001 is still busy on the river, measuring flow speed and volume.
The speed of the river's flow is influenced by the terrain of the riverbed, so it's not about measuring a single point, but rather the cross-sectional flow volume.
This means that a cross-section must be selected, a marker placed on the opposite bank, a water level ruler installed in the river, and using the naked eye for the alignment of three points in a line, before using a propeller flow meter to measure line by line along the "cross-section."
This measurement method is quite traditional and requires a longer time; under favorable conditions during the day, it takes about two and a half hours to complete, but at night it doesn't work.
At night, a lantern needs to be hung on the marker for the cross-section, and a laser rangefinder used on shore to direct the measurement ship for positioning by anchoring.
