Decrease in production capacity of soils is one of the problems in the country. This decrease is affected by factors such as soil erosion, especially surface erosion. Exit of more than 2 billion tons of sediment per year from the watersheds of the country shows the depth of the disaster. Among other factors that play a major role in reducing the fertility of soils is the salinity of land. This phenomenon occurs in natural resources (low lands) and agricultural lands (inappropriate drainage and improper management). Preparation of soil salinity map is one of the first steps in identifying these areas.
There are several methods that can be used to achieve this goal. One of these methods is the application of satellite imagery and spectral reflections in order to provide a map of salinity in different regions of the country, because these images are completely new and up-to-date and display the latest changes on the Earth's surface.
In this paper, which is the result of implementation of research project, the application of satellite imagery in preparation of Qazvin plain salinity map using satellite images of Landsat ETM in 2000 and Landsat TM in 1987 in a spectrophotometric manner was investigated. Comparison of the obtained results with experimental data of soil samples and field observations confirms the high accuracy (83.3%) of the prepared Qazvin salinity map by the spectral method.