Abstract:The fusion technology based on measured hyperspectral and multispectral data was used to remote sensing inversion of soil salinity to improve the multispectral model precision, and the difference for different seasons was analyzed. Yongji of Hetao Irrigation District, a typical salinization region, was chosen as the study region for establishing hyper-multispectral inversion model of spring and autumn, respectively. The optimal spectral transformation and multiple stepwise regressions were used to get the characteristic bands and spectral indices by using the measured data of the hyperspectral inversion model and Landsat-8 OLI multispectral inversion model. Additionally, the fusion model was established with measured hyperspectral and multispectral data by multiple stepwise regression based on characteristic spectral indices. The results showed that the reflectivity of hyperspectral was 36.83% higher than that of the multispectral, and the average reflectivity in spring was 23.78% higher than that in autumn. The R2 of the training set and validation set of the hyper-multispectral inversion model with characteristic spectral indices were 0.651 and 0.635 on average, the RMSE were 2.44g/kg and 2.49g/kg on average, respectively, R2 were 36.19% and 35.64% higher than those of training set and validation set of the multispectral inversion model, and the RMSE were 34.28% and 41.72% lower than that, respectively. In addition, The accuracy of multispectral, hyperspectral and fusion inversion models in spring was higher than that in autumn, the R2 of the training set was improved by 6.03%, 6.05% and 4.40% on average, and the verification set was improved by 19.07%, 12.21% and 1.75% on average. The average salinity of the spring and autumn was 6.05g/kg and 5.97g/kg which used the hyper-multispectral fusion model inversed, respectively, and the average relative errors with the measured salinity were 9.65% and 10.68%, respectively. On the whole, the soil of this region was mainly highly salinization in spring and moderate salinization in autumn.
