基于ZY1E遥感影像的杞麓湖流域耕地土壤有机质含量预测

Prediction of soil organic matter content in cultivated land of Qilu Lake basin based on ZY1E remote sensing images

  • 摘要: 【目的】 研究杞麓湖流域耕地土壤有机质(SOM)含量和卫星影像光谱的关系,明确土壤SOM的光谱特性,建立土壤SOM含量的反演模型,为杞麓湖流域耕地土壤精确施肥提供参考依据。【方法】 基于杞麓湖流域ZY1E高光谱遥感数据,选择原始反射率(RF)、一阶微分(FDR)、比值土壤指数(RSI)和归一化土壤指数(NDSI)作为自变量,与SOM含量进行相关分析筛选出敏感波段,分别构建一元线性回归模型和多元逐步回归模型,并反演出流域耕地SOM含量。【结果】 杞麓湖流域土壤中SOM含量不同光谱反射特性趋势相近,土壤的光谱反射率在900、1200、1500和2000 nm处出现吸收谷;对光谱进行不同数学变换,可提高土壤SOM含量与光谱反射率的相关性,其中NDSI和RSI的提升效果最佳;通过对各模型的精确度进行比较,以反射率的RSI构建的多元逐步回归模型拟合效果最优,其决定系数(R2)为0.80,均方根误差(RMSE)为6.96,验证模型SOM实测值和预测值的R2为0.82,RMSE为3.65;运用GIS空间分析功能,根据最优模型反演流域耕地SOM含量,多集中在35~45 g/kg,处于较高水平,且杞麓湖流域耕地土壤的SOM含量从西南向东北表现为低—高—低的分布特征。【建议】优化耕地土壤SOM含量变化的特征波长提取,可提高预测模型的精度;采用ZY1E高光谱遥感数据进行耕地土壤养分监测,可解决传统地理统计的受冗余信息影响问题,并为土壤精确施肥管理提供数据支持,提高土壤肥力和作物产量。

     

    Abstract: 【Objective】 To study the relationship between the content of soil organic matter(SOM) in cultivated land within the Qilu Lake basin and the spectra of satellite images, clarify the spectral characteristics of SOM, establish an inversion model for the content of SOM, which could provide reference basis for precise fertilization of cultivated land soil in Qilu Lake basin. 【Method】 Based on the ZY1E hyperspectral remote sensing data of the Qilu Lake basin, the original reflectance(RF), first order differentiation(FDR), ratio soil index(RSI) and normalized soil index(NDSI) were selected as independent variables, and the correlation analysis with SOM content was carried out to screen out the sensitive bands, and the univariate linear regression model and multiple stepwise regression model were constructed respectively,and the SOM content of cultivated land in the basin was inverted.【Result】The spectral reflectance characteristics of soil with SOM contents in Qilu Lake basin had similar trend, and the spectral reflectance of soil had absorption valley at 900,1200, 1500 and 2000 nm. The correlation between SOM content and spectral reflectance could be improved by different mathematical transformations of the spectrum, and NDSI and RSI had the best improvement effects. By comparing the accuracy of each model, the stepwise regression model constructed with the reflectance RSI had the best fitting effect, its coefficient of determination(R2) was 0.80, and the root mean square error(RMSE) was 6.96, the R2 of the measured and predicted values of the SOM in validation model was 0.82, and the RMSE was 3.65. Using GIS spatial analysis function,the SOM content of cultivated land in Qilu Lake basin was retrieved according to the optimal model, and most of the SOM content was concentrated in 35-45 g/kg, which was at a relatively high level. Moreover, the SOM content of cultivated land soil in Qilu Lake basin showed a low-high-low distribution from the southwest to the northeast.【Suggestion】Optimizing the extraction of characteristic wavelengths for the variation of SOM content in cultivated land soil can improve the accuracy of the prediction model; using the hyperspectral remote sensing data of ZY1E to monitor the nutrients in cultivated land soil can solve the problem of being affected by redundant information in traditional geostatistics, and provide data support for the precise fertilization management of soil, thereby enhancing soil fertility and crop yields.

     

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