The hydrological station for the Shilichangchuan project is designed to
measure the total runoff from the watershed during a major rainstorm. The
most outstanding feature of the this station is the concrete trench built
across the gully serving as a flume of known cross section for accurate
measurement of flow rates. Once the flow velocities are measured at various
depths, the flow rate through the flume is determined through pre-established
calibrations.
Sediment load from each runoff is determined by collecting sediment samples
in the flow, which is done by suspending a sampler at fixed depths in the
flow. Each sample is dried and weighed to measure its sediment content.
The sediment load is found by correlating the sediment content with the
runoff rate.
At the time of my visit, there was no flow in the river (and had been for
some time), and the hydrological station was unmanned. Some automatic recording
devices were in operation, one of which was a precipitation gauge located
outside the station.
Picture source: George Leung (1995)