This year in the UK, November 9th-15th was the Environment Agency’s annual Flood Action Week, which aims to encourage the public to better understand their property’s individual flood risk, especially as the climate is changing and weather patterns are becoming more severe.
According to the Environment Agency, in England alone, over 5 million homes are at risk of flooding and the average cost of flooding to a single home is over £30,000. This is a significant problem, which is why the UK government recently announced a £5.2bn investment to strengthen flood defences in vulnerable areas.
While this record investment is welcomed, and will help greatly to protect against the more predictable types of flooding, specifically tidal and fluvial (river), the more unpredictable flooding, usually caused by rainfall, such as pluvial (surface water) and flash flooding still poses significant risk.
This risk is enhanced as the climate warms up, because in simple terms, a warmer climate holds more moisture. In fact, for each degree of warming, the air’s capacity for water vapour goes up by about 7% according to the Center for Climate and Energy Solutions. And the world is getting warmer.
According to a report in 2018 by the Intergovernmental Panel on Climate Change (IPCC), human activities are estimated to have caused approximately 1oC of global warming above pre-industrial levels. The report also claims that global warming is likely to reach 1.5oC between 2030 and 2052 if it continues to increase at the current rate.
In the UK, increased rainfall is already apparent. The 2018 UK State of the Climate report, completed by the Royal Meteorological Society, evidenced that the UK’s climate is becoming wetter.
According to the report, the most recent decade (2009-2018) has been on average 1% wetter than 1981-2010 and 5% wetter than 1691-1990 for the UK overall. Furthermore, the amount of rain from extremely wet days has increased by 17% when comparing the same time period.
The dangers of extremely wet days were laid bare in February 2020, in the form of both Storm Ciara and Storm Dennis.
Storm Ciara hit large parts of the UK in early February, bringing consistent high winds and heavy rain, with over 250 separate flood warning generated as a result. Yorkshire, Cumbria, Lancashire and other areas experienced severe flooding, with experts at PwC estimating insurance claims costing over £200m as a result.
Less than a week later, Storm Dennis hit. The UK was already saturated following Storm Ciara and, as such, the rainfall Dennis delivered brought more flooding and misery. Both the Rivers Wye and Severn reached their highest ever recorded levels and flooding saw major incidents declared in South Wales, Herefordshire, Worcestershire and Shropshire.
Fixing the damage caused by Storm Dennis is estimated to cost £225m, bringing the bill for both Storms Ciara and Dennis to well over £400m.
Coping with flooding
With the threat of heavy rainfall and flooding growing rapidly, for water companies, taking effective steps to mitigate the risk is essential.
The demands on the UK’s existing waste water networks are already great. Population growth is rapidly forcing the expansion of urban areas in order to meet the demand for new housing, impacting the quantity of water entering sewer networks and reducing the capacity of a sewer to cope with flood events.
Water companies also face various problems associated with pipe blockages. When undetected, blockages have the potential to cause untreated sewage to back up and potentially flood drains and streets. As well as causing physical damage to the pipe network, blockages can be expensive and time-consuming to remove and can lead to financial penalties from regulators.
When pairing together the challenges of maintaining a Victorian-era sewer network with climate change and urbanisation, UK water companies are finding themselves under increasing pressure to find smart, cost-effective solutions.
Waste water network monitoring is an excellent way of ensuring the efficient performance of a sewer system. Level sensors and flow monitors can act as an early warning indicator for problems such as blockages and flooding, providing the accurate data used to identify issues before they escalate.
With climate change significantly altering weather systems, waste water networks will be expected to cope with greater intensities of rainfall more frequently. While Flood Action Week is encouraging the public to take precautions, behind the scenes, water companies continue to invest heavily to do the same.