carbon (DOC) seeping into water from peat, and its removal ... carbon ends up in the atmosphere as CO2. .... amount of C
Soil and water conservation Opportunities to combat climate change Sustainable Uplands & Moors for the Future Research Note No. 15
September 2007
What is the Water Framework Directive? This European legislation aims to improve our water by creating integrated River Basin Management Plans with coordinated objectives for all river catchments in the EU. The WFD aims to protect and improve the environmental status of these catchments, promote sustainable use, and reduce the effects of floods and droughts so that all catchments achieve ‘good status’ by 2015. Currently, a single catchment may be managed by different authorities and organisations depending on its use, who may conflict over management. The WFD brings these groups together to plan how catchments should be managed for all their competing uses without causing environmental degradation. Challenges to achieving good status include effects of changing agricultural subsidies on land use and the uncertain impacts of climate change. There is little guidance about what good practice means in practice for each river basin and
different users may have conflicting ideas about what ‘good status’ may mean. Erosion is one of the biggest concerns for implementing the WFD in upland catchments, as the sediment can affect fish populations. There may also be increased interest in planting trees along upland rivers and restoring upland catchments so that they can hold water more effectively (for example through grip blocking) to help reduce downstream flooding.
Why is our water turning brown? Peak District reservoirs supply 450M litres daily to surrounding settlements, so the quality of water in upland catchments is important for water companies and consumers. Brown streamwater is largely caused by dissolved organic carbon (DOC) seeping into water from peat, and its removal costs water companies millions in treatment costs every year. Brown water is unappealing, can increase the chance of bacteria contaminating drinking water, and could increase the formation of cancer-causing tri-halomethanes. Water colour is a growing problem in the UK. Some studies show a 65% increase in DOC over
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the last 12 years. There are many possible reasons for this, including warmer winters, decreasing atmospheric pollution, gripping and more droughts due to climate change. In addition to water treatment costs, there are concerns that this may worsen climate change, when carbon ends up in the atmosphere as CO2. Water coming off gripped catchments contains much more DOC than undrained catchments, but the relationship with other forms of land management remains unclear. For example, while some believe that burning practices are to blame, others have found less DOC coming off regularly burned land than unburned plots.
Why have upland catchments been blamed for human diarrhoea outbreaks? Cryptosporidium is a single-celled parasite found in most livestock (particularly cattle) and wild mammals. The parasite causes diarrhoea and can be passed to humans. It can contaminate water courses via animal faeces, and there are limits on the level of Cryptosporidium that should be present following water treatment. Treatment costs can be high however as chlorine may not be effective in eliminating Cryptosporidium. Upland catchments have been linked to Cryptosporidium outbreaks in humans in the past. Upland streams are particularly vulnerable when there are high densities of livestock and wild animals, but also because the cool damp environment promotes the spread of the disease.
What role can upland catchments play in flood protection? Since the water table is usually close to the surface in peatlands, there is often little room to store extra water when it rains (like a wet sponge). Therefore upland catchments have “flashy” responses, with any additional water going straight into upland streams, which swell rapidly into torrents that may cause flash flooding downstream.
Flock of sheep being herded in the Peak District National Park. Sheep can spread Cryptosporidium
Gullies and drainage ditches can in many locations help conduct rainwater to streams even more rapidly, compounding this problem. In some small areas, however, the ditches and gullies can reduce peak flows during smaller rainfall events, because the dried out peat has a little bit of extra storage space. However, for the larger rainfall events that cause flooding, the ditches and gullies in these locations still do lead to larger floods locally and the ditches cause carbon and biodiversity loss. Current evidence suggests that while gully blocking might help to delay water flows from uplands, they may have little effect lowland flooding. Sheep can also contribute to the flooding problem by compacting the ground and reducing the soil’s capacity to absorb water, which flows much faster into streams. Almost nothing is known about whether rotational burning affects flood risk.
Above: Model showing effect of gullies on water table depth on the Kinder Scout plateau Right: Gullies on Bleaklow, Peak District National Park
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What is the potential for uplands to store carbon? Peatlands are the single largest store of carbon in the UK. Peatland stores around twenty times more carbon than forests in this country (around 3 billion tonnes). Peat bogs also absorb carbon from the atmosphere (where it contributes towards climate change as carbon dioxide). However, a recent Nature paper states that 80% of the carbon lost from UK soils comes from peatland. The UK Government’s carbon inventory suggests that peatlands absorb 0.7 megatonnes of carbon per year, while more recent research by researchers from the Sustainable Uplands team suggests they absorb less than half as much. This is equivalent to 24 tonnes of carbon per sq. kilometre per year. However, under future climate change, peatlands
Could carbon offsetting schemes pay for upland restoration? No-one knows the answer to this question yet. However, the best long-term study of a pristine peat catchment suggests carbon storage of 60 tonnes of carbon per sq. km per year (Fred Worrall, Durham University). The worst loss of carbon has been recorded in a heavily drained site that was loosing 100 tonnes of carbon per km per year (Martin Evans, Manchester University). Therefore, if the heavily drained site was restored to its original condition, then the storage created and the loss avoided would be equivalent to 160 tonnes of carbon per sq. km per year (or 1.6 tonnes of carbon per hectare). If it is assumed that this transition takes 10 years, that the one-off restoration cost was £188 per hectare (based on grip blocking accessible areas), and that clients were prepared to pay up to £30 per tonne of carbon absorbed then a simple model shows that the project would break even after 11 years. After twenty year period the amount of carbon
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are likely to lose more carbon than they absorb. Models suggest that even the best managed peatlands could become a net source of carbon by 2035. Poorly managed or damaged peats are already losing carbon, mainly in stream water as eroded soil (“particular organic carbon”) and brown water (“dissolved organic carbon”). This means that if damaged peatlands could be identified and restored to a pristine condition, then significant amounts of carbon could be returned to the soil. Models developed by Fred Worrall from the Sustainable Uplands project (co-funded by Moors for the Future and Natural England) suggest that across the UK as much as 400,000 tonnes of carbon could be stored a year in this way. This is equivalent to 2% of car traffic in England and Wales per year. The Peak District alone has the potential to absorb 13,000 tonnes per year. sequestered would be 23 tonnes of carbon. That is equivalent to a profit of £505 per hectare. It should be noted that other forms of restoration in less accessible areas are significantly more expensive to undertake, so these figures are a best-case estimate. Estimates of the area of peat in the UK vary between 14000-29000 km2. Therefore, if all of this peat were in the worst known condition and could be made into the best known condition then the maximum gain would represent 67 megatonnes of carbon saved, or 50% of total annual CO2 production in the UK, and a profit of £1.5 billion. This would not only avoid a large amount of CO2 loss, but create a new sink that would continue to absorb carbon into the future. These figures are only initial estimates and contain a high degree of uncertainty. More research is required to understand: how different forms of moorland management affect carbon storage; how long it takes for restored peatlands to return to original condition; and how climate change will affect restoration.
Other Research Notes in this series: 1 - Breeding Bird Survey of the Peak District moorlands
9 - Air Pollution in the Peak District
2 - Peak District Moorland Gully Blocking in Deep Peat
13 - Future of Upland Farming
12 - Carbon Flux
3 - Peak District Moorland Stream Survey
14 – Looking after moorland habitats
4 - Heavy Metal Pollution in Eroding Peak District Moors
15 - Soil & water conservation: opportunities to combat climate change
6 - Monitoring of Burning in Uplands A Rapid Assessment Protocol
16 - Tourism & recreation: opportunities and threats of the visitor economy
Contact Us Moors for the Future Partnership, The Moorland Centre, Edale, Hope Valley, S33 7ZA
Sustainable Uplands Project, Sustainability Research Institute, School of Earth & Environment, University of Leeds, Leeds LS2 9JT
Tel: 01629 816581
Tel: 0113 3433316
www.moorsforthefuture.org.uk
www.see.leeds.ac.uk/sustainableuplands
Email:
[email protected]
Email:
[email protected]
The Moors for the Future Partners are: Natural England, National Trust, Peak District National Park Authority, United Utilities, Severn Trent Water, Yorkshire Water, Sheffield City Council, Moorland Association, Defra, Country Land and Business Association, National Farmers Union
Funded by the Rural Economy & Land Use Programme, a joint Research Councils programme co-sponsored by Defra & SEERAD
