What are the Different Types of Floods?

Ranging in impact from minor inconvenience to major disruption, floods touch the lives of thousands of people every single year. In England alone, more than 5.2 million homes are at risk of flooding. Put into monetary figures, the statistics are even more startling: the management of flooding costs the UK approximately £2.2bn a year.

Over recent years, floods have hit the headlines on several occasions. At the beginning of 2014, parts of England experienced the wettest January on record. Who can forget the striking pictures; coastal towns thwarted by high tides and stormy seas; entire streets submerged in metres of flood water; roads and buildings left battered and damaged. But not all floods are equal and there are in fact many different types. Here’s a helpful overview.

Coastal Flooding

Coastal areas often bear the brunt of severe storms, especially if these have gathered pace over the oceans. Extreme weather and high tides can cause a rise in sea levels, sometimes resulting in coastal flooding. Low-lying seaside areas usually have defences against the water - whether that’s man-made defences or natural barriers such as sand dunes. As global warming develops, coastal flooding is expected to be a recurring and increasingly severe problem.

River Flooding

River flooding is one of the most common types of inland flood; occurring when a body of water exceeds its capacity. When a river ‘bursts its banks’ - typically due to high rainfall over a prolonged period of time - localised flooding can cause considerable damage to surrounding properties, as well as posing a significant safety threat. To prevent flooding, rivers needs good defences, especially in flat or populous areas.

Flash Flooding

Caused by heavy and sudden rainfall, flash flooding happens when the ground cannot absorb the water as quickly as it falls. This type of flood usually subsides quickly, but while it lasts can be fast-moving and dangerous. Flash flooding can be prevented by good drainage systems and by avoiding over-development on floodplains.

Groundwater Flood

As opposed to flash floods, groundwater flooding takes time to occur. As rain falls over an extended period, the ground becomes saturated with water until it cannot absorb any more. When this happens, water rises above the ground’s surface and causes flooding. This type of flooding can last for weeks or sometimes even months.

Drain and Sewer Flooding

Sewer floods are not always attributed to the weather. As well as rainfall, they could occur as a result of a blockage or similar failure within the drainage system. Drain and sewer flooding may be internal (within a building) or external.

While there may be many different types of floods, they all share one common attribute: the potential to wreak havoc. Understanding the risks and taking steps to mitigate them is key.

In the UK, there is a national move away from flood defence to flood risk management and enabling communities to take reasonable responsibility to protect their homes, work places, businesses and communities. To read more about this topic, see this article: Predicting and Mitigating the Risk of Floods.