Soil Salinity Mapping Based on ETM+ Data in Iran Arid Rangeland (case study: Damghan region)

Document Type: Research and Full Length Article

Authors

1 Ph.D. in Combat Desertification, Yazd University, Yazd, Iran

2 Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran

Abstract

Soil salinity has long concerned people in arid and semi-arid rangelands. One of the most essential cases of information for managers of natural resources is, preparation of soil salinity maps. Developing such maps using traditional methods includes spending a lot of time and cost. Satellite data has broadened and integrated our vision for this purpose. This study was conducted in order to develop a model for salinity map using ETM+ satellite data related to year of 2012 and salinity values in Damghan rangelands. The geometric and atmospheric correction of satellite images were carried out. Necessary processing such as; fusion of multispectral bands with panchromatic bands, Tasseled cap transformation, the Analysis of Principal Components, and rationing for composite bands creation were also performed. A total number of 114 surface soil points with the depth of 0-15 centimeters were picked through random sampling and their Electrical Conductivity (EC) was measured. Spectral values for each sample were extracted by different bands and the relation between spectral values (i.e. main bands, Tasseled Cap bands, Analysis of Principal Components, soil and vegetation index) with Electrical Conductivity values of the samples were investigated. Values were categorized by Factor Analysis of variables into four categories and three models were determined for developing soil Electrical Conductivity map according to the highest correlation. Results revealed that the highest correlation was found between the principal bands of blue, green, red (about R=0.7), Tasseled cap 1 & 2 & 4(R=0.68) and indicators SI1, SI2, SI3(R=0.7), GVI, BI(R=0.68), INT1, INT2, MND, WDVI (about R=0.7) and the second component of the main component. Finally, the stepwise correlation model was used for mapping the soil salinity according to the utilized variables and their maps extracted. Results showed that Landsat ETM+ images are good tools for preparing estimate salinity maps of arid rangelands.

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