At the end of last year, The Environment Agency shared that 5.2 million homes and businesses across England are at risk of flooding, that’s one in every six properties.
Roughly half of these are at risk of flooding from rivers or the sea, whilst the other half are at risk of surface water flooding. And it is not only properties that are at risk of flooding, so are many critical infrastructure sites that if affected the impact of their flood damage could reach further than the flood waters themselves. Without doubt flooding is one of the most significant risks that the UK faces today and in future years. The UK Government has set out policies and strategies for mitigating and adapting to an increase in flood risk, including the Environment Agency’s National Flood and Coastal Erosion Management Strategy. However, it is clear that it is down to landowners, business owners, householders and local communities to be proactive and implement flood risk management measures in order to protect their assets.
This article considers the main causes of flooding in the UK and discusses how climate change is increasing the risk to property owners. As we know, climate change is an immediate threat to humanity and one which is irreversible without significant action. The impact that climate change is having on flood risk in the UK is devastating and we must move from mitigative to adaptive measures in order to withstand the impacts of flooding in the coming years. How we do this, and exactly which adaptive measures are chosen, will have a massive impact on the degree of resilience achieved.
Causes of flooding in the UK
Coastal flooding, which is driven by extreme sea levels, is the result of a combination of factors, namely storm surge, tides, wave setup and mean sea levels. It is when these components act simultaneously that the worst floods occur. In the UK coastal flooding has been regarded as the second highest risk of civil emergency (Cabinet Office, 2015), after pandemic influenza, with an estimated £150 billion of assets at risk (Environment Agency, 2009). Over the last century there have been a number of significant coastal floods which have damaged thousands of properties, creating high levels of homelessness, and sadly resulted in loss of lives, the most devastating of which was the 1953 North Sea flood.
Fluvial (river) flooding is mainly caused by excessive rainfall or heavy snow melting upriver, leading to high water levels downriver overflowing the river’s edges. When this occurs simultaneously with extreme coastal water levels, flood levels can be particularly high. This combination of coastal and fluvial flooding is termed compound flooding and can bring detrimental consequences to both coastal and inland towns. There are documented occurrences of London being impacted, such as in 1928 when a storm surge in the North Sea, combined with a high spring tide and sudden melting of heavy snow upriver, led to severe flooding along the River Thames and surrounding areas. As a response to this, and the 1953 flood, the UK has improved its coastal flood defences considerably, but are we prepared for what is to come?
Impacts of climate change on flooding
In the winter of 2013/2014, a combination of heavy and prolonged rainfall and the largest tidal surge on the east coast of England since 1953 led to significant coastal, fluvial and surface water flooding for an extended period of four months. In January 2014, Southern England received two to three times more rainfall than the long-term average, proving to be the wettest January on record (Thorne, 2014).
These excessive rainfall events are a direct consequence of climate change, which is warming the earth’s atmosphere and increasing its capacity to hold moisture. As such, scientists are predicting the UK will receive around 10 percent more rainfall per year by 2100, compared to 1986-2005 (Carbon Brief, 2014). We are already seeing the impacts of climate change on rainfall in the UK. Between 2000 and 2014, 45 percent of rainfall records were broken (The Met Office, 2014) in terms of wettest year, wettest period and wettest months on record. This increase in rainfall, combined with rising sea levels, suggests the frequency and severity of flooding in the UK will rise significantly over the coming years. We must have effective resilience measures in place to withstand the impacts of such events. Defra (2016) estimated the economic damages from the 2013/2014 floods were in the region of £1 billion to £1.5 billion, with 46 percent of this allocated to homeowners and businesses. It is clear that the measures the UK had in place at this time were not enough to protect assets and reduce the knock-on effects to other parts of society. If significant investment and a more holistic approach to flood risk management is not in place over the coming years, the consequences of future flooding will be difficult to recover from.
The UK Government’s response
The UK Government announced in July 2020 a new £5.2 billion investment for building new flood defences to better protect 336,000 properties in England by 2027 (Defra, 2014). There is no question that this is a step in the right direction with regards to investment into flood risk management, but in order to cope with the long-term projections of flooding, the risk must also be managed at catchment level – before the flood reaches the property.
In an attempt to provide some structure to future investments, the UK Government has placed a statutory duty on the Environment Agency (EA) to develop, maintain, apply and monitor a national flood and coastal erosion risk management strategy. This document was first published in 2011 but revised in July 2020 with an Action Plan to follow in April 2021 detailing how this will be implemented over the coming years.
It is estimated that for every £1 spent on protecting properties against flooding, £5 in damages are avoided (The Environment Agency, 2020). However, this does not consider the fact that floods are becoming more severe and frequent. Over the next few decades, with the impacts of climate change and the demand for new properties to be built on floodplains, the level of investment and choice of resilience measures seen in the past decade will not be enough. A shift towards catchment management and ensuring communities can recover quickly from floods is paramount. The Environment Agency’s strategy recognises this and provides the following actions to be implemented alongside traditional flood defences:
- Avoiding inappropriate development in the floodplain.
- Making greater use of nature-based solutions that take a catchment led approach to slow the flow of or store flood waters to improve resilience to both floods and droughts. However, this would require large changes in current agricultural practices to move away from intensive farming methods which lead to the soil becoming compacted and in turn restricts percolation of rainwater and contributes to local surface water flooding.
- Better preparing and responding to flood and coastal incidents through timely and effective forecasting, warning and evacuation.
- Helping communities and local economies recover more quickly after a flood or ‘building back better’.
- Making properties and infrastructure more resilient to future flooding.
As part of the strategy, emphasis is placed on building resilient infrastructure and ‘building back better’ when replacing or refurbishing current assets. Infrastructure has a particular importance with regards to flood resilience due to the significant knock-on effects to other businesses and livelihoods when disruptions happen. Recent floods have highlighted the vulnerability of critical infrastructure in the UK and the economic damage that flooding causes when effective resilience measures are not in place.
Over two thirds of properties in England are dependent on infrastructure sites and networks located in flood risk zones (Environment Agency, 2019). In order to cope with the projected rise in flood severity over the coming years, we must put infrastructure resilience at the forefront of flood risk management. The EA’s strategy supports this in setting an objective for risk management authorities to work alongside infrastructure providers to ensure resilience is built into future investments. It will be interesting to see how the 2021 Action Plan suggests this resilience is achieved, given the various constraints and limitations that often come with infrastructure developments.
In summary, the recent investment and strategy provided by the UK Government is a positive step and has recognised the additional broader range of resilience measures required to combat the impacts of climate change on flooding. Yet, this is merely the start of the journey, and for the value of the strategy to be realised it must be implemented effectively – through stakeholder consultation and educating asset owners to the risks they face. The responsibility now lies with property owners to take a proactive approach in protecting their assets and seeking advice from flood management experts.
For more information on how our flood defence specialists can protect your business from the risk of flooding please contact Ian Paton.