Debenham Flood Management Project

Debenham is in the headwaters of the River Deben and a number of tributaries meet in the village.

In most summers the river dries up completely, but heavy rainfall events can cause the village to flood. The most recent flood was in 1993 when approximately 33 properties were recorded as having been flooded. There have been other floods in 1912, 1927, 1936, 1944, 1947, 1956, 1968, 1994 and 1995. The Environment Agency currently carries out maintenance through the village twice a year to remove vegetation from the watercourse.

River through Debenham during typical summer

 

 

 

 

 

The management of flood risk to Debenham is complex due to the three tributaries of the river meeting in the village and results, from an Environment Agency study, indicated that the costs of many traditional flood management measures are prohibitive. Thus, we are exploring a natural flood management approach, slowing the rate at which flows enter the river network. Working with landowners and the Essex and Suffolk Rivers Trust, we identified a range of measures which could help reduce flooding in Debenham, and provide water quality and habitat benefits. These include features such as small flood storage areas and ponds.

We incorporated the most promising natural flood management features into a hydraulic model to assess their potential benefits and to ensure that they wouldn’t result in additional flooding to other properties. The model showed that together, these features could reduce flood risk in Debenham in smaller more frequent flood events, but that further measures might also be needed. Click here to view the Natural Flood Management Modelling Report.

At present, two small features have been constructed at Debenham Hall Farm and Aspall Hall, by the East Suffolk Internal Drainage Board, funded by Suffolk County Council and the Essex and Suffolk Rivers’ Trust. The total cost of these two features is under £10,000.

Natural flood management feature upstream of Debenham. This pond is designed to impound circa 640m3 water in storm conditions.


 

 

 

 

 

 

We are now engaged in detailed discussions with other landowners and seeking funding to secure two larger, but similar, features in the coming year.

Once in place, we will use these natural flood management features as exemplars, hoping to persuade more landowners to embrace this approach on their land. The more of these slow the flow features we can install, the better the flood protection for the village – and the greater the environmental benefit.

The Environment Agency modelling clearly demonstrated that larger flood storage reservoirs, modelled on the Gulls and Derry Brook, do significantly reduce water levels in Debenham. However the construction and maintenance costs of these features are much greater than the benefits they provide. The funding provided by the Government is a fixed amount based on the benefits the project provides. As a result, significant funding from other sources (public and private) would be required to progress these features.

Sub Group Leads:

Gill Dinwiddie, Environment Agency - Email: gillian.dinwiddie@environment-agency.gov.uk
Jane Burch, Suffolk County Council - Email: jane.burch@suffolk.gov.uk