When we talk about flooding, or issue flood warnings, we always think about what the likely impacts on people, property and essential infrastructure (big roads, railways, water works, power stations) will be. The more severe the impacts the higher the level of warning. The terms we use to describe flood risk are also governed by the level of expected impacts. This blog provides some examples of those different impacts.
We issue three levels of flood warning: flood alerts, flood warnings and severe flood warnings. You may well be familiar with the graphics and descriptions we use (below).
We use green, yellow, amber and red colours to describe the forecast risk. Green represents a very low risk, yellow low, amber medium and red high. The colours don’t just reflect the likelihood of flooding but also the impacts it will cause. We use this matrix to decide the colour to use.
Flood Alert and low (yellow) risk
At our lowest level of warning or risk we’d typically expect rivers to be coming out of their banks with water entering floodplains (rivers don’t burst their banks, they simply come over the top!). Impacts may lead to minor disruption and flooding to low-lying roads and gardens.
You might see large areas of farmland in floodplains flooded, sometimes requiring livestock to be moved to higher ground.
When we issue flood warnings and describe flood risk as medium we expect to see significant impacts. These will include flooding to homes and businesses, possibly affecting whole communities. There are also likely to be impacts on local infrastructure and, in some cases, damage to it. Disruption to travel and business are also probable.
The fact that we have issued one or more flood warnings does not automatically mean flood risk will be described as medium in our outlooks. Our assessment of overall risk will depend on the context of the flooding, its overall impact on a County scale and the likely effects on responding organisations.
In addition to the impacts shown above you should expect:
Flooding to homes and businesses.
Flooding affecting whole, or large parts of, communities.
Main roads and railways being significantly affected.
Disruption to public events
For us to issue the highest level of warning or describe risk as high we will be confident that serious impacts will be probable and there may well be a real risk to life as well as property. It is rare for us to issue these warnings or describe risk as high and we will normally have consulted other responders (local authorities, police and fire and rescue) before we do so.
Impacts that may well be seen at this level of warning or risk include:
Major disruption to critical transport routes (eg: motorways and railways)
Damage or disruption of critical infrastructure (eg: water treatment plants, electicity sub-stations, roads)
Flooding to large urban areas
Large scale evacuations of residents
Overwhelming or damage of flood defences
So that’s a quick guide on what to expect at different severities of flooding. Don’t forget you can access our latest warnings (updated every 15 minutes) here:
And our 3 day assessment of flood risk (updated daily) here: