| YANG Yang,GAO Shu,ZHOU Liang,WANG Yunwei,LI Gaocong,WANG Yaping,HAN Zhuochen,JIA Peihong. 2017. Classifying the sedimentary environments of the Xincun Lagoon, Hainan Island, by system cluster and principal component analyses. Acta Oceanologica Sinica, 36(4):64－71 |
| Classifying the sedimentary environments of the Xincun Lagoon, Hainan Island, by system cluster and principal component analyses |
| 系统聚类和主成分分析在现代沉积环境划分中的应用-以海南新村港潟湖为例 |
| Received:December 19, 2015 Revised:June 22, 2016 |
| DOI：10.1007/s13131-016-0939-1 |
| Key words:surficial sediment grain size lagoon sedimentary environment statistical analysis numerical simulation Hainan Island |
| 中文关键词: 表层沉积物 粒度 沉积环境 统计分析 数值模拟 海南岛 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | YANG Yang | State Key Laboratory for Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | | | GAO Shu | State Key Laboratory for Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | sgao@sklec.ecnu.edu.cn | | ZHOU Liang | State Key Laboratory for Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China
Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | | | WANG Yunwei | College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China | | | LI Gaocong | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | | | WANG Yaping | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | | | HAN Zhuochen | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | | | JIA Peihong | Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University, Nanjing 210093, China | |
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| Abstract: |
| An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology, ecology, tourism and aquaculture studies. We attempt to deal with this issue, using a case study from the Xincun Lagoon, Hainan Island in southern China. For the study, surficial sediment samples were collected, together with hydrodynamic and bathymetric surveys, during August 2013. Numerical simulation was carried out to obtain high-spatial resolution tidal current data. The sediment samples were analyzed to derive mean grain size, sorting coefficient, skewness and kurtosis, together with the sand, silt and clay contents. The modern sedimentary environments were classified using system cluster and principal component analyses. Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud (ESSSM) and slightly silty sand (SSS), which are distributed in the central lagoon and near-shore shallow water areas, respectively. Mean grain size varies from 0 to 8.0Ф, with an average of 4.6Ф. The silt content is the highest, i.e., 52% on average, with the average contents of sand and clay being 43% and 5%, respectively. There exists a significant correlation between mean size and water depth, suggesting that the surficial sediments become finer with increasing water depth. Cluster analyses reveals two groups of samples. The first group is characterized by mean grain size of more than 5.5Ф, whilst the second group has mean grain size of below 3.5Ф. Further, these groups also have different correlations between mean grain size and the other grain size parameters. In terms of the tidal current, the average values of the root mean square velocity (RMSV) are 7.5 cm/s and 6.9 cm/s on springs and neaps, respectively. For the RMSVs that are higher than 4 cm/s, a significant positive correlation is found between the content of the 63-125 μm fraction and the RMSV, suggesting that the RMSV determines the variability of the very fine sand fraction. Based on system cluster and principal component analyses (PCA), the modern sedimentary environments are classified into three types according to the grain size parameters, RMSVs and water depth data. The results suggest the importance of grain size parameters and high-spatial resolution hydrodynamic data in differentiating the coastal sedimentary environments. |
| 中文摘要: |
| 以表层沉积物的粒度参数、水动力和水深数据为依据，基于系统聚类和主成分分析法，分析探讨了海南岛东南部新村港潟湖的现代沉积环境。结果表明，潟湖底质类型主要有极粉砂-砂质泥，粉砂-砂质泥，粉砂质砂，极粉砂质砂和砂五种类型，其中以极粉砂-砂质泥和粉砂质砂为主，分别分布在潟湖中部和近岸浅水区域。沉积物粒度组分以砂（平均含量43%）和粉砂（平均含量为52%）为主，黏土含量较少（平均含量为5%）。平均粒径变化范围为0-8.0 Ф，均值为4.6 Ф，平均粒径与水深呈显著的正相关关系，表明沉积物随水深增大而逐渐变细。聚类分析结果表明，平均粒径可分为2组，第一组平均粒径>5.5Ф，均值为6.8Ф，第二组平均粒径<3.5Ф，均值为2.2Ф。2组平均粒径分别与分选系数、偏态和峰态之间呈现出不同的相关关系。数值模拟结果显示，研究区大潮和小潮期间的均方根流速（RMSV）平均值为7.5和6.9 cm/s，且当RMSV大于4 cm/s，RMSV与63-125μm含量呈明显的正相关关系，这表明RMSV决定了潟湖中极细砂含量的分布。聚类和主成分分析结果表明，采用适宜的粒度参数（平均粒径、分选和峰态）、高空间分辨率的RMSV和水深数据，可将研究区沉积环境划分为3类。这样划分充分考虑了水动力，物源，地形及其相互作用，说明系统聚类和主成分分析法是划分沉积环境的有效手段。 |
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