多源土地覆被产品在长三角地区的一致性分析与精度评价

    Consistency analysis and accuracy assessment of multi-source land cover products in the Yangtze River Delta

    • 摘要: 土地覆被数据是全球环境问题,人类活动对生态系统影响评估等相关研究的重要数据源。近年来国内外生产了众多全球尺度或国家尺度上的土地覆被数据集,这些数据集在应用于特定区域研究时精度的可靠性以及多源数据集间的一致性对数据集的选择有着重要意义。该研究以长三角为研究区域,采用混淆矩阵、构成相似性分析和空间一致性分析等方法,对CCI_LC、FROM-GLC、GLC_FCS30、GLCNMO、GlobeLand30和CGLS_LC 6种土地覆被数据集进行了基本精度验证及一致性分析,并探讨了面向不同用户需求的土地覆被数据产品的适用性。结果表明:CCI_LC、FROM-GLC、GLC_FCS30、GLCNMO、GlobeLand30和CGLS_LC在长三角地区的总体精度分别为76.89%、78.42%、84.67%、74.26%、80.61%和85.43%;产品间土地覆被类型面积估算的相关系数均大于0.9;FROM-GLC、GLC_FCS30和GlobeLand30三套产品对长三角地区65.51%的土地分类有完全一致性,产品间一致性分别为72.23%、77.99%和76.41%。6种产品对于广泛分布且占研究区大部分面积的耕地、林地、水体和建设用地具有较好的分类精度,湿地、裸地、灌丛和草地分类结果较弱,需要辅助其他数据产品使用。结合地形地貌分析来看,长三角地区土地覆被分类精度整体受地形起伏影响较小,但丘陵密布的浙江省的部分区域受地形影响出现了分类不稳定的情况。从城市发展的角度看,长三角地区土地覆被分类精度受到城市经济发展活跃程度影响。面向用户应用需求来看,耕地类型上CGLS_LC数据具有最优表现,林地和建设用地类别上GLC_FCS30和CGLS_LC具有相近的优秀表现,而水体类别则是FROM-GLC数据更具有优势。

       

      Abstract: Abstract: Land cover change is one of the most important data sources for global environmental issues, such as the impact assessment of human activities on ecosystems. Since a great number of land cover datasets have been produced at the global and national scale in recent years, it is necessary to scientifically evaluate the reliability of these datasets in specific areas and the consistency between multi-source datasets in the selection of products. There are great changes in land cover, leading to high demand for the land cover data in the Yangtze River Delta, which is one of the most active and open regions in economic development with the strongest innovation capabilities in China. Taking the Yangtze River Delta region as the study area, this study aims to assess the relative accuracy of six land cover datasets (CCI_LC, FROM-GLC, GLC_FCS30, GLCNMO, GlobeLand30, and CGLS_LC) using the accuracy validation and consistency analysis. Five ways were selected to verify the accuracy, including the confusion matrix, overall accuracy, Kappa coefficient, user and producer accuracy. The correlation of land cover types in the study area was analyzed to calculate the proportions of various types in land cover products and the correlation coefficients. Three 30m-resolution land cover products (FROM-GLC, GLC_FCS30, and GlobeLand30) were also compared via the consistency distribution of classification, overall consistency, quantity and allocation disagreement between them. The results show that the overall accuracy of six products in the Yangtze River Delta region were 76.89%, 78.42%, 84.67%, 74.26%, 80.61%, and 85.43%, respectively, indicating that all of land cover products behaved fine accuracies. The correlation coefficients of land cover types were greater than 0.9 in six products. The best correlation was achieved in the GlobeLand30 with the most reliable estimation on the area of land cover types. Three 30m-resolution land cover products had 65.51% similar classified pixels, while, the overall consistencies between the products were 72.23%, 77.99%, and 76.41%, respectively. A fine data support was obtained from three land cover products, although with a little pixel confusion. In addition, the greatest stability was achieved in GLC_FCS30 with high accuracy of land cover types, particularly on the second-level categories for a more detailed description of land cover. High accuracy of classification was obtained in six land cover products for the cropland, woodland, water body, and impervious areas that were widely distributed in most of the research area. Nevertheless, there was a low accuracy of classification for the wetland, bare land, shrub and grassland. There was less influence of topographical fluctuations on the accuracy of classification in topography and geomorphology. Specifically, only a few unstable topographical classifications occurred in the hilly areas of Zhejiang Province. Correspondingly, the economic level dominated the accuracy of classification in urban development. The land cover products also considered the needs of different users. The best performance of CGLS_LC was achieved in cropland, and the similar excellent performance of GLC_FCS30 and CGLS_LC was found in woodland and impervious areas, while FROM-GLC was the most suitable for the water body.

       

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