Stroud Valleys Natural Flood Management Project

The Stroud Valleys Natural Flood Management project is an innovative project working to reduce flood risk, improve water quality and recover nature throughout the catchment of the River Frome and all its tributaries, including the Slad Brook, Painswick Stream, Nailsworth Stream, Ruscombe Brook and all their named and unnamed tributaries.

We are working with landowners, community flood groups and partner organisations to implement a whole catchment approach to slowing flows and restoring more natural drainage. We implement a wide range of measures dispersed around the headwaters that will cumulatively act to slow flows and reduce flood risk.

The project, which has been running since 2014, aspires

'To create a river catchment where water management is fully integrated into land management practices. Where public bodies, private companies and local communities work together to manage water within the landscape, creating valuable habitat for wildlife and people, and limiting flood risk downstream.'

Explore the Stroud Valleys Natural Flood Management project through a compelling introductory film. Learn about its purpose and hear from those impacted by flooding. Discover the diverse range of partners, landowners, and farmers collaborating to implement natural flood management solutions in the Stroud Valleys.

For more information, contact George Maslin, the Stroud Valleys Natural Flood Management Officer. Email: george.maslin@stroud.gov.uk

Like other parts of Gloucestershire, the Stroud Valleys suffered extensive flooding during the summer of 2007.

Every year since has seen flooding in some parts of the Stroud Valleys, including most recently Chalford on the middle Frome, and Bridgend and Eastington on the lower Frome.

Of particular concern to residents and the District Council is the designation by the EA of the Slad and Nailsworth Valleys as "rapid response catchments", which means they are at increased risk of flash flooding.

After the flooding in 2007, community flood action groups were established in the Slad and Painswick Valleys and also the lower Frome and subsequently on the Middle Frome at Chalford. They have campaigned for better protection for residents and properties from flooding, but over the years, communities and authorities have realised that the Upper River Frome and its tributaries are not suited to hard engineered solutions. This is in part due to the physical nature of the catchment and the distribution of the properties at risk, but also due to the heritage and aesthetic value of the Stroud valleys.

In 2012, the Environment Agency commissioned a report into the feasibility and potential benefits of implementing Natural Flood Management (also called Rural Sustainable Drainage) (RSuDS) throughout the catchment of the Frome and associated tributaries.

Acting on the findings of the study, the Severn and Wye Regional Flood and Coastal Committee (RFCC) agreed to fund a project officer to implement and promote natural flood management in the Frome catchment. A formal partnership between Gloucestershire County Council, The Environment Agency, the RFCC and Stroud District Council was established to implement the work, and under a collaborative agreement, Stroud District Council agreed to employ the project officer. The work has been ongoing since then.

To implement the approach and achieve real reductions in flood risk will require extensive partnership working between communities, land managers and farmers. The project is seeking help and assistance from owners of riparian woodland and agricultural land to implement measures to reduce run-off and slow flows to help reduce flood risk for down stream communities. Many interventions to restore or create habitats will also slow flows, so we work in partnership with Gloucestershire Wildlife Trust on many of our projects.

Information about how natural flood management works and what we are trying to achieve.

Natural flood management (NFM) aims to reduce the downstream maximum water height of a flood (the flood peak) or to delay the arrival of the flood peak downstream, increasing the time available to prepare for floods. It works by restricting the progress of water through a catchment by making the catchment rougher and more difficult for water to flow quickly over land and in stream. The phrases "Slow the flow" or "Working with natural processes" are sometimes used to describe this approach to reducing flood risk. NFM strategies can be loosely classified by their likely location and distribution in a catchment They rely on one, or a combination, of the following underlying mechanisms:

a. Attenuation by using, and maintaining the capacity of, ponds, streams, floodplains and soils to attenuate water

b. Increasing soil infiltration. Allowing water to soakaway can reduce surface runoff. Free-draining soil will make saturation less likely, and evaporation from soil can also make space for water.

c. Slowing water by increasing resistance to flow. For example, by planting floodplain or riverside woods or constructing large woody structures in channels & gulleys or on flood plains.

Benefits of Large Woody Debris in streams

The Stroud valleys NFM project is using Large Woody Debris to help slow down the rate at which peak flows travel downstream and to spread the peak over a longer time period. The Land Drainage Act 1991 requires owners of water courses to maintain and remove obstructions to flow and historically, wood and fallen trees have been removed from streams and water courses. Whilst managing banks and removing obstructions can be essential to reduce flood risk in some locations, there are places where leaving trees or adding woody debris dams will have a variety of beneficial effects.

Wood debris gathers naturally when large and long sections of tree fall into and across the channel. These large sections start to gather smaller sticks and leaves which provide a permeable surface that allows water through, but crucially, reduces the rate of flow of water in the stream during high flows. Research has demonstrated that both small and large woody debris are essential for a healthy, functioning water course.

Woody debris changes the physical shape of the channel and can push flows out of the channel onto the bank. It helps to create pools and riffles, providing a variety of habitats for fish and aquatic insects and therefore attracting mammals and birds. Importantly for our purposes, Large Woody Debris can slow the movement of silt and sediment downstream. Silt can increase flood risk by reducing the amount of space for water in a channel. Large Woody Debris slows the rate at which a flood peak travels downstream by providing a physical barrier to flows. A large number of debris dams in a short stretch of stream can be more effective than a single large structure. Large Woody Debris can help to store and attenuate water. This is particularly the case when water is pushed out of channel and onto the flood plain, such as on the Dillay Brook in the photos below.

Using wood sourced from the immediate steam side is a sustainable and economic way of reducing flood risk and improving water quality. The Stroud valleys NFM project is seeking sustainable and long term solutions to reduce flood risk for residents and we will seek to use wood from normal woodland management and thinning to provide materials for the construction of large woody debris dams.

We have been working with partners and private land owners for the last 10 years and some of our key achievements to date include:

Over 1000 interventions throughout the wider Frome Catchment
25% of the catchment now draining through NFM features
1m reduction in peak river levels (between the two most closely comparable recent heavy rainfall events) on the Slad Brook
Over 1000 people from local and national groups have come together to learn more about NFM
50 local land managers and contractors worked together to implement NFM actions
Strong partnership working and networking locally and regionally
Establishment of a monitoring network for NFM in Stroud Valleys
Positive feedback and engagement from the community

An important aspect of any pilot project is to provide learning and experience for others who want to undertake similar work.

We are working in partnership with a range of organisations in order to develop methodologies and survey techniques for monitoring Natural Flood Management. We are currently working with the University of Gloucestershire, the Wildfowl and Wetlands Trust, Gloucestershire Wildlife Trust and the Environment Agency in order to monitor and research NFM in the catchment.

Key areas of focus include gathering baseline data on how Large Woody Debris structures perform in rain events and how they evolve over time. Morphological change, as well as changes to the river habitat and biodiversity are also of interest as we wish to capture information on the multiple benefits of NFM. We are also discussing with the Environment Agency how we can build on work they are undertaking at a national level to provide evidence for the benefits of Natural Flood Management.

In some areas of the catchment, we are able to compare historical flows under a given rainfall event with flows and levels we now experience after installation of natural flood management measures. The Slad valley in particular provides a good opportunity for comparison because it has a number of flow gauges that have been collecting data over a reasonable time period before we carried out work.

On March 9^th2016, the Stroud Valleys had approximately 35-40mm of rain over 12 hours. This is roughly half the monthly total expected for March. The EA were able to compare this event with a similar one that occurred in November 2012, before the Stroud valleys NFM project started. We looked for an event of similar magnitude and intensity, but importantly, we also looked at how saturated the ground was before the rainfall occurred.

The graph shows the two peaks aligned in the 10 hours over the event and shows a very substantial reduction in peak level. We have checked the gauges to ensure that there were no technical errors or problems and also compared the 2012 data with other events pre-construction The November 2012 graph is a consistent level of response. We are satisfied that the data, for both events is reliable.

As with any comparison it is important to bear in mind that no two events will ever be identical, we looked for two rain events that were closely comparable in terms of total rainfall, duration, intensity, preceding conditions and seasonality. We have also looked at ground saturation levels. In both cases, the soil moisture deficit is zero, indicating full saturation in both cases. It is important to note that the base flow level for 2012 was higher, indicating greater preceding ground saturation, and therefore potential run-off.

However, it is also important to note that the total rainfall over the 10 hours prior to the peak was higher in the 2016 event.

We would welcome any ideas or suggestions for research from academic institutions. The projects in the Stroud Valleys now provide a significant opportunity for those wishing to undertake research on the different benefits of natural flood management.

Please contact the project officer, George Maslin on george.maslin@stroud.gov.uk if you would like to discuss research proposals.

Technical principles of Natural Flood Management for small streams and catchments through an informative film.

Whilst the film is not an exhaustive list of all techniques available, we hope it provides a good introduction for others who are looking to design, implement and build their own community lead, small scale NFM projects.

We firmly believe that the key to Natural Flood Management is to develop local community lead projects that are able to implement a significant number of low cost, low risk, small scale structures over a large area in partnership with local communities, landowners and local partnerships.

We hope this film will provide other communities with the confidence to implement effective, low cost works in their areas, and do so over a relatively short time period.

Download a comic which explores nature based solutions to modern environmental challenges.

Sound of a River is an innovative downloadable graphic comic based in the Stroud district.

Written by Stroud District Council officer Chris Uttley and illustrated by local artist Joe Magee, the book tells the story of Monica, a girl who sets out to find out why her house has flooded. She travels back in time to learn that historical changes made to the way the river flows have not only resulted in the loss of wildlife and plants, but also increased the likelihood of flooding.

The title is based on the idea that a healthy river generates a variety of sounds, therefore the healthier and more natural the river, the more sounds it creates. Historical land drainage and river engineering have simplified and deepened channels, speeded up flows and causing the river to fall silent.

The book is free-to-download

A short film supported by Stroud District Council and the CCRI (Countryside and Community Research Institute).

Part 1 of the series 'Tales Of The Riverbank', documenting the Stroud Valleys Natural Flood Management Project.

Living On A Floodplain presents reflections from Tim Davies, a resident of Stonehouse, Stroud, UK., and member of BARFF - Bridgend Against River Frome Flooding action group. Tim provides a personal reflection from the perspective of a local resident whose home has flooded in the past. In the film, he details his ways of dealing with the vulnerability of living on the floodplain of the River Frome, and the differences that the Natural Flood Management project has made to the communities in the whole river catchment.

Part 2 of the series 'Tales Of The Riverbank', documenting the Stroud Valleys Natural Flood Management Project. The film “Natural Flood Management in the Stroud Valleys” highlights how the actions undertaken by volunteers, landowners and partners in the Stroud NFM project are changing the watercourses and helping nature to recover in the Stroud Valleys.

Poetry and Film

We have been working with artist and film maker Antony Lyons and Stroud based poet Adam Horovitz to create pieces of work that take an artistic view of our NFM work.

Antony has produced a film that is a poetic contemplation of Wet Woodland & River Woodland habitat, in the context of Natural Flood Management in the Cotswolds (UK). The film, Fluid Forests, has a three-part structure:

Flowing, slow movement; of water through the forest floor; of wind in leaves; and activity of birds.
Stillness and birdsong in the flooded forests; falling leaves; cycles of growth and decay; moss, fungi and the submerged world of primordial ooze.
Springs and tufa cascades on ferny hillsides above the floodplains. Life-giving water emerging from subterranean worlds into ancient-echoed lush landscapes. Calcareous deposits of tufa; frequently found below bubbling springs in the Stroud Valleys

Fluid Forests is supported by the Stroud Valleys Natural Flood Management project (Stroud District Council) and the Countryside and the Community Research Institute (CCRI).

Adam Horovitz has produced three poems for the project that you can read below:

A river lives to creep through pools, delve under fallen trees. It rises and sinks with the days, the weeks, the seasons. Shifts shape, shrinks, grows. Shivers through dams and chuckles over stone.

Its waters always return; they cannot be destroyed or made. A river just is: older than gods or mammals; a force for change that carves wayward paths through soil, stone, brick. No structure can resist a risen river.

Nor can a stream be tamed; merely appeased. Offer it a broken tree, another. Stones tumbled from the bank to push back water, slow the stream down, divert it under a water-bridging tangle of root and trunk.

A stream should make patterns in the landscape, mirrors framed in fallen leaves, gullies, rushes, lakes. Let fish gather in pools draped in the arms of trees and insects burrow deep into their rotten wood.

Work with water. Let its fingers play tender through the lives of human, beast and rooted thing so life can build and burgeon. The slowness of streams strengthens rivers. Prepares them for the coming of a flood.

Let’s just for a moment work things backwards here: the brick walls laid to ward off water even before it rose through the carpet like a ghost, before it rushed out into the shrinking river, are being uncemented, carted off in hods to trucks.

The house, stripped bare of furniture, begins to dry. Water, like a run of salmon, races uphill, returns to source, where it will rise as heavy rain, become clouds thick as paint, dissipate into an iron sky edged with blue.

Now arrest the clock. Follow water to where it winds among fields, becomes a stream at the sharp edge of two woods.
A straight track, unwound and cut from its coiled path, un-littered with the stuff of life.

Here, water is being made into energy. Only able to travel fast, it foams into fists to punch its way out, to find the sea.

Now, while the clock is stopped, think like a beaver. Push trees that died and fell last winter into the water’s mouth.

Take stones and stem the tide-rage that sings within it. Slow the beat of its heart. And then restart the clock. Let it move forward this time, as the rain falls fierce like a scouring angel among trees.

Rain cannot raise this stream to frenzy. The water seeks out far too many paths to worry its way through as it slips down to the river mouth carrying trace memories of soil, stone and bark gently beneath the town; past houses that need no walls now to divert a flood.

Stood on a slight ridge, we look up the field towards trees scattered at the valley’s lip.

The pasture seems dry. A little mud at the gate, but no sign offlood. I ask: What work was done here? and look around, confused. A few years ago, this field ran wellie-high with water when the rains came hard

says Chris. Water raced from springs, washed soil and grass away. Fields unusable under flood,

the farmer asked for help. It’s harder to mimic nature than to build, so we did both. We built this ridge.

I step down. The raised turf reaches to just below my knee. There’s another ridge over there says Chris. He points to the wood,

holds up a photo of a lake. Recognise this field? We won a prize for this – even the judges had to ask what had been done.

A stitch in the field to slow the water’s rush. An invisible intervention to foil floods. This field is a field is a field

until it is a lake where cows can come to drink and wade in the muddy winter run-off of overloaded limestone springs.

Subtle transfiguration at the edge of woodland. Place of reformation where mankind and water run together. Measured harmony of change.