An optical fiber sensing system according to the present disclosure includes an optical fiber (10) provided on a water discharge gate (30) of a reservoir or in a vicinity of the water discharge gate (30), a reception unit (21) configured to receive an optical signal including a vibration pattern from the optical fiber (10), and a detection unit (22) configured to detect whether an opening amount of the water discharge gate (30) is appropriate, based on a vibration pattern included in the optical signal.

The present invention discloses improved means of venting bottom hinged water control gates through the abutments over a wide range of tailwater elevations while minimizing the hazard of trapping water born debris in the abutment vents. A single pipe, or a plurality of pipes, may be provided. Check valves may be provided to exclude water borne trash.