When searching for images of submarine pipelines, the resolution capability of the measuring instrument and the diameter of the pipe must first be considered. The footprint of the measuring instrument must be smaller than the diameter of the pipeline, and the smaller the footprint, the higher the resolution. Our working group also used the multibeam sounding system (RESON 9001) to measure the ocean outfall pipe in Jishuei River and compare the images. The frequency of RESON 9001 is 455 kHz, which belongs to the submarine detection instrument with high resolution capability. Its analytical ability should be better than 0.45m. Therefore, it should be possible to obtain high-resolution images when measuring on an ocean discharge pipe with a diameter of 1.7m or an oil pipeline with a diameter of 0.6-1.0m. Using the multibeam sounding system to measure the ocean outfall pipe in Jishuei River. The unconnected part of the end of the discharge pipe was intercepted and drawn as a map(as shown in the figure). The white part in the picture (shallower water depth) is the ocean discharge pipe. It can be seen that the end of the sea discharge pipe is not connected with the main pipe. The terrain on the north side of the sea discharge pipe has obvious brush-darkness (the part with darker color). It is also possible to clearly know the depth of the pipeline or the hollowing out of the bottom (as shown in the figure) from the high-resolution image and the contour map. If you need to know more clearly, you can also draw a profile map.

The image map (top) and contour map (bottom) of the ocean outfall pipe in Jishuei River by the multibeam sounding system.