Subsurface Propagation Velocity Estimation Methods in Ground-Penetrating Radar: A review

Velocity estimation is one of the most crucial tasks in ground-penetrating radar (GPR) surveys. It is an integral part of GPR data analysis for interpreting GPR-generated images of subsurface media. Error in velocity estimation leads to wrong interpretations of underground scenarios. Since the beginning of GPR development, researchers have proposed various velocity estimation procedures. In this article, a survey of different subsurface propagation velocity estimation techniques is presented. Based on the survey methods, GPR environment, and mathematical models involved, different available techniques are presented in a classified manner. A few techniques are experimentally validated and analyzed for their performance. Finally, the impact of wave velocity on GPR imaging is demonstrated on practical GPR measurement data.