洱海流域常用非同源LULC产品一致性分析和精度评估

    Consistency analysis and accuracy evaluation of commonly-used non-homologous LULC products in Erhai Lake Basin of China

    • 摘要: 高精度的土地利用/土地覆盖(land use/land cover, LULC)信息对于应对当前的环境挑战至关重要。尽管全球高分辨率 LULC 数据产品蓬勃发展,但多源数据存在不同程度的不确定性,在区域尺度如何选择适宜的 LULC 产品成为各领域应用中的难题。该研究以洱海流域为例,结合国土变更调查数据,通过公里网格采样、实地调查、高分影像解译获取了 2 947 个验证样本,对 7 套常用非同源 LULC 数据产品进行了面积、空间一致性、混淆程度分析和精度评估,定量分析了 LULC 产品制图精度的影响因素以及各数据集优缺点与适用性。结果表明:1)洱海流域8 套土地覆被数据集中高一致性区域、中一致性、低一致性区域分别占总面积的 64.13%、34.00%和 1.87%,且均存在对灌木和草地的错分、混淆严重的现象,不同产品对不同区域、不同地类的刻画能力差异明显。2)各 LULC 产品的总体精度在 69.5%~81.1%之间。相较其他开源 LULC 数据,ESA_WC 提供了较好的数据质量和空间细节,尤其对于破碎景观下的耕地识别。3)香农多样性指数对洱海流域土地覆被空间一致性差异影响最大,其次是灌木林地占比,而高程标准差、斑块面积大小和云覆盖频率的影响并不明显。对洱海流域土地覆盖进行全要素研究时,10 m 分辨率数据可选择总体精度最高的 ESA_WC;30 m 分辨率数据中CLCD 数据的精度较高,但相比其他产品显著低估了不透水面面积,不适用于城市扩张等研究。针对特定的应用需求,可参考该文提供的 7 种 LULC 产品的分类精度和优缺点,有针对性地进行数据选择。

       

      Abstract: Land Use and Land Cover (LULC) is the direct and concentrated reflection of the interaction between human activities and natural geographical environment. High-precision LULC information can also depend mainly on the global climate change, material cycle and dynamic balance of water and heat. Current environmental challenges were remained with the rapid increase in remote sensing observation platforms, the free disclosure of high-resolution satellite remote sensing data and the advancement of LULC mapping technology. Freely available medium and high-resolution land cover products are emerging for the open source. The medium and high resolution LULC datasets have also been constructed worldwide. However, there are different degrees of uncertainty in the multi-source data. It is a high demand for the suitable land cover products at the regional scale in various fields. Therefore, it is very important to evaluate the accuracy of the current commonly-used land cover data at the regional scale. Taking the Erhai Lake Basin as the study area, the consistency analysis was carried out to evaluate accuracy of commonly-used non-homologous LULC products. 2 947 validation samples were collected using Third National Land Survey data, the kilometer grid sampling, field surveys, and high-resolution image interpretation. Seven commonly-used heterogeneous LULC data products were evaluated, in terms of area, spatial consistency, confusion levels, and accuracy. The influence of LULC product mapping accuracy was quantitatively analyzed from four aspects: shrub forest proportion, landscape pattern index, elevation standard deviation and average patch area. The applicability of each dataset was also evaluated. The results reveal that the high, moderate, and low consistency areas were represented by 64.13%, 34.00%, and 1.87% of the total area, respectively, among the eight datasets of land cover. Notable confusion and misclassification occurred in shrub land and grassland, indicating the significant differences in the various products to represent different regions and land cover types. The overall accuracy of the LULC products was ranged from 69.5% to 81.1%. Notably, ESA_WC was offered the best data quality and spatial detail, especially for the cultivated land in fragmented landscapes. Additionally, the Shannon Diversity Index (SHDI) was found to share the most considerable impact on spatial consistency of land cover in the Erhai Basin, followed by the proportion of shrub land. In contrast, there was the less effect of some factors, such as elevation standard deviation, patch size, and cloud cover frequency. In all features of land cover, 10 m resolution data should prioritize the highest overall accuracy provided by ESA_WC. Among them, CRLC data was better performed, if the shrubland and grassland were not subdivided. While for 30 m resolution data, CLCD demonstrated the relatively high accuracy. The impermeable surface area was significantly underestimated, compared with the rest products unsuitable for urban expansion. This finding can serve as a valuable reference to assess the classification accuracy, strengths and weaknesses of the seven LULC products. Targeted data selection was facilitated for the specific applications. The accuracy of LULC products was directly evaluated for the applicability and adaptation of the data. The finding can provide the scientific basis for ecological environment protection, rational utilization of resources and sustainable development in plateau mountainous areas.

       

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