Mapping of bare soil surface parameters (moisture, roughness, texture) from one TerraSAR-X radar configuration
Résumé
In this paper, surface bare soil parameters (moisture, roughness and texture) mapping was carried out in central Tunisia (North Africa) using one TerraSAR-X radar configuration (one incidence angle, one polarization). Firstly, we analyzed statistically the relationships between TerraSAR-X backscattering signals function of soil moisture and different roughness parameters (the root mean square height Hrms, the Zs and the Zg parameters) at 36° and HH polarization. Results have shown a high sensitivity of real radar data to all soil parameters. Then, we proposed an algorithm combing the TerraSAR-X images with different continuous thetaprobe measurements for the retrieval of surface soil moisture. Empirical relationship was established between the mean moisture values retrieved from the SAR images and the percentage of clay over 36 test fields. Validation of the proposed approach was carried out over a second set of 34 fields, showing that highly accurate clay estimations can be achieved. Finally, for spatial and temporal surface roughness estimation, we proposed empirical relationships between radar and soil roughness parameters (Hrms and Zg parameters). The proposed model was calibrated over 39 test fields, and then validated over 40 other plots.