Soil salinity and alkalinity seriously threaten crop production, soil productivity and sustainable agriculture, especially in arid and semi-arid areas, leading to land degradation, therefore, spatial distribution of these parameters are really important for successful management of such areas. The surface soil salinity and sodium adsorption ratio (SAR) have been modeled in this article. Auxiliary data were terrain attributes derived from digital elevation model (DEM), remote sensing spectral bands, and indices of vegetation and salinity derived from Landsat 8 OLI satellite. In total, 118 soil samples were collected from depth of 0-15 cm in homogenous units at Doviraj plain in the southern part of Ilam province, western Iran. Saturated electrical conductivity (ECe), SAR and other soil properties were analyzed and calculated. To model ECe and SAR parameters with the auxiliary data, stepwise multi linear regression (SMLR) and random forest (RF) regression were applied. The highest accuracy were obtained through RF model with validation coefficient of determination (R2val) =0.82 and 0.83 and validation root mean square error (RMSEval)=7.40 dS/m and 11.20 for ECe and SAR respectively. Furthermore, results indicated that strongest influence on the prediction of soil salinity followed by Band10, principal component analysis (PC3), Vertical Distance to Channel Network (VDCN) and Analytical Hill Shading (AH). Also, Band10, Band11, Flow Accumulation (FA) and Topographic Wetness Index (TWI) were the important covariate in alkalinity prediction through RF model. Finally, it is suggested that similar techniques can be used to map and monitor soil salinity and alkalinity in other parts of arid regions.