The cost of soil degradation in England and Wales Appendix D: Economic dimensions of soil degradation This Appendix reviews the approach to assessing the economic impacts of soil degradation using an ecosystems framework. Degradation processes and impact on soil condition Soils, and their inherent physical, chemical and biological properties, are a critical component of land-based natural capital. As such they provide a range of services that are of value to people. The Millennium Ecosystem Assessment (MA, 2005) 1 developed a methodological framework that linked major ecosystems (such as mountains, wetlands and enclosed farmland) to the generation of ecosystem services. These are classified into provisioning, regulating, cultural and supporting services (Table 1). This approach, applied more recently in the UK National Ecosystem Assessment (UK NEA, 2011) 2 , links these services to benefits to people in term of ‘final’ goods and services. A range of techniques can be used to derive economic values for these goods and services as shown in Table 1. Table 1 Generic approach to the classification and valuation of ecosystem services Ecosystem service Examples of services Benefits to people Techniques of valuation * Examples of valuation Provisioning of material goods and services Agricultural production, Mineral extraction, Water supplies, Land for development Agricultural commodities, Minerals , Energy, Water use , Adjusted market prices , Productivity, Revealed preference Market prices of: agricultural commodities; farm land values net of subsidies to farmers Regulating ecosystem processes Flood control , Erosion control Carbon storage, Water purification Flood damage avoidance, Social cost of carbon, Water quality Waste management Productivity Costs & income based methods Replacement goods Avoided urban flood damage/flood defence costs, social value of carbon storage, water treatment costs Cultural, non material services Heritage, Landscape, Amenity , Recreation, Social relations Heritage sites, Landscape features, Countryside walks, Tourist visits Revealed preference, Stated preference Willingness to pay for: heritage preservation, green-space, access to the countryside Supporting other Soil Crop yields, Productivity, Willingness to pay for 1 MA (2005). Millennium Ecosystem Assessment (http://www.milleniumassessment.org/en/index.asp (Accessed 10/08/2011) 2 UK NEA (2011) UK National Ecosystem Assessment: Synthesis of the Key Findings. UNEP-WCMC, Cambridge Draft report Page 1 Cranfield University
Transcript
The cost of soil degradation in England and Wales
Appendix D: Economic dimensions of soil degradation This Appendix reviews the approach to assessing the economic impacts of soil degradation using an ecosystems framework.
Degradation processes and impact on soil conditionSoils, and their inherent physical, chemical and biological properties, are a critical component of land-based natural capital. As such they provide a range of services that are of value to people. The Millennium Ecosystem Assessment (MA, 2005)1 developed a methodological framework that linked major ecosystems (such as mountains, wetlands and enclosed farmland) to the generation of ecosystem services. These are classified into provisioning, regulating, cultural and supporting services (Table 1). This approach, applied more recently in the UK National Ecosystem Assessment (UK NEA, 2011)2, links these services to benefits to people in term of ‘final’ goods and services. A range of techniques can be used to derive economic values for these goods and services as shown in Table 1.
Table 1 Generic approach to the classification and valuation of ecosystem services
Ecosystem service Examples of services
Benefits to people Techniques of valuation *
Examples of valuation
Provisioning of material goods and services
Agricultural production, Mineral extraction,Water supplies,Land for development
Agricultural commodities, Minerals , Energy,Water use ,
Willingness to pay for habitat and biodiversity protection and enhancement
In the ecosystem framework adopted by the Millennium Assessment, soils are considered to provide a range of supporting services that underpin the delivery of provisioning, regulating and cultural services that are more directly associated with benefits to people. Supporting services include the formation of soil itself, the cycling of atmospheric gases, water and nutrients, and the ability of soils to support a range of species and habitats, whether natural or man-made (Table 2).
The human-induced degradation of stocks of soil resources, for example by erosion due to intensive farming on hillslopes, can have a negative effect on a wide range of supporting services. Indeed, different types of soil degradation affect these supporting services in different ways and to varying degrees (Table 2). Thus, in the ecosystems framework, soil degradation has an indirect effect on welfare of people by reducing the support provided by soils to provisioning, regulating and cultural services.
1 MA (2005). Millennium Ecosystem Assessment (http://www.milleniumassessment.org/en/index.asp (Accessed 10/08/2011)
2 UK NEA (2011) UK National Ecosystem Assessment: Synthesis of the Key Findings. UNEP-WCMC, Cambridge
It is noted that natural and long term geomorphological processes, including erosion and deposition, can generate beneficial effects, such as the formation of alluvial silts. In the predominantly managed environment of the UK, however, soil degradation associated with human activity implies negative impacts on soil stocks and flows of services.
Table 2 Soil degradation affects the ability of soils to provide ‘supporting’ ecosystem services
Soil degradation processes
Supporting Services Units (examples)
Ero
sion
Com
pact
ion O
rgan
ic
loss
Loss
of
so
il bi
ota
Diff
use
pollu
tion
Sea
ling
Soil formation mm/year x x xAtmospheric gas cycling CO2te/year x x x xWater cycling mm/day x x x xNutrient cycling N03/year x x x x x xBiodiversity and habitats species composition
X denotes interaction between degradation process and service
The Effect of Soil Degradation on Indicators of Soil Condition The condition of soils affects their ability to support a range of services. For a given type of soil, whether mainly mineral or organic, soil condition can be expressed in terms of physical, chemical and biological properties as shown in Table 3. Thus, the degree of degradation of a soil can be described as a rate of change in key indicators of soil condition. As previously explained, different degradation processes affect soil condition in different ways. Erosion, for example, not only affects soil depth but also soil structure, water holding capacity, and soil carbon, nutrients and biota. Soil compaction mainly affects the physical properties of soils, especially in terms of structure and hydraulic conductivity and permeability. For its part, the sealing of soil surfaces closes off soils to most natural processes, but particularly affects their hydraulic properties.
PhysicalDepth mm xStructure : bulk density/packing density
Kg DM/m3 x x x
Hydraulic conductivity/permeabilityRun off
mm/day
mm runoff
x x
Avail water capacity ml/m3 soil x xChemicalOrganic carbon C kg/t soil x x xSoil NPK NO3 /ha x xEcological
Draft report Page 2 Cranfield University
The cost of soil degradation in England and Wales
Soil biota Species nr x x x x xX denotes main interactions
Degradation: declining stock and flows Degradation of the soil resource refers to a decline over time in the value stock of soil assets and a reduction in the value of future services provided by them. The concept is similar to that of depreciation of a physical asset, evident in the reduction of its remaining value over time. Thus in Figure 1, the value of degradation is the change in the value of soil over an accounting period, equivalent to the depreciation of physical assets. Degradation, if continued and unabated, would eventually lead to complete loss of soil assets.
Figure 1 Graphical representation of the degradation of the value of stocks of soil
The stock : flow relationship can be expressed as a difference equation as follows Δ S t= f (St ,X t ,Z)
where St is the stock at a particular point in time t (for example taken to be a given year end) and delta S is the change in S during the time period t (is t a point or a period?) Xt = (X1, ..., Xn) are external variables that are associated with change in the stock characteristics of soils such as land use and soil structure Zt = (Z1, ..., Zm) are the ‘state’ variables such as type of soil and topographical that do not change. Usually f < 0, indicating that the degradation has a negative effect on the stock value.
ThenSt+1=St+Δ St
orSt+1−St=f (St , X t , Z)
If f, the degradation function, is independent of St, then the general case applies as follows
ST=S0+∑t=0
T−1
f (X t , Z )
The stock value at any point in time is a function of the initial stock value and the cumulative effects of degradation (or appreciation) over time. If, however, as often might be the case, there is an interaction between stock and degradation (either increasing or decreasing exponentially relative to stock value) then a more complex relationship applies:In some situations, degradation may interact with remaining stocks to cause a rapid and catastrophic loss, as may happen with severe erosion or landslide events.
Draft report Page 3 Cranfield University
The cost of soil degradation in England and Wales
From an economic perspective the value of a stock at a point in time is determined by the present value of the future flows of services, discounted at the social discount rate:
PV St=∑t=0
T−1
❑b¿¿
Where the present value of soil stocks PV St is the discounted sum of the future flows of benefits of soil services b¿ less any costs associated with the maintenance of soil stocks c ¿ for successive periods. Benefits and costs here are a function of opening stock values in successive periods. The social discount rate is given by r.
Thus a change in the stock value is indicated by the change in the present value of flows of services rendered. For example: the reduction in carbon content of soils associated with emissions to atmosphere results in costs borne by society measured at the social cost of carbon. The present value sum of these emissions can indicate a decline in the value of soil carbon stocks between any two points in time. A similar approach can be used in principle to value soils as a medium for food production. It is noted however that some degraded services may be substituted by other ‘replacement’ inputs, such as artificial fertilisers. This does not reduce the loss of stock value. Rather it replaces the natural functions of soil at an additional cost.
Expenditure on soil conservation will, if effective, reduce the rate and hence costs of soil degradation. In economic terms, expenditure will be justified if the benefits of avoiding or reducing degradation (and hence the benefits of maintaining soil stocks) exceed the costs of conservation. Put another way, soil conservation is economically worthwhile if the present value of the future flows of soil services secured by conservation measures exceed the present value of the costs of conservation. Similarly for example, the costs of implementing regulations to prevent the discharges of hazardous chemicals to land, or of restrictions on land use in hilly areas that could cause erosion, are in theory justified in terms of the avoidance of the economic costs of soil degradation.
Where decisions result in changes in the flow of costs and benefits over time, the choice of the discount rate is important. Low discount rates, which place relatively high value on future benefits and costs, tend to favour soil conservation measures and the avoidance of degradation. Conversely, high discount rates place less value on longer term conservation strategies. Thus, the economic argument for soil strategy often rests on the choice of the discount rate that reflect societal preferences for benefits now rather than later3.
It is impossible, and unnecessary, to determine the value of soil stocks. It is possible, however, to determine variation in the condition of stocks of soils and the likely implications for flows of services. In this way, the change in the value of the stock of soils can be ascertained by estimating changes in the value of (selected) service flows due to degradation. This is the approach adopted here, using the ecosystems framework.
The counterfactual ‘without degradation’ situation It is required to identify a baseline counterfactual situation against which the economic costs of degradation can be ascertained. The counterfactual is the condition of soils, both in terms of stock and flow values, that would prevail in the absence of degradation, (St+1=Stabove).
Given the predominantly managed soilscapes of the UK, the counterfactual is set in the context of each dominant soilscape. Thus, the degradation that arises from a particular land use is identified together with the costs of degradation associated with that particular land use., eg the losses in agricultural production due to compaction and or erosion on soils under arable farming. As explained below, the analysis focuses on loss of value added and additional costs, whether associated with replacement or mitigation.
3 See HMT (2003), The Green Book. Her Majesty’s Treasury, London for a discussion on the choice of discount rates for public investment appraisal
Draft report Page 4 Cranfield University
The cost of soil degradation in England and Wales
Classification of economic impacts of degradation Although the ecosystems services framework is used here, it is useful to incorporate other ways of classifying the effects of soil degradation that have been used in earlier work on environmental valuation. These include distinguishing between on site and off site effects, between use and non use values, and between private and public goods.
On-site and off-site effects: on site effects occur on the site where degradation occurs, usually as a result of the way that a site and its soils are used. They are felt by those who use or occupy the site, such as farmers or recreational users. On site effects mainly arise as a direct result of soil degradation, usually in the immediate term. Off-site effects occur beyond the site of degradation such as increased run off leading to increased flooding and flood damage. Off site effects may take some time to manifest themselves. They may be associated with a range of possible causes, such that it is difficult to attribute them to a particular degradation process on a particular site. The costs associated with off-site effects tend to exceed on-site costs, indicative of market failure. The spatial extent of off-site effects varies according to the nature of ‘emissions’; at the local or catchment scale in the case of effects on the hydrological cycle at the global scale for effects on GHG cycles.
Use and non- use values. The concept of Economic Value considers the economic values for goods and services provided by the natural environment (Perman et al. 1999)4 by distinguishing between direct and indirect use, and non-use. These concepts can also be used to determine the value of a marginal change in an environmental asset, such as soil5. Thus, degradation may affect the functions of soils and the instrumental value provided by soils in ‘use’, either directly as in the case of erosion effects on agricultural production or indirectly by, for example, reducing the ability to absorb water which in turn contributes to flooding. Degradation can also affect non use values, such as the intrinsic value of soil (and its associated biophysical properties) now (existence value) and for future generations (bequest value). Furthermore, degradation can reduce the option value of soils, reducing their potential for future use or non-use. Option value may include the value of delaying a decision where it is thought that new information available in future could lead to more informed decisions and better outcomes. Reference is made to these aspects of soil valuation in the following analysis.
Valuation methods A range of valuation methods can be used as referred to in Table 1 (Defra, 2007)6.
Changes in outputs and inputs valued in market prices, adjusted where relevant to remove the effects of policy intervention such as taxes and subsidies and non-competitive market practices. Examples include the value of agricultural commodities whose quantities and or qualities change as a result of soil degradation, of soil substitutes/fertility supplements such as fertilizers which are required to replaced damaged soil functions.
Productivity based methods which measure the increase or reduction in the value of inputs or outputs in a production process, such as the value of lost yields due to soil erosion, expressed in terms of adjusted market prices as referred to above.
Damage costs estimate the costs incurred as a result of an environmental impact, such as that associated with flooding of property caused by run off from eroded or compacted land surfaces.
Defensive expenditure or replacement cost which value a service in terms of the cost of avoiding losses if the service is no longer available, such as the cost of building flood defences to guard against flooding or the cost of measures to prevent erosion. Revealed preference or hedonic methods seek to elicit that part of the price of a final marketed commodity that is attributable to the quantity or quality of the land-based service, for example relatively lower sale prices for land on which soils are degraded.
4 Perman, R. Ma, Y., McGilvray J. and Common, M. (1999). Natural Resource and Environmental Economics , Second edition, Pearson. See p 379. 5 TEV comprises the sum of Consumer Surplus (values derived by consumers of services over and above the price they pay for them) and Producer Surplus (the revenues received by producers of services less production costs). TEV therefore subtracts costs associated with producing environmental services, such as for example, the costs of fertilisers used in food production in ‘enclosed farm’ ecosystems. 6 Defra, 2007 An introductory guide to valuing ecosystem services. Report published by the Department for Environment, Food and Rural Affairs. London, UK. 68pp.
Draft report Page 5 Cranfield University
The cost of soil degradation in England and Wales
Stated preference methods involve asking people how much they would be willing to pay for an improvement or avoid a loss in a particular good or service, or to accept compensation for a loss or for foregoing a potential benefit.
Benefit transfer, though not a valuation technique in itself, involves the transfer of values or value functions derived from completed studies for use elsewhere. This may be appropriate where the characteristics of soil services and context are very similar e.g. (farming and yields), or where the estimates of benefits associated with soil services have been disaggregated so that the influence of particular factors on benefits (such as siltation of watercourses, flood flows and the costs of floods of a given magnitude), can be separately identified and applied.
All of these methods are subject to estimation bias of one kind or another, and sensitive to the assumptions inherent within them.
Estimates of soil degradation Relatively few studies have been undertaken to specifically quantify the non-market benefits of soil to society. However, a screening of the keywords associated with the references in the CAB Inventory shows that the valuation of soil is often associated with other resources (Table 4). Soil is fundamental to many ecosystem services and valuation must therefore encompass its impact on other types of benefits. In other words, the social value of soil cannot be determined without also understanding the social value of its impact on water storage and flood regulation, fertility provision, pollution attenuation, sequestration and so on. This consistent with Millennium Ecosystem Assessment view that soil is part of the ‘supporting services’. It may mean however that the linkages between human welfare and soil are insufficiently articulated.
Much of the literature values the welfare provided by soil as a result of research on other natural resources. For example, Yun et al., (2008) valued the impact of restored secondary forest in part of Guangxi Zhunang, China since 1981, providing a social value for the role that this played in helping to maintain soil fertility and prevent soil erosion. This value was found to far exceed the direct value associated with timber, herb and fruit extraction. A study by Bofu et al. (2008) on the Lugu Lake watershed concluded in similar vein, that the benefits provided by regulating services such as oxygen provision, carbon sequestration, and soil and water conservation greatly outweighed the production benefits from the watershed. Some literature argues for careful accounting of the services derived from soil and a synthesis of approaches and data between different national institutions to prevent double accounting and confusion (Tzschupke, 2008). Other literature presses for soil conservation in sensitive areas using the argument of greater social wellbeing to justify the investments that would be required. For example, Thomas (2008) proposed that rangeland soils in Asia and North Africa could provide water, biodiversity, and carbon sequestration benefits if payment was forthcoming for these environmental services. A further segment of the literature has tried to determine the value of agricultural soils. Williams et al. (1993) attempted to determine the farm value of topsoil in spring wheat production areas of Montanan, USA and Alfsen et al. (1996) attempted to determine the cost of soil erosion to Nicaragua, in terms of lost productivity and the changes that this would make to patterns of imports and exports, and rural employment in agriculture.
Despite their importance, it has been suggested that soils degrade because markets fail to account for the social cost of poor soil management as well as the non-market benefits provided by soils. For example, Huguenin et al., (2006)7 discussing soil fauna, which “enhanced soil drainage, creating passages for roots, aerating the soil, and recycling organic matter and nutrients”, stated that since these benefits were not represented in markets, they were not protected. Indeed, they concluded that private human activity would therefore continue to harm the soil environment, ecosystems, and social welfare, because these externalities were not accounted for.
7 Huguenin, M.T., C.G. Leggett and R.W. Paterson (2006). Economic valuation of soil fauna European. Journal of Soil Biology42: 1. 16-22
Draft report Page 6 Cranfield University
The cost of soil degradation in England and Wales
Table 4 Keyword search associated with references that included “soil” in the abstract or subject heading of the inventory in the CAB directory Resource or service keywords Economic method
keywordDecision support systems
Key word No Key word No Key word No Key word NoAir 11 Crop 25 Valuation 123 cost*benefit analysis 8 Climate 17 Livestock 5 Contingent valuation 36 value*benefit analysis 1Global warming 1 Food 3 Willingness to pay 29 Multi*criteria analysis 1Atmosphere 5 Human 12 Non-market benefits 27 Risk 8Carbon 20 Recreation 20 hedonic 8 Score 1 Land 72 Tourism 9 travel cost 3 Rank 3Wetland 10 Fishing 2 stated preference 5Woodland 3 Hunt 5 revealed preference 1 Soil 135 Amenity 7 benefit* transfer 6 Landscape 15 Aesthetic 5 production function 2 Beach 1 Conservation 51 market price 9 Coast 4 Ecological 21 Social method keyword Water 63 Energy 6 participatory 2 Marine 2 Power 2 Visual 2 Sea 6 Wind 4 survey 29 Biodiversity 23 Pollution 29 questionnaire 3 Animal 3 Health 6 Fish 5 Mine 5 Plant 20Fauna 3 Ecosystem 25Flora 3 Ecosystem service 9 Fung 2 Environment 55Forest 51 Natural resource 18 Micro 5Agriculture 48
In the UK, these problems have been apparent in peat soils where many ecosystem goods and service are under threat (Rawlins and Morris, 2008)8. In pristine peat soils, the decay of organic material is relatively slow, but in their degraded state, this increases, leading to reduced carbon sequestration, or, in extreme cases, large losses of carbon through gaseous emissions as well as dissolved forms, and losses of particulate carbon through soil erosion (Natural England, 20109, Morris et al, 201010 ). . In Europe, 100,000km2 of peatland has been lost and the remainder are under threat In the UK Fens, an estimated 16% of the peat stock recorded in 1850 remains and much of the remaining stock will be irreversibly degraded in the next two to three decades (Oats, 2002) and in the Somerset Levels, there has been extensive subsidence and shrinkage estimated to be 1 to 1.5 cm per year (Brunning, 2001).
ADAS (2006)11, commissioned by Defra, attempted to value the “monetary” benefits of soils services in England and Wales in terms of: i) carbon storage and sequestration, ii) water storage and flow mediation, iii) nutrient cycling and crop production, iv) supporting construction, v) natural attenuation of pollution and contamination, vi) archaeological and landscape heritage protection and vii) support of ecological habitat and biodiversity. The main findings of the review are summarized here.
Carbon storage and sequestration. Globally, soils contain approximately twice the carbon that is stored in the atmosphere. In the UK, peat is the most important store of soil carbon. However, this is greatly threatened by agricultural use in the lowlands and by drainage of upland peatlands for sheep grazing or more recently for locating wind farms. ADAS provided a wide range of values for the social cost of emitting carbon, ranging from £35 to £140 t-1. Given a social cost of £70 t-1 used by the UK Government, the value of carbon sequestration in land converted from arable use to permanent woodland or biomass production was estimated to be about £110 ha-1 a-1 and a change from 8 Rawlins, A. and Morris, J. (2009). Social and economic aspects of peatland management in northern Europe:, with particular reference to the English case. Georderma, doi:10.1016/j.geoderma.2009.02.022 9 Natural England (2010): England’s peatlands. Carbon storage and greenhouse gases (NE257). Natural England, Sheffield. 56 pp.10 Morris J., Graves, A., Angus, A., Hess, T., Lawson, C., Camino, M., Truckell, I. and Holman, I. (2010). Restoration of Lowland Peatland in England and Impacts on Food Production and Security. Report to Natural England. Cranfield University, Bedford.11 ADAS (2006) Economic Valuation of Soil Functions Phase 1: Literature Review and Method Development. Report prepare for Defra, London, UK. 103pp
Draft report Page 7 Cranfield University
The cost of soil degradation in England and Wales
grassland to woodland was even greater (£302 ha-1 a-1). The social cost of carbon losses from highly organic soils was also found to be high, ranging from £105 ha -1 a-1 from drained upland peat to £882 ha-1 a-1 for lowland peat, often exceeding the benefit from the agricultural or forestry land use which caused the peat loss in the first place (ADAS, 2006). This broad conclusion was also reached by Morris et al (2010)12 who showed that restoration of degraded peatlands in Natural England’s Wetland Vision areas could make a net contribution to overall welfare once allowance was made for soil carbon storage and other ecosystem benefits.
Water storage and flow mediation. The ADAS report notes that the value of the soil in water storage and flow mediation is significantly changed as a result of uses that impede infiltration, because of surface compaction or capping from urbanisation or poor rural land management. The main social benefit of water storage and flow mediation is reduced flood risks and this can be valued in terms of “public willingness to pay for averting increased flood risk”, for example using “the cost of mitigation to reduce flood risk.” It can also be measured in terms of reductions in estimated damage costs.
Siltation of waterways can also impede navigation. During 2006/07, £5.5 million was spent on managing accumulated sediment in watercourses managed or owned by British Waterways in England. In Fowey harbour in Cornwall, between 35,000 and 50,000 tonnes of silt is dredged each year at an annual cost of £90,000.
The sealing of soil in urban areas with impermeable materials such as concrete and tarmac reduces soil permeability and infiltration, increasing the amount of rainwater run-off (by as much as 50%124) and the probability of urban flooding. For example, the Environment Agency estimated that two-thirds of the 60,000 plus homes and businesses affected by the summer 2007 flooding were flooded because drains, culverts, sewers and ditches were overwhelmed13 at an insurance cost exceeding £2bn14. . A share of this cost could be attributed to loss of soil water storage capacity that could be provided by sustainable urban drainage solutions, highlighting the rising incidence of flooding caused by urban drainage problems. This would represent insurance claims totalling approximately £2 billion
Nutrient cycling and crop production. Nutrients are provided by atmospheric deposition, N-fixing soil bacteria, and mineralisation of organic matter. The value of this was found to be substantial. In a grass sward managed to contain white clover, the replacement value of N-fixation was approximately £86 ha-1 a-1 (assuming £150 t-1 N fertiliser). Lost production estimates indicated that there was a high cost to letting the soil degrade. For example, the cost of deviating from best management practices resulted in yield losses worth from £19 ha-1 to £960 ha-1 for UK crops. The cost of allowing pH to drop from 6.5 to 5.0 ranged from £70 ha -1 to £300 ha-1 and soil compaction was estimated to cost about £159 ha-1 for sugar beet.
Supporting construction. Variation in the ability of the soil to support construction appeared to have little impact on land values, reflecting the high premium on development land in comparison with other land uses and the relatively low impact of different soils on costs of development, except where access is a major cost. It is worth bearing in mind however, that urbanisation greatly alters the ability of the soil to provide other ecosystem benefits, in terms of water storage and flood abatement, attenuation of pollutants and contaminants and support of biodiversity. A review by Wood et al, 200515 concluded that soil sealing and damage to soil profiles were perhaps the biggest impacts on soils in the urban context, although little or no assessment had been made of the economic or social consequences. More recently Defra have issued guidance on codes of practice for soil management on construction sites, supported by a number of cases studies that show that soil damage during construction can have significant on site and off site costs. (Defra 2009)16. An examination of aerial photographs of London in 200517 found that 12 square miles (32 square kilometres) of front gardens
12 Morris J., Graves, A., Angus, A., Hess, T., Lawson, C., Camino, M., Truckell, I. and Holman, I. (2010). Restoration of Lowland Peatland in England and Impacts on Food Production and Security. Report to Natural England. Cranfield University, Bedford.13 125 Environment Agency (2007): Review of 2007 summer floods. Environment Agency, Bristol 14 Association of British Insurers (2007): Summer floods 2007 – Learning the lessons. ABI, Swindon.15 Wood, G.A, Kibblewhite, M.G., Hannan, J.A., Harris, J.A. and Leeds-Harrison, P.B. (2005) Soil Based Services in the Built Environment, Report to Defra, National Soils Resources Institute, Cranfield University, Bedford. May 2005 16 Defra 2009, Construction Codes of Practice for the Sustainable Use of Soils on Construction Sites, Department for Environment, Food and Rural Affairs, September 200917 London Assembly (2005): Crazy paving: The environmental importance of London’s front gardens
Draft report Page 8 Cranfield University
The cost of soil degradation in England and Wales
were under paving; this is 67% of the total area of front gardens in Greater London and 3% of the total land area. This is the equivalent of 22 Hyde Parks127. Continued increases in soil sealing are likely to add considerably to the pressure on drainage systems and increase the risk of urban flooding.
Natural attenuation of pollution and contamination. Soils attenuate pollutants through adsorption and degradation of the contaminant to less toxic compounds. They can attenuate the impact, for example, of heavy metals, pesticides, phosphorus, sediment, pathogens, nitrate and acid deposition. However, this is a complex process and scientific understanding is incomplete. A particular difficulty lies in finding marginal values for water quality, since studies may be undertaken in the context of achieving particular thresholds that comply with regulation or notions of good water quality. An alternative approach is to use the cost of abatement measures, applied for example to agriculture, to meet policy defined targets for water quality such as those defined in the Water Framework Directive. For example, a scheme for reducing N, P, and faecal contamination from farms devised by Cuttle et al. (2006) estimates the cost of reducing pollution from farms. ADAS (2006) suggests that this could be used to determine the cost to society of deviating from best management practice or achieving water quality standards. Whilst small reductions in losses are relatively inexpensive (reducing losses by 1 kg ha-1 a-1 was estimated to cost approximately £3 ha-1 a-1), large reductions are substantially more expensive (reducing losses by 5 kg ha-1 a-1 was estimated to cost approximately £98 ha-1 a-1).
On the whole, deviating from best management practices reduces the ability of the soil to attenuate pollutants and contaminants. This affects the well-being of a wide range of stakeholders, such as recreational users of water, water and electricity companies, and individuals who may be drinking contaminated water. The cost of these externalities to society varies widely. For example, deviation from best management practice could impose N and P attenuation costs that vary from £1.2 - £253 ha-1 a-1 depending on the degree of deviation from best management practice. Land use change can also impose costs for example changing from extensive grassland or setaside to arable may impose costs of between £12 - £159 ha-1 a-1. United Utilities is restoring approximately 6,000 hectares of peatland as part of their Sustainable Catchment Management Programme (SCaMP). Savings of between £1.2 and £2.4 million per year in avoided water treatment costs are expected.
Archaeological and landscape heritage protection. Soils protect archaeological site and to artefacts. ADAS (2006) suggests that society has a preference for preservation of heritage and culture and this is also demonstrated by planning regulations within the Town and Country Planning Act. The social value of the role that soil plays in preserving archaeological sites has not been determined, and only one study attempts to value willingness to pay for policy measures to protect archaeological heritage on farmland (Hanley, 1996). ADAS suggests that money devoted to protecting archaeological sites on farmland within the Environmental Stewardship Scheme can be used as a proxy for public willingness to pay for preservation of archaeological sites.
Support of ecological habitat and biodiversity. The role of soil in supporting ecological habitat and biodiversity is crucial. Soil itself contains many important bacteria that are critical to the other services provided by soil, such as N-fixation, or attenuation of pollutants and contaminants. But soils are also the substrate for ecological habitats and biodiversity. These in turn command very high social value as valuation studies and policy and statutory guidelines can testify. A recent report by Jacobs et al., (2008) estimated that the landscape and habitat value of UK farmland to society was worth £845 million per year to society whilst the biodiversity value was worth £307 million per year. These benefits are compromised by poor management, leading to eutrophication, soil erosion or compaction, for example, resulting in air pollution or changes in plant communities. The degree of social value attributable to the role that soil plays within this is not well understood and is difficult to determine.
Information gaps. Several information gaps are reported by ADAS (2006) who concludes that:
There is need for better understanding of links between soil quality and water quality change to values and propose that new technical and economic measures may also be needed. They suggest that improvement in models and modelling is required to understand marginal changes in water storage and peak flow events in catchments, consequent to land use changes, for example, as a result of afforestation or urbanisation. Linked to this is the need for cost information for land uses under various scenarios and estimates of the benefits of reducing flood risks.
Draft report Page 9 Cranfield University
The cost of soil degradation in England and Wales
given the importance of soil water relations, linkages between soil condition, impacts on water quality, and resultant benefits need to be better understood. Linked to this, a better understanding is needed of the marginal value of changes in water quality , and hence the costs of soil degradation.
a better understanding is needed of the linkages between soil type, soil fertility and soil workability are needed, since these are not reflected in land values. In particular, a better understanding of the marginal changes in soil functions and the link with the provision of services from different soils is needed, for example, in terms of an increase or decrease in nutrients or attenuation of pollutants and contaminant loss from soils.
current data are insufficiently complete for predicting across different scenarios of land use, soil types and climates, which therefore hinders valuation at a national level.
environmental and social datasets need to be developed to confirm the importance of soils as a strategic natural asset linked to relating to major policy areas
These conclusions from ADAS (2006) were used to inform the current study, in this case using an ecosystems framework and as far as possible deriving estimates at the national scale.
More recently a Defra sponsored review of Soil Functions, Quality and Degradation – Studies in Support of the Implementation of the Soil Strategy for England18 examined the costs and benefits of Soil erosion mitigation measures distinguishing between on site and offsite costs (see below). Interestingly, it concluded that, within the limits of data available, most mitigation measures have negative economic benefit (in terms of net present values). However, some mitigation measures, such as cover crops, land use change, agro-forestry and shelterbelts, are likely to have a positive impacts not only on soils but also on biodiversity and landscape value, but these ecosystem services were not included due to lack of data.
Estimates of Soil Degradation at the National Scale A number of estimates of the costs of soil degradation in the UK have been derived, usually in the context of estimating the environmental externalities of agriculture (Table 5). Estimates vary considerably, mainly reflecting differences in the extent to which economic impacts have been attributed directly to soils or associated mainly with environmental media such as water, such as water pollution or flooding.
Pretty et al19, for England and Wales, and Hartridge and Pearce20 for the UK, estimated costs of about £21 and £25 million/year respectively that could be directly attributed to soils, while recognising that soil condition contributed to other impacts. The Environment Agency21 for England and Wales (2002), however, attributing a large proportion of flood damage costs to soil erosion and compaction, estimated the cost of soil degradation at £257 million /year. A more recent assessment by the Environment Agency (2007)22 revised the estimates to between £120 and £219 million/year.
Estimates of the economic impacts of soil degradation included in the National Environmental Accounts for UK Agriculture have been around £9 million/year (Eftec, 200423, Jacobs, 200824) mainly associated with the removal of contaminants from water. Costs associated with water run-off and flood generation from farm land have not been directly attributed to soil but rather categorized under water related costs. Furthermore, climate change impacts, are not specifically attributed to soils in the accounts even though the bulk of GHG are associated with loss of soil carbon. The GWP of emissions to atmosphere accounted for the largest single negative environmental cost attributed to 18 Defra : Sub Project C of Defra Project SP1601: Soil Functions, Quality and Degradation – Studies in Support of the Implementation of the Soil Strategy for England. 19 Pretty, J., Brett, C., Gee, D., Hine, R., Mason, C., Morison, J., Raven,H., Rayment,M and van der Bijl, G. (2000), An assessment of the total external costs of UK agriculture, Agricultural Systems, 65(2), 113-13620 Hartridge, O., and Pearce, D.W., (2001) Is UK Agriculture Sustainable? Environmentally Adjusted Economic Accounts for UK Agriculture, Department of Economics, University College London, mimeo.21 Environment Agency. 2002. Agriculture and Natural Resources: Benefits, Costs and Potential Solutions, Environment Agency, Bristol22 O’Neill, D. (2007) The Total External Environmental Costs and Benefits of Agriculture in the UK. Report prepared for the Environment Agency. UK. 34 pp.23 Eftec (2004). Framework for environmental accounts for agriculture. Final report. Submitted to Defra (NR0103) for Defra, 20 March 2006. London, UK. 57 pages24 Jacobs (2008). Environmental Accounts for Agriculture. Final report submitted to Defra. 175 pp
Draft report Page 10 Cranfield University
The cost of soil degradation in England and Wales
agriculture at over £1 billion annually. It can reasonably be argued that a large share of these costs can be attributed to the condition and ‘pathway’ function of soils.
It is also noted that soils make a significant contribution to landscapes and biodiversity, but it is difficult (i) to derive a reliable estimate of these values and (ii) determine how values might vary with soil condition. The Environmental Accounts for Agriculture25 estimated the value of ‘agriculturally managed’ landscapes and habitats to people at £616M and £1,088 M per year respectively in 2007 prices. Semi-natural landscape and habitats would greatly add to this. All of which, along with urban landscapes, contribute to a multibillion £ tourist and recreation industry. Soils fundamentally support the provision of these ‘cultural’ services., but it is not known by how much.
Table 5 Estimates of the Costs of Soils Degradation for the UK
Source Scope Estimate £M(year) Factors included Pretty et al, 2000 Environmental costs
of Agriculture £14 M/yr (1996) £82.3 M /yr£52.3M/yr
Damage to infrastructureLoss of organic matterRemoval of P and soil from water
Evans, 1996 Soil Erosion wind
water
£0.84M/yr (1996)£2.45M/yr£4.22M/yr£24-51M/yr
Lost outputOffsite property damage Offsite water industry costsSoil Structure and flooding Evans (1995, 1996; cited by Pretty et al., 2000) estimated that thecosts of sedimentation in England & Wales was £4 million fordamage to roads and property, £0.1 million for traffic accidents,£1.19 for footpath loss and £8.47 for channel degradation.
Hartridge and Pearce, 2001
Environmental costs of Agriculture
£25M/yr (2000) Attributable to soils
Evans R (1995). Soil Erosion and Land Use.
£30M/yr
£8.2M/yr
Local Authority data suggest property and roads from soil erosion Annual cost of dredging reported by Evans (1995) of which £7.8m due to agric .
Environment Agency, , 2002
Environmental costs of Agriculture
£257M/yr (2002)
£115 M
£74 M£8 M
£8 M*£69 M
*£20 M*£28 M
*partly attributable to soils
Attributed to agricultural soils
Soil structure-flooding (property and council damage Soil erosion (soil erosion carbon dioxide loss) Soil erosion (soil erosion on-farm costs) Soil erosion (accidents, stream channels) Soil/water (faecal pathogens bathing water pollution decreasing health risks) Soil/water (faecal pathogens) Soil/water (nutrients, pesticides, soil, organic waste, faecal pathogens - loss of fisheries values)
eftec, 2004 Environmental Accounts for Agriculture, UK
£9M/yr (2003) Soil erosion damage costs £9.1 million. only the costs of dredging river channels of soil deposition in England and Wales.
Jacobs, 2008 Environmental Accounts for Agriculture, UK
£9M/yr (2007)£37 M/yr
Soil erosion damage based on eftec, 2004Removal of sediment in drinking water assumed to be 50% of “other” costs given by OfWAT
Flood damage costs due to agriculture at £234M/yr for the UK at 2006 prices, some of which can be attributed to soil condition Annual cost of eutrophication of lakes at £27 M/yrfor England &Wales, degraded river quality at £45.4 M/yr
25 Jacobs (2008). Environmental Accounts for Agriculture. Final report submitted to Defra. 175 pp
Draft report Page 11 Cranfield University
The cost of soil degradation in England and Wales
and degraded estuary quality at £2.5 million for England some of which may be attributed to soil degradation
Environment Agency, 2007 (O’Neill)
Environmental impacts of Agriculture
£120-£219M/yr (2007)Includes£29 to £128 M
£82 M£9M
£21 M
Soil – Flooding (property and council damage (agric 14%) Soil cultivation (agri 95%) (CO2 loss) Soil erosion (agri 95%) (accidents, stream channels) Water treatment cost of soil erosion
Eutrophication due to diffuse pollution from agriculture: £20m to £33m per year in England & Wales
Defra , 2009 Soil Strategy , for England and Wales (drawing on aforementioned sources)
Total £206-315M (2009)Includes £45 M/yr
£82 M/yr£29-128M/yr£50-60/yr
Soil erosion due to agriculture: includes water treatment, damage to property and dredging stream channels; damage to crops; removal of sediment from watercourses Loss of soil carbon as per EA 2007Flooding as per EA 2007Sediment removal in urban drainage systems
Adopting this broader view, the Soil Strategy for England and Wales 26estimated the costs of soil degradation at £206-£315 M/year, combining the costs of soil erosion (including onsite damage to crops) (£45M/year), loss of soil carbon (£82 M/year), flood damage due to run off from degraded soils (£29-£128 m), and sediment removal in urban drainage systems (£50-60M/year). The assessment recognized that this was an incomplete estimate.
European and international estimates of Soil Degradation A comprehensive review of the economic costs of soil degradation was carried out by the Gorlach et al, 2004 for the European Commission27. The study included the six degradation processes considered here for the England and Wales cases, together with salinisation and landslides that have greater relevance in other parts of Europe. The study reviewed evidence from literature of soil degradation costs. It identified over 60 studies that quantified the economic impact of soil degradation, the majority of them coming from Australia and North America. Generally, the review concluded that there is limited evidence from Europe, and most of what there is comes from the UK. Reference is made to the pre-2004 studies listed in Table 5 above.
Gorlach et al derived estimates of the costs of erosion, contamination and salinisation. For erosion (Table 6), a central estimate for average annual costs in Europe was equivalent to £96/ha in 2010 prices, of which 9% were onsite and 91% offsite costs. This estimate was used to estimate the total costs of soil erosion in Europe (£7.5 bn/year in 2010 prices), weighted by areas liable to erosion and the likely severity of erosion where it occurs. This generated an average value of £50/ha/year (2010 prices) for erosion on sites in 13 European countries covering 15.5 million ha where erosion is known to occur.
26 Defra, 2009 Safeguarding our Soils: A Strategy for England. Report published by the Department for Environment, Food and Rural Affairs. London, UK. 48pp.27 Gorlach, B.. Landgrebe-Trinkunaite, R., Interweis,E., Bouzit,M, Darmendrail D. And Rinaudo J.D. (2004). Assessing the Economic Impacts of Soil Degradation. Final Report to European Commission. DG Environment. ENV.B.1/ETU/2003/0024. Ecologic, Berlin.
Draft report Page 12 Cranfield University
The cost of soil degradation in England and Wales
Table 6 Estimates of the Cost of Soil Erosion in Europe (Euros (2003)/ha/yr)
Onsite costs Off site costs TotalProduction losses
/damageMitigation costs Damage costs Mitigation
High 11 29 169 26 235Central 8 3 86 26 122
(£962010)Low 0.50 0 21 0 22Based on Gorlach et al, 2004.Rounding errors. Exchange rate: 2003/2004 Euro 1.5/GBP1; Inflation: UK 2003/4 to 2010/11 at 1.19
For soil contamination, mainly drawing on case study evidence grossed up to the regional scale, Gorlach et al (2004) estimated total cost of soil contamination at Euros 24.9 bn (2003 prices) equivalent to about £20 bn in 2010 prices., most of it associated with damage and clean up costs (Table 7).
Table 7 Estimated Total Costs of Soil Contamination in Europe (M Euros, 2003)
The EC study concludes that the private onsite costs of soil degradation are ‘not a major cause of concern in most cases’. They do not appear to exceed 0.5% of the gross value added of agriculture, although the extent of losses can be much higher in the most affected areas. By comparison, offsite costs are much more substantial, ranging from 1.1% to 8% of agricultural value added for the 13 countries examined. Overall, offsite costs typically exceed on site costs by more than a factor of 7, except for contamination, on site costs may account for a greater share of total costs. The study notes that the majority of the costs of soil degradation are not felt by people causing it, but rather by those in other locations who bear the consequences without compensation. It also notes that off site costs are subject to much greater uncertainty in their estimation compared with on site costs.
Approach to Economic valuation of soil degradation An ecosystem services framework is adopted here to assess the economic costs of different processes of soil degradation. Many of the services provided by soils are intermediate supporting services that underpin provisioning, regulating and cultural services. Emphasis is placed on the generation of ‘final goods’ that are of value to people. Consistent with other classification approaches, these final goods incorporate onsite and offsite effects, private and public goods, as well as use and non use benefits (Table 8). Soil degradation reduces the quantity and quality of soils as a component of natural capital and hence reduces the quantity and quality of flows of ecosystem services. These changes in stocks and flows are expressed in economic terms where possible.
Draft report Page 13 Cranfield University
The cost of soil degradation in England and Wales
Table 8 Generic classification of costs of soil degradation and basis for valuation
Type of cost Ecosystems perspective Economic perspective Basis for valuation On site: Productivity loss, Damage costs Mitigation costs
Mainly provisioning services eg agricultural productionCultural services to on site users
Mainly ‘private’ costs borne by individuals and organisationsSome non market costs borne by site users
Mainly market prices Non market prices for uncompensated site users
Offsite: Damage costs Mitigation costs.
Mainly regulating eg flood control and cultural services eg recreational/property/heritage values
Public costs borne by society at large
Combination of market and non market (surrogate) prices Non monetary (intangible) impacts
Total Combined on- and off site
Combined private and public costs
Mix of market prices (adjusted for taxes and subsidies) and non market prices. Non monetary (intangible) impacts
Onsite costs here are those mainly (but not exclusively) borne by those who cause degradation and as such are mainly ‘private’ costs to individuals and organisations. Offsite costs are borne by third parties, usually without compensation, and are therefore mainly public/societal costs. Some on-site costs may be public costs that accrue to users, such as walkers in the countryside, whose non market benefits are reduced without compensation (assuming they cannot go elsewhere to derive the same net benefit).
The majority of on-site private costs can be valued using market prices. The valuation of offsite, public costs may involve a mix of market and non market prices. It is noted, however, that onsite costs may include some non market costs, such as the stress or loss of amenity or reputation caused by a degradation process, such as a serious soil erosion incident on farm land.
From an economic viewpoint the cost of soil degradation is the sum of onsite and offsite costs (with some adjustments to market prices to remove the effect of taxes and subsidies). As referred to above, evidence to date suggests that offsite costs exceed on site costs by a large margin, and that the onsite benefits of soil conservation may be less than the costs involved. This might not, however, be the case from the public perspective. Thus, much of soil policy is concerned with identifying total costs of soil degradation, and where appropriate, using cost effective policy measures to reduce degradation in the public interest. This may involve a mixture of regulatory, economic and voluntary instruments (Table 9).
Draft report Page 14 Cranfield University
The cost of soil degradation in England and Wales
Table 9 Classification of costs for soil degradation by erosion
Private PublicErosion
Process and impacts
Productivity Loss/ Input substitution
Damage costs
Mitigation cost –loss/damage avoidance
Damage costs(social costs) Market or non market values)
Mitigation cost /damage avoidance (
Market prices* Market prices*
Market prices*
Market (net of subsidies and taxes) and/or non market prices
Actual expenditure (Revealed) or expressed preferences to avoid loss
Water quality impacts : damage to fisheries, reduced amenity and property values
Nutrient removal Water quality protection/improvement
Sediment transport
Siltation -, increased flood risk Sediment removal from roads Discolouration,
Soil conservation programmesWater treatment
Atmospheric (GHG) emissions
Atmospheric gas emissions at cost of carbon
Regulation and monitoring Soil carbon conservation and restoration
Local Air quality impacts
Dust /air borne particulates. Health impacts. Deposition removal/clearance
Air quality monitoringWTP for air quality standards
Biodiversity, landscape and amenity
Damage to landscapes and features, eg pathways and structures
Protection and buffering , RestorationAgri-environment payments
*taxes and subsidies are remove from market prices to derive the economic, societal values of private goods
Drawing on the MA and UK NEA frameworks, Table 10 and Table 11 show the potential relationships between (i) ecosystem services (classified by provisioning, regulating and cultural), impacts types and final goods degradation and (ii) the processes of soil degradation and the estimation methods that can be used to estimate biophysical relationships and economic values. There is considerable commonality in these relationships amongst the different degradation processes. Furthermore, the degradation processes may occur simultaneously, with combined effects. This framework is used to help focus on selected major impacts for each degradation process as discussed below. It is noted that information is not available to quantify and value all interactions.
It is noted that, for most purposes, it is the way that land and its soils are used in combination with other inputs, such as physical and human capital which creates value, and hence the cost of soil degradation when it occurs. Furthermore, the value associated with land use, and the economic consequences of soil degradation, are particularly context and spatially specific. For example, the significance of soil erosion, runoff and flood generation depends largely on the scale damages to property and livelihoods that result from flooding. Thus there is a critical geographical dimension to
Draft report Page 15 Cranfield University
The cost of soil degradation in England and Wales
the assessment of the costs of soil degradation that we endeavour to address. This is entirely consistent with a risk based approach, combining assessment of probability of the degradation process with an assessment of the consequential costs (or loss of benefits).
As explained earlier, the costs of soil degradation can be aggregated for a given year, or aggregated over a future period and expressed as a present value sum. In theory, the total cost of degradation in a given period is equivalent to the change in the value of stocks of soil, ie a reduction in asset value.
Summary of approach to economic assessment of soil degradation The approach used here involves three main steps ().
(i) Classification of soilscape comprising combinations of soils type and land cover/uses and assessment of degradation probabilities and impacts on relevant soil indicators
(ii) Assessment of the relationship between soil degradation, changes in soil indicators and changes in the ecosystem services provided by soils
(iii) Valuation of the impacts of soil degradation on ecosystem services (£/unit of impact) and of the resultant costs of soil degradation, aggregated at the appropriate scale and time horizon.
Figure 2 Approach to the assessment of the costs of soil degradation
Draft report Page 16 Cranfield University
The cost of soil degradation in England and Wales
Table 10 Estimating the impact of soil degradation on ecosystem services (1) erosion, compaction, organic matter (linked to particular soilscapes)
erosion compaction organic matterService Type of
impact Final goods and units
Biophysical relationship : estimation method
Economic valuation Estimation method
Biophysical relationship : estimation method
Economic valuation Estimation method
Biophysical relationship : estimation method
Economic valuation Estimation method
Prov
isio
ning
Food production
Yield loss (soil capacity: fertility, soil water )Yield loss (crop damage)
Table 11 Estimating the impact of soil degradation on ecosystem services (2) Diffuse contamination, Biota loss and Sealing (linked to probability maps –soilscapes)
Diffuse contamination Biota loss Sealing Service Impact Final goods
and units Biophysical relationship : estimation method
Economic valuation Estimation method
Biophysical relationship : estimation method
Economic valuation Estimation method
Biophysical relationship : estimation method
Economic valuation Estimation method
Prov
isio
ning
Food production
Yield loss (soil capacity: fertility, soil water )Yield loss (crop damage)
t, £/t, £ food Bio/chemical - yield impact modelHeavy metal contamination of food systems
Production functions, market prices adjusted Mitigation expenditure
Bio-chemical –yield model Soil biota support to fertilisation/pollination
Production functions, market prices adjusted Mitigation expenditure
Land use change: bio mass loss
Production functions, market prices adjusted
Timber/bio mass
Yield loss t,£/t, £, timber, bio mass
Bio/chemical - yield impact model?
Production functions, market prices adjusted Mitigation expenditure
Bio-chemical –yield model
Production functions, market prices adjusted Mitigation expenditure
Land use change: bio mass loss
Production functions, market prices adjusted
Water supply
Reduced baseflow
Reduced soil AWC
Water Ml, £/Ml, £
Soil biota to Soil moisture/deficit index ?
Production functions, market prices adjusted.
Soil sealing impact on base flow index Soil moisture/water logging impacts
Production functions, market prices adjusted.
Energy (hydro)
Reduced baseflow
Power kW, £/kW, £
Reg
ulat
ing
Climate change (GWP)
GWP t CO2e, £/tCO2e, £
Carbon flux model Carbon prices Carbon flux model Carbon prices Carbon flux model Carbon prices
Soil loss and yield impact : production function Defensive expenditure, : public health impacts
Flood regulation (run off &
Flood risk Mean mm depth runoff Qn, peak flow
Water erosion run off models, average depth
Defensive expenditure (flood protection),
Water run off – change in depth : change to
Defensive expenditure (flood protection),
Draft report Page 19 Cranfield University
The cost of soil degradation in England and Wales
flood generation)
Qn £ Av AnDamage (AAD) according to land use
mm, Qn peak flows (Linked to erosion risk)
Damage cost avoidance (flood risk)
hydrograph ? Damage cost avoidance (flood risk)
Flood regulation (sedimentation)
Flood risk management expenditure
m3/km silt deposition and removal . £/m3 and £/km desilting
Water erosion , sediment transport model
Defensive expenditure (river maintenance).
Water quality
Water quality objectives
N,P transport and concentrations ppm, water treatment costs £/m3Eutrophication costsDiscoloration: ppm, £/m3 treatment
Soil/water pollutant transport and nutrient cycling models.Atmospheric deposition models Erosion linked
Damage cost and damage avoidance (treatment costs, £/m3): Revealed and stated preference : wtp to maintain water qualityCost of regulation and monitoring
Biota loss effects on soil and water nutrient and water quality cycling- models - linked to diffuse contamination
Damage cost avoidance (treatment costs, £/m3): Revealed and stated preference : wtp to maintain water quality
Sealing reduces soil and water nutrient and water quality cycling- modelled estimates -source of diffuse contamination
Damage cost avoidance (treatment costs, £/m3): Revealed and stated preference : wtp to maintain water quality
Waste assimilation
Waste services
Reduced capacity: discharge limits?
Linked to biota loss and loss of nutrient cycling capacity
Cost of alternative waste disposal options
Biota loss effects on soil nutrient cycling- models Linked to diffuse contamination
Damage cost avoidance (treatment costs, £/m3): Revealed and stated preference : wtp to maintain water quality
Sealing reduces soil and water nutrient and water quality cycling- modelled estimates -source of diffuse contamination
Damage cost avoidance (treatment costs, £/m3): Revealed and stated preference : wtp to maintain water quality
Cul
tura
l
Landscape and amenity
Landscape character and value
Loss of landscape features and qualities: ha affected, £/ha reduction .
Property values: degraded land, house values (water quality realted)
