TOPS gate


The TOPS gate is fitted to an existing or new spillway to increase the water level in the dam from as low as 0,5m to 10m.

It can be fitted to an ogee type spillway, either straight or curved in plan, without lowering the water level in the dam or changing the profile of the spillway crest. Because it’s opening action is outwards and upwards, it can be placed on side channel spillways with a flat discharge slab.

The TOPS gate will open automatically in response to the rising water level in a dam to pass floods and will close automatically to retain the increased full supply level in the dam. On a spillway containing more than one TOPS gate, the opening sequence is set so that gates will open in sequence in response to the incoming flood hydrograph to both attenuate the inflow peak and to release the reduced discharge downstream, thereby providing flood control.

If required, the TOPS gate can be opened manually to release large discharges for either environmental purposes, or to draw down the dam water level for emergency dam safety purposes. It can also be operated remotely by telemetry, if required.

The TOPS gate is therefore as flexible in operation as electro-mechanical gates, yet it is not reliant on electro-mechanical means to operate but will open and close automatically. The TOPS gate is therefore suitable on dams in remote sites or where electro-mechanical mechanisms or operator performance cannot be guaranteed.

The TOPS gate meets all requirements to ensure Dam Safety.