Overview

Welcome to the River Eau information page - last updated 6th September 2022

This page provides information about the River Eau, with a focus on the flood risk associated with this river, the causes of flooding, completed investigations and ongoing work in the area. Please use the links below to view different sections, or scroll down to view the whole page.

Key points
Geography of the area
History of flooding
Flood risk management
Incident response
Upstream catchment
Previous investigations
Previous maintenance
Routine maintenance
What we don't do and why
Planned work
Natural flood management options
Funding, policy and strategy

 

Key points

• The most recent bathymetric survey (2021) showed that the bed level (including any siltation)  of the River Eau is lower than it has been in all available records, including 1947 as well as a survey undertaken in the 1970’s. The survey also confirmed that the height of the raised embankments downstream of Scotter is lower than the bank levels in the village and some of the left bank channel side levels downstream of the village are actually lower than the bed level in the village, meaning that water should start to fill the downstream floodplain before any flooding occurs in the village. This indicates that the cause of property flooding is water entering the village more quickly than it can exit, causing levels to rise before it can reach the downstream floodplain. This is being confirmed as part of the modelling work currently being undertaken. Click here for more details.  

 

• Some properties on both Riverside and Lindholme were built on areas that flooded in 1947 and 1981. Click here for more information.  

 

• A number of investigations have been completed since the flooding in 2007 to establish what, if anything, can be done to reduce flood risk to properties in the village. Click here for more information. Many options have been discounted due to little/no impact, or actually increasing flood risk. The options that may have the biggest impact are individual property resilience measures (flood doors, etc.), natural flood management techniques upstream to slow the flow, and an upstream flood storage area.
  • Natural flood management (NFM) measures will slow the flow upstream and have some effect on levels in the village during a small to medium sized flood event, which are those with around a 5% chance of occurring in any given year. For events of a larger scale (that happen on a much less frequent basis) these measures tend to be less effective as the sheer volume of water takes over. We have to find innovative ways to fund these NFM projects, which can be possible as a lot of the measures have multiple environmental benefits that can attract small sources of funding. The amount of NFM measures required to make a real difference to levels in the village is large but each one will help to some extent.
  • Individual property protection can help in some circumstances but is not necessarily a complete solution for systems like the Eau. This is due to the rapid onset of flooding, meaning less warning and therefore time to prepare, as well as the high ground water levels that occur during a flood which can bypass some protection measures.
  • A large upstream storage area could technically be constructed to protect the village from flooding. These large reservoir structures do exist across the country and work by being a dry area of land that can be flooded during a flood event to hold back water from the downstream areas at flood risk. These types of schemes are extremely costly so are usually only fundable if they are able to protect many hundreds of properties downstream. The shortfall of funding for a scheme such as this would be in the multi millions, with the Defra funding available to us only able to cover a small percentage of that.

 

• We are continuing to work closely with Scotter Parish Council and provide information and advice where possible.

 

Geography of the area

The River Eau is a 15-mile-long watercourse that flows through rural Lincolnshire from Harpswell to Susworth, before joining the River Trent through a flapped outfall. The Northorpe Beck, Manton Sewer and Dar Beck all flow into the River Eau.

The Eau catchment covers an area of 48 square miles, is relatively flat and predominantly consists of drained agricultural land.
Some other systems that feed the River Trent, such as the those found in the Isle of Axholme, are constructed as pumped catchments and due to being below sea level have to work against gravity to discharge in to the River Trent. The River Eau is more natural, with some modifications, and is above sea level.

The smaller watercourses that discharge into the Eau are maintained by the Scunthorpe and Gainsborough Water Management Board; the river Eau itself is designated as main river. The Environment Agency has permissive powers, but not a duty, to carry out maintenance, improvement or construction work on designated main rivers

Downstream of Scotter, the Eau passes through more agricultural land, washlands and finally between earth embankments to its flapped outfall to the River Trent.

Live river level data for the Eau in Scotter can be found at River level information for River Eau at Scotter - GOV.UK (flood-warning-information.service.gov.uk)

The River Eau through the village of Scotter. 

The Ordnance Survey maps from 1886, 1907, 1972, 1974, 1978, 1986, 1992 and 1994 tell the story of the growth of Scotter village.

In 1886, the small village consisted of a school, chapel, public house and rectory to the south of the River Eau with scattered rural properties to the North. The river was crossed by two main road bridges at The Green and what now has become the A159 Bridge and by several small footbridges. The Dar Beck is also shown as an open water course. There were no other water courses shown on the map.
In 1907 there were no significant changes.
By 1972 there were wholesale changes to the village with a large development of semi and detached properties being built north of the River Eau and associated highways. There were also a large number of detached properties that were built adjacent to the river on the north side (Riverside).
1974 and 1978 showed no significant changes.
1986 showed new houses built on the south side of Riverside. A new development of properties (Lindholme) built upstream of the Green Bridge both north and south of the river along with three vehicular access bridges.
No significant changes in 1992.
By 1994, additional properties were built within Lindholme on the south side but away from the river
The latest Ordnance Survey shows new property adjacent to the Green Bridge on the south side and new property adjacent to turning head in Lindolme, also to the south.

 

History of flooding

The village of Scotter is built around the River Eau, with Lindholme and Riverside Roads running parallel to the channel.

The village was flooded in 1947, and again in 1981.
More recently, the village flooded during June 2007 due to a combination of surface water and river water, with over 30 properties affected. This was considered to be between a 1 in 50 year event and 1 in 100 year event (between 1-2% chance in any year).
Summer flooding is often caused by thunderstorms with a large quantity of water falling in a relatively short period of time. Particularly dry ground can worsen the effects as the water is not absorbed as easily.

Flooding was experienced again in November 2019 with prolonged and persistent rainfall events.

2019 monthly rainfall data for the Lower Trent catchment shows that the 5 months leading up to November were exceptinally wet. 3 of those 5 months received more than double the long term average rainfall you would expect in those months.

 

Winter flooding is often caused by prolonged rainfall over days or weeks. The ground becomes saturated and sensitive to further rainfall.  Factors including snow/ice melt, cold hard ground and already full or partially full rivers add to this situation and result in rivers, such as the Eau, filling rapidly.

In 2019, the 4 closest rain gauges to the River Eau (Owston Ferry, Cadney, Upton, Toft Newton) recorded between 39mm – 54mm in 24 hours between 7^th and 8^th November 2019. This amounts to between 70% - 102% of the November long term average.

 

Historic flood map (all flooding).

 

Flood risk map for the village of Scotter. High risk means that each year this area has a chance of flooding of greater than 3.3%. Medium risk means that each year this area has a chance of flooding of between 1% and 3.3%. Low risk means that each year this area has a chance of flooding of between 0.1% and 1%. Very low risk means that each year this area has a chance of flooding of less than 0.1%
The map below shows flood risk for the wider area surrounding the tidal section of the River Trent. 

Lidar data shows the topography of the area. Scotter is clearly seen as lying within a ‘funnel’ of the floodplain – large flat areas upstream, relatively higher ground either side of the village, widening again downstream.

Lidar map of Scotter and surrounding area.

 

The first property in Scotter begins to flood at 5.3mAOD. The maps below show the ground levels above 5.3mAOD in green and ground levels below 5.3mAOD in blue. This shows that the cause of flooding from the River Eau is the rate and amount of water entering Scotter from upstream. For the flooding to be caused by a back up from downstream, the whole of the floodplain in blue on the right bank of the Trent would need to fill up first before getting to a height that would affect the village. This floodplain runs from Morton to Burton Stather which is approx. 27.5km in linear length and up to 5km wide in places.

 

The graph below shows embankment heights and river bed levels along the River Eau. It shows that the embankments in the village are higher than those downstream, illustrating that the downstream flood storage area would need to be completely full before this had any impact on flooding in the village. 

 

Flood risk management

The Environment Agency has permissive powers to carry out flood risk management work on main rivers, and in exercising these powers, we must consider the flood risk.  We prioritise our effort and funds in areas where it will provide the most benefit and the budget is directed primarily to high risk areas to protect people and property. 

Risk Management Authorities (RMAs) for the River Eau are:

• The Environment Agency - Environment Agency - GOV.UK (www.gov.uk)
• Lincolnshire County Council - Managing flood risk – Lincolnshire County Council
• West Lindsey District Council - Flooding | West Lindsey District Council (west-lindsey.gov.uk)
• Anglian Water - Flooding (anglianwater.co.uk)
• Severn Trent Water - Flooding | In My Area | Severn Trent Water (stwater.co.uk)
• Scunthorpe and Gainsborough Water Management Board - Scunthorpe & Gainsborough WMB - Shire Group of IDBs (shiregroup-idbs.gov.uk)

As part of our work with communities, we recently offered a suite of virtual training to Flood Wardens during February and March. Topics included Incident Management, the role of a Flood Warden, co-ordinating a Flood Warden group, marketing and recruitment and finally fundraising. We plan to develop some more targeted workshops, covering items such as insurance and well-being.

A map showing the watercourses managed by the Environment Agency and by Scunthorpe and Gainsborough Water Management Board can be viewed here or at the bottom of this page. 

 

Incident response

We issue Flood Alerts and Flood Warnings for the River Eau when needed. To sign up for this free service and receive these notifications, please visit Sign up for flood warnings - GOV.UK (www.gov.uk)

Our incidents range from Category 1 (major flooding) to Category 4 (no impact). We will use our resources to react to the incidents posing the highest risk, which will depend on various factors such as weather forecast, people and properties at risk and environmental impact.

Our duty officers, who operate on a 24/7 roster, monitor the river levels in the village and the outfall from the Eau into the Trent (we have a CCTV camera pointing at the outfall). Our Field Team also carry out patrols in the area to check for issues in the river during heavy rainfall.

To find out more about becoming a Flood Warden for your community, please look at the Flood Warden information, which is also available at the bottom of this page.

 

Penstock operation 

The Environment Agency agreed modified incident response procedures with Scotter Parish council for operating the River Eau penstocks several years ago. 

Originally, the procedure was to open all four penstocks at the River outfall when the level in the village reached 4.2m AOD. However, at a Parish Council meeting the Environment Agency were asked to lower the threshold for opening the penstocks to 4m AOD, which was agreed by both parties.  
The Environment Agency later added that all four penstocks would be opened if 4m AOD was forecast in the village, based on rainfall totals and predictions, and soil moisture index, which gives a lead time of up to 12 hours.  

As this is an additional operating procedure, put in place at the request of the Parish Council, we will only operate the penstocks when 4m AOD is forecast or reached in the village. Additional opening of all penstocks when levels are lower is not only ineffective for flood risk purposes, but it also increases siltation at the outfalls, which can cause them to become blocked and makes operating them more difficult. This is demonstrated in the image below, taken after a period of trialling having all 4 penstocks permanently open.  

In order to reduce this siltation, we routinely operate the penstocks to build water levels in the downstream area before opening them, allowing the increased volume of water to flush the silt away from the valves and into the River Trent.  

Our incident response operation works 24 hours a day, 365 days a year, with not only operational staff on call but also numerous other roles which not only update the forecasts but also provide the Flood Warning Service based on the forecast and actual river levels; as well as roles which instruct our operational staff to instigate patrols and operate our structures accordingly. If levels reach the agreed threshold, we will open the penstocks. We will also issue flood alerts and warnings where needed.  

 

Upstream catchment

The upstream catchment is a complex issue as it covers multiple local authority areas, Internal Drainage Boards and our own activities, as well as riparian ownership. We are working with partners in the upstream catchment on queries that have been raised to us, including factors affecting the speed and quantity of water entering the Eau.

 

Previous investigations

We have looked at the possibility of an upstream storage reservoir to reduce flows on the River Eau during heavy rainfall events, using a Flood Estimation Calculation Record. A scheme large enough to reduce the flood risk in Scotter would be a multi-million pound project; the funding from DEFRA we would receive for this, known as Grant in Aid, would only cover a small percentage of the total cost based on the small number of properties that would benefit. This would leave a very large funding gap which would require public and private contributions.

Multiple, smaller areas of Natural Flood Management (NFM) water storage is an alternative option. A large number of these small scale projects would be required to achieve a tangible benefit to properties in Scotter. This option would not provide the level of flood protection DEFRA require to attract Grant in Aid funding. However NFM schemes can provide multiple benefits to the environment so there may be opportunities that arise over time where other funding from other sauces could fund projects that provide environmental enhancements. Changes to the way the country provides land management funding are in progress which may be able to fund the management of these schemes to make them more affordable in future.

A model for a flood relief culvert through the A159 road bridge was completed in 2009.

When compared with existing water levels, a flood relief culvert was found to only drop water levels by 50 mm during high river levels. Removing the bridge completely only reduced levels by 100 mm. These reductions would not reduce the risk of flooding as they would only reduce the height of flooding that would occur even at lower levels, but the properties at risk would still be flooded. Constructing a flood relief culvert has little benefit since the A159 bridge does not appear to be the primary cause of flooding.

A Flood Estimation Calculation Record has been carried out to look at the possibility of an upstream storage reservoir to reduce flows on the River Eau during heavy rainfall events. This concluded that the volume of storage required was so large that the cost of construction and land compensation would be unaffordable.

A sensitivity analysis was carried out to model the difference between a heavily vegetated and well maintained channel. The modelling data showed that some targeted desilting of the worst affected areas can help reduce levels although would not change the risk category of those affected by flooding. 

Widening the downstream channel would potentially reduce water levels within the village, although it would not change the risk category of those affected by flooding as the properties would still flood. This option would involve excavation, compensation for land use and disposal of waste material, making it unaffordable.

Downstream of the A159 bridge.

By using raised defences to defend properties, the water is constrained to narrower channels and therefore levels are raised. Considerable banks/walls would be required to retain even low flows and risk may be increased because if defences were to overtop or breach then inundation is sudden and to a higher depth. Each bridge would have needed to include stop logs or raised parapets to prevent creating a flow route. This option would also be unaffordable.

It was thought that a combination of widening downstream and building raised banks upstream could be a practical solution as excavated material from one area could be used in the other. Although the combination of measures would lower the water level between The Green and A159 bridges, the water level would be raised along Lindholme.

Summary:

• Adding a flood relief culvert has little benefit due to the small impact of the A159 bridge. 
• Flood levels are somewhat sensitive to roughness but increased maintenance is unlikely to reduce flood risk.
• Other alternatives are limited though many have been explored, for example raised banks potentially increase risk due to raised water levels and impact on surface water drainage.

 

Previous maintenance

Historically around the UK, rivers were frequently dredged to improve land drainage and support agricultural production. After the Second World War there was a greater need for food production. Rivers were deepened and widened to drain land and increase flow to create more land for agriculture - often with unintended consequences, such as flooding downstream.

The 1970s to the 1990s brought a change in direction because of an increased understanding of how rivers work and the effect dredging has across the catchment. Funding steered away from land drainage and management, to protecting people and property, resulting in a decrease in dredging for land management.

The Water Framework Directive has been transposed into UK legislation, and thus remains in place. It requires us to consider the impact of dredging on the ecological health of rivers, but does not prevent us from carrying out dredging where it is needed to protect people and property.

 

Routine maintenance

The frequent maintenance carried out for the River Eau has (until recently) concentrated on the downstream part of the catchment; grass cuts on the embankments, maintenance around the outfall and winter treeworks.

In 2020 we increased the maintenance to include more treeworks, weed removal (in the village and downstream) and silt removal in targeted areas.

March 2020 – weed and silt removal downstream of Scotter village

This work was targeted in areas where there was an increase in silts and weed in the channel.

The work removed significant amounts weed and associated silts and debris on these stretches.  Water Voles are present at this location, so the work was carried out under a Water Vole Licence.  A Licenced Ecologist was present to ensure that the works were compliant with the Wildlife and Countryside Act 1981.  The works improved channel capacity and conveyance in the river along these sections.

November 2020 – De-weeding downstream of Scotter village

We completed works to remove weed from within the river channel downstream of Scotter village over an approx. 1800m stretch of the river. These works removed a significant amount of weed, helping to increase the conveyance of the river as it leaves the village, ensuring that it can flow freely during the winter period.

December 2020 – weed removal in Scotter village

Our contractors removed weed in-channel by hand, which enabled them to cut the weed close to the bed of the river. These works helped to increase channel capacity through the village and ensured that the River Eau could flow freely during the winter period.

December 2020 – tree removal in Scotter village and downstream area

Our field team carried out treeworks in Scotter village, and this was done within the river channel to remove any trees or branches which could reduce the flow in the river.

In the downstream area of the river, we removed fallen trees. 

September 2021- weed cutting downstream of the village, with the cleared channel shown in the images below. 

 

October 2021 - Weed spraying on the section of river within the village.

We have also cleared silt from in front of the River Eau outfall onto the River Trent. This type of work helps to ensure that the outfall is free from silt so it can operate without being impeded by any build-up of debris or obstructions from around the flapped outfall.

Silt removal at the outfall.

August 2022 - grass cutting in the downstream section using a flail.

 

What we don't do and why

Our programme includes a range of activities that are prioritised and timetabled using information from inspections, maintenance standards, levels of flood risk, and from legal and statutory obligations. Dredging is one of these maintenance activities, and we look at dredging as an option where it’s technically effective, good value for money, does not significantly increase flood risk for others downstream and is environmentally acceptable. Understanding where dredging will – and won’t – reduce flood risk is key. We must be sure it will reduce flood risk to local homes and businesses and won’t increase flood risk downstream. The effectiveness of dredging also varies substantially from river to river and within a particular river, so we assess it on a location by location basis. 

Dredging options in excess of the targeted desilting work we already carry out is not something considered suitable for the River Eau. On many rivers, including the Eau, natural processes cause silt to return and accumulate in the same places very quickly and therefore it is not cost effective. There is also no evidence to suggest that dredging would make a significant impact on flood levels. Our upcoming surveys will allow us to do further targeted desilts which is a much more sustainable way to manage the river.

We have a duty to consider the environmental impact of all our flood risk management work. Depending on the location, dredging may damage wildlife and ecosystems. Removing vegetation can remove shade and increase water temperature, making fish more susceptible to stress in hot weather. Dredging also may harm fish spawning ground and disturb river life. Previous studies have shown dredging on the River Eau to provide limited benefits and cause substantial environmental damage, and it is not considered a sustainable option.

 

Planned work

We are currently working on structures at the outfall, including electrification (not automation) of the gate/penstock and weed screen assessments.

 

Repair work 

We carried out repair work on the right (north) bank of the River Eau in February/March 2022. This involved repairing the raised embankments downstream of Scotter, before the Eau joins the Trent. Once repaired, these embankments were no longer be grazed by livestock and will be maintained with additional grass cuts by our field team.  

This is part of a wider package of work following the 2019 storms and flood events, where we will repair multiple assets across the East Midlands. The funding for this work has been allocated nationally for 2019 recovery work. 

 

Debris screen removal 

We are currently in phase one of a project to automate the River Eau outfall penstocks, which involves getting electricity to the structures. As part of this project, we removed the debris screen near the outfall. The Environment Agency operates hundreds of outfalls on the River Trent, and the River Eau is currently the only one with a debris screen. We understand this may cause concern, however the removal of the screen will not impact on flood risk due to the size and number of penstocks at the outfall. We have a site specific contingency plan in place as part of our normal incident response procedures, as with other outfalls. 

 

Planned investigations

We are committed to trying to reduce flood risk for the residents of Scotter and the surrounding area. A great deal of effort has previously been dedicated and continues to go into finding solutions for the Scotter area that are both cost effective and that adhere to the various rules we as a public body must adhere to when delivering projects of this nature.

On top of the enhanced level of regular maintenance work we have carried out this year we are also doing the following:

• Commissioning a new hydraulic model of the river Eau using latest river modelling techniques
• Carrying out a feasibility study in to Natural Flood Management (NFM) measures that may be possible upstream
• Working with Scunthorpe and Gainsborough WMB to consider drainage of the surrounding land downstream of Scotter, during and after a flood event. This includes gathering evidence for potential use of the IDB pump station at Black Bank (the former River Eau outfall).
• Commissioning the electrification of the outfall into the river Trent at Susworth

LiDAR survey 

The Environment Agency commissioned a contractor, Texo DSI, to conduct a LiDAR river channel survey of the River Eau, in December 2021/January 2022. This survey has now been completed and we will share the outputs with the community when they are available. The start and end points of the LiDAR survey can be seen on the map below.  

The survey was carried out by UAS (Unmanned Aerial System), more commonly known as a drone. All surveys were conducted within the current CAP 722 guidelines governing the use of drones commercially in the UK under Texo DSI’s Enhanced Permissions for Commercial Operation from the Civil Aviation Authority (CAA). T

The drone survey will provide current Lidar information to support data management and any future work. 

Bathymetric survey 

We are undertaking a new bathymetric survey of the River Eau. This was originally planned for January 2022, however this has now been rescheduled and will now take place from 14th March 2022. During this time, you may see our contractors wading through the River Eau, or using a boat to capture the required data. Please do not be alarmed by this; they will have all of the relevant permissions and safety procedures in place.    

The bathymetric survey, alongside the LiDAR survey, will provide current bed and river level data to support data management and any future work. We will share the results with the community as soon as possible.

 

Natural flood management options

Working with natural processes to reduce flood risk - GOV.UK (www.gov.uk)

What is Natural Flood Management? - CaBA (catchmentbasedapproach.org)

Combating the effects of climate change | Cumbria Wildlife Trust

This year we’ve held a number of site meetings with landowners upstream of Scotter, whose support we need to deliver Natural Flood Management (NFM) on the ground. We have also included the Scotter catchment in a pilot study for NFM opportunity mapping which concluded in spring 2021, to quantify the scale of flood risk reduction NFM could achieve, potentially releasing further GiA funding. In December 2019 we succeeded in gaining a £50,000 allocation of Local Levy funding from the Trent Regional Flood and Coastal Committee to be spent on NFM, to combine with partner contributions from Lincolnshire County Council for this work. We will continue to consider alternative funding opportunities, and have recently referenced Scotter in a response to Defra regarding frequently flooded rural communities that current funding rules do not adequately support.

 

Funding, policy and strategy

Flood and coastal erosion risk management: policy statement - GOV.UK (www.gov.uk)

National Flood and Coastal Erosion Risk Management Strategy for England - GOV.UK (www.gov.uk)

We cannot eliminate the risk of all flooding, but the nation’s investment in flood and coastal defences has been effective at better protecting properties and reducing the impacts of flooding on peoples’ lives and livelihoods. We have seen progressively fewer properties flooded following recent incidents. In the floods of summer 2007, about 55,000 homes and businesses were flooded. In the winter 2015/16 floods it was around 21,000 and during the winter 2019/20 floods it was around 4,600.

We must continue to do what we have been doing: building and maintaining strong defences to reduce the risk of places being flooded. In the face of a changing climate, we need to also make our places more resilient to flooding and coastal change, so that when it does happen it causes much less harm to people, does much less damage, and ensures life can get back to normal much quicker.  

We understand the difficulties faced by landowners and in particular farmers whose land is affected by flood water. The devastating effects of climate change are indeed only making the situation more difficult for those that live in high risk areas. The extreme rainfall experienced in just the last 18 months has demonstrated the likely consequences being faced. 

The funding policy set by DEFRA guides us towards protecting people and property as a priority. This means that capital funding to protect farmland alone is difficult to justify within current Partnership Funding rules, and we have to instead consider the best way to manage water within the catchment. Unfortunately our assessments show a hard engineered scheme to provide flood protection for all residents in Scotter is not fundable under current Partnership Funding rules, which require us to move properties in to a lower flood risk banding to obtain Grant in Aid (GiA) funding. We are instead looking for ways to achieve multi-beneficial natural flood management (NFM) interventions upstream to slow run off, reducing the flood peak and therefore managing water levels through the village.

For information on protecting yourself from flooding and becoming more resilient, please visit Prepare for flooding: Protect yourself from future flooding - GOV.UK (www.gov.uk)