Is Flooding Getting Worse?
In the last week of February 2022, parts of the U.K. experienced significant flooding following three named storms within five days of each other, a reminder of the impact the weather can have on our lives and livelihoods. At the same time, communities across the world in Australia experienced devastating floods and a number of people tragically lost their lives.
It is now accepted that the increase in greenhouse gas emissions from human activities resulting in global climate change is to blame. Climate change is supercharging the water cycle’s evaporation process and changing weather patterns, resulting in an increased frequency of extreme weather events of extreme rainfall events.
An analysis of the wettest February on record for the U.K. (which occurred in 2020) concluded that the extreme rainfall experienced was made about three times more likely due to climate change. A separate study of the flooding experienced in central Europe in July 2021 showed that climate change had increased the intensity of daily maximum rainfall by up to 19%.
Does Climate Change Affect Flooding?
Moisture content within the air is dependent on the temperature. For every 1 °C rise, the air can hold approximately 7% more water (IPCC, 2017). According to the UN Environment Programme (UNEP), higher temperatures result in more cloud formation from surface evaporation. More clouds can hold more rain which correlates to a higher frequency, duration, and intensity of precipitation and storm events.
Climate change is amplifying the processes involved in storm formation, causing updrafts to grow stronger and wider, pulling in more warm air from surrounding regions which leads to more rain. These storm systems are essentially a tower of upward-moving winds that feed themselves by sucking in warm air from nearby. When the air rises high enough, it cools and condenses into rain. Storms can generate their own weather, such as creating cold pools of air near the ground that trigger more convection.
Experts predict storms and weather systems will intensify as the effects of climate change become more apparent, bringing as much as 50 percent more heavy rain to the U.K. by the end of this century.
How will the U.K. be Impacted?
European-wide climate simulations of current and future weather patterns has spotted some warning signs about future weather and storm events. Scientists have found that extreme precipitation events are expected to increase over most of the U.K.
The position of the Atlantic jet stream is expected to change, which will have significant knock on effects to the weather experienced within the U.K. and across Europe.
That change arises because the Arctic is currently warming faster than areas at mid-latitudes, resulting in less of a temperature difference between the two regions. In response, the jet stream is expected to shift northwards in many simulations, bringing warm moist air from the Mid Atlantic behind it. The result is that the U.K. will see more severe storms throughout the year. The modelling also suggests that when dry spells occur they will be much more prolonged.
Other Influences on Flooding:
Agricultural land use in rural upstream areas has a vital part to play in flood risk management. Upstream areas which were once covered in forests have been gradually lost due to intensive farming and deforestation to make way for livestock grazing. The impact is that deforestation exacerbates the effect of flooding, by increasing both the speed and amount of surface run-off, as well as decreasing the amount of rainfall intercepted.
The health of soil is also dependent on the existence of trees. When deforestation occurs, the top layer of soil can be dislodged, known as soil erosion. When the top layer of soil is unstable, it is unable to retain any of the water that falls on it, resulting in increased surface run-off, in turn increasing the potential for flooding downstream.
Deforestation also increases the risk of flooding indirectly. When deforestation occurs, the trees capacity to take in carbon dioxide is also removed. Carbon dioxide is the gas that continues to accumulate in the Earth’s atmosphere, which is a major contributor to warming global conditions.
As well as deforestation, flooding in urban areas is often caused by urban development itself. Impermeable surfaces such as roads and pavements significantly increase the speed of surface water runoff, while severely hindering infiltration. This was highlighted in the significant London surface water flooding during the summer of 2021. Urban drainage systems, designed to manage and discharge this additional surface water runoff, have been effective in the past.
However, these urban drainage systems are now struggling to cope with the rainfall and additional surface water run off many urban areas are now experiencing. Their lack off effectiveness is a combination of climate change causing more intense precipitation, increased urbanisation, and outdated infrastructure that’s not able to cope with the new heavy rainfall experienced today.
This is also not helped by the poor maintenance of drains and gullies, which often become blocked with debris following storm events.
It should be noted however that engineering solutions cannot always provide solutions, and even the largest capacity drainage systems have the potential to be overwhelmed if the storm is significant enough.
Flooding mechanisms are far more understood today than at any other time. It is known that climate change is significantly increasing the risks of flooding, while additionally land use plays an significant role.
There are measures now in place to help mitigate the effects of flooding, forming a jigsaw of flooding risk management, including elements such as: SuDS, Natural Flood Management, Planning regulations, anti-flood technology like self-closing airbricks and Property Flood Resilience (PFR). All these measures ensure the effects and impacts of floods can be reduced and managed for future generations.
How Can We Help?
It may be the case that you’ve already started to see small indications flooding is get worse in your local area, or even property flooding following heavy rainfall. Is there more puddling of surface water? Does your garden seem forever waterlogged? Or is that local stream overflowing its banks getting too close for comfort?
These are issues we hear and deal with every day.
At FPS Environmental we are a renowned team of leading Flood Risk Consultants, Engineers and Environmental Professionals at the forefront of flood mitigation. It is our aim and passion to help those in need who are experiencing flooding at their property or business, as well as offering advice to those who are unsure.
We offer a range of consultancy services which address flood risk and flood mitigation across the whole of the U.K. such as:
- Flood Risk Assessments;
- Flood Surveys;
- Homebuyer Flood Risk Reports;
- Drainage Designs;
- Surface water Assessments;
- Managing Fire Water Runoff.