Yang Qinye, Wu Shaohong, Gong Peng, Liu Qinhuo, and Susan Kaspari for their great help with the research. The work is supported by the Special Funds for Major State Basic Research Project （Grant No. 2002CB412408）, by the National Natural Science Foundation of China （Grant Nos. 40371093, 40201005, 40471097）, by 0pening Fund projects of State Key Laboratory of Remote Sensing Science in the Institute of Remote Sensing Applications （Grant No. SK040006）, by 0pening Fund projects of State Key Laboratory of Estuarine and Coastal Research of East China Normal University （Grant No. 0310）.
文摘基于风景生态学 andGee 信息 Tupu 的图形、量的方法论，这篇论文学习风景黄河三角洲(YRD ) 的空间时间的进化特征，它被黄河(年) 尾部隧道的周期的物理秋千在 1855-2000 期间建立。根据关于 YRDand 年尾部隧道的空间时间的进化的研究，我们断定 Qingshuigou 隧道到达了它的限制，一条新流动隧道迟早多年应该被建立。它建议年隧道的移动应该接受它在以前的隧道之中通过消沉流动的自然规则并且能被人造的努力执行。论文在河口在 YR 流动为淤泥的高内容的处理外面讨论这些问题和交替的方法。
