Lock Reversal Cessation
Lock Reversal Cessation
An important briefing for river users
Changes to the way we manage high river levels on the Rivers Great Ouse and the Nene
This briefing describes a change in the way we use locks to manage increased flows and high river levels, a practice known as ‘lock reversal’.
What is lock reversal?
Lock reversal is the practice of discharging flood water through a lock; effectively opening a lock to help manage river levels during periods of heavy rainfall, increased flow and high river levels.
Our studies show that reversing locks, to manage water levels on the River Nene, does not significantly contribute to reducing flood risk. Operating the locks in this way can reduce flood risk in some smaller flooding events by creating a little more capacity in the channel to move flood water more quickly downstream. However, in larger flood events lock reversal has little or no flood risk benefit as locks and other structures become overwhelmed by flood water.
Using lock structures to manage water levels when river flows are high creates strong currents and white water in and around locks. The strong currents are hazardous for river users and anyone in the vicinity of an open lock, including our staff who often have to visit locks in poor light or stormy conditions.
Boats can be drawn into an open lock and turned over by the strong currents. We send out messages to pre-registered river users (River Advice to Boaters) when locks are reversed but despite these being issued to warn boaters of the risk of navigating in these circumstances, we have still seen incidents where boats have been sunk in reversed locks and users lucky to escape with relatively minor injuries.
Anyone falling into a reversed lock would quickly be submerged. The strong currents and white water would make it difficult for anyone attempting to get out of the lock.
Stopping lock reversal will make our rivers safer places; however, stopping it will result in a change in flood risk to some properties and land on some occasions.
The onset of flooding may occur earlier in the immediate vicinity of a lock that is no longer being reversed. Water is likely to come out of bank on to the flood plain more frequently and for longer in some events, but this won’t necessarily lead to property flooding. River levels are likely to remain high for longer.
What we are doing
We propose to stop reversing locks on the River Nene after September 2016. This will reduce the safety risks for river users, the general public and our staff. This will not significantly increase flood risk in the local area. We have explored other ways to eliminate the safety risks; however, we have been unable to find a practical and affordable solution at this time.
We are in the early stages of reviewing lock reversal on the River Great Ouse. We will only stop reversing a lock once we have a good understanding of the role the lock plays in reducing local flood risk. We will make decisions about the long term use of locks on the River Great Ouse on a lock by lock basis.
River Advice for Boaters will continue to be issued.
We will continue to monitor the impact of not reversing locks during high levels to ensure that flood risk and safety are managed.
Find out more
The changes won’t take effect until after September 2016. Between now and then we will be speaking to the customers most affected by this change. We will arrange community drop-in events in the communities affected by this change on the River Nene through the summer (July, August and September). Each event will be promoted locally, through local marinas/boat yards/clubs and affected property/land owners/occupiers will be invited to attend.
Come along and find out more about the safety risks, the impact on flood risk, the evidence behind our decision to stop lock reversal and to discuss flood prevention. Staff will be available to discuss the change, listen to concerns and answer questions.
Get in touch with us
If you have any questions or concerns about these changes, please contact our Customer Services team in the first instance. Please call 03708 506 506 (Monday to Friday, 8am to 6pm) you will then be directed to the most appropriate team to answer your question.
Please use our incident hotline 0800 807060 (Free phone, 24 hour service) to report any non-emergency incidents at our locks. This number is answered 24/7 and reports are passed directly to the area staff (also on duty 24/7) for information or action.