Effect of dielectric properties of moist salinized soils on backscattering coefficients extracted from RADARSAT image

This paper presents the experimental results regarding changes in the dielectric properties of artificially moistened and salinized soils and on soil samples taken from a salt lake. The complex dielectric constants of soil samples were measured using a microwave network analyzer. We evaluated the real and imaginary parts of dielectric constants of artificially moistened and salinized soil samples prepared in the laboratory as a function of microwave frequency, salinity, and water content The frequency and the salinity of soils have little influence on the real part of dielectric constant ε\´. The results show that, in the frequency range of 1-6 GHz, the imaginary part ε" has greater sensitivity to soil salinity. The dielectric constant measurements for soil samples collected in Jilantai Salt Lake are in agreement with the results of the artificially moistened and salinized laboratory soil samples. These dielectric measurements were subsequently compared with the backscattering coefficients extracted from a RADARSAT image (C-HH) that was acquired at same time with the soil sampling at the Jilantai Salt Lake area. We discovered that the correlation coefficient between σ⁰ extracted from the RADARSAT image and ε" measured in the soil sample is 0.70. The correlation coefficient between σ⁰ and the soil sample salinity is 0.69. This suggests that soil salinity has a significant contribution to the backscattering coefficient, σ⁰ recorded in a SAR image. Consequently, a SAR image can be a useful tool for monitoring soil salinity.