Modelling the Backscattering Coefficient of Salt-affected Soils: Application to Wadi El-natrun Bottom, Egypt

One of the most crucial environmental problems affecting developing countries in arid and semi-arid regions is soil salinity. Its detection using radar imaging systems is one of promising domains of remote sensing research. Detection is based essentially on the relationship between the quantity of existing salts in the soil, the soil moisture content, and the dielectric properties of this mixture. Due to the components of the mixture and their corresponding dielectric properties, backscattering of these types of soils can be modelled and monitored. Parameters influencing the radar detection of saltaffected soils are grouped into two main groups: those related to the sensor and those related to the target. Some of these parameters cause information attenuation during monitoring of the saltaffected soils; however, others give us information that help to better understand the phenomena. Some of the latter parameters can be controlled and others are imposed. Most previous studies neglected the effect of the presence of salts combined with the other parameters on the backscattering coefficient. In this paper, we present the salinity effect on the calculation of the backscattering coefficient using several backscattering models. The results show that the high dielectric constant, due to the extensive presence of salts, has a significant effect on the backscattering value. To validate the modelling approach with actual data, four RADARSAT-1 satellite images in standard modes were selected for the area of Wadi El-Natrun, Egypt, where fieldwork was conducted simultaneously with some of the RADARSAT-1 image acquisitions.