Validation and comparison of physical models for soil salinity mapping over Kuwait territory using landsat-OLI and field data

The aim of this study is a validation and comparison among four different physical models for soil salinity mapping in arid land. The considered models were developed for different geographic regions around the world, i.e. Latino-America (Mexico), Middle-East (Iraq), North-Africa (Morocco) and Asia (China). Moreover, they consider different spectral bands and mathematical functions in their conceptualization (linear, second order, logarithmic and exponential). To achieve these objectives, three main steps were considered. Landsat-OLI image was radiometrically standardized and soil salinity maps were derived using the considered models. Synchronously with OLI data acquisition, a field soil sampling was organized and 100 soil samples with different degrees of salinity were collected and geographically localized using accurate GPS (σ ⩽ ± 30 cm). Then, soil laboratory analysis was accomplished to derive electrical conductivity (EC-
_Lab
) for validation purposes. Statistical analyses were then conducted between predicted salinity maps (EC-
_Predicted
) and the measured ground truth (EC-
_Lab
). Obtained result showed that the predictive model based on second order polynomial function and integrating the SWIR bands provides the best results in comparison to the ground truth (EC-
_Lab
), with correlation coefficient (R
₂
) of 0.97, an index of agreement (D) of 0.84 (p ≪ 0.05), and low overall RMSE of 11%.