关键词: EM38, 电导率, 线性模型, Tikhonov正则化

Abstract: 【Objective】In this paper, apparent electrical conductivity(ECa) measured by EM38 at different heights above the soil was used to determine lateral variations of apparent electrical conductivity at different depths in a coastal saline field.【Method】Tikhonov regularization is an effective technique for the solution of ill-posed linear inverse problem. Electrical conductivity profiles were inversed through solving a nonnegative lease squares problem by combining the McNeil's linear model theory of EM38 with Tikhonov regularization. The prediction error of the depth profile of electrical conductivity was analyzed. Finally, sensitivity of the model was assessed by adding noise to the observed data from a normal distribution.【Result】There was a significant correlation between mean of electrical conductivity for the whole soil profile and mean of ECa measured at different heights above the soil. Moreover, the inversed data of soil electrical conductivity using linear model can characterize well the changing trend of electrical conductivity for the whole soil profile. It is noteworthy the average prediction error of this model is about 40%, and the model was more sensitive to the layers which having larger prediction error. It suggested that accuracy of prediction can be improved by strengthening the measurement stability of EM38 equipment in field.【Conclusion】The results demonstrated that an integrated approach of the linear model and Tikhonov regularization can be used to inverse EM38 data to the electrical conductivity profile quantitatively, which presented a great potential way for soil investigation and management.

Key words: EM38, Electrical conductivity, linear model, Tikhonov regularization