Our response to Storm Chandra
How we responded before and during Storm Chandra
Crane installing temporary pumps at Northmoor Pumping StationJanuary brought more than twice the usual rainfall, with a third of this rain falling in only two days. Wet weather continued in February, and by the 19th, the Parrett and Tone catchment had already received 171% of the usual rainfall for the month, and the Axe and Brue catchment had received 197%.
Ahead of Storm Chandra, we reduced water levels to create maximum capacity for incoming rain. The flooding would have been much worse if we hadn’t - Currymoor had been pumped down completely before refilling in less than four days.
Our trigger points plan sets out when we consider deploying mobile pumps. The criteria were originally set after the 2014 floods, with an expectation that it would take around 10 days for pumps to be deployed once the thresholds were met. This was considered to be enough time before Currymoor filled and water made its way towards properties at risk in Northmoor and Saltmoor.
The trigger points were reviewed and revised following the 2023 floods, and amendments were made to initiate temporary pump deployment discussions sooner. They will be reviewed again following the floods this year. The plan is published on gov.uk – you can access it via this link: Somerset Levels and Moors: reducing the risk of flooding - GOV.UK.
Deploying extra pumps is a significant investment, so it’s important to have clear trigger points that help us act at the right moment. Additional pumping triggered by the plan doesn’t guarantee flood prevention; it does ensure we can begin removing floodwater as soon as conditions allow.
Submersible pumps ready to be installed near LangportOnce pump deployment is started, a huge construction operation gets underway. We mobilise local equipment, and other equipment is brought in from around the country. Road closures are organised and staff begin the complicated process of installation. There are a lot of things that need to be in place before the pumps start running.
Athelney spillway began running on Sunday 25 January. The pump deployment was already well underway, with a 180-tonne crane arriving on site at Northmoor Pumping station the following morning.
It takes several days for water to move from Athelney to the pumping stations through the network of ditches and rhynes. Extra pumps at Northmoor were operational on 28 January and at Saltmoor on 29 January, ahead of levels in the drains rising significantly, so these pumps were in place when they were needed.
Significant improvements have been made to pumping stations over the past 12 years, including upgrades to permanent pumps, and modifications to make additional pump installation quicker and more efficient. These improvements mean that we have been able to install extra pumps in record time this year.
Operations and pump deployment since Storm Chandra
We have deployed pumps to 19 locations on the Somerset Levels and Moors during this event, including 28 ultra-high volume pumps and a large number of high volume pumps. Pumps are deployed in order of priority, with those that have the greatest impact on reducing flood risk being installed first.
For several weeks following Storm Chandra, river levels upstream of Burrowbridge were too high to run any pumps. Extra pumps were installed first at Northmoor and Saltmoor pumping stations, which are rarely inhibited by the river, because the tidal River Parrett usually has room to pump at these locations.
Pumps in the drain at NorthmoorThese temporary pumps are fed by a network of drains and ditches that lead to the pumping stations. These channels can only convey a certain amount of water. The temporary pumps are submersible - there has to be enough water in the drains in order for them to operate, and many of our installations are of a greater capacity than the drain network can provide. Sometimes pumping has to be paused while water makes its way through the network of rhynes. In order to improve flows to the pumping station, we created a bypass channel around a privately owned bridge on the Northmoor Main Drain.
We have also installed pumps on other watercourses that come under the purview of other organisations. This includes putting in temporary pumps on the Park Brook near Moorland, which is a Viewed Rhyne managed by the Internal Drainage Board.
We have used the Bridgwater Canal as a flood relief channel. This is owned and managed by the Canal and River Trust, and we work with them so that the channel can be used safely and effectively, as the canal has very little gradient and was not built to carry high flows. It is used by pumping water in at Fordgate and pumping the same volume of water out at Bridgwater docks, which is discharged into the River Parrett over the old locks.
Water flowing from the Parrett to the Sowy over Allermoor spillwayIn this flood event we have been able to use the increased capacity of the Parrett Flood Relief Channel. Improvements since 2014 mean that more water can be diverted down this channel, and flood alleviation schemes built in Aller and Westonzoyland have helped protect properties downstream. We have diverted extra flows by opening Monksleaze Clyce while the spillways are still running, outside of our normal operating procedures.
We have installed pumps at Dunball to relieve some of the pressure created by sending water down the Parrett Flood Relief system. The Dunball pumps can only run for two to three hours per tidal cycle, when the Dunball Sluice gates are closed and there is enough water in the channel. The pumps discharge a relatively small amount of water compared to the natural discharge through the gates when they are open. For most of the tidal cycle, the open gates release up to a maximum of 75 cubic metres of water per second into the Severn Estuary. When these gates have to close to prevent tidal flooding, the pumps take over, but they only discharge 10-15 cubic metres per second during the short period of high tide.
While the Dunball pumps are not as powerful as natural processes, and they may have less impact on reducing flood risk to property than other pumps, they do help relieve pressure on the lower Sowy and King’s Sedgemoor Drain.
Now that river levels have dropped, we have been able to install extra pumps at upstream stations, including Westover, Midelney and Huish Episcopi. At the peak of this flood, around 30 square miles of low-lying, mainly agricultural land was flooded. It will take some time for all this water to be pumped off the moors.