The transient electromagnetic method combined with high-density inversion is used for geological investigation and prediction of ancient river courses within 100 meters below the surface. The point distance is 5 meters, the emission current is 30 A, and the sampling interval is 0.8 μ s。

Inversion diagram of high-density resistivity method

Inversion diagram of transient electromagnetic method

There is a low resistance anomaly between 20 m and 30 m at the left end of the survey line (indicated by the red dotted line in the figure). Gravel and cobble are exposed on the surface, and high resistivity anomalies are present near the surface. The inversion results of transient electromagnetic method are basically consistent with the high-density data.