Mapping soil surface salinity using remote sensing data of ETM+ (Case study: North of Agh Ghala, Golestan Province)

This study was done in order to submit a model for salinity map made with ETM⁺ satellite data and salinity values in a district in North of Agh Ghala in Golestan province. The Geometric and atmospheric correction of Satellite images were carried out Processings such as; multispectral bands fusion with panchromatic band, tasseled cap transformation, principal component analysis, and ratioing for composite bands creation were done. The regular sampling grid with 2×10 km dimension and different intervals were designed and performed on the study area. Soil samples (169 samples) were taken from 0-5 cm depth with intervals of 50, 100, 250, 1000 m and their electrical conductivity (EC) were measured. The location of the samples was determined by GPS and samples location map was made with GIS software. Spectral values for each sample were extracted by different bands. Correlation between spectral values i.e. (main bands, tasseled cap bands, principal component analysis and composite bands) with electrical conductivity values were investigated for 80% of the samples. By determining correlated bands and selecting desirable bands for contributing in model, primary results showed that correlation between electrical conductivity values with B4 bands, brightness, greenness and fuse B4 were significant in 1% level. After selecting the best model, cross validation was calculated with 20% samples for determinating ME and RMSE parameters. Cross validation results showed the suitable estimation of model with ME and RMSE values was equal to -0.18 and 55.6 dS/m, respectively. Finally, salinity map was prepared using submitted regression model. In this research, results confirmed that salinity changes can be evaluated by digital data of ETM⁺ and it's composites in district of north Agh Ghala with 2000 ha area.