This blog been written by a member of the Newground Flood Team.
During times of heavy rain, drainage systems can become overwhelmed (especially if highway gullies are blocked with debris), causing roads to quickly become flooded. Whilst most drivers are aware of the risk of driving through floodwater to themselves and their vehicle, one consequence which can cause significant damage can be overlooked: bow waves.
A bow wave is a wave that forms in front of a moving object when it travels through water. This barrier-like wave peaks around the front of the vehicle and travels with the vehicle as it moves. The faster the vehicle travels, the larger and more intense the bow wave becomes, extending from the vehicle and crashing into businesses, properties and infrastructure.
Intensifying flood conditions: During a flood, when water levels are already rising around at risk buildings, a bow wave can send additional water cascading over a kerb, door threshold, or any Property Flood Resilience measures. This can worsen the situation and exacerbate flood damage.
Damage to infrastructure: In addition to damaging properties or businesses, the force and velocity of large bow waves can pick up debris in the floodwater and damage infrastructure such as roads, pavements and walls. Several vehicles driving through floodwater can create a similar effect to that of a large coastal wave crashing into cliff sides and eroding them.
Causing an obstruction: If a vehicle travels too fast through floodwater, the bow wave can overtop the bonnet and flood the engine, potentially leaving the vehicle stranded. If this happens in the middle of the road, it will cause an obstruction for any evacuation or emergency services operations.
If a flood warning is issued for your area, this means flooding is expected and you should take immediate action to protect yourself and your property. If you have any PFR measures, deploy them and ensure all valuables are secured to a safe height. If you live near a road which has flooded previously, or if your property is located close to the road (either in distance or topography) and you experience careless, dangerous or reckless drivers, ensure you document the incident, record the registration plate and notify the police via 101.
It is advised that motorists do not enter water deeper than 10cm (4 inches). If you are certain the water is low level and not flowing, wait until any traffic ahead of you has cleared the floodwater and the water has settled. Observing how the vehicles before you travelled through the water can give you an idea as to the depth of water. You should stay in the middle of the road and drive through very slowly, no more than 3-4mph which is recommended by Green Flag.
During a flood, communities are already concerned, worried or stressed. If you must drive through low-level floodwater, be courteous to avoid worsening their situation.
