The local salinity maps of the present-state taking the sites Musaib and Dujaila as an example [Fig. 3(a) and (b)] are in a good agreement with ground data (R2 = 0.830 in Musaib, and 0.826 in Dujaila). We consider that these maps are reliable. As for the regional salinity map (Fig. 4), the accuracy evaluation revealed that 23 of the 121 regional samples taken along two transects and the surface EC of 27 soil profiles in pilot sites that were not used for modeling were abnormal due to internal problem of samples, most probably, derived from laboratory analysis (because the correlation among Cl −, Na+, and EC is very low, e.g., R2 = 0.047); however, the remaining 98 samples show a good accordance with remote sensing predicted salinity. The observation accuracy is 80.9%, and the statistical accuracy of the regional salinity map obtained by linear regression analysis at the confidence level of 95% is 80.02% (Fig. 5). Therefore, the regional map presented in Fig. 4 was considered reliable. The agreement between the measured and remote sensing predicted salinity as shown in Fig. 5 is higher in the high salinity part than low salinity one. This is probably due to the fact that coarse-resolution LST has lower sensitivity to low salinity. An overestimation of about 2–10 dS/m may occur in some places in the weakly salinized areas. However, the sensitivity to low salinity can be improved if high resolution LST data are available. One may have concern about the reasonability to use soil surface temperature, LST, as salinity indicator which was finally retained in the models for the nonvegetated areas. As Wu et al. [29] argued, it is commonly known that thermal conductivity of materials is temperature (T)-dependent, and the former is associated with electrical conductivity (EC). However, the interrelationship between the thermal and electrical conductivities is complex and may change significantly depending on materials, e.g., soil types. Some authors have explored the possibility to use the thermal band to identify the salt-affected soils but they have not discussed the mechanism behind. Abu-Hamdeh and Reeder [57] ascertained the relationship between thermal conductivity and salinity, and found that thermal conductivity decreases with the increase in the amount of added salts at given moisture content. Sepaskhah and Boersma [58] found that the apparent thermal conductivity is independent of water content at very low water contents. Consequently, in driest condition (at lowest moisture or water content), thermal conductivity is associated with the salt amount—salinity.