Digital Soil Mapping Using Drone-Borne Ground-Penetrating Radar

A drone-based ground-penetrating radar (GPR) is introduced for digital soil mapping in this chapter. The radar system is lightweight and consists of a handheld vector analyzer (VNA), a computer stick, and a differential GPS for positioning. A power bank is used to provide electricity for the whole radar system. A smartphone or tablet controls the radar and GPS measurements remotely. Full-wave inversion is used to retrieve the soil dielectric permittivity from the soil surface reflection, hereby to estimate volumetric soil water content through a petrophysical relation. The radar works in the frequency domain, and data processing is carried out in the time domain to focus on the surface reflection only. A look-up table (LUT) is pre-calculated to reduce the processing time during inversion, formulated as a least-squares problem. Soil moisture maps are generated by kriging interpolation. We present several examples of soil moisture maps produced in agricultural fields in Belgium