Estimation of Parameters of Contaminated Ground Layers Using Electromagmetic Waves Hodographs

In this paper practical results of the long-term (1999-2007) application of Ground Penetrating Radar (GPR) technique for estimation of electrical parameters of contaminated ground layers are presented. Contaminations were caused by oil products. GPR technique includes the procedures of profiling, taking hodographs according to the Common-Midpoint (CMP) method and data optimal processing. GPR data processing was applied to acquire the estimations of values of ground layers thickness and their relative dielectric permittivity e by solving the GPR inverse problem. For data processing were used the methods of weighted least squares, the recursive Kalman filter, the maximum likelihood and the Nelder-Mead optimization. The comparative analysis of these methods allows to define the most expedient technique for the practical estimation of the ground electrical parameters using GPR data. The acquired values of e were connected with the degree of ground contamination which was attested by measurements of a floating layer thickness of oil products in the observation wells and their concentration in the ground. The monitoring data acquired in 2007 shows in comparison with the year 2006 the values of ground contamination degree estimated by GPR technique were decreased from 2.7% up to 58.8% for different observation wells. These decreases were confirmed by measurements in the observation wells.