What Are Temporary Flood Barriers and How Effective Are They In Flood Risk Reduction?

In times of extreme weather, rivers in some communities can swell, that’s why flood barriers are kept in place to keep homes safe. Permanent flood defences are a primary measure in flood risk reduction strategies all across England, however, temporary flood barriers are crucial in the same way.

What Are Temporary Flood Barriers?

Temporary flood barriers are quickly set up in pre-planned locations should the need arise where there are no permanent defences for pertinent situations. They are designed with portable metal frames and covered with waterproof material.

If a flood is expected to occur, temporary flood barriers are quickly arranged in place. When the risk has alleviated or passed, they are then removed, overseen and stored. In the event that they need to be put up again, then they will be so.

Why and Where Are Temporary Flood Barriers Used?

If a permanent flood defence has not been or cannot be practically built in an area, the Environment Agency uses temporary flood barriers to manage floods.

A typical example where temporary flood barriers are used is in towns and villages with economies and communities located near the river, such as riverfront restaurants and bars. In these premises, it would be disruptive to put up a permanent flood defence.

Deployment plans have been prepared by the Environment Agency for over 100 high flood risk areas across England. With these plans set in place, it is easier and quicker to deploy the barriers when necessary, however, these systems may also be established in certain locations where it is physically and technically practical to do so to avert flooding.

Other than temporary barriers, demountable defences may likewise be built in some areas. The structural foundations of these systems are permanent, and when there is threat of flooding, the barriers are deployed. Demountable flood defences are utilized to lessen the visual impact of permanent barriers, such as those built in Bewdley and Shrewsbury on the River Sern.

There, the demountable defence supports the open view of the river and accessibility throughout the old towns.

How Do Temporary Flood Defences Work?

Temporary flood defences as a system may be plastic or metal barriers. There are also types that are water-filled or sand-filled containers as well as sandbags and pumps. This equipment is deployed to a site and is set up for flood risk management for a limited period of time. 

When the system has served its purpose, it is removed from the area. It is used there again or in some other location when needed. The foundation of a temporary flood barrier is not fixed, and is simply the ground where it is based. Minor ready-made modifications may otherwise be employed to ensure the stability and performance of the equipment.

Recent experience of the Environment Agency signified that these systems can quite be efficient in quickly and easily protecting areas against floodwater in pertinent situations. Early flood forecast is however necessary for the safe and sturdy deployment of this equipment.

A range of factors contribute to installing the best option of this flood defence system on a particular situation, and these include the location and its ground conditions, the duration of the flood, the flood scenario, the water depth and the flow rate. Operational factors are critical in the same way, such as the area accessibility and the availability of resources, namely the disposal of installation equipment and skilled staff.

Limitations Of Temporary Flood Barriers

The protection provided by temporary barriers for floods is not as effective as that offered by permanent defences. The typical failure rates of temporary flood systems are at 20% to 30%. Nonetheless, good advanced planning can reduce this rate.

Large wave action cannot be controlled by this system, and to a certain extent, all of them leak. Pumps are therefore necessary to accompany them.

Additional support would need to be incorporated to temporary barriers once they are installed, including security measures to protect the barriers and the installation, and to prevent theft and vandalism. Lighting should be arranged, too, as a health and safety measure, among others.

When Temporary Flood Barriers Are Used

Temporary defences are practical if permanent options are not affordable, or in situations when new defences still need to be completed. 

Numerous utilities provide capital for temporary flood barrier systems to complement the Environment Agency’s capacity of 40 km of barrier and more than 250 pumps. England’s endeavour to fight floods significantly include temporary flood barriers.

Nevertheless, the limitations of these systems should be carefully considered, and their benefits, in relation to permanent defences can be relatively marginal.

Flood risk is an increasing challenge in England, and although some may deem temporary barriers as a dangerous distraction, they remain to be a credible contribution to this endeavour.

The deployment of these systems in major floodings have been widely reported by media and were greatly appreciated by those they have saved.