This week I attended one of the National Emergency Briefing screenings near me. While I wasn’t a fan of the Celebrity Gogglebox presentation style, with Chris Packham on the sofa seeing what Jennifer Saunders and others thought about the climate emergency, it did give me enough of an idea about the individual presentations to want to follow them up, and there is a really good website to do so here.
The two points which struck me particularly were the following:
- Professor Tim Lenton warning about what would happen if the weakening Atlantic Meridional Overturning Circulation (AMOC) hit a tipping point which, in some models, “shows that London would be -20°C in three frozen months of the year, and Edinburgh would be -30°C in five and a half frozen months of the year. And yet the summers will still be hotter than today because it’s a 2°C warmer world.”
- Professor Hayley Fowler warning of the risks of mega floods: “These storms can produce two thirds of a year’s rainfall in just a couple of days. Over London, that would mean about 35cm of rainfall falling over a large area. A flood of this scale will be a national crisis. Recovery would take years.” She also warned that by 2050 1 in 4 properties – 8 million in England – will be at risk of flooding.
And since flooding often follows a heatwave such as the one we are currently experiencing, I thought I would look at the risk of long-term flooding in a bit more detail, which is when I came across the government’s check the long term flood risk for an area in England website. When you put in your postcode, it assesses your flood risk under four different categories:




It then explains how they measure the risk and the kinds of things which tend to affect it. All in all a good resource, and the modelling behind it is what the 1 in 4 properties at risk of flooding by 2050 is based on.
In July 2021, several European countries were affected by severe floods. The floods started in the United Kingdom as flash floods causing some property damage. Later floods affected several river basins across Europe including Austria, Belgium, Croatia, Germany, Italy, Luxembourg, the Netherlands, Romania and Switzerland. At least 243 people died in the floods, including 196 in Germany, 39 in Belgium, two in Romania, one in Italy and one in Austria. It was thought that some of the affected regions may not have seen rainfall of this magnitude in the last 1,000 years.
A study using climate simulations on a grid of 2.2km squares published in June 2021 had come to the following conclusion:
Intense rainstorms are expected to be more frequent due to global warming, because warmer air can hold more moisture. Here, using very detailed climate simulations (with a 2.2 km grid), we show that the storms producing intense rain across Europe might move slower with climate change, increasing the duration of local exposure to these extremes. Our results suggest such slow-moving storms may be 14× more frequent across land by the end of the century. Currently, almost-stationary intense rainstorms are uncommon in Europe and happen rarely over parts of the Mediterranean Sea, but in future are expected to occur across the continent, including in the north. The main reason seems to be a reduced temperature difference between the poles and tropics, which weakens upper-level winds in the autumn, when these short-duration rainfall extremes most occur. This slower storm movement acts to increase rainfall amounts accumulated locally, enhancing the risk of flash floods across Europe beyond what was previously expected.
As Professor Fowler says:
Our infrastructure was built for a climate that no longer exists. Raised reservoirs, drainage, housing and transport were designed many years ago when extreme rainfall was rare and less severe. As rainfall intensifies, risks such as dam overtopping and cascading failures rise.
The government also produces monthly reports on rainfall, soil moisture deficit, river flows, groundwater levels and reservoir levels. This includes a wonderful map of the year’s rainfall:

What struck me was that the report looked at exactly the same things (river levels, groundwater levels and reservoirs) but, because they were concerned with low levels of rainfall, did not even mention flood risk. The rainfall scale only goes up to >125mm rainfall within a month as a maximum, which looks hilarious when compared with the 271.5mm of rainfall over 48 hours in parts of Belgium in 2021.
There have been no new reservoirs built in the UK since 1992, just another one of the gifts of water privatisation discussed previously. The government announced last year that it had “seized control of the planning process” to build two reservoirs due to be complete in 2036 in the Cambridgeshire Fens and 2040 near Sleaford in Lincolnshire respectively.
Professor Fowler says the probability of dam overtopping is increasing. So how’s the review of reservoir safety going?
In 2019, there was a failure of a dam at Toddbrook Reservoir in the Peak District. The operation to pump water out of the reservoir to safeguard Whaley Bridge seems to have been dominated by concerns about the fish. The independent review commissioned into the incident identified the rather alarming fact that:
“…the reservoir and its Owner can be compliant with the legislation without the reservoir necessarily being safe.”
Among the report’s recommendations were the following:
- There is a systematic review of how the current Reservoirs Act, and the associated Regulations and Guidance, are implemented. This should consider the roles and responsibilities of qualified engineers, whether compliance with the Act is sufficient to ensure safety, and how safety is formally assured.
- The potential of an Inspecting Engineer issuing a Certificate of Safe to Operate be explored. This should include a review of practice in other safety critical infrastructure sectors. It should also consider liability implications and whether some form of qualifying statement may be needed to accompany the certificate.
- The statutory maximum period between inspections is reviewed to determine if it is still appropriate in every case in the light of the ageing reservoir stock.
In his follow up report looking at the reservoir system in general in 2021, Professor David Balmforth made this extraordinary statement:
This raises the question of what is meant by “safe”. In other infrastructure sectors and with reservoirs in other countries, safety is assured by managing risk, and by reducing that risk so far as is reasonably practicable – the terms “reasonable” and “practicable” being well understood in practice and in law. For a reservoir, risk is defined as a combination of the likely failure of the dam (or other reservoir structure) and the impact that an uncontrolled release of water would have on the area downstream, particularly the likely loss of life. I have therefore recommended that in future the assurance of reservoir safety should be managed on the basis of risk, and that the amount of effort (and cost) associated with that process should be in proportion to that risk. In this way the public can be assured that the hazard posed by reservoirs is being managed in an objective and transparent way.
It would appear that reservoir management is playing catch up on the whole concept of risk management.
What has followed is a policy paper from the Environment Agency on the launch of a reservoir safety reform programme. However the public consultation on the proposed reforms has already been delayed until later this year. And the page about the consultation process does not suggest anyone is in any hurry.
















