Report reveals flooding in Horncastle caused by heavy rainfall not delayed closure of flood defence
The Environment Agency report looks at what happened during the floods and recommendations for the future
Last updated 27th Feb 2024
The Environment Agency said a two-and-half-hour delay in closing a sluice gate in Horncastle was not the cause of the flooding that occurred after Storm Babet in October 2023.
Findings suggest that even if the sluice gate had been closed on time, the peak of the river would have been delayed by only an hour, indicating that the defences might not have held back the floodwaters regardless, which impacted 197 properties in Horncastle and a further 31 homes in Kirkby-on-Bain.
On Friday, October 20, Lincolnshire was pelted with what was reportedly two months’ worth of rain, and Horncastle was amongst the areas most severely impacted. Following the 2007 floods, which impacted over 200 properties, the town saw the introduction of an £8.1 million Flood Alleviation Scheme in 2017.
Despite these measures, many residents have criticised the flood defences as inadequate, after the market town and nearby villages experienced significant damage throughout the weekend.
In a report issued to Horncastle Town Council, the Environment Agency stated:
“The investigation has concluded the delay in closing the sluice gate did not cause the flooding in Horncastle. This was caused by heavy rainfall over catchments downstream of the reservoir which was in excess of the scheme design.”
“The scheme was designed to reduce the risk for a one in 100 chance in any year flood. The modelling has shown Storm Babet over the tributaries was a far greater flood event with a one in 1,000 chance in any year. It was an extreme flood.”
Since the storm, the Environment Agency claims it has addressed the issue with the sluice gate’s operating system by eliminating the system setting that could override the control panel setting.
It has also reportedly updated the procedures used by duty teams regarding the operation of the sluice gate and has decided to keep the sluice gate partially closed at all times to mitigate the risk of impacts should the gate’s operation fail in the future.
The organisation has also promised to maintain its ongoing dialogue with the community, aiming to identify further measures to mitigate flood risk throughout the town.
In the days after Storm Babet, local farmer John Harrison highlighted a defect in the flood defences that he had observed. His land is part of the flood relief strategy, designated to hold back floodwater. However, he reported that due to an incorrectly positioned switch for several hours, water was instead redirected back into the river.
“I was down at midday and I could see immediately the mechanism was holding water back from going down the river, but the return valve was open,” he recalled. “So it was like getting in a bath and you turn the tap on and haven’t put the plug in.”
At a Community Flood Defence Update held at Batemans Brewery in Wainfleet in February, spearheaded by Skegness & Boston MP Matt Warman, officials from Lincolnshire County Council shared insights from the ongoing investigation.
Matthew Harrison, Flood & Water Manager at LCC, clarified that the EA was leading the investigation, but highlighted: “There were a multitude of events that led to flooding in Horncastle, it wasn’t a single event.
“There are various water courses that feed into the town and not all of those are covered by the flood defence scheme that was put in place previously.”
Furthermore, he mentioned that the council is conducting around 230 separate investigations related to 850 properties across the county that experienced internal flooding following Storms Babet and Henk.
“It’s on a scale that we haven’t seen before,” he added.