Monitoring Soil Salinity Changes, Comparison of Different Maps and Indices Extracted from Landsat Satellite Images (Case Study: Atabieh, Khuzestan)
Fatemeh Golabkesh 1, 2  
,   Navid Ghanavati 2  
,   Ahad Nazarpour 3  
,   Timmor Babaei Nejad 2  
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Department of Soil Sciences, Khuzestan Science and Research Branch, Islamic Azad University, Ahvaz, Iran
Department of Soil Sciences, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
Department of Geology, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
Ahad Nazarpour   

Department of Geology, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran, Iran
Submission date: 2020-02-18
Final revision date: 2020-05-29
Acceptance date: 2020-06-03
Online publication date: 2020-10-16
Soil salinity is the dominant process in the degradation of arid and semi-arid soils, which in turn reduces crop yields, increases erosion, and exacerbates desertification. In recent years, soil salinity has affected much of the land in the Atabieh area located in the west of Khuzestan province in Iran. The purpose of this study was thus to evaluate and map soil salinity changes in the region over 15 years using Landsat 7 and 8 satellite images. To that end, the spectra of saline soils in the study area were extracted from the satellite data, and after the initial pre-processing in EVNI software version 5.3, the SI1, SI2, SI3, BI, NDVI, and NDSI indices were prepared. Using the supervised classification method, the salinity map with four different classes was then plotted in Arc GIS version 10.2, and the changes in saline soil area were investigated. Moreover, field surveys, surface soil sampling, soil EC measurement and identification of available minerals were performed by X-ray diffraction (XRD) technique and satellite images. Among the studied indices, the BI index with the highest correlation (0.71) was considered as the best index, and NDVI with the correlation coefficient of 0.35 at the 95% confidence level, was the best index for vegetation cover. Examination of changes in BI index by Landsat 7 images showed that the non-saline land area decreased from 1023.54 ha in 2000 to 143.43 ha in 2010, while the area with medium salinity increased by 14.57%. Besides, the salinity severity in the NDVI index had a growth rate of 72.86%. In turn, XRD studies confirmed the presence of abundant evaporate minerals (Halites, Calcite and Dolomite) corresponding to the values (real numbers) of salinity and mineralogical maps obtained from the Landsat 8 images.