The flooding that occurred in parts of North Lincolnshire in early December, 2013 has once again raised the issue of the strength of the flood defences in place in the area.
The reach (or stretch) of the Trent in North Lincolnshire has flood defences in place. Therefore flooding from the river can only occur if the defences overtop (occurs when the water rises over or above the top of the defences) or breach (occurs when the defences partially collapse).
The flooding that occurred in Burringham was caused by overtopping of the defences. The Environment Agency (EA) considers those defences currently in place to have an approximate standard of protection of a 1:200 year event. A 1:200 year event is the flood that you might expect to see once every 200 years; in other words there is a 0.5% probability of this event happening in any given year.
The proposed Lincolnshire Lakes development site did not flood. Master developer Lucent’s hydrology partner, Peter Brett Associates has undertaken extensive hydraulic modelling. This modelling accords with what happened in early December, that is the Trent defences begin to overtop in a 1:200 year event and that the Lincolnshire Lakes site is not at risk of flooding in a ‘current conditions’ 1:1,000 year event providing the defences do not breach.
Lucent’s proposal for Lincolnshire Lakes is to raise the development such that, even in the event of a breach failure of the raised banks there will be a 1:200 year standard of protection for the next 100 years. As part of this development it is proposed to reinforce the existing flood defences to the benefit of the communities currently relying upon them. The proposed reinforcement on the right bank will be either through intermittent (passive breach arresters) or through continuous sheet piling. Both these methods will shore up the soft defences presently in place. The reinforcement would change neither the height nor the appearance of the existing defences.
This reinforcement will both reduce the likelihood of a breach developing (such as may have occurred at Keadby, a few miles to the north of Burringham) and reduce the flooding that would result in such a breach.
In essence, we are proposing to reduce the residual risk of flooding to the residents of Burringham and other communities on the right bank of the River Trent.