Studies On Dielectric Behavior Of Saline Soil And Its Effect On Backscattering Coefficients Extracted From Radar Image

Nowadays, soil salinization,one of the main types of land degradation and desertification in the world, is caused by unreasonable human activities and the vulnerable ecological environment. Saline soil distributes widely in our country, from the tropics to the cold temperate zone, seaside to the interior, moist area to the extreme arid wilderness area and so on. Xinjiang is not only our country's important oasis agricultural region, but also full of natural resources. Along with the land development, the changing land utilization, the technical progress, the balance of water and salt is being destructed. Because of these reasons, importantance of detection of the soil salinization is enhancing. The traditional method of field orientation observation is not only time-consuming, laborious and less observation range, representative of poor, bur also can not achieve dynamic monitoring of large areas of land. Optic remote sensing has certain limit with withdrawing the soil salinization information purely through the spectral response. However, in the microwave, the changes in soil salinity will affect the soil dielectric constant, thereby affecting the backscattering coefficient of the soil surface, which was detected by radar remote sensing offers the possibility of soil salinization.This article chose the saline soil dielectric model (correction of moist salt soil Dobson dielectric model) as a typical study foundation of soil dielectric constant simulation model, analyzed the model parameters on the influence of soil dielectric constants. Wei-kuqa region with typical oasis field measured data in the study area were used to verify the suitability of saline soil permittivity model. According these data, we processed the different polarization mode radar image, after extracted corresponding sampling point, to the scattering factor. The different polarization radar image processing, sampling points are extracted backscattering coefficient and soil response relationship between the dielectric constant for microwave remote sensing of soil salinity monitoring scientific theory and evidence provided. After the analysis, to between the scattering factor and the soil coefficient of dielectrical loss's response relation provides the scientific theory and the basis for the salinified area soil microwave remote sensing monitor.The results of the study indicate that: (1) radar low frequency region, response of real part of soil dielectric constant are strongly effected by the volume of soil water content, but imaginary part soil dielectric constant not only closely related with the soil water content, also has obvious response to soil salinity. So we must not ignore the soil salinity factors on the dielectric constant impact. (2) the soil moisture content, the salt content and the coefficient of dielectrical loss have the very good relevance. This is exactly consistent with the arid area saline soil's natural condition and provides our soil dielectric characteristic study with valuable referrence. (3) soil moisture content, salt content change immediately influence the pickling earth coefficient of dielectrical loss change, thus this affects the radar backscattering coefficient to the salinified soil coefficient of dielectrical loss responds, the cross polarization pattern's radar phantom and the salinified soil coefficient of dielectrical loss's response degree is most remarkable, correlation coefficient R2≈0.75 have a certain degree of potential. Through the radar image inversion soil salinity is entirely possible.