Sediment distribution of Wende River in Jilin City based on multi-frequency electromagnetic technology

River sediment has dual properties of disaster and resource. How to seek advantages and avoid disadvantages is a key problem during practical process. Using geophysical method to efficiently detect the distribution of river sediment is an important mean to solve problems above. The river sediment of Wende River in Jilin city was taken as the main research object, and GEM-2 multi-frequency electromagnetic instrument was used to carry out the electromagnetic measurement of river sediment with a length of about 20 km at five frequencies of 425 Hz, 1 475 Hz, 5 175 Hz, 24 075 Hz, and 63 025 Hz, and an average line spacing of 60 m, based on the high sensitivity of electric exploration to low resistivity anomalies. The plane position and depth range of the river sediment were defined based on post-processing data. The results show that multi-frequency electromagnetic instrument GEM-2 can effectively detect the distribution of river sediment, and the boundary of sediment stratification is relatively clear. Based on the apparent conductivity contour map and the apparent resistivity-depth inversion map of the survey line, it could be inferred that the sand layer may be distributed at a depth of 2 m, 6 m and 10 m below the water surface respectively, corresponding to the detection depths of high-frequency 63 025 Hz and mid-frequency 5 175 Hz and low-frequency 425 Hz of GEM-2 instrument. The results obtained could provide theoretical and practical basis for similar exploration and research in future.