A Nondestructive Conductivity Estimating Method for Saline-Alkali Land Based on Ground Penetrating Radar

Abstract

During the saline-alkali land improvement process, the soil conductivities throughout the whole land area are usually investigated in advance to grade the soil salinization. As a new soil investigating technique, ground penetrating radar (GPR) has been widely used in geographical and agricultural applications. Nevertheless, there are still challenges in applying GPR to saline-alkali soil conductivity predictions, because it is very difficult to separate the direct path wave (DPW) and the land surface reflecting echoes under near-field condition. To realize fast soil conductivity predicting, a novel waveform correlation analyzing method based on the pulsed GPR technique is proposed in this article. By this method, the saline-alkali soil conductivities can be estimated directly by waveform comparison instead of complex equation solving. Experiments are performed on specific saline-alkali land with different surface morphologies located in the western Jilin province, northeast China. An empirical relationship between GPR echoes and the saline-alkali soil conductivities is established by the measurements in the first survey line. Then, this empirical formula is used to predict the soil conductivities in the second survey line to verify the methodology. Analyzing results show that the estimated conductivities are consistent with the WET (water content, electrical conductivity, and temperature) sensor measurements and the soil sample measuring results. Based on the nondestructive GPR technique, the proposed method can provide a fast and efficient way to estimate the conductivities of the saline-alkali land.