Evaluating the Spatiotemporal Variations of Soil Salinity Using Remote Sensing Technique (Case Study: Rudasht, Isfahan)

Remote sensing technique is an effective and reliable tool in management and monitoring soil salinity. Saline lands can be assessed, mapped, and monitored in different regions using remote sensing techniques. This study was conducted in the Rudasht Region of Isfahan with the aim of investigating changes in soil salinity and its relationship with soil water, as well as the state of vegetation using spectral ratio indices of remote sensing techniques in different years. To achieve this goal, multispectral LANDSAT series of 1994, 1998, 2014, and 2017 were used and three spectral ratio indices were calculated, including Normalized Difference Vegetation Index (NDVI), Normalized Difference Salinity Index (NDSI), and Normalized Difference Water Index (NDWI). Also, 100 soil samples were taken from a depth of 0-30 cm with appropriate spatial distribution from the Rudasht region to measure the electrical conductivity (EC) to match the ground data and the results of the spectral ratio indices. The results indicate that during these 23 years, salinity has increased and a large part of the studied area with dense vegetation has turned into low density vegetation and saline lands. According to the results, allocating fresh water with low EC to farmers in the second half of the year may be a good solution to deal with salinity problems. Also, the findings show that the Rudasht region is exposed to severe salinity and if not properly managed, there is a risk of turning agricultural lands into uncultivable saline lands.