| Soil salinization is one of the main types of land desertification and landdegradation in the world today,it is due to natural climatic conditions, such astopography, hydrology and geology, soil water and salt movement and unreasonablehuman activities and the fragile environment caused by land degradation. Xinjiang isboth an important oasis agricultural area and the country's resources and energyarea,with the land development and land use change, the progress of scientific andtechnological level of salt and water balance is destroyed, making the salinized soiltype, quantity, distribution and causes to change, so intensification of soilsalinization monitoring is important. Traditional field orientation methods ofobservation is not only time-consuming, laborious, and observation points arepoor,representation is not well,too.It can not achieve the dynamic monitoring oflarge areas of land. Optical remote sensing to extract pure spectral response of soilsalinization have certain limitations.For microwave remote sensing, on the one hand, microwave remote sensingband penetrating more than the optical remote sensing band to reflect the followingcharacteristics of the soil surface;on the other hand, the scattering of soil microwaveband emission intensity and is closely related to the soil salt content, so the use ofmicrowave monitoring soil salinization will be an excellent complement to thedevelopment of optical remote sensing and provide theoretical and experimental basisfor the use of microwave remote sensing monitoring of soil salinization.This articleform radar data parameters to explore the interaction between radar data parameters(polarization, incidence angle, spatial resolution) and surface characteristics(dielectric constant) and propose the most suitable radar data parameters for salinesoil information extraction.The results show that:(1) Due to the increase of the incidence angle, thebackscattering coefficient change large,the same polarization is greater than the cross-polarization of each incidence angle,the backscattering coefficient in30oincidence angle is max amd the image brightness values is highest, difference betweenthe maximum and minimum of the backscattering values in33o incidence angle ismost, the department of backscattering values is high. It is very conducive to theextraction of the saline soil.(2) From the correlation between the scatteringcoefficient and the dielectric constant, the cross-polarization mode is higher. VHpolarization mode R=0.5119, HV polarization mode R=0.4917, HH and VVpolarization mode is low, HH polarization mode R=0.3209, VV polarization modeR=0.2720.(3) Soil backscattering of various degree salinization of coefficient in thesame polarization is relatively high, and two kinds of the same polarizationbackscattering coefficient are nearly same, and in the cross-polarization approach isrelatively low, and these two cross-polarized backscattering coefficient are nearlysame, too. Varying degrees of salinization of soil in the same polarizationbackscattering coefficient greater than the cross-polarization, with the increase ofthe degree of salinization of soil,the backscattering coefficient decline. Differentdegree of soil salinization in the same polarization that backscattering coefficient isnearly same and have better separability in the cross-polarization. Large amount ofinformation contained in the cross-polarization data than the same polarization data.(4) In summary, the combination of optimal radar data parameters in this study is:the incidence angle33o,12.5m resolution, the VH polarization, so that the accuracyof the information of the salinization extraction increased from62.5408%to79.6529%in study area. |
PDF Full Text Request