Flood for thought: Pluvial flooding

The final part of our ‘Flood for thought’ series this month will cover ‘Pluvial flooding’ also known as surface flooding.

There is more to flooding than just coastal and river flooding. It is suggested that between 2 and 3 million people are at risk of pluvial flooding in the UK, which is around 1/3 of the number of people that are at risk of flooding. Pluvial flooding occurs as a result of poor drainage, or simply an inability for our drainage systems to cope with a high volume of water.

A pluvial flood occurs with or without an independent body of water having an affect – such as a river or dike. This is one of the most common mistakes people make when they consider their own flood risk – you don’t have to be near water in order to be affected by flooding.

Pluvial flooding usually happens in two ways:

Intense rainfall – Too much rainfall is bad business for most of our drainage systems, as they aren’t designed to be able to take on a mass amount of direct water flow. Once the drainage system is overwhelmed, water can simply flow out onto the streets and begin to rise and flow to other areas.

Run-off water – Soil and hillsides can only absorb so much water. Once the ground reaches its’ maximum capacity for holding water there is nowhere else for it to go, except to stand and rise.

Pluvial floods are typically small floods and only affect a very limited area. There is no ‘flow’ to be concerned about as there is with a fluvial flood or flash flood. Pluvial floods are also typically a few centimeters deep, and occur in combination with fluvial floods or coastal floods. The size and frequency of pluvial flooding is directly affected by climate change, meaning that they will happen more often and cause more damage heading into the future.

This is the final blog for the series ‘Flood for thought’. By now you should be an expert on the different types of flooding. If not, don’t worry – you can contact me with any questions that you have. Email me at Kevin@floodsense.co.uk