Flood Risk Management: Maintenance work – East Midlands Area

Closes 30 Sep 2023

Opened 1 Sep 2022

Overview

The East Midlands Flood Risk Management Area covers the cities of Nottingham, Derby and Leicester, alongside towns, villages and countryside with a population of over 3 million people, and we maintain over 1300km of watercourse to help protect the >139,000 properties at risk of flooding.

This page provides information on our maintenance work along watercourses that are designated as ‘Main Rivers’ in the East Midlands Area. The Environment Agency has powers to carry out maintenance, improvement or construction work on Main Rivers to manage flood risk. You can view a map of Main Rivers here.

Other rivers are called ‘ordinary watercourses’. Lead local flood authorities, district councils and internal drainage boards carry out flood risk management work on ordinary watercourses.

Contents
Landowner responsibilities
Flood Risk Management Assets
Raised defences
Debris screens
Flood storage areas
Gated structures
Culverts
Outfalls
Pumping stations
What we do and why
Asset inspecting
Grass cutting
Weed spraying
Aquatic weed cutting
Tree and bush work
Maintenance and operational checks
Repair works
De-silting
Environmental considerations
Birds
Water voles
Reptiles
Badgers
Pollinators
Partnership working
Useful links
Contact details

 

Landowner responsibilities

We appreciate community support to allow us to successfully maintain flood defences, which will help keep communities resilient to flooding and climate change.

If you own a property or land which includes or is directly next to a Main River, you are probably a riparian owner. You can find more information on riparian ownership, including your rights and responsibilities, by visiting Owning a watercourse - GOV.UK (www.gov.uk)

Here are just a few of the things you can do to help:

  • Enable us to access to flood defences so that we can inspect and maintain them – make sure any defences on your property are accessible and report anything that may cause access issues.
  • Apply for a Flood Risk Activity Permit if you plan to carry out works on or near a main river. Activities that may require a permit include works on the river bank itself, building structures (sheds/fences) and/or gardening (e.g. digging into and/or planting trees) on or near the raised flood embankment. Some works are exempt from this, as long as you meet certain conditions. 
  • Avoid disposing of waste materials, including garden waste, into or close to a river. Large items such as branches can get caught in underground culverts and weed screens, which can lead to local flooding. Waste materials also have the potential to cause pollution to rivers, and you may be committing an offence.

 

Our flood risk management assets

We have a range of flood risk management assets across the area, which all have a different purpose and function. A flood risk management asset is any structure that reduces the risk of flooding to people and property, such as embankments, flood gates or flood storage reservoirs. Please see below for a brief overview of the types of assets we manage and how they work.

 

Raised defences

There are thousands of kilometres of raised embankments and flood walls across the country.

A flood embankment is constructed from earth, and may include a clay core to reduce seepage through the embankment. A flood wall can be constructed from brick, masonry, concrete, pre-cast units, sheet piling or a combination of these materials. These raised defences allow river levels to increase without causing flooding, unless the height of the river exceeds the design height of the flood defence, which can happen during extreme rainfall events.

 

Debris screens

These are important assets. Properly designed, they help us to safely manage and remove debris from watercourses that could otherwise block structures, making flooding worse. They can also be used to stop debris damaging other infrastructure and act as security screens to protect against people becoming trapped.

 

Flood storage areas

Flood storage areas can usually be described as one of the following:

  • online – water is temporarily stored within the river channel and its floodplain;
  • offline – water is diverted from the river channel, stored in a separate area and then released back to the river  when conditions are suitable.

In general, online storage works are normally located in the upper catchment while offline storage works are more common on larger rivers with wide floodplains. Some complex flood storage schemes include a combination of online and offline components, designed to act in conjunction.​​​​​​​

Flood plains that are modified to increase their natural flood storage are often described as washlands - a term that can be used in the context of either online or offline flood storage. Some flood storage areas may contain water throughout the year, whereas others may be dry for the majority of the year.

 

Gated structures

These structures are used to control water levels for flow management, flood control and navigation. There are many different types including sluice gates, mitre gates and radial gates. Some may be passive, meaning they operate on water pressure alone, while others require mechanical or electrical operation. 

 

Culverts

Culverts provide closed passages for water to flow through/under urban areas and infrastructure embankments. Although they are most commonly made from pre-cast, reinforced concrete, other materials including plastic and steel are sometimes used. Brick-lined culverts were historically common and many are still in use. Culverts may have different shapes depending on the type of watercourse they are part of and some may be one-off designs due to site specific challenges. Culverts may have a debris screen at the entrance, to prevent objects from entering the enclosed space and causing a blockage, but this will depend on the risk around each individual culvert.

 

Outfalls

Outfalls are structures where water discharges into a river, either above or below the normal water level. Common considerations with outfall construction and maintenance are scour protection, access restriction (particularly for larger outfalls) and flap-gates to stop flow reversal during flood conditions.

 

Pumping stations

The main purpose of pumping stations in relation to watercourses is land drainage, water abstraction and sometimes the emptying of flood storage reservoirs. The intake of water into a pumping station is always below the water level.

The main components of a pumping station are the power supply, which often requires grid connection and a backup diesel generator if the location of the pump is critical; the pumps themselves, often more than one to allow for continued operation during maintenance or breakdown; trash screens; scour protection; and the pump house, which should be sensitive to the architectural character of the area.

 

 

What we do and why

 

Asset Inspecting

We have a team of asset inspectors who routinely inspect all our assets to make sure they are at the required condition to manage flood risk. Where we identify assets that have fallen below this condition, we will consider the best options for repair, based on risk. During and after high river levels, we increase our inspections to assess any damage caused by the assets being under pressure.

 

 

 

Grass cutting

We start our grass cutting programme on raised embankments from April onwards and deliver multiple grass cuts during the summer months.

Our field team routinely grass cut to help keep the right amount of grass cover on the embankment. The grass helps to knit the surface together to protect the core of the embankment from erosion and animal burrows. This is necessary for the embankment to be effective and to protect property from flooding.

Maintaining the banks in this way also allows our Asset Inspectors to inspect the banks thoroughly, to ensure that they provide the protection that they are designed to provide, otherwise known as the 'standard of protection'. 

We try to cut early so the grass is not long enough for nesting birds, and so that visibility is good. If the grass is too long, we will walk the banks to be cut before starting work. A 10m distance will be left between the work area and any ground nesting birds.

 

Weed spraying

Large broad leaved weeds can block out the sunlight, which impedes grass growth, so we need to regularly cut and spray off the broad leaves during the summer months. 

Our embankments are managed as flood defences as a priority.  However, we do recognise that our activities can have an impact on the immediate habitats. When we carry out maintenance, we work in partnership with our internal biodiversity team to ensure that we assess and control our risks.  We are also trialling various initiatives to reduce these impacts, including leaving grass verge margins, planting trees in the floodplain, and planting wildflower meadows where they will not result in any reduction in our ability to provide flood protection to the local community.

 

Aquatic weed cutting

We start weed cutting in June so that we do not impact spawning fish earlier in the season. The timing of the weed cutting on particular stretches of the river depends on personnel and machinery requirements, weather and flow conditions.

Aquatic weed control is important for maintaining watercourses. If weed is left to grow unchecked, it can restrict the river channel and cause increased siltation, impeding the river capacity and flow. Detached weed can also collect around bridge structures and flood defence assets, potentially blocking pumps and sluices, causing a flood risk.

We use a combination of weed cutting boats and excavators to cut and remove weed. These operations have the potential to disturb habitats and mobilise silts, so we carry out monitoring of the temperature and dissolved oxygen levels of the watercourse before, during and after weed cutting to prevent an environmental incident. Our fisheries and biodiversity teams support us to ensure that we assess and control our risks and we aim to leave a cover margin of vegetation on the riverbanks for wildlife.

Upon removal, the cut weed is left to de-water, or to flow down to a weed screen for removal, where there is no risk that it will get caught in any structures. This allows for any aquatic insects, invertebrates and eels to safely return back to the river. Weed is removed in a way that should not impact fish, but if any are accidentally caught in the weed they will be placed back into the water immediately. We also leave some stretches undisturbed for wildlife, and marginal vegetation as habitat.

 

Tree and bush work

We carry out tree and bush work over the winter months. This involves cutting back tree branches or bushes that impact on the flow of the water or are likely to fall into the watercourse and cause a blockage, increasing flood risk. We also remove any felled trees from the river where there is cause for concern.

Whilst our priority is to protect people and property from flooding, we also have a duty to protect the environment. Our work only takes place at suitable times during the year to avoid any disruption to nesting birds. Where we have removed branches and tree trunks from the river or banks, we leave them in the nearby area to provide habitat for wildlife. Potential bat roosts are also identified and worked around.

 

Maintenance and Operational checks

We routinely carry out maintenance and operational checks all year round on watercourses and flood defences. This includes checking that water can move freely through the channel and clearing any blockages, checking and clearing debris screens, checking and operating structures to ensure they will perform correctly when needed and reporting any issues that will require further investigation and/or work with our partners and landowners.

 

Repair works

In addition to our routine maintenance work we regularly carry out repairs and improvement work on our flood defences. This includes repair work on assets that have been damaged or have fallen below their required condition, as well as work to upgrade and modernise some of our older assets.

 

De-silting

We carry out desilting in locations where we know it will make a difference.

We use high pressure water jets to remove silt build up around structures such as outfalls, to make sure they can operate properly.

We will desilt watercourses where there is evidence that silt levels will increase flood risk to properties, desilting will not increase flooding downstream and if this work is compatible with restrictions around protected species.

Desilting and other work to improve a river channel’s ability to increase flow does form an important part of our work to reduce the risk of flooding. In recent years we have typically spent between £50million and £55million per year nationally on work to improve the conveyance of water. Of this, between £9million and £11million is for dredging which allows us to dredge approximately 100-200km of river channel each year. We must, however, ensure that the money we spend on flood risk management achieves the greatest benefit to people and property. Dredging’s effectiveness does vary substantially between locations and we therefore target our dredging work where we can be confident it will achieve effective and sustainable reductions in flood risk.

It is the case that some rivers have been dredged more heavily in the past but this was largely to enable navigation rather than to manage flood risk. Dredging can, and does, contribute to reducing flooding in some locations. In others, dredging can be an extremely inefficient and ineffective way to manage flood risk, as the natural processes in many rivers can cause the silt to return and accumulate in the same places very quickly.

 

 

 

 

 

Environmental considerations

Like everyone, we have an obligation under the law to protect certain species of wildlife when carrying out work. That’s why it’s vitally important that we review environmental risk before we start work.

 

Birds

All wild birds are fully protected during their breeding season by the Wildlife and Countryside Act 1981. This makes it an offence to;

  • kill, injure or take any wild bird,
  • take damage or destroy the nest while being built or in use,
  • take or destroy an egg.

In addition, certain rarer, species listed on Schedule 1 are protected against disturbance during this period. This includes kingfisher and bittern.

The habitats, ecology and breeding season vary between species. Some species breed all year round, but most breed during the March to August period, using reed beds, river banks and grassland as nesting sites. Some species are also known to use machinery that is stationary for long periods of time.

The optimum time for grass cutting, to avoid nesting birds, is late August to Mid-March but this will partially depend on species present and weather conditions. Our in channel weed cutting standards encourage us to leave marginal habitat undamaged along the watercourse.

We will carry out breeding bird surveys prior to work where there is long grass and immature scrub, or where leaving marginal vegetation is not possible.

 

Water voles

Water Voles are fully protected by the Wildlife and Countryside Act 1981 due to their significant decline in numbers and distribution.

This makes it an offence to;

  • capture, kill or injure
  • damage, destroy or block access to their places of shelter
  • disturb them in a place of shelter

Water vole habitats include ditches, vegetated banks, rivers, streams, ponds and marshes. They prefer still waters or little flow with water present all year round, and steep banks for burrowing.

They have a ranging diet of tall grass and herbs with some parts of shrubs and trees eaten in winter.

Their peak breeding season is April to June but they can have four litters a year, and in July/August their numbers are at their highest. Young males and low ranking females will be dispersing in July and will use newly created habitats if available. They are very short lived and have very high winter mortality rates.

Water voles were once common but have now disappeared from 94% of their former sites, although they are still found throughout Britain. Within the Environment Agency we have substantial knowledge of the locations of most populations and have assisted in reintroductions.

Water vole conservation benefits from appropriate grassland management. The Environment Agency have developed environmental options that provide best practice for flood risk maintenance and the conservation of the species.

 

Reptiles

We have six species of reptiles in England; sand lizard, viviparous lizard, slow-worm, smooth snake, grass snake and adder.

All species of reptile are afforded some protection (killing, injuring and trade) by the Wildlife and Countryside Act 1981. The sand lizard and smooth snake are also fully protected as an EU species (Conservation of Habitats and Species Regulations 2017). This makes it an offence to capture, possess, disturb, kill, trade or damage any place they use for breeding or resting. *Adders are our only venomous snake. Snake bites are very rare and usually caused by people picking them up so don’t try and move adders. Seek expert advice if they need to be moved. Seek medical help if you are bitten.

Different species use different habitats including scrub, sand dunes, heathland, brownfield sites, but all can be found in long grassland. They hibernate in winter within walls such as stone walls and coastal sea defences. They emerge in early spring and are very vulnerable during the early months while basking as they are less mobile in lower temperatures. Spring is the breeding season for all reptiles, but their breeding patterns vary. Grass snakes will lay eggs and use compost heaps whilst slow-worms give birth to live young in September. The slow-worm is very sedentary and will often breed within a stone wall, hedgerow and long grassland site whereas the adder and grass snake will travel much wider within suitable habitats.

Sand lizards and smooth snakes have a very limited distribution and the others are usually limited to areas of good semi-natural habitats such as grass.

Grass cutting can have impacts on reptiles, so we work with our biodiversity team to identify sites that maybe suitable for reptiles and to check if they are present by undertaking a survey. At sites where they have been found or there is a high chance that they are present it is recommended to cut grass during the winter months of November to February.

If grass cutting is essential at other times of the year, we will carry out a walk over survey prior to the cut to move animals into refuge areas and a high (15cm) cut is recommended. Areas of long grass will be left in parts of the site as shelter, on a permanent basis or a rotational system. Grass cuttings can also be used to create compost heaps off the flood bank for breeding sites for grass snakes and slow-worms.

 

Badgers

Badgers and their setts are fully protected by the Protection of Badgers Act 1992.

This makes it an offence to:

  • kill, injure or take them;
  • damage a badger sett or any part of it;
  • destroy a badger sett;
  • obstruct access to, or any entrance of, a badger sett;
  • disturb a badger when it is occupying a badger sett.

Badgers live in social groups and have a variety of setts within their territory. This includes the main breeding sett, annexe’s, subsidiary and outlier setts. The cubs are mainly born in winter, December to February. They are totally dependent and below ground until April. Not all setts are occupied all year round.

Badgers are omnivorous and can occupy a wide range of habitats from ancient broad leaved woodland, grasslands and even urban garden areas. They are commonly found in our flood defences, as many of these areas are low lying and the banks are the only high ground during high water conditions.

The methods and timing of our maintenance work must ensure that disturbance is kept to a minimum and machinery avoids setts and any damage to them. In the very rare cases where we cannot avoid disturbance or actual interference, during vegetation maintenance, then a licensing option will be sought from Natural England. We will also work with our biodiversity team to carry out a site by site assessment to ensure the work reduces the disturbance and eliminates any potential damage.

 

Pollinators

Where grass has been uncut, many plants will have been able to flower, providing good sources of nectar for pollinators which are key to biodiversity.

Longer grass will increase flowering and insect productivity, and this provides food for many protected species including bats and birds. Whilst it is not illegal to cut grass, we consider whether it is necessary. We may consider a change in timing or leaving refuge areas where there is less risk to the flood embankment.

 

 

Partnership working

Flood risk management is complicated; flooding can happen from different sources, and for different reasons. The Environment Agency is just one Risk Management Authority involved in managing flood risk. Others include Local Authorities, Lead Local Flood Authorities, water companies, highways authorities and Internal Drainage Boards (IDBs). We all work in partnership to manage flood risk, and to respond to flooding incidents. IDBs also undertake some maintenance work on our behalf, where specific agreements are in place.

 

 

For details of our maintenance programme in your area please visit https://environment.data.gov.uk/asset-management/index.html

For details of the rights and responsibilities of a riparian landowner please visit https://www.gov.uk/guidance/owning-a-watercourse

 

Would you like to find out more about us or about your environment?

Call us on

03708 506 506 (Monday to Friday 8am to 6pm)

Email

enquiries@environment-agency.gov.uk

Visit our website

www.gov.uk/environment-agency

Incident hotline 0800 807060 (24 hours)

Floodline 0345 988 1188 (24 hours)

 

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Thank you for visiting this information page. Please email EMDenquiries@environment-agency.gov.uk or call 03708 506 506 if you have any futher questions about our maintenance work. 

Audiences

  • Recreational and commercial river users
  • Fishing clubs and representative associations
  • Members of the public with an interest in the river, the species and conservation
  • Businesses
  • Members of the public
  • Environment Agency customers
  • IDBs
  • District and parish councils
  • Land owners
  • Members of the public
  • Recreational and commercial river users
  • Community groups
  • Flood action groups
  • Environment Agency colleagues

Interests

  • Flood management