BETTER LAND FORBETTER WATER:Scenarios for changeModelling changes in agricultureto improve water quality in England

J Shi, R Davis and J Densham

February 2006

BETTER LAND FORBETTER WATER:Scenarios for changeModelling changes in agricultureto improve water quality in England

This document is a summary of a full project report: Shi, J, Davis, R andDensham J (2006) Better Land for Better Water: Modelling land-use change toimprove water quality in England. RSPB/WWF/Water UK. To receive a copy ofthe full project report, or further copies of this summary, please contactJim Densham at the RSPB, jim.densham@rspb.org.uk or download fromwww.rspb.org.uk/waterwetlands/lawandpolicy/diffusepollution.asp

Contentspage

Executive summary 1

1 Introduction 2

2 The catchment approach 4

3 Water quality: what are we aiming for? 5

4 How big is the nutrient problem? 6

5 Scenarios for change 8Scenario 1: Good Agricultural Practice (GAP) 8Scenario 2: Business As Usual (BAU) land-use forecast 9Scenario 3: Agri-environment Measures 10Scenario 4: Wildlife-Rich Landscape with GAP 12Scenario 5: Radical Change 13

6 Conclusions 14

Select bibliography 15

Acknowledgements

The authors would like toacknowledge the substantialcontribution of the ADASCatchment Management team, inparticular Mark Shepherd, withoutwhom the report would not havebeen written; the support andadvice of members of the TechnicalSteering Group, in particularHannah Bartram, Penny Johnes,Robert Oates and Jacob Tompkins;the additional helpful advice ofSue Armstrong-Brown, LouiseHeathwaite, Liane Jarman,Tom Le Quesne, Ken Smith andGwyn Williams.

Andy H

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Cover photograph byAndy Hay (rspb-images.com)

• Nutrient pollution of water damages ecosystems and costs watercustomers money. The results of this project show that over half ofEngland’s rivers may be at risk of damage from phosphorus pollution.

• Discharges from sewage works are still a significant source of pollution inthe water environment. In the six catchments modelled, the estimatedcontribution from sewage outfalls ranged from 9% to 60%.

• Common Agriculture Policy reform measures alone are unlikely to lead toa healthy water environment. However, good practice techniques andsimple, low-cost agri-environment measures, combined with CAP reform,could make a real difference, but only if widely and consistently applied.

• The creation of more areas of wildlife habitat, combined with support forextensive and low-input farming, would have multiple benefits, and helpachieve required water standards.

• In some areas, land-use change may be needed to tackle chronicpollution problems, or protect ecologically sensitive sites or drinkingwater sources. This could involve taking land out of intensive arableproduction or significant reductions in livestock numbers.

• The land use patterns identified by this project, which meet WaterFramework Directive standards and biodiversity targets, will have majorimplications for agricultural systems, agri-environment resources, andadvisory support. An important next step will be to developunderstanding of ways to meet forthcoming water legislation andmaximise other environmental benefits for wildlife and landscape, whilstensuring that farm businesses can adapt and remain profitable.

Executive summary

1

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Water, agriculture andnutrientsFarming covers over 70% of the landof the UK. As well as providing uswith food, farmers maintainlandscapes and wildlife, and supportthe life and livelihoods of thousandsof people in rural communities.

But, agricultural activity can alsodamage the environment. Where soilsare poorly managed, and wheremanure, fertilisers or pesticides areapplied inefficiently or at the wrongtime, this can affect the quality of waterreaching our rivers, lakes and seas.

One of the most serious problemsfacing the water environment ispollution by plant nutrients – inparticular, nitrogen and phosphorus.These substances are essential forplant growth; but too much of themin the wrong place can lead to aphenomenon known aseutrophication. Eutrophication –literally the over-feeding ofecosystems – results in oxygendepletion, changes in waterchemistry, food-chain imbalances,increases in toxic algal blooms andthe collapse of populations ofsensitive species. The MillenniumEcosystem Assessment, a UnitedNations project using data fromnatural science groups around theworld identified eutrophication asone of the three most serious threatsto biodiversity and ecosystemfunction, alongside climate changeand habitat loss.

Eutrophication is threatening some ofEngland’s most precious wildlife.English Nature, the Government’snature conservation advisors, reportedin 2005 that over 100 of England’smost sensitive wildlife sites have beendamaged by diffuse pollution. Manyspecies are also at risk, including plants

like the water violet, birds like thebittern, and valuable fish stocks ofsalmon and trout. Pollution by nutrientsalso affects drinking water, leading toincreasing treatment costs for watercompanies and their customers. It isestimated that the current costs ofaquatic eutrophication in England andWales are in the order of £250 millionper year.

How do nitrogen andphosphorus enter water?Plant nutrients can reach water frommany sources, but the mostimportant of these are sewageoutflows and run-off from farmland.

Phosphorus and nitrogen enter theagriculture system in the UK in theform of inorganic fertilisers and, inparticular phosphorus, withinlivestock feed. Nitrogen is susceptibleto leaching from soils where it canenter groundwater and surfacewaters whereas phosphorus generallybinds to soil and enters water whensoils are eroded. Both nitrogen andphosphorus can be recycled tofertilise plants through animal manureand slurry but poor management ofthese organic materials can increasethe risk of them enteringwatercourses in runoff.

The proportion that comes fromagriculture is increasing, as higherstandards of water treatment reducethe contribution from human waste.In 2002, it was estimated thatagriculture was responsible foraround half of the phosphorusentering water in England, and 70%of the nitrogen. The focus of thisreport is agricultural diffuse pollution;however, it is important toacknowledge further action will beneeded to clean up sewagedischarges too, if we are to improvethe health of our waters.

1 Introduction

2

Poor management of animal

manure and slurry can increase

the risk of nutrients entering

watercourses in runoff

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What action is being takento tackle the problem?The UK Government recognises theneed to address diffuse agriculturalpollution, and included a pledge todo so in its 2005 General ElectionManifesto. Action is needed now, ifthe UK is to protect and restoreaquatic and wetland wildlife, andprotect water customers fromfurther costs. The UK also needs toact, if it is to meet new standards forwater quality laid down in theEuropean Water FrameworkDirective, a new law covering all thesurface and ground waters of theEU; and to meet existing obligationsunder the Nitrates, Bathing Water,Birds and Habitats Directives, andunder the Countryside and Rights ofWay Act.

The Government is at presentworking on plans to promotecatchment sensitive farming andachieve better water quality. Wealready have a good understandingof the kinds of practical measuresthat could help. We are less certain,however, about how much action isneeded in different areas; and howrecent reforms to the CommonAgricultural Policy might contribute

to solving the problem. The projectdescribed in this report wasdesigned to improve ourunderstanding of these issues andhope that it will support theGovernment in making appropriatechoices for the management of thischallenging and importantenvironmental problem.

Better land for better water:scenarios for changeThis report summarises the resultsof an 18-month project, jointlyfunded by the RSPB, Water UK andWWF, and developed with technicalsupport from ADAS. The project’saim was to explore the changes infarmed land-use and managementthat might be necessary to achievenutrient levels in rivers compatiblewith healthy aquatic ecosystems.Because phosphorus is generallyconsidered to be the limitingnutrient in freshwaters, andtherefore has the most potentialfor environmental impacts if levelsare increased, this is the main focusof the report. The full technicalreport, from which this summary isderived, is available online atwww.rspb.org.uk/waterwetlands orfrom the project partners.

3

Eutrophication is threatening

some of England’s most

precious wildlife

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What is a catchment?A catchment or watershed is thearea of land from which water drainsinto a river, lake or estuary. How thisland is managed affects both thequality and quantity of water reachingwater bodies. Because of this,catchments are often thought of as thenatural units of water management.

To manage catchments effectively,we need to understand the links

2 The catchment approach

between water quality and geology,hydrology, climate and land use.One way to do this is by usingcatchment-scale models. These builda ‘picture’ of a catchment, allowingresearchers to manipulate differentfactors, to explore the effects onwater quality. This project employeda catchment-scale model to predictthe effects of changes in agriculturalland-use and management on loadsof phosphorus reaching the water.

Catchment Location Geology and climate Predominant land-use

A SW England Average annual rainfall 1000 mm, greensand Dairy and sheep farming,and clay grading into alluvium and valley gravels some beef

B E England Average annual rainfall 580 mm, light soils Intensive arable farming withpigs as the major livestock

C NE England, Average annual rainfall 855 mm, carboniferous Sheep farming dominant,uplands limestone and millstone grit large areas of Site of Special

Scientific Interest

D NW England Carboniferous limestone, millstone grit, boulder Improved grasslands, dairyclay over coal measures and sheep

E SW England Average annual rainfall 750 mm, oolitic Mixed farming with alimestones with tributaries draining off clays proportion of field vegetables

F S England Average annual rainfall 750 mm, weald clay, Arable dominant but urban land-with chalk predominating in some areas uses occupy as much as 15%

Sample catchmentsThe project modelled the effectsof land use and managementchanges in six representativesample catchments. Thesecatchments, described below,although real, were chosen torepresent different climates, soilsand land-uses within England.

100%

80%

60%

40%

20%

0%

■ Grass

■ Arable

■ Rough

■ Wood

■ Water

■ Urban

Figure 1

Land-use in the sample catchments

Table 1

Details of the six sample catchments

Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

4

Water quality can be measured inmany different ways. In England,data is collected on theconcentration of specific chemicals,on water levels and flows, and onthe presence, absence or abundanceof particular organisms.

However, scientists have recognisedrecently that the ecological health ofwater – its ability to supportcharacteristic plants and animals –is a vital measure of its quality.This principle is enshrined in a new

3 Water quality: what are we aiming for?

European law called the WaterFramework Directive (WFD), whichpromotes the sustainablemanagement of water across Europe.

This project aimed to understandhow agriculture might need tochange, to achieve phosphoruslevels compatible with healthyecosystems and new standardsunder the WFD. The relationshipbetween phosphorus levels and riverlife is complex, and it was decidedthat for this project, threshold values

already established by theEnvironment Agency forimplementing the Water FrameworkDirective would be used, see table 2.The values chosen are specific todifferent river types, depending uponsize and geology. They reflect currentAgency thinking, and so are anappropriate benchmark for GoodEcological Status, the central standardof the WFD. It is recognised, however,that they may need to be adapted inthe future, as understanding ofaquatic ecology grows.

Productivity Threshold Productivity Threshold

low (organic/ confidence moderate/high confidence

siliceous) (calcareous)

Not at risk <0.02 high <0.06 medium

Probably at risk 0.02–0.04 medium 0.06–0.1 medium

At risk >0.04 high >0.1 medium

Table 2

Type-specific P values for river types, used as a proxy for Good

Ecological Status (source: Environment Agency)

Appropriate threshold values for

phosphorus have been chosen

by the Environment Agency to

indicate risks to Good Ecological

Status of water

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The problem in Englandand its sourcesThe project compared existingphosphorus levels in rivers inEngland with the ecologicallyrelevant threshold values,developed to help implement theWater Framework Directive.The results indicate that between51% and 71% of rivers incatchments are at risk of ecologicalimpacts from phosphorus,depending on the underlyinggeology of those catchments.

4 How big is the nutrient problem?

Concentrations of phosphorus inrivers are the result of ‘point’ sourcedischarges, such as sewage outflows,and diffuse sources such as farmlandand roads. The project assessed 688river stretches, looking at phosphorusconcentrations before and after thepoint of a discharge by a sewagetreatment works. More than 60% ofstretches showed significant pointsource influences. This is despitephosphorus treatment plants beingadded to many sewage treatmentworks.

Figure 2

Percentage of rivers of three dominant geology types at risk of not

achieving ecologically relevant standards of phosphorus

100

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Geology type

Calcareous

■ At risk

■ Not at risk

% o

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Phosphorus from sewage and

agricultural runoff is putting

over half of England’s rivers at

risk of ecological impact

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The problem and itssources in samplecatchmentsAs well as analysing national dataabout nutrients in rivers, the studylooked in more detail at the levelsand sources of phosphorus in oursample catchments. Data on humanpopulation numbers was used towork out how much of thephosphorus reaching water comesfrom sewage, rather than diffusesources. The reduction in agricultural

phosphorus export needed, toachieve our target threshold levelswas then calculated. In each case, itwas assumed that the reduction inphosphorus loss from agriculturerequired was proportionate to itscontribution to the overall load;and that a similar, proportionalreduction would be required frompoint sources.

The results from the project’scatchment analysis show that

phosphorus levels vary substantiallybetween catchments. Upland areastend to have lower levels ofphosphorus than lowland areas, andareas with low rainfall tend to havehigher concentrations because ofthe limited potential for dilution. Thescale of change required to achieveour WFD-relevant standard variedsimilarly, with the greatestchallenges in areas with largenumbers of livestock or with lowannual rainfall.

■ Baseline P load

■ Target P load

Figure 4

Baseline agricultural phosphorus load and targets reductions

required from agricultural activities

Figure 3

Pollution sources contributing to total P export under baseline calculation

100

80

60

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20

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■ People

■ Animals

■ Rainfall

■ Land

Pro

po

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n o

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lo

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(%

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9080706050403020100

TP

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(t)

Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

7

The project developedcatchment-specific scenarios totest the impacts of differentfarm practices and patterns ofland-use on phosphorus loadsto rivers. In each case, theresults are recorded as thepercentage of the targetreduction achieved.

This scenario was designed toassess the effects of changing farmpractice within existing land-uses.A review of previous research wasused to estimate the level ofnutrient reduction that might beachieved using a range of goodpractice measures. These includedimproved soil management, moretargeted manure and fertiliserapplication and pollution mitigationmeasures. Two variants of the GAPscenario were tested, based on theirpotential cost for farm businesses.

Scenario 1a: Basic GAP – Lowcost/no cost measures, some ofwhich could reduce costs to farmbusinesses.

Scenario 1b: Advanced GAP –Measures under Basic GAP, plusmeasures that would incur moresubstantial costs to the farm(including capital investment).

5 Scenarios for change

Results: With basic GAP, between3% and 14% of the requiredreductions were achieved, and withadvanced GAP, between 3% and36%. Application of GAP wasgenerally more effective in arablethan in grassland catchments.

Implications: Significant reductionsin agricultural phosphorus export canbe achieved by the use of low costmanagement measures, particularlyin areas dominated by arable land-uses. However, these will not beenough on their own to achieveecologically healthy, threshold levelsof phosphorus in rivers.

Catchment

B

Catchment

C

Catchment

D

Catchment

E

Catchment

F

Figure 5

Percentage of target reduction with Good Agricultural Practice

40

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■ Basic GAP

■ Advanced GAP

% o

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Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Scenario 1:Good Agriculture Practice (GAP)

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This scenario modelled the changesin land-use following theimplementation of CommonAgricultural Policy reforms,predicted by a Cambridge Universityproject for Defra. The mostsignificant predicted changes by2015 were reductions in livestocknumbers, intensification ofremaining livestock enterprises, andsome increases in arable and farmwoodlands. Analysis of regionalvariation was used to develop anappropriate scenario for each of thesix project catchments.

Results: The contribution to thetargeted level of reduction was asmuch as 20% in the grassland andupland catchments, but negative inthe intensive arable catchment.

Implications: Under the BusinessAs Usual scenario, some substantialreductions to phosphorus loads canbe expected in some areas but, inothers, the contribution will be verysmall, and in arable areas the effectmay even be negative. Furtheraction will be required to meetstandards relevant to WFD.

Figure 6

Contribution to target reduction under the Business As Usual scenario

25

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-5

% o

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Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Scenario 2:Business As Usual (BAU) land-use forecast

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CAP reform measures alone are

unlikely to be enough to restore

a healthy water environment

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Scenario 3 applied options availableunder the Environmental Stewardshipscheme in England (ELS and HLS), withthe aim of understanding how agri-environment support would contributeto reductions in phosphorus loads, iffunding was unconstrained.

Scenario 3a studied the effect ofselected ELS options including soilmanagement, livestock reduction andinput reduction measures. Theestimated uptake of options in thesample catchments was based ondata from the ELS pilot areas.

Scenario 3b attempted to model theeffect of HLS options on nutrient export.Since the options for HLS were notfinalised at the time of the study, inorder to predict uptake the optionswere compared to uptake of similaroptions under the CountrysideStewardship Scheme. The optionsmodelled included semi-naturalhabitat creation options (for example,fens and reedbeds), arable reversionto grassland, and restoration of low-fertility grasslands.

Results: ELS and HLS gave resultsin the order of 1–5% contributiontowards target reduction. Theserelatively small contributionsprobably reflect the limited predicteduptake of measures, combined withthe challenge of accuratelymodelling subtle changes likely tobe brought about by ELS/HLS, ratherthan the quality of the optionsthemselves.

Implications: To be effective, it islikely that agri-environmentmeasures would need to be takenup over large areas and bestrategically located in thecatchment. Doubts exist as towhether funding and expert adviceare currently available to achieve thisadequately in all English catchmentsnotwithstanding the fundingallocated by Defra to 40 catchmentsunder the England CatchmentSensitive Farming Delivery Initiative.

■ ELS

■ HLS

Figure 7

Percentage contribution to target P reduction with ELS and HLS

6

5

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2

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0% o

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Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Scenario 3:Agri-environment Measures

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Targeting agri-environment

measures to the right places

is likely to make them more

effective in reducing the

amount of phosphorus

entering water

Matt S

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Scenario 3c combined the results ofmodelling BAU, Advanced GAP andELS. By modelling these measurestogether, the project estimated themaximum reductions that might beachieved, from the expansion andenhancement of current policyinstruments. This scenario is basedon universal application of goodpractice measures, and thewidespread adoption of basic agri-environment measures, overlyingCAP reform impacts.

Results: The scenario predicted inthe order of a 30–35% P reductionagainst target in the upland andarable catchments. Measures wereless effective in lowland catchmentswith livestock.

Implications: Widespread andeffective application of improvedagricultural practice, combined withgood uptake of Entry Level agri-environment measures could have asubstantial impact on pollution byphosphorus. Further action will stillbe required, however, to meetecological water standards in manyareas, particularly in areasdominated by intensive livestockfarming.

Figure 8

Percentage of contribution to target P reduction with BAU + ELS +

Advanced GAP

40

35

30

25

20

15

10

5

0% o

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t re

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Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Scenario 3c:BAU + ELS + Advanced GAP

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A combination of low-cost

measures could make a real

difference in upland

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Farmed landscapes provideimportant habitats for species suchas skylark, corn bunting and blackgrouse. However, the delivery ofGovernment Biodiversity Action Plantargets will also require the re-creation of much larger areas ofhabitats such as heathland,wetlands and woodland. TheWildlife-Rich Landscape (WRL)scenarios were designed to deliverlandscape-scale benefits forbiodiversity and developed withinput from local conservation staff,referencing Local Biodiversity ActionPlans. Basic GAP outcomes, fromScenario 1, were incorporated intothe design. In general, this scenariowas characterised by more mixedfarming, decreased inputs,extensification of livestockenterprises and a greater area andvariety of semi-natural habitats.

Results: Significant reductions inagricultural P loss were achieved.Even so, the results suggest that aWFD-compliant result could only berealised in the upland catchment,with other catchments reachingabout 40% of the target reduction.

Implications: The creation of moresemi-natural habitats to supportwildlife, and a shift to moreextensive and mixed farmedbusinesses, would make asubstantial contribution to meetingtargets. However, in some areas thisalone would not be sufficient toachieve ecologically healthy levels ofphosphorus in rivers. No economicassessment of this scenario wasincluded, but it is acknowledged thatthis scenario assumes substantialchanges to the level of farmingactivity in some parts of thecatchments and would requiresignificant public support.

100

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■ P reduction

■ Livestock change

% o

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Contribution to target P reduction with the WRL scenario. Graph also

shows the reduction in livestock numbers associated with the scenario

Intensivedairy

Intensivearable

Upland Grassland Mixed Generalarable

Scenario 4:Wildlife-Rich Landscape with GAP

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The creation of more semi-

natural habitat would help

achieve better water qualityD

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The aim of the Radical Changescenario was to alter land uses toachieve our phosphorus targets ineach catchment. The scenario wasdeveloped by building on changesmodelled in the WRL scenario, andconsidered phosphorus reductionsfrom all agricultural sectors. For eachcatchment, phosphorus reductionswere achieved through land usechanges such as increases in roughgrazing, reductions in livestocknumbers and reduced fertiliser andmanure inputs.

Results: Five catchments achieved100% of the targeted reduction.Significant changes in livestocknumbers were required to bring thisabout. The intensive arable catchmentachieved significant reductions, butfailed to reach the target, reflectingthe difficulty of controlling phosphorusconcentrations in areas with lowrainfall.

Implications: In some cases, radicalchanges to land use may be needed,to protect drinking water sources orecologically sensitive sites, and asrequired by the Water FrameworkDirective. Policy, advisory andfunding drivers are not currentlygeared to deliver change on thisscale, and the consequences forfarming and the rural economy mustbe considered. Even with suchchanges, there may be areas where itis difficult to achieve target levels ofphosphorus, particularly whereclimate change further reducessummer rainfall levels.

■ P reduction

■ Livestock change

Figure 10

Contribution to target P reduction with Radical Change. Graph also

shows the reduction in livestock numbers associated with the scenario

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Scenario 5:Radical Change

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In some areas, land-use change

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6 Conclusions

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Water pollution by phosphorus is aserious problem, with costs forwildlife and water customers.Action is needed now to tacklephosphorus discharges fromsewage effluent, and to reduceagricultural phosphorus reachingUK rivers.

On the basis of modellingphosphorus losses from sixrepresentative catchments withcontrasting land-use patterns,adoption of best practice and thechanges in land use expected toresult from CAP reform will havebenefits for reducing diffuse pollutionfrom agricultural land. However,these alone will not be sufficient tomeet Water Framework Directivestandards. Further measures will beneeded to address chronic problems,

protect ecologically sensitive sitesand drinking water sources. Theseinclude the uptake of good practicemeasures on all farms, the creationof more areas of semi-natural habitatand, in some cases, more radicalland-use change.

The land use patterns identified bythis project, which meet WFDstandards and biodiversity targets,will have major implications foragricultural systems, agri-environment resources, andadvisory support. An important nextstep will be to developunderstanding of ways to meetforthcoming water legislation andmaximise other environmentalbenefits for wildlife and landscape,whilst ensuring that farm businessescan adapt and remain profitable.

Figure 11

Summary of scenario results

■ Advanced GAP

■ BAU

■ HLS

■ WLR

■ Radical Change

% o

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dairyIntensive

arableUpland Grassland Mixed General

arable

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The land-use patterns identified

by this project will have major

implications for agricultural

systems, agri-environment

resources and advisory support

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Select bibliography

For full reference list, see technical report Shi, J, Davis, R and Densham J (2006) Better Land for Better Water:Modelling land-use change to improve water quality in England. RSPB/WWF/Water UK, available atwww.rspb.org.uk/waterwetlands/lawandpolicy/diffusepollution.asp

Cambridge University (2004) BusinessAs Usual Projection of AgriculturalOutputs for the Water FrameworkDirective – Final Report. http://www.environment-agency.gov.uk/aboutus/512398/516810/516841/

D’Arcy, B J, Ellis, J B, Ferrier, R C,Jenkins, A and Dils, R M (Eds) (2001)Diffuse Pollution Impacts. CIWEM,Terence Dalton Publishers, UK, 61–71.

Dampney, P, Mason, P, Goodlass, G andHillman, J (2002) Methods and measuresto minimise the diffuse pollution of waterfrom agriculture – a critical appraisal.Defra project report NT2507.

Defra (2002) The Government’s strategicreview of diffuse water pollution fromagriculture in England: Agriculture andWater: A diffuse pollution review.Department for Environment, Food andRural Affairs, 2002.

Defra (2004) Developing Measures toPromote Catchment-Sensitive Farming. Ajoint Defra-HM Treasury Consultation.

English Nature (2002) Policy mechanismsfor the control of diffuse agriculturalpollution, with particular reference togrant aid. Research Report 455.

Haygarth et al. (2003a) Cost curveassessment of phosphorus mitigationoptions relevant to UK agriculture. Defraproject report PE0203.

Haygarth, P, Johnes, P, Butterfield, D,Foy, R and Withers, P (2003) Land usefor achieving ‘good ecological status’ ofwaterbodies in England and Wales: atheoretical exploration for nitrogen andphosphorus. Supplementary report forDefra project PE0203.

Haygarth, P, Scholefield, D, Chadwick, D,Cardenas, L, Butler, P, Shepherd, M,Goodlass, G, Withers, P, Chambers, B,Lord, E, Cottrill, B, Smith, K, Harris, D,Ferrier, R, Stutter, M, Carvalho, L,Anderson, J, White, P, Cuttle, S, Dewhurst,R, Heathwaite, L and Johnes, P (2004)Reviewing the potential for reductions ofnitrogen and phosphorus inputs in currentfarm systems. Defra project report ES0201.

Haygarth, P M, Granger, S, Chadwick, D,Shepherd, M and Fogg, P (2005) Aprovisional inventory of diffuse pollutionlosses. Report for Defra’s CatchmentSensitive Farming Group.

Johnes, P J (1996) Evaluation andmanagement of the impact of land usechange on the nitrogen and phosphorus

load delivered to surface water: theexport coefficient modelling approach.Journal of Hydrology 183, 323–349.

Johnes, P J (2000) Quantifying the non-point source contribution to nutrientloading on freshwaters in 32 UKcatchments. Verh.Int. Verein. Limnol. 27,1306–1309

Johnes, P J, Moss, B and Phillips, G L(1996) The determination of water qualityby land use, livestock numbers andpopulation data – testing of a model foruse in conservation and water qualitymanagement. Freshwater Biology, 36,451–473

Mainstone, C P, Parr, W and Day, M(2000) Phosphorus and River Ecology.English Nature.

Withers, P J A, Davidson, I A and Foy, RH (2000) Prospect for Control Non-pointPhosphorus Loss to Water: A UKPerspective. Journal of EnvironmentalQuality 29,167–175.

Zaimes, G N and Schultz, R C (2002)Phosphorus in Agricultural Watersheds.A Literature Review. Department ofForestry, Iowa State University, Ames,Iowa.

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Partners

Technical reviewer

The RSPB is the UK charity workingto secure a healthy environment forbirds and wildlife, helping to create abetter world for us all. We belong toBirdLife International, the globalpartnership of bird conservationorganisations.

for birdsfor peoplefor ever

Water UK is the association of waterservice companies. On behalf of itsmembers and their customers itpromotes research and debate onland management and protection ofthe water environment.

This report is part of WWF–UK’sNatural Rivers Programme, which issupported by HSBC. The programmeis developing innovative techniquesfor the management and restorationof rivers and wetlands for the benefitof people and nature.

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ADAS is a specialist research andconsultancy company, covering awide range of environmental issues.We understand the science of landand water interaction, and arecommitted to applying science toimprove water quality andmanagement.

Andy H

ay (rspb-images.com

)

The RSPB, UK HeadquartersThe Lodge, Sandy,Bedfordshire SG19 2DL

www.rspb.org.uk/waterwetlands

RSPB registered charity no 207076

WWF-UKPanda House, Weyside Park,Godalming, Surrey GU7 1XR

www.wwf.org.uk

WWF-UK registered charity no 1081247

Water UK1 Queen Anne’s Gate,London SW1H 9BT

www.water.org.uk