There is now high confidence that climate change has increased the likelihood and intensity of catastrophic floods. Usually physical barriers are put in place to try and control floods and limit damage. But increasingly, resilience is being strengthened by harnessing biodiversity and ecosystem services.
Innovation examples
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4. Water and coastal regions / Flood prevention and control / Innovation examplesProtecting Venice with mobile flood barriers
Photo: ©Ministero delle Infrastrutture e della Mobilità Sostenibili Provveditorato Interregionale per il Triveneto concessionary Consorzio Venezia NuovaThe Venetian Lagoon is an enclosed bay in which the city of Venice is situated. Over the centuries, the city has sunk several centimeters. This has been exacerbated by groundwater pumping from underneath the city and rising sea levels. In response to the increased threat of flooding, an integrated system of flood barriers named the Mose System has been installed to isolate the lagoon from the sea during high tide. The Mose construction began in 2003 and was officially completed in 2021. It consists of a series of barriers and mobile gates. Seventy-eight bright yellow floodgates, or caissons, are situated at the bottom of the lagoon’s three channel inlets. They have a total length of 1.6 km. When inactive, these 78 floodgates are filled with water. During high tide, compressed air is pumped into the floodgates causing them to rise. As the gates lift, a temporary dam is created. When the seawater level returns to normal, the gates fill again with water and sink back into their original resting position. The hinges keeping the floodgates in place have a calculated load capacity of 100 to 300 tons. This is enough to withstand a tidal wave.[1] Such flood barriers have proven effective. But challenges include high cost, reliance on early warning systems due to length of time needed to close, and maintenance to prevent the structures clogging with sand.[2]
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4. Water and coastal regions / Flood prevention and control / Innovation examplesFlow-through dams for flood control
Getty Images /© Yevgeniy SambulovFlow-through dams, aka perforation or dry dams, are built for downstream flood prevention. The main purpose of this type of dam is flood control. The dam opening (spillway) is at the same height as the river bed. Water is allowed to flow naturally when there is no excess water. But the opening slows the flow when water levels rise. One advantage compared to reservoir dams built to store water is that sediment is more easily removed. Another is their more limited impact on biodiversity (e.g., by preserving fish migration routes).[1] The dams can be built with materials such as bricks, concrete, timber and earth. In Japan, a flow-through dam is being built for the Asuwa River in the town of Ikeda. Called the Asuwagawa Dam, it is scheduled for completion by 2026. It is a gravity-type dam with large tunnels at its base for river water to flow through, except during a flood when water is pent up and gradually released downstream. In July 2004, torrential rains completely inundated the Japanese Fukui Prefecture. Thousands of houses were flooded and lives lost. It was as a result of this that local governments revived a several decades old plan to build the dam. Other suggestions for flood control had previously included widening the river embankment or building a multi-purpose dam.
Proven technologies
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4. Water and coastal regions / Flood prevention and control / Proven technologiesBreakaway walls
The US Department of Homeland Security
Getty Images /© Hans HansenBuildings elevated up to or above flood level as a flood adaptation measure often have open foundations consisting of columns or other structures. This is to allow waves and water to pass through at high velocity. However, breakaway walls allow foundations to be closed off and used for storage, parking or other purposes when water levels are normal. Breakaway walls are not part of a building’s structural support. Their design and construction is such that they are intended to collapse under high flood and wind force without damaging the rest of the building. The US Department of Homeland Security has published detailed design and construction guidance for breakaway walls which are publicly available.
- Contracting type: Locally available materials
- Technology level: Medium
- Country of origin: United States
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesLight-weight flood protection barriers
Aquobex
Getty Images Plus /© BanksPhotosAquobex is a UK-based company offering more than 37 flood protection and barrier products. They range from flood-proof doors and vent covers to waterproofed walls and passive and mobile flood barriers. Examples include a light-weight flood barrier that can be mounted on sockets pre-installed on a doorway with a few screw caps.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: United Kingdom
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesMulti-purpose mobile flood barriers
Water-Gate
Photo: © MegasecurWater-Gate barriers are an alternative to traditional sandbags for flood control, protection and prevention. The barriers can be installed during a flood and remain stable irrespective of water flow and direction, or slope of terrain. It is described as being ideal for flash floods. It can be installed in front of a door, window, garage, elevator door, parking lot, underground entrance or a similar place. It can also be installed directly along a coastal bank to prevent overflows in response to coastal flooding or rising sea level.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: Canada
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesFlood bags containing super absorbent powder
QuickDam
Getty Images /© Cheryl RamalhoQuickDam sells a range of flood protection products. Examples include flood bags containing super-absorbent powder that swells and turns into a gel-like substance on contact with flood water. As the bag swells and grows, it creates a barrier between the protected property and the water. Bags can be stacked one on top of another depending on the height needed for protection. They can for example be used to contain or divert flood water away from doors, windows and garages. While QuickDam provides products also suitable for saltwater, the flood bags are more appropriate for inland flooding.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: United States
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesLow-level flood bags with super-absorbent polymer
Gravitas International Ltd.
Getty Images /© BilanolA HydroSack®️ is a barrier against low-level flooding activated on contact with water. The sack, or bag, contains a mixture of the super-absorbent polymer (SAP) commonly found in disposable diapers plus sustainably sourced wood pulp. Because bags weigh very little (less than 0.5 kg), they must be activated before being placed in position so as not to be displaced by floodwater. They are activated either by being soaked in a bucket of water for 2–3 minutes or dowsed in water using a hose. Once activated, the product is effective for up to 6 months. But it does not revert to its original state once dry. The bags are claimed to be biodegradable and can be discarded on the ground after use.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: United Kingdom
- Availability: Europe
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4. Water and coastal regions / Flood prevention and control / Proven technologiesTemporary mobile flood barriers
NOAQ Flood Protection AB
Photo: © NOAQ Flood Protection ABSandbag barriers for flood protection often require huge amounts of sand and manpower to build. This can be a limiting factor in the event of flash floods. One alternative is a temporary mobile barrier made of materials such as plastic that can be rapidly deployed to protect vital infrastructure, commercial properties and homes. NOAQ Flood Protection AB has developed such a barrier- the NOAQ Boxwall. Designed to be free-standing, lightweight and easy to handle, individual barrier components connect without needing any tools and are anchored in place by utilizing only the weight of the floodwater itself. Available in two damming heights, 50 cm and one meter, an individual box weighs less than 1 percent of a corresponding sandbag dike and is faster to deploy.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: Sweden
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesLarge-scale flood barrier tubes
FloodBlock
Getty Images Plus /© oobqooFloodBlock inflatable barriers are another flood protection alternative to sandbags and aluminum barriers. They consist of inflatable tubes connected by aluminum junctions that fill with water once contacted by a flood. When filled, they transform into a flood barrier system that can stretch over long distances (up to 1,000 meters). The tubes have been specially developed so they can be set up within hours to manage larger-scale flood events and used by the private sector or municipalities. Versions include temporary structures and passive barriers installed over a longer period.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: United States
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Proven technologiesNatural flood management
Scottish Environment Protection Agency
Getty Images Plus /©InstantsNatural flood management (NFM) involves a variety of soft engineering and green infrastructure measures designed for flood control. The aim is to reduce floodwater volume and delay floods flowing downstream by protecting, restoring and optimizing the natural functions of catchments, floodplains, rivers and the coast. Coupled with hard engineering, natural flood management may help reduce flood risk downstream. Measures seek to create natural structures and reduce soil compaction to slow water and to increase ground infiltration. The Scottish Environment Protection Agency has developed its Natural Flood Management Handbook as a practical guide to assessing the benefits of implementing such approaches.
- Contracting type: Free
- Technology level: Medium
- Country of origin: Scotland
- Availability: Worldwide
Frontier technologies
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4. Water and coastal regions / Flood prevention and control / Frontier technologiesPrefabricated pumping stations
Grundfos
Getty Images Plus /©Jim SugarDuring heavy rainfall, stormwater pumping stations support flood control by pumping large volumes of water away from areas needing protection. The pumped water is then discharged into sewers or lakes. Compared to traditional concrete pumping stations cast on-site, prefabricated solutions are often more cost-effective and flexible, and can be installed quicker. Grundfos provides a variety of prefabricated pumping stations for drainage water, rainwater or wastewater. They may be made of materials such polyethylene or polypropylene which are generally more crack and leak resilient than concrete. The prefabrication comes with pipes, valves, pumps and level controllers (for fluid level measurement) pre-installed. The company has installed pumps in countries such as Malaysia to help meet their growing flood management needs.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: Denmark
- Availability: Worldwide
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4. Water and coastal regions / Flood prevention and control / Frontier technologiesSelf-closing flood barrier (SCFB)
Hyflo B.V.
Getty Images /© fury123The self-closing flood barrier design was developed in the Netherlands and commercialized in the late 1990s as an alternative flood protection measure when permanent structures are not a viable option. The barrier is not visible when resting vertically below ground within a steel or concrete trough. During a flood, water spills into the trough causing the barrier to float and rise automatically. Once the trough has filled, it is locked watertight. This overcomes the challenges of having to set up temporary structures stored off-site such as flood-doors and floodgate systems, which rely on adequate warning time to put in place. The barrier can be built in various lengths, with a basin of high-density polyethylene, concrete or stainless steel.
- Contracting type: For sale
- Technology level: Medium
- Country of origin: The Netherlands
- Availability: Worldwide
Horizon technologies
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4. Water and coastal regions / Flood prevention and control / Horizon technologiesHybrid flood defense systems
THIRD NATURE
Photo: © Third NatureThe concept developed by the Danish architectural practice THIRD NATURE (or TREDJE NATUR) is described as “pop-up climate change adaptation.” It explores how the joint challenge of major flooding and lack of parking space might be solved. This design “pop-up” envisions building a parking facility on top of a reservoir that fills with stormwater during heavy rain. The parking structure moves up and down as the reservoir fills and empties with water, corresponding to the height of the displaced water. Hydraulic and mechanical lifting and steering mechanisms balance the weight of cars within the parking structure to ensure a secure and even vertical movement. The practice has teamed up with engineering companies COWI and RAMBØLL to develop structural models and financial calculations for the project. As cities become more crowded, such hybrid adaptation solutions could become increasingly relevant.
- Contracting type: N/A
- Technology level: High
- Country of origin: Denmark
- Availability: N/A
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4. Water and coastal regions / Flood prevention and control / Horizon technologiesMechanical jacks to raise houses during floods
FloodJack International Ltd.
Photo: © FloodJack InternationalDriven by first-hand experience of devastating floods and the need for solutions to protect properties and residents, inventor Andrew Parker designed the FloodSafe House in 2012. The FloodSafe system is designed to detect a flood event. Detection triggers the house to rise above the floodwater on a specially designed mechanical jack system. The design has been developed for modular developments commonly used in affordable and social housing. A full-size prototype has been built and tested.
- Contracting type: N/A
- Technology level: High
- Country of origin: United Kingdom
- Availability: N/A
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