Flood forecasting in the UK: what should we learn from the Winter 2013/14 floods?

Contributed by Liz Stephens and Hannah Cloke

This is my final post as a HEPEX guest columnist 2014. I’ve decided to write with Hannah about a paper we co-wrote about the floods in the UK last winter. The full paper can be found here (paywall).

It was very nice of the climate system to give HEPEX scientists in the UK two major flood events to learn from during HEPEX’s first decade. The Summer 2007 floods provided significant impetus for improvement to hydrological ensemble forecasting capabilities, and the events of Winter 2013/14 provided a good testing ground for these improvements.

While there were countless newspaper articles devoted to criticism of the government’s role in the damage and disruption caused by last winter’s flooding, the role of forecasting was seen as a success.

Forecasts of upcoming floods contribute to reducing flood risk as a whole, enabling preventative actions: such as closure of barriers and placement of temporary flood defences:

With an early ‘heads-up’, emergency responders, including police, fire and rescue, and local authorities can begin to devote resources to an imminent flood event, checking on critical assets, ensuring that their equipment is in the right places and in good working order, and that enough people are on shift.

Changes to flood forecasting in the UK, brought about in response to the Pitt Review of the 2007 summer floods, have led to considerable improvements not only in how floods are forecasted, but also in the coordination of early warning and emergency response. The formation of the joint Environment Agency / Met Office Flood Forecasting Centre facilitated a radical change in practice and coordination between the two organisations, providing a strategic overview of flood risk across the country from forecasters with both meteorological and hydrological expertise.

The development of a probabilistic storm surge model out to a 7-day lead time came just in time, with the then Secretary of State for Environment, Flood and Rural Affairs, Owen Paterson, stating that “from the earliest signs of a possible surge threat, Government Departments and agencies, local resilience fora and local authorities were making preparations.”

However, the forecasting system for fluvial floods doesn’t currently extend out to the same lead time as that of the surge model, with the Met Office’s ensemble flood forecasting model only currently running out to 3 days. Given the significant benefits seen from having longer time to prepare for the December storm surge, furthering UK capabilities for probabilistic river forecasting should be seen as a key priority if we are to learn a forecast lesson from the winter 2013/14 floods.

Stephens, E., & Cloke, H. (2014). Improving flood forecasts for better flood preparedness in the UK (and beyond). The Geographical Journal. doi: 10.1111/geoj.12103

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4 Responses to Flood forecasting in the UK: what should we learn from the Winter 2013/14 floods?

  1. Chris Skinner says:

    Thanks Liz, this is an interesting post. I think even with storm surges there needs to be an improvement in how the forecasts are communicated and translated to actions on the ground. In regards to the event last year in the Humber Estuary, there was almost no warning or preparation – the alert for flooding was actually given after the city centre of Hull had already flooded, and evacuations were made just 40 minutes prior to some defences over-topping (this was probably due to someone looking over the wall at the water level however). The general sense in the area is one that the event caught most people by surprise.

    • Liz Stephens says:

      Hi Chris, yes I think our comments are related more to what is communicated to emergency responders than to the public. It would be interesting to know why the warnings were made so late to the public, I guess it will be partly related to the EA only having a duty to give at least 2 hours notice, or maybe they are extremely concerned about the risk of giving a false alarm to the public.

  2. Thanks for the article Liz. I can certainly endorse the improvements gained in the use of the surge ensembles in Scotland – the build up to the North and East Coast flood of the 5th December was picked up by the surge ensembles 5 days in advance and the risk communicated to responders through the Flood Guidance Statement.

    As for fluvial flood forecasting, the Scottish Flood Forecasting Service does utilise a 5-day deterministic forecast using Met Office ‘Best Data’. At present we’re limited to a 2-day ensemble forecast using MOGREPS but there are early plans to consider what opportunities there are for using the 6-day rainfall ensemble that is being planned.

  3. Liz Stephens says:

    Hi Michael, great news that there are early plans to use the 6-day ensemble. Hopefully our paper will promote these kinds of plans to the relevant people!

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