Flooding: Working with nature, not against it

Pumlumon cpt Montgomeryshire Wildlife Trust

The Wildlife Trusts believe that the current flooding crisis means there has never been a stronger incentive to re-think our relationship with water, and how we use our land and the space in our towns and cities.

Flooding needs to be addressed through a range of solutions, but working with nature rather than against it is the key to a more flood resilient future.  

Once the urgent need to help people, homes and businesses has receded, the Government needs to invest in creating towns and rural areas that are more resilient to extreme weather events in the longer term.

We need to:

  1. Make the land work more effectively as a sponge by restoring water retaining habitats over large areas

  2. Create more places where flood waters can be held back or stored.  These places often become recreational areas for people too

  3. Make more space for rivers

  4. Create places on farmland which will store floodwaters and protect the best areas for food production - giving water room - eg create small flood storage areas on parts of the farms that are less productive - protecting a larger areas from extreme weather

  5. Design into our buildings, towns and cities places that collect and capture water, such as green roofs, sustainable drainage systems, rather than it torrenting off hard surfaces into rivers

The Wildlife Trusts' Vice President Professor Chris Baines explains how nature has a positive role to play in the way we manage land and how Wildlife Trusts in towns, cities and the wider countryside are making the landscape work better for wildlife and for people too.

 

 

Make the land work more effectively as a sponge by restoring water retaining habitats over large areas

Now is the time for UK Governments to prioritise investment in landscapes that could provide the natural solutions so badly needed to help prevent flooding in future. Habitats such as upland bogs and moors, woodlands, wetlands and species-rich grasslands act as giant sponges, absorbing and holding water and slowing down water run-off into rivers.

Upland bogs and moors, woodlands, wetlands and species-rich grasslands act as giant sponges, absorbing and holding water and slowing down water run-off into rivers

There are already some excellent examples of how restored landscapes have made space for water, for example, in upland areas where old drainage ditches have been blocked and overgrazing reduced.  This allows vegetation like sphagnum mosses and heather to regenerate, helping to hold water in the hills for longer and reducing peak flows downstream during high rainfall events.  Across the UK Wildlife Trusts are working on habitat restoration schemes which slow down water and reconnect rivers with their floodplains, making space for water.  We need these types of approaches to be significantly extended across the country.  This can only happen if investment in flood defence is rebalanced towards these more sustainable solutions

The Pumlumon Project in Montgomeryshire covers an area the size of Bristol and is the source of eight major river systems: the Severn, Wye, Rheidol, Ystwyth, Elan, Teifi, Tywi and Irfon.  It is now widely accepted that there is a direct link between upland land management and the severity of lowland flooding.  Previous studies have shown how strategic tree planting, restoring hedgerows, fencing out watercourses and reducing stocking levels all help to increase the permeability of upland soils, reducing rapid run-off during heavy rain.

At 752m, Pumlumon is the highest point of the Cambrian Mountains, which are themselves the largest watershed in Wales.  The Pumlumon Project area consists of more than 3,700ha of hydrologically active habitats.  These include wet heath, raised bog, blanket mire, valley mire, and wet woodland.  The Project’s ditch blocking work (p4) affected the water-holding capability of a 1,013ha catchment area, raising the water table by an average five centimetres and retaining an extra 155 million litres.  The project also improved the permeability of the soil by changing grazing regimes, reducing stocking densities in some areas, and planting broadleaf trees.  The aim now is to implement this management regime across the remaining catchment.  If a substantial proportion of the project area receives appropriate management.

Restoring the Culm Grasslands of Devon
Devon Wildlife Trust has been working with farmers to restore areas of a special kind of species-rich wet grassland called culm grassland.  This grassland can act as a sponge, holding water following rainfall and releasing it slowly over time.

Early results from a recent study of the hydrology of these grasslands undertaken by Devon Wildlife Trust in association with the University of Exeter indicate that species-rich grasslands may be better at preventing downstream flood risk than intensively managed grasslands or grasslands that have scrubbed-up or developed mature woodland cover.  ‘Improved’ pasture holds 47 litres of water per square metre, whereas Culm grassland holds 269 litres per sqm.  See What has Culm ever done for us?

There’s an important connection to make here with future funding for the agri-environment schemes that support our remaining species-rich grasslands. We’re doing some work right now on the serious declines in species-rich grasslands across the country – it’s an area of real concern.

Sussex Trees of River Uck
Trees on the River Uck is an innovative project that hopes to decrease the impacts of flooding in Uckfield town, by restoring natural river features such as floodplain woodlands.

TrUck was formed in recognition of the benefits of a natural catchment scale approach to river health, people and wildlife

After heavy rain, the water levels in the River Uck catchment naturally rise and fall very quickly.  Years of changes to the river have increased the speed that water from the land and urban areas enters the river.  These river changes have also hugely reduced the area available to naturally store floodwater upstream of Uckfield.  This makes the natural ’flashiness’ of the Uck’s river flooding even more extreme.

These and other factors have contributed to some sizeable and damaging urban flood events in the town of Uckfield and its surrounds.

Sussex Wildlife Trust is a a partner in the project that aims to reduce rapid water flow in the River Uck catchment, through strategic woodland creation, installation of hedgerows, and small scale natural enhancements where possible. TrUck was formed in recognition of the benefits of a natural catchment scale approach to river health, people and wildlife.

Create more places where flood waters can be held back or stored – these places often become recreational areas for people too

Potteric's rare black-necked grebes, bittern, avocet, whooper swans, 15,000 golden plover and black darter dragonflies make it a fabulous place to unwind.

Yorkshire Wildlife Trust’s Potteric Carr wetland reserve saved hundreds of Doncaster homes from flooding in 2007.  During heavy rainfall, the water ends up in this flagship wetland reserve rather than flooding south Doncaster housing, before gradually soaking into the ground, and draining into streams and watercourses.  There are other benefits too.  A reed bed and aerobic filter (originally constructed to protect the reserve's wildlife from surface pollution) ensures that the water leaves the wetland cleaner than when it arrives.  

Potteric Carr cpt Matthew Roberts

And, as any visitor will tell you, Potteric's rare black-necked grebes, bittern, avocet, whooper swans, 15,000 golden plover and black darter dragonflies make it a fabulous place to unwind.  It's the ultimate win-win.

London Wildlife Trust is working to restore Crane Meadows, which lie to the immediate east of Heathrow Airport.  The meadows are being restored to improve their water management capabilities and enhance the site for wildlife biodiversity: a win-win for local communities.  About 30% of the site was formerly hard standing; about 20% of the site has now been restored to grassland.  Old meanders of the River Crane have been reconnected. The increased volume of the river coupled with the creation of high and low flow channels has increased the river's ability to store storm water, whilst still achieving great benefits for aquatic biodiversity. The 10% of hard standing that remains at the site is an old car park – and London Wildlife Trust is aiming to remove this, restoring it to soft landscaping and creating further enhancements to the reserve.

Sheffield Wildlife Trust's Centenary Riverside plays a key role in Rotherham’s future.  Designed as a floodplain, it forms part of Rotherham’s Flood Alleviation scheme which holds back potential flood water and protects industrial and residential areas nearby.

Create places on farmland which will store floodwaters and protect the best areas for food production - giving water room - eg create small flood storage areas on parts of the farms that are less productive - protecting a larger areas from extreme weather

The project demonstrated the benefits that can be gained by simple, low-tech, landscape-scale flood alleviation measures

The Staffordshire Washlands scheme covers 18,700 hectares.  A major aspect of the Staffordshire Wildlife Trust’s work in this area was the Farming Floodplains for the Future project.  This aimed to determine whether the farmed landscape could be viably managed in ways that effectively reduce flood risk downstream, while at the same time enhancing the natural environment.  The project demonstrated the benefits that can be gained by simple, low-tech, landscape-scale flood alleviation measures. See Farming Floodplains for the Future.

These flood storage areas, comprising both natural and artificially created depressions on the floodplain, actively function to retain floodwaters when the river or watercourse spill level is exceeded and then they drain out slowly after the flood peak has passed.  The schemes are collectively contributing to an overall flood attenuation function on the watercourses on which they are located, which ultimately help to reduce the flood risk in the downstream towns of Stafford and Penkridge.

Sites where shallow floodwaters are retained in these floodplain depressions for longer during the spring-summer period can also help to enhance local wet grassland and other wetland interests (eg to encourage feeding, nesting and breeding by wader and wildfowl bird species) if the vegetation is managed appropriately.  You can read more in the the project's 2012 monitoring report, attached below (Monitoring report)

Shropshire Wildlife Trust is working with a farmer in the north of the county whose land was subject to extensive surface water flooding and run off, with this ultimately running into a tributary of the River Perry.  The scheme is still under construction but a basin has been created where the water and silt can be captured, holding back flows.  This work has already reduced the incidence of surface water flooding on the access track to the farm and fields further up the sub-catchment.  The excavation of a long swale - a low area of marshy land - allows free drainage of previously blocked field drains.  The new basin and swales and buffer strips around them will be seeded with wildflower and grass mixes in the spring.

Make more space for rivers

Countries around the world are discovering to their cost that cutting rivers off from their natural floodplains causes problems.  A natural river’s channel and floodplain are inextricably linked and play a vital role in shaping and sustaining the ecology of rivers, wetlands and the rich diversity of life they support.  They work together to deal with high and low levels emanating from upstream.

Floodplains have a vital role to play in dissipating heavy water flows.  By contrast, preventing water from reaching a floodplain combined with river dredging often increases erosion and sediment supply downstream.

The aim is to reap the benefits that natural support systems provide such as flood-prevention, waste management and cleaner air

The Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire is working in The Nene Valley on large-scale habitat restoration and creating functioning ecosystems as an integral part of land management – such as putting back river meanders.  The aim is to reap the benefits that natural support systems provide such as flood-prevention, waste management and cleaner air.  See more info here.

Cheshire Wildlife Trust is restoring areas along the course of the River Gowy to reconnect it to its floodplain - from its source on the Sandstone Ridge to where it joins the River Mersey, then extending up the Mersey corridor to include Frodsham Marsh and on through Runcorn and into Warrington.  The vision for the Gowy and Mersey Washlands is to restore, recreate and reconnect a network of wetland habitats providing ecosystem services in conjunction with high-quality nature conservation resources which will benefit local people, the environment and the local economy.

Warwickshire Wildlife Trust is involved in The Tame Valley Wetlands Partnership which was set up in 2005 to deliver large area conservation throughout the Tame Valley Living Landscape area, between Birmingham and Tamworth, covering 9,500 hectares (95km² area).  The work of the Partnership shows that conservation and enhancement of biodiversity can go hand-in-hand with social and economic regeneration.  There is increasing public recognition of the wider benefits of naturally functioning floodplains and their role in flood control, including enhanced protection for settlements downstream, the maintenance of a diverse and rich landscape and the restoration and re-creation of lost wetland biodiversity.

Yorkshire Wildlife Trust is working to restore landscapes along the River Hull, the most northerly chalk river in the UK.  The river flows through the urban centres of Driffield, Beverly and Hull and is bounded by major tourist destinations such as the Holderness Coast.  Informed management of the river floodplain and surrounding land could alleviate costly flooding within the urban centres, as well as delivering more wide-scale ecosystem services such as reduced pollution.

Design into our buildings, towns and cities places that collect and capture water - such as green roofs, sustainable drainage systems - rather than it torrenting off hard surfaces into rivers

The habitats and wetlands act as a sponge, absorbing run-off from the development, filtering pollutants and providing flood protection in the event of a breach of the sea wall

Avon Wildlife Trust's Portbury Wharf lies on the land between Portishead and Royal Portbury Dock, adjacent to the Severn Estuary.  Planning consent for the Port Marine housing development here was granted on condition that the developers designate a nature reserve on the adjoining land.  The habitats and wetlands act as a sponge, absorbing run-off from the development, filtering pollutants and providing flood protection in the event of a breach of the sea wall.  It is used an example in Defra's best practice guide here (see page 46). It is hugely enjoyed by the local community - see its webpage here.

Sussex Wildlife Trust is a partner in ARC – Arun & Rother Connections – an initiative which is promoting measures to prevent the Arun and Rother river catchments from flooding so badly.  After the heavy rains in January 2014, there was severe flooding in parts of West Sussex and the residents of Pulborough were particularly badly affected.  The scheme is working to address the fact that 90% of flooding here comes from surface water run-off.  ARC is promoting rain gardens and Sustainable Urban Drainage Systems.  They are going to be running community water events during 2014. See Sussex Wildlife Trust's blog on natural flood defenders here.

London Wildlife Trust has an on-going flood-management project called Lost Effra -  named after a river - which is working with local communities on a water management strategy for Herne Hill in south London, an area which is prone to flooding. See the PDF below of its recent report A new way to manage water further below pp 32 - 54 for relevant information. Key recommendations on p. 66. London Wildlife Trust also published London: Garden City? which revealed the scale of the capital's garden loss - at the time of publication (2011) this was at a rate of two and a half Hyde Parks per year. Hard surfacing – including decking and paving – increased by over 25 per cent in the 100 month study period. Gardens can do much to act as sponges and help stop water flowing too fast, overwhelming rivers.Tame Valley, Warks cpt Mike McFarlane

Downloads

FilenameFile size
a_new_way_to_manage_water_-_live_draft_feb_2014.pdf5.13 MB
monitoring_report_v2_25_nov_12.pdf3.78 MB