陈红艳, 赵庚星, 陈敬春, 王瑞燕, 高明秀. 基于改进植被指数的黄河口区盐渍土盐分遥感反演[J]. 农业工程学报, 2015, 31(5): 107-114. DOI: 10.3969/j.issn.1002-6819.2015.05.016
    引用本文: 陈红艳, 赵庚星, 陈敬春, 王瑞燕, 高明秀. 基于改进植被指数的黄河口区盐渍土盐分遥感反演[J]. 农业工程学报, 2015, 31(5): 107-114. DOI: 10.3969/j.issn.1002-6819.2015.05.016
    Chen Hongyan, Zhao Gengxing, Chen Jingchun, Wang Ruiyan, Gao Mingxiu. Remote sensing inversion of saline soil salinity based on modified vegetation index in estuary area of Yellow River[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2015, 31(5): 107-114. DOI: 10.3969/j.issn.1002-6819.2015.05.016
    Citation: Chen Hongyan, Zhao Gengxing, Chen Jingchun, Wang Ruiyan, Gao Mingxiu. Remote sensing inversion of saline soil salinity based on modified vegetation index in estuary area of Yellow River[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2015, 31(5): 107-114. DOI: 10.3969/j.issn.1002-6819.2015.05.016

    基于改进植被指数的黄河口区盐渍土盐分遥感反演

    Remote sensing inversion of saline soil salinity based on modified vegetation index in estuary area of Yellow River

    • 摘要: 快速获取土壤盐分的含量、特征及空间分布信息是盐渍土治理、利用的客观需求。该文针对黄河三角洲盐渍土,以垦利县为例,基于Landsat 8 OLI 多光谱影像,在传统植被指数的基础上引入短波红外波段进行扩展,提出了改进植被指数;然后基于改进前后对应的植被指数,分别采用多元逐步回归(multivariable linear regression,MLR)、反向传播神经网络(back propagation neural networks,BPNN)和支持向量机(support vector machine,SVM)方法构建土壤盐分含量的遥感反演模型,并进行模型验证、对比和优选;最后基于最佳模型进行研究区土壤盐分含量的空间分布反演和分析。结果显示:相对传统植被指数,扩展后植被指数可增强与土壤盐分的相关性,大幅降低指数间的多重共线性;采用上述3种方法建模,改进后模型的精度比改进前都有提高,验证集决定系数R2提高0.04~0.10,均方根误差RMSE降低0.13~0.73,相对分析误差RPD提高0.25~0.34,改进后模型RPD均大于2.0,普遍达到性能良好;对比3种建模方法,SVM建模精度最高,BPNN模型次之,MLR分析精度最低,最佳模型为基于改进植被指数的土壤盐分含量支持向量机反演模型,建模集R2和RMSE为0.75、3.48,验证集R2、RMSE和RPD为0.78、3.02和2.56,模型较为准确、可靠;基于该模型反演的研究区土壤盐分含量整体较高,盐渍化程度空间分布表现为自西南部农业生产区至东北沿海区域逐渐加重,与实地调查一致。研究表明基于Landsat 8 OLI多光谱影像,引入第7波段对植被指数进行改进,从而构建土壤盐分含量的支持向量机模型,可获得较好的土壤盐分空间分布反演结果。

       

      Abstract: Abstract: Fast acquisition of the soil salt content, characteristics, and spatial distributing are the objective needs of saline soil management and utilization. This paper focused on the saline soil on the Yellow River Delta, and took Kenli County as an example. Based on the multi-spectral remote sensing image of Landsat 8 OLI, the traditional vegetation index (VI) was extended by adding the short-wave infrared band, and the modified vegetation index (MVI) was put forward. Then, based on the corresponding VI and MVI, using multivariate stepwise regression (MLR), a back propagation neural network (BPNN), and the support vector machine (SVM) method respectively, the remote sensing inversion models of soil salinity were built, validated, and compared. Finally, the spatial distribution of soil salinity was analyzed using the best model in the study area. The results indicated that the correlation between the vegetation indices and soil salinity was heightened and the multicollinearity between vegetation indices was greatly reduced by extending the traditional vegetation index. Extended normalized difference vegetation index(ENDVI) and extended ratio vegetation index (ERVI) which were added band 7 were selected as the modified vegetation index(MVI). Using MLR, a BPNN and the SVM method, the precision of the models based on the MVI was improved compared to the VI with the calibration coefficient of determination (R2) raised between 0.05 and 0.11, and the calibration root mean squares error (RMSE) reduced between 0.09 and 0.55, the validation R2 raised between 0.04 and 0.10, the validation RMSE reduced between 0.13 and 0.73, and the validation relative prediction deviation (RPD) raised between 0.25 and 0.34. The models based on MVI obtained generally good performance with the validation RPD greater than 2.00. The main reasons improved the model precision were that the band 7 on Landsat 8 OLI had more information and the MVI including band 7 could more protrude the difference in vegetation coverage and production status. Comparing the three modeling methods, the SVM achieved the highest accuracy, the second was the BPNN, and the MLR analysis resulted in the lowest accuracy. With the calibration R2 and RMSE of 0.75 and 3.48, the validation R2, RMSE and RPD of 0.78, 3.02 and 2.56, the SVM model of soil salinity based on MVI was the best and obtained very high accuracy and reliability for remote sensing inversion of soil salinity content. The spatial distribution of soil salinity content in the study area was analyzed based on the best model. The statistical information of the inversed soil salinity was very close to the measured value of soil samples, the soil salinity content in the study area was very high generally, the area that belonged to severe saline soil and solonchak accounted for 77.91%, and the spatial distribution of soil salinization showed that the soil salinity content was gradually increased from the southwest agriculture region to the northeast coastal region, which was consistent with the field survey and geostatistical analysis. Therefore, the experiment indicated that the vegetation index was modified by introducing the band 7 based on Landsat 8 OLI, and the SVM model of soil salinity was built, which could obtain better inversion result of soil salinity spatial distribution.

       

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