Document Type : Research Paper

Authors

• Ebrahim Babaean
• Mehdi Homaee
• Aliakbar Norouzi

Abstract

Monitoring soil water content as one of the important components of drought monitoring, especially in agriculture, is highly important to study the climate changes in Iran. In this study, we proposed a method to retrieve and monitor soil surface water content using microwave remote sensing data. The study was based on 8 images of ASAR C-band in global monitoring (GM) mode and horizontal-horizontal (HH) polarization, acquired January 2012 to March 2012, as part of Zanjanrood watershed located in Zanjan province. Total backscattering coefficient () contributed by soil was calculated. The relationship between processed RADAR signals and TDR based soil surface water content measurements was investigated using spatial autocorrelation (Morans Index) and modeling spatial relationships (ordinary least square, OLS). A significant coefficient of determination (R²=0.68^**) was observed between both volumetric water content and total backscattering. Cross validation of the results indicated that the model had an acceptable performance with the RMSE and relative error of 0.032 cm³ cm^-3and 11%, respectively. However, the proposed model had a tendency to slightly underestimate (MBE=0.011 cm³cm^-3) the estimations. In all, ASAR GM data GM has the potential of being used to retrieve soil water content under no vegetation cover condition.

Keywords

• Backscattering coefficient
• Regression model
• Active microwave
• Global mode (GM)