Lower Witham Flood Resilience Project - Information Page

The Lower River Witham Catchment is a large area of drained marshland between Lincoln and Boston. Throughout history embankments have been created alongside watercourses, and drainage works undertaken in the catchment. These works have made the surrounding land highly productive for farming and allowed communities to develop.

Some of these embankments are now over 200 years old. The extent and frequency of flood incidents is putting these structures under increased pressure, and the local community and economy at risk.

In 1997, the Lower Witham Strategy recommended reinforcement of key embankments, whilst allowing some areas to flood, to relieve the pressure on the system. Since then, 30km of embankments have been reinforced, but repeated high flows have damaged more. The recommended storage options have not been implemented, due to availability of suitable sites and difficulties in meeting HM Treasury funding rules of the time.

Flooding in 2019 has again highlighted the need to update the long-term plan to manage flood risk in the area.   ​ 

The Environment Agency are working with Arup and Jacksons to deliver this project. Working with local stakeholders, we aim to utilise the community’s local knowledge and aspirations for the area to develop a sustainable flood management plan with the long-term goal of improving resilience to future flooding.

Contact us direct via the Team's dedicated email address: lowerwitham.floodresilience@environment-agency.gov.uk

The project will take a twin track approach, to repair and reinforce the most critical structures in the short term, sustaining the current arrangements for managing flood risk, while the longer-term strategic approach to a changing climate is developed. It is recognised that changes to the way that we currently manage flood risk will take longer to agree and implement, and we want to ensure that structures will last until new arrangements are in place.

Phase One

A programme of the most urgent work will take place to sustain current assets, improve catchment resilience and continue to provide flood protection for communities and businesses in the Lower Witham area. This could include repairs and refurbishment of existing assets, including embankments and control structures.

The assets currently included in Phase 1 are Grand Sluice at Boston and various embankments along the River Witham and its tributaries. The Grand Sluice was built over 250 years ago to prevent tidal water entering the Lower Witham. It has been refurbished a number of times during its working life, most recently in the 1980s, and is now due for another upgrade in the next few years.

In early June, dive surveys were carried out across the sluice to understand its state of repair. It’s important that the Environment Agency doesn’t just inspect what is happening above the water line but below it too.

By bringing in divers, we can get additional surveys looking at parts of the sluice that wouldn’t normally be visible from the land. They can also better understand the River Witham too.

We also used sonar surveys in combination with lidar data to build a full 3d model of the Grand Sluice, the riverbed and the channel sides. The screenshot below shows the sonar survey combined with lidar data to build this model. The dive survey supplements this.

All this information will be used to better inform the work on the Grand Sluice before it gets underway next year.

Phase Two

Phase two will be to update the Lower Witham Strategy

Phase Three

Phase Three will be to deliver works recommended by the Strategy Update.