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From big science to better water

Country-wide study compares effects of agriculture in large river catchment areas across the UK

December 2012

Environmental impact is one of the big problems agriculture has to address. And some big problems can only be tackled with large-scale, ambitious experiments, such as the Demonstration Test Catchments (DTC) project, launched by UK scientists in 2009.

The £6.5M project funded by Defra in co-operation with the Environment Agency (EA) and Welsh Assembly Government (WAG), aims to find out if different farming practices can reduce pollution from agriculture, whilst delivering sustainable food production and wider environmental benefits across whole river catchments.

Two researchers gauge water at the River Eden. Image: EdenDTC/Clare Benskin

Two researchers gauge water at the River Eden. River catchment areas are a defining part of the UK’s fresh water system. Image: EdenDTC/Clare Benskin

Reduction in water quality is a major problem associated with farming in the UK. Excess nutrients and pesticides can be leached from farmers' fields and manure stores into rivers and the underlying groundwater. The erosion of soil is also a significant problem, leading to silt in the river. Singly or together these pollutants can reduce the biodiversity of the river which is one way we measure the ‘health’ of our environment. So algal blooms may proliferate and the siltation of the riverbed reduces oxygen for the species that live there, further affecting the dependent food chain – fish, birds and mammals.

There are solutions, such as building ponds and ditches to slow or divert run-off, but these have mostly been employed at local levels. The DTC project is looking to take such practical solutions and see how they can be applied more widely to achieve improvements in water quality over whole catchments.

“Catchment science is a new science,” says Project Secretariat Bob Harris. “It involves understanding the complex catchment system better by researching at the plot or field scale and then predicting the outcomes of the way land is managed at the landscape-management level.”

Find the river

The DTC is a big project, featuring manipulative experiments and control areas spread across many tens of hectares of land in Cumbria, Norfolk and Hampshire. These three separate catchments (Eden, Wensum and Avon respectively) were selected as being typical of land use or farming type in England and Wales, whilst taking into account previous research or engagement with the local farming communities.

IS4L will work on high containment viruses, such as FMD, pictured. Image: IAH

Trust me, I’m a scientist: the luminous dye reveals leaks and where water flows. Image: EdenDTC/Clare Benskin

On all three catchments, the programme's researchers are trying a combination of measures, such as reducing the pollutant source or its mobilisation, intercepting the pathway and protecting the receptor (river or groundwater), to gauge progress rather than rely on a single change. Harris adds that it's this combination of measures that they hope to test at the scale of the catchment, rather than the performance of any one individual measure.

So far, Harris says the high quality and intensity of data collection is letting scientists build an understanding of the land-water system that obviates the traditional requirement to have long term data sets to observe trends. “If you understand the system well enough then you can interpret changes in the water quality signal,” he says.


The impetus behind the DTC was that policy-makers wanted stronger evidence – beyond a few limited studies and hearsay – proving that local measures on farms, such as matching the application of nutrients to crop needs, or better manure management, actually make a difference to water quality at river catchment scale. “There was also a desire to get the best academic brains working together and focused on specific areas, rather than just undertake another project on their own stretch of river,” says Harris.

The Eden catchment in Cumbria is a mixed arable and livestock farming area. The headwater catchment is a typical upland farming environment where rainfall is high and slopes are steep. The main problems are typical too – excess of nutrients nitrogen and phosphorus in rivers and groundwater. “There are many small farms which are facing manure management problems as they increase stocking levels to stand still economically, while the land available to spread manure remains the same,” says Harris. “The focus on measures here is in manure and drainage water management together with the interception of run-off using ponds and wetlands.”

The Wensum area in Norfolk is a complete contrast to the Eden (Google Earth provides a tour of the site – see external links below). In the Wensum, water drains an area of low topography which is a predominantly arable catchment with large farms run on a commercial and profitable basis. Harris says that the Wensum farm systems are well funded and equipped and farm management is generally quite technically informed. ”Measures to be tested here involve a mix of treating the run-off in the drainage ditches by creating a wetland but also reducing the mobilisation of nutrients by minimising tillage or more effective application of fertiliser,” Harris explains.

The Wensum  DTC area. Image: Wensum DTC

The Wensum DTC area. Image: Wensum DTC

The Avon, the third catchment, is also a mixed farming landscape. It has large scale arable farming like the Wensum – but with steeper slopes, and there are also more livestock and mixed enterprises, as well as a high profile for recreational fishing. “Here the emphasis is mostly on reducing sedimentation of the river bed by better management of the agricultural soils,” says Harris. “This means blocking obvious pathways, for example moving farm gateways, and observing the performance of constructed wetlands.”

Each catchment is not fully instrumented, nor is farmland being manipulated over the whole catchment. The manipulation is being done in smaller areas of around 10-50 hectares in each of the three main catchments, where £4M of instruments have been installed to monitor water flow, as well as relevant chemistry and biology. For comparison there are control areas with no manipulation.

“We are now embarking on a 'programme of measures' to address pollutant flux from the agricultural businesses in each location, hopefully to see a change in water chemistry after the changes on the farm,” says Harris.

Country feedback

Being some way from each other, each catchment area has a degree of autonomy and different projects underway.

In the Avon for example, researchers are identifying the different types of nitrogen and phosphorus present in the water. Farming is not the sole cause of diffuse pollution, but according to Defra it does contribute approximately 60% of nitrate, 25% of phosphorus, and 70% of sediments entering UK waters, amongst other pollutants. Hence, the Avon team hope to show through analysing different nitrogen and phosphorus isotopes how much the different sources contribute  to inform appropriate actions to take.

The Avon researchers are also investigating why so many farms don’t have proper storage facilities for slurry. Working with the farming community, they found that obstacles included doubts as to whether the investment would give a reasonable return. The view that no such facility was needed was also encountered, as were other problems such as planning regulations.  

The Eden site is taking a closer look at the type and quantity of sediment in the river to find out how it affects the health of the watercourse. The Eden team are developing “fingerprinting” processes for tracking sediment pollution back to its source which could provide catchment managers with information about high risk areas.

The Eden team is also using cameras to monitor animals’ movements and measuring the water quality downstream. This hopes to answer the question of whether water quality suffers because of organisms from livestock faeces getting into rivers or by animals having physical access to watercourses.

The Wensum DTC team are using apps to visualise  data. Image: Google Earth

The Wensum DTC team are using apps to visualise data. Image: Google Earth

The sites are also using networking applications and computer software to bring the DTCs to the digital domain. The Wensum site has fused satellite and local data to explore and visualise the site in Google Earth. Developed by GIS (Geographic Information System) expert Gilla Sunnenberg, it allows viewers to take a virtual tour of the Wensum and features information from monitoring sites on soil types and land cover, as well as photographs from the catchment.

The Wensum team has also developed an augmented reality smartphone application. It overlays the phone’s camera view with additional information about the ecosystem services observed. This application can help people explore more nature’s benefits as they walk along the river and it will be compared to how people use traditional maps.  

West of the fields

The DTC project is an epic-scale study designed to tackle a mammoth problem. But even this huge undertaking is not quite alone in the UK. A similar multi-million pound experiment – the North Wyke Farm Platform (NWFP) – is under way in Devon, UK. Funded by the Biotechnology and Biological Sciences Research Council (BBSRC), the NWFP covers 67 hectares and will compare different approaches to sheep and cattle farming on grassland ecosystems, also measuring water and nutrient run-off from fields in minute detail.

However, the NWPF covers field-scale processes over a single site as opposed to DTC’s catchment scale at multiple sites. “Similar, but different!” says Harris. “We therefore complement each other and in due course must find ways of linking better and collaborating on research and policy questions.  Collaboration and co-operation are the key to solving these seemingly intractable problems of growing more food without detriment to the environment.”

Co-ordinating such an immense project demands this level of cooperation. On a technical level, the DTCs specialised monitoring kit is an asset for other researchers on different projects to use. “The data and information is being collected in a DTC database run by the Freshwater Biological Association (FBA) that is open to all who want to join in or even do their own thing as long as the results are shared.”

 All about  teamwork: researchers identify drain start and end points. Image: EdenDTC/Clare  Benskin

All about teamwork: researchers identify drain start and end points.
Image: EdenDTC/Clare Benskin

From a scientific management perspective, Harris says involving and including the local stakeholder community in each catchment is essential for the ‘co-creation’ of knowledge. “Team building, among the researchers and between researchers and the policy community, is important,” he says. “And you have to build trust with the farmers or you’re dead in the water.”

Harris also has to avoid the three catchment areas' consortia splitting into three separate projects, and ensure the programme remains linked to other big funders’ initiatives, such as the Catchment Sensitive Farming (CSF) initiative funded by the Environment Agency and Natural England, and those research programmes run by the Natural Environment Research Council (NERC). “We hope to be able to sustain the research platforms to be able to answer questions that catchment managers have in the future, says Harris.

Harris says they also wish to develop a ‘tool kit’ of guidance, models, simple spreadsheets, and test kits that catchment managers can use to understand the land-water interactions in their area and then choose or target measures accordingly. “We also hope that the way of working and the scaling up processes that we develop, using models based on the data we collect, will be an exemplar for future predictive work.”

Although the initial DTC funding will run out in 2014, work will continue to 2017 and Harris says the intention is that the research platform will continue beyond as a collaboratively funded exercise. “We are encouraging the DTC consortia to produce results on an on-going basis,” he says.

The DTCs are holding their first national conference on 21-22 January 2013 in London.