| Abstract:
Soil salinization is a predominant process in the degradation of arid and semi-arid soils that causes reduced the yield of crops, increases erosion and intensifies desertification. The Zahed Shahr studied area is located in the south and east of Fasa city, Fars province and in recent years the soil salinity has affected large areas of the farms and gardens in this area. The aim of this study was to evaluate the salinity changes of the soils during a 17 year period using Landsat 7 and 8 satellite images using the spectral angle mapping method. To do research, the salty soil spectra were extracted from satellite data and then using supervised classification the areas with salty soil were identified changes in salinity soils in ArcGIS software were investigated. Field studies, soil surface sampling, chemical analysis and spectral analysis of soil were performed by Spectroradiometer, and X-ray diffraction analysis for mineral identification was done. The results obtained from visible and shortwave infrared Spectroradiometer, and X-ray diffraction analysis showed the presence of evaporites minerals (calcite, halite, gypsum). By comparison with real ground data, the spectral angle mapper method was identified to be efficient in the classification of soil salinity. The results of the SAM method for a period of 17 years show four times spatial increase in soil salinity in this area. The area of saline soils has increased from 1600 hectares in 2000 to 6500 hectares in 2017.
|