The Economics of Desertification, Land Degradation, and Drought

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Flooding and Aquifer Recharge Richards (1997) estimated off-site benefits related to conservation practices in the Tequila watershed in Bolivia. The main off-site benefits were identified as flood prevention and increased infiltration of water in the soil (due to reduced runoff) and thus higher water availability in the aquifer. Recreational Damage Estimates Soil erosion can also have recreational impacts, as particles and pollutants reduce the water quality and freshwater fishing possibilities. In addition, siltation and weed growth interfere with boating and swimming activities, thus decreasing the site’s recreational value. Clark (1985) indicated recreational damages on freshwater fishing, marine fishing, boating, swimming, waterfowl hunting, and accidents. Using travel cost models, Feather, Hellerstein, and Hansen (1999) estimated the benefits of freshwater-based recreation, wildlife viewing, and hunting of the Conservation Reserve Program in the United States. Bejranonda, Hitzhusen, and Hite (1999) examined property values at 15 Ohio state park lakes to analyze the effect of sedimentation and found higher property values on lakes with less sedimentation. Comprehensive Studies Comprehensive studies, including valuation of several off-site costs at once, were carried out by a number of authors. An early study by Clark et al. (1985) and a study by Pimentel (1995) both calculated various off-site costs associated with wind and water erosion in the United States. Tegtmeier and Duffy (2004)—based on previous work by Clark (1985) and Ribaudo (1986), among others—provided national estimates of total annual cost damages attributable to water-based soil erosion in the United States. Pretty et al. (2000) provided an assessment of the total external costs of agriculture in the United Kingdom. Krausse et al. (2001) estimated the economic costs of sedimentation effects in New Zealand, and Hajkowicz and Young (2002) did the same in Australia between 2000 and 2020. More recently, nonmarket valuation approaches, such as contingent valuation method and choice experiments, have been used to value several off-site effects. A study by Colombo, Calatrava- Requena, and Hanley (2003) used contingent valuation and found that a majority of the catchment’s population is willing to pay to reduce off-site damages. Colombo, Hanley, and Calatrava-Requena (2005) also conducted a choice experiment in the Alto Genil and Guadajoz watersheds in southern Spain. Respondents were found to care about the negative effects of soil erosion on surface and groundwater quality, landscape desertification, and flora and fauna. Social impacts (rural employment) also turned out to be important. A positive willingness to pay could also be found regarding the size of area benefiting from soil erosion control programs. Global Benefits Nkonya et al. (2008b) also indicated global off-site benefits associated with conservation measures that increase the biomass on the field and, hence, that lead to increased carbon sequestration. Carbon accumulation due to conservation measures is estimated at 0.2 to 0.7 tons of carbon per hectare per year (Vagen 2005). Earlier studies of carbon sequestration revealed a value of $3.50 per ton of carbon stored, though this value is debatable and is bound to fluctuate according to the evolution of carbon markets. Global Off-Site Costs Basson (2010) estimated the annual global cost of siltation of water reservoirs is about $18.5 billion for storage structures, with the replacement costs of silted-up reservoirs accounting for a little more than 50 percent of the total cost (Figure 3.7). The annual loss of hydroelectric power (HEP) and damage to HEP infrastructure is about $5 billion; the loss due to the reduction of irrigation reservoir capacity is about $3.5 billion. These losses do not include other losses due to siltation, such as the loss of potable water and related health effects. Thus, the estimated losses could be regarded as being conservative. 78
Figure 3.7—Global loss due to siltation of water reservoirs (US$billion) 5 3.5 Source: Basson 2010. Estimation of the Indirect Costs of Land Degradation 10 The indirect costs of DLDD represent their impacts across all sectors of the economy—for instance, through price transmission mechanisms or transactions on the input markets—as well as their human impacts (migration, food security, poverty, and so on). Thus, economywide effects of soil erosion do not simply equal the lost production multiplied by a given price. Due to the linkages across the sectors of the economy—as well as between supply and demand—the production, demand, prices, and trade of all commodities, beyond the crops directly affected by soil loss, will also be affected. Further, in several countries, agriculture is the main component of rural households’ livelihood strategies; thus, another indirect effect of land degradation is its impact on poverty and poverty rates—for instance, through income effects. Several links among the environment, agriculture, and poverty are reviewed in Vosti and Reardon (1997). Also, lower production levels of particularly staple foodcrops can cause or increase food insecurity problems, especially when population is growing (Diao and Sarpong 2007). Indirect effects are difficult to assess; therefore, only a few studies have attempted to measure at least some of these costs. Some of those studies are briefly reviewed here. Alfsen et al. (1996) estimated the impact of soil erosion on GDP, imports, exports, and consumption using a computable general equilibrium (CGE) model of the Nicaraguan economy to explicitly consider interlinkages between agricultural activities and other parts of the economy. Model results suggest that there are significant production impacts due to soil erosion and that this also affects trade, labor, private consumption, and investment. Gretton and Salma (1997) estimated an econometric model of the impact of degradation (irrigation salinity, dryland salinity, soil structure decline, and induced soil acidity) on the agricultural output and profitability, based on state-level data from New South Wales, Australia. The econometric analysis indicated that agricultural output and profits depend on the type of degradation. The results suggest that the expansion of some farming systems, and the associated increased degradation due to salinity, provides a net increase in production and profits in the medium term, whereas soil structure decline and induced soil fertility lead to negative net effects. 54 Other studies using a larger-scale approach include village CGE (Holden and Lofgren 2005), national CGE (Alfsen et al. 1996), and multisector CGE (Coxhead 1996). Effects of soil loss on the economy and on poverty were estimated by Diao and Sarpong (2007) in Ghana. They estimated that the declines in the national and rural poverty rates between 2006 and 2015 were 5.4 and 7.1 percentage points less, respectively, when soil loss is taken into account. Furthermore, the projected slowdown in production growth of staple foodcrops, such as maize, would cause food security problems, given that the population of Ghana is expected to grow at 2 percent per 54 Other structural econometric models were developed for example by Pender and Gebremedhin (2006). 79 replacement costs of silted up dams Loss of hydropower Loss of irrigation productivity .
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IFPRI Discussion Paper 01086 May 20
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Contents Abstract vii Acknowledgmen
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List of Figures 1.1—Conceptual fr
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ABSTRACT Attention to land degradat
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ABBREVIATIONS AND ACRONYMS ADB Asia
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SCAR Soil Conservation in Agricultu
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In the present report, the conceptu
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Framework: Confronting Action versu
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understand these arrangements in or
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Figure 1.3—Prevention, mitigation
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on assessments at the micro level (
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does not clearly distinguish betwee
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Figure 2.1—GLASOD (1991) global a
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International Earth Science Informa
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Box 2.1—Continued Normalized Diff
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Figure 2.4—Loss of annual NPP, GL
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Figure 2.7—Annual loss of NPP in
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Table 2.2—Nitrogen application ra
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Figure 2.12—Areas affected by hum
Page 40 and 41: output—which is a selection of su
Page 42 and 43: GLADIS also underlines the linkage
Page 44 and 45: Box 2.2—Continued A map on global
Page 46 and 47: Table 2.3—Global land degradation
Page 48 and 49: Table 2.3—Continued Project and d
Page 50 and 51: Table 2.4—Continued Location 10 2
Page 52 and 53: Table 2.6—Extent and severity of
Page 54 and 55: National Level Policies As discusse
Page 56 and 57: Such support has also been directed
Page 58 and 59: Migration, either as outmigration o
Page 60 and 61: The preceding discussion shows the
Page 62 and 63: Results Correlation Analysis Consis
Page 64 and 65: Figure 2.23—Relationship between
Page 66 and 67: Effects of Land Degradation On-Site
Page 68 and 69: soils and higher land productivity.
Page 70 and 71: Acknowledging the work of GLADIS, a
Page 72 and 73: health, education, security, enviro
Page 74 and 75: Box 3.1—Recent major economic ass
Page 76 and 77: An appropriate economic tool for a
Page 78 and 79: Figure 3.4—Cost of action and cos
Page 80 and 81: enefit—for example, income. This
Page 82 and 83: Figure 3.6—Ecosystem services fra
Page 84 and 85: Replacement Cost Approaches The rep
Page 86 and 87: Box 3.2—Measuring land degradatio
Page 88 and 89: land degradation and conservation m
Page 92 and 93: year (Diao and Sarpong 2007). Sonne
Page 94 and 95: Bringing together the different cos
Page 96 and 97: This section discusses the most imp
Page 98 and 99: governing land use patterns (Leeman
Page 100 and 101: promotion of community forest manag
Page 102 and 103: Box 4.3—Reducing emissions from d
Page 104 and 105: Soil Nutrient Depletion Soil nutrie
Page 106 and 107: that the yields of salt-tolerant wh
Page 108 and 109: Figure 5.3—Forest area as a perce
Page 110 and 111: Figure 5.5—Per capita water stora
Page 112 and 113: Introduction 6. CASE STUDIES Five c
Page 114 and 115: Salinity The effects of salinity on
Page 116 and 117: Third, to correctly decide which ac
Page 118 and 119: Costs of Action and Inaction We eva
Page 120 and 121: The NGOs and religious organization
Page 122 and 123: have a strong influence on NRM (And
Page 124 and 125: We estimated the cost of action (de
Page 126 and 127: Figure 6.15—Costs of action and i
Page 128 and 129: Of interest to us is the strategy t
Page 130 and 131: 7. PARTNERSHIP CONCEPT The review o
Page 132 and 133: degradation. All this should be don
Page 134 and 135: Finally, the global assessment of D
Page 136 and 137: the experience of and lessons learn
Page 138 and 139: Table 7.3—Example of E-DLDD resea
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8. CONCLUSIONS Since the publicatio
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lowest in the region. From a socioe
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Table A.1—Land degradation assess
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Table A.2—Continued Author Region
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Table A.3—Continued Author Countr
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Table A.5—Costs of land degradati
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Figure B.1—Land use systems of th
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REFERENCES Abelson, P. 1979. Cost B
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Benin S., E. Nkonya, G. Okecho, J.
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Clark, E. H. 1985. The Off-Site Cos
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De Jager a., D. Onduru and C. Walag
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Foster, V., and C. Briceño-Garmend
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Holden, S. and H. Lofgren. 2005. As
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Lapar, M. L., and S. Pandey. 1999.
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Nachtergaele, F., M. Petri, R. Bian
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Pender, J. L. 2009. “Food Crisis
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Sauer, J., and H. Tchale. 2006. Alt
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Tan, Z. X., R. Lal, and K. D. Wiebe
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———. 2010. “Assessment of L
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