Environment | Whatever the weather
With more extreme weather events becoming the norm, it is paramount that the dams and hydro industry continue to future-proof infrastructure and counteract the impacts of climate change
Above: Flooded houses in Thessaly, Greece during September 2023
EXTREME RAINFALL IS NOW considered to be a worldwide phenomenon which means the risks are even greater as decades old infrastructure wasn’t built to withstand such conditions. This is also why the work of organisations such as World Weather Attribution (WWA) are becoming even more important. Formed by researchers from institutions such as Imperial College London, The Royal Netherlands Meteorological Institute, the Laboratoire des Sciences du Climat et de l’Environnement, and the Red Cross Red Crescent Climate Centre, WWA works with climate scientists and other experts worldwide to help provide critical knowledge and insights on weather, databases, modelling and impacts. Recently researchers from Greece, the US,
Netherlands, Germany, and the UK collaborated to assess if human-induced climate change altered the likelihood and intensity of heavy flooding that led to widespread impacts across the Mediterranean region. From 3-10 September 2023 torrential rain fell across Spain, followed by very heavy rain and floods caused by the low-pressure weather system Daniel in Greece and Bulgaria, and then the devastating extreme rainfall that led to floods in Libya. All three individual rainfall events caused severe flooding, submerging settlements, leaving thousands homeless and killing at least 34 people in Bulgaria, Spain, Turkey, and Greece. While the flood-induced Libyan dam failures led to more than 4000 casualties, hundreds of fatalities with thousands of people unaccounted for. According to WWA, the severe flooding across the
Below: Aftermath of the Derna valley dam collapse due to Storm Daniel in Libya during September 2023 Editorial credit: seraj elhouni /
Shutterstock.com
region was caused by very heavy rainfall that fell, in the case of Spain in less than 24 hours, whereas it lasted 24 hours in Libya and up to four days over Greece and Turkey. In summary, the researchers state that the return time for the event in Spain is a 1-in-10 to 1-in-40- year event; for central Greece a 1-in-80 to 1-in-250-year event; for the large Greece-Bulgaria-Turkey region a 1-in-5 to 1-in-10-year event; and over Libya a 1-in-300 to 1-in-600-year event – the magnitude of which is far outside that of any previously recorded events.
WWA admits that although there are mathematical uncertainties in their research, they can still be confident that climate change did make the events more likely. For example, it is considered that an increase in rainfall intensity of around 10% would be expected given current warming levels (some reports suggest that the Mediterranean is a climate hotspot and warming 20% faster than the global average), while studies focussing on extreme rainfall with future warming also show an increase in heavy rainfall, rendering it probable that the observed increase in heavy rainfall is indeed a trend due to climate change. As the researchers stress, this disaster “also points
to the challenge of needing to design and maintain infrastructure for not just the climate of the present or the past, but also the future”. For example, last year Greece experienced a summer of extreme heatwaves and fires, including the largest fire ever recorded in the EU, followed by Storm Daniel which devastated the centre of the country. In addition, deforestation and relatively high rates of urbanisation have changed the landscape over time, increasing the number of people and assets exposed to flooding, and reducing stormwater drainage. While in Libya, the volume of water and overnight timing of the dam failures meant that anyone in the path of the water was at increased risk, not just those who are typically highly vulnerable. This means, WWA says, taking into account the long- term decline in average rainfall, and at the same time, the increase in extreme rainfall like this heavy rainfall event; a challenging prospect, especially for Libya that is a country plagued by crises.
Underprepared The UK is another country which continues to
experience extreme weather events. In February 2022, the country experienced three named storms in one week for the first time (Dudley, Eunice and Franklin) and more than 370 properties were affected, mainly by river flooding. In July 2021, parts of London received a month’s rain within a couple of hours which led to over 1500 properties suffering from surface water flooding as a result. And more recently, heavy, persistent and widespread rain affected much of England when Storms Babet and Ciaran struck in October and November 2023. The Met Office reported that 18-20 October was the third wettest independent three-day period for England and Wales dating back to 1891. And by the end of October, Storm Babet alone had caused 2200 homes to be flooded. Despite the increasing risk of flooding, the UK government has been accused of being underprepared for such extreme weather events, according to a new report by the National Audit Office (NAO). Called Government Resilience: Extreme Weather, the independent public spending watchdog’s report assesses four extreme weather risks: droughts, surface water flooding, storms, and high temperatures
16 | January 2024 |
www.waterpowermagazine.com
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