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Buoyant Compliant Weir: Protection from Flooding & Low Cost Hydropower Generation

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

Buoyant Compliant Weir technology offers five important contributions to the post-carbon economy:

  • Pop-up containment of flash flood waters. All Buoyant Weir components are helicopter-transportable and non-site-specific permitting rapid installation from storage.
  • ​Electrical power generation from streams or rivers for remote local communities.
  • Long-term river power generation with substantial economic and environmental advantages over legacy technologies.

  • Passively bi-directional tidal range energy infrastructure for lagoon and estuary configurations offering competitive economics and superior environmental footprint.

  • Offshore tidal generation barriers running parallel to coastlines vulnerable to inundation flooding from rising sea levels.   

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

The Buoyant Compliant Weir is a low-cost, environmentally friendly and easy-to-install facility that holds back water like a weir, dam or rock wall. It creates a water level difference between upstream and downstream waters. This barrier holds back rainwater at source for a sufficient time to mitigate the maximum surge height of flood waters in a valley below. The technology can be temporary as a pop-up barrier to protect against flash floods. It can also be installed as permanent solution for weirs and as an alternative to costly rock walls in tidal energy schemes.


How Does it Work

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 cylinder, held back by anchored tendons. The cylinder 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.

Video: Demonstration of the movement made by the bi-directional membrane, as it reconfigures itself with the tide changing direction.

Pop-Up Containment of Flash Flood Waters

The design of the Buoyant Compliant Weir is simple, lightweight and robust. All components can be transported by road or flown by helicopter. They are also non-site-specific which permits rapid installation from storage. This makes the technology suitable for disaster relief responses. 


Only a few days’ notice is needed to install the weir as an upland reservoir. It can then be removed again for re-use.

River and Inland Flood Protection

The Buoyant Weir can be used temporarily or permanently with VerdErg Renewable Energy's VETT low-head hydropower technology to generate electrical energy.

With the compact VETT-in-a-Box, electrical power generation is possible from streams or rivers for remote communities. The plug & play VETT-in-a-Box is a compact design, itself offering the potential for airlifting ‘pop-up’ facilities to remote community locations or to areas of disaster relief.


​When paired with the larger Standard VETT, long-term power generation from rivers is possible with substantial economic and environmental advantages over legacy technologies.

Video: Demonstration of the movement of the Buoyant Compliant Weir at high and low tide, on the flood and ebb current. 

Buoyant Compliant Weir in Tidal Setting


The Buoyant Compliant Weir generates passively bi-directional tidal energy from lagoon and estuary crossing configurations.

The technology functions as tidal generation and coastal protection infrastructure, relevant for lagoons, estuary crossings and extended offshore alignments parallel to coastlines, particularly coastlines vulnerable to rising seawater levels.

The Buoyant Compliant Weir offers competitive economics and superior environmental footprint to incumbent sea wall and tidal barrier technology. Because construction costs are dramatically reduced compared to conventional technology, the Buoyant Compliant Weir can run for great distances offshore and parallel to coastlines that are vulnerable to rising sea levels, providing protection and affordable offshore tidal generation barriers.

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

Interactive maps provided by online coastal risk screening tools show much of the UK East coast and North European coast from France to Denmark is liable to global warming-related sea level rises. Similar areas at risk can be found worldwide.

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

The low construction cost and the ultra-low head needed to economically run the Buoyant Compliant Weir in combination with VETT generation ensure that coastal protection can be self-financing, contribute to substantial levels of green energy, and provide new low-impact road, rail and communications coastal highways.


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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