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Buoyant Weir: Protection from Flooding & Low Cost Hydropower Generation

The Buoyant Weir is a new simple technology for flood mitigation and disaster relief, and hydropower infrastructure.


It is a low-cost, environmentally friendly and easy-to-install facility that holds back water like a weir, dam or rock wall, thereby creating a water level difference between upstream and down waters. It holds back rainwater at source for a sufficient time to mitigate the maximum surge height of flood waters in a valley below. Only a few days’ notice would be needed to install such an upland reservoir. It can then be removed again for re-use.

The Buoyant Weir is also installed as permanent solution for weirs and as an alternative to costly rock walls in tidal energy schemes.

Video: Demonstration of the Buoyant Weir operation across high and low tides.

The Buoyant Weir is a waterproof membrane spread perpendicularly across the expected course of upstream flood water. The downstream edge of the membrane is attached to a buoyant tube, held back by anchored tendons. The tube rises under its own buoyancy, lifting the membrane to prevent water from flowing past. The Buoyant Weir can be designed for a desired “uplift" so that it will be known at which water level increase the Buoyant Weir will begin to overtop.

Buoyant Weir in Tidal Setting

In a tidal energy as well as offshore flood protection setting the Buoyant Weir will operate in either direction from the tides and automatically rises and falls under different tidal water levels.

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Image: The Buoyant Weir at high tide on flood current, with the tide flowing into an estuary or lagoon. 

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Image: At low tide on the ebb current. 

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Image: The weir on the ebb current, as the tide recedes and waters move away from the shore. 

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Image: At low tide on the flood current. 

River and Inland Flood Protection


The Buoyant Weir can be used temporarily or permanently with VerdErg Renewable Energy's VETT-in-a-Box hydropower technology or Standard VETT system to generate electrical energy. The VETT-in-a-Box also offers the potential for airlifting ‘pop-up’ Buoyant Weir facilities to remote or disaster relief community locations.



Physical model testing was carried out at HR Wallingford in August 2023, successfully demonstrating the Buoyant Weir's operations

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Image: Testing of the Buoyant Weir at HR Wallingford. 

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