Assessing the Importance of Livestock Water Use in Basins

CSIRO PUBLISHING www.publish.csiro.au/journals/trj The Rangeland Journal, 2009, 31, 195–205 Assessing the importance of livestock water use in basins S. E. Cook A,B, M. S. Andersson A and M. J. Fisher A A International Centre for Tropical Agriculture (CIAT), Cali, Colombia. Corresponding author. Email: s.cook@cgiar.org B Abstract. Recent concern over food prices has triggered a renewed interest in agricultural production systems. While attention is focused mainly on cropping, a complete analysis of food production systems should recognise the importance of livestock as major consumers of resources – in particular water – and as providers of food and other products and services. We propose that there is a need to examine not just food systems in isolation, but combined food and water systems, both of which are described as in a critical condition. From this broader perspective, it appears even more important to understand livestock systems because first, a total evaluation of agricultural water productivity – the gain from water consumed by agriculture – cannot be made without understanding the complexities of livestock-containing systems and; second, because in most tropical river basins, livestock systems are the major consumers of water. To identify total water productivity of livestock-containing systems, we describe concepts of agricultural water productivity and review the complexities of tracking the flow of water through livestock-containing systems: from inputs as evapotranspiration (ET) of forage and crops to outputs of valued animal products or services. For the second part, we present preliminary results from water use accounts analysis for several major river basins, which reveal that for Africa at least, livestock systems appear to be the major water consumers. Yet, little is known about the fate of water as it passes through these systems. We propose that livestock-containing systems offer substantial scope for increasing total water productivity and that there is considerable merit in improving the capacity to analyse water consumption and water productivity through such systems. Without removing this major source of uncertainty, the potential for systemic improvement to meet the world food and water crisis remains undefined and hence under-acknowledged. Additional keywords: food security, livestock systems, poverty, rangeland, water productivity. Introduction Evidence is emerging of a resurgence in the global demand for agricultural produce. This is fuelled by several factors (von Braun 2007): one is accelerated aggregate growth; a second is the growth in energy prices, which encourages a diversion from crop production for food to production for biofuel; and a third factor is climate change, which may threaten food production in drier areas. Historically, global food production has increased by 2.3% annually (World Bank 2007). To meet global demand for food and biofuels, agricultural production would even need to grow at a rate of 3.3% per year (Etter 2007). The demand for total volume, content and value of food is changing (Delgado et al. 1999, 2002). High value products are in more demand than before. Demand for animal products has increased more than demand for cereals (Steinfeld et al. 2006). Over the past 15 years, China has seen a three-fold increase in consumption of milk products, and very strong gains in the consumption of fish, fruits, meat and oil crops (FAO 2009). By 2050, meat consumption in East Asia is expected to more than double (Molden 2007). Consequently, prices for butter and milk
Australian Rangeland Society 2009 have tripled and beef prices have doubled since 2000 (von Braun 2007). The demand for feed grain has increased, with 28% of current grain production used as animal feed (World Bank 2007). Although total meat production has more than tripled in developing countries between 1980 and 2004 – as opposed to an increase of only 22% in developed countries – domestic production in many developing countries is failing to keep pace with demand (Steinfeld et al. 2006; FAO 2009). As a consequence, developing countries, as a group, have changed from being net exporters to net importers of agricultural produce over the past 50 years (Upton 2001; Upton and Otte 2004). Today, the largest import item in developing countries is dairy products. Volumes of beef, pig and poultry meat are also growing rapidly (Upton 2004). The projected changes in food demand, together with continued population growth and future changes in global climate, will have profound effects on the use of the world’s water resources. Under just a ‘business as usual’ scenario, global water withdrawal is projected to increase by 22% in 2025, driven mainly by domestic, industrial and livestock uses (Rosegrant et al. 2002). The latter alone already show growth rates exceeding 50% 10.1071/RJ09007 1036-9872/09/020195 196 S. E. Cook et al. The Rangeland Journal (Steinfeld et al. 2006). The volume of water needed to meet the crop demands projected for 2025, could require an additional 800 km3 of water, a volume nearly equivalent to 10 times the annual flow of the Nile (Postel 2001; Molden 2007). For subSaharan Africa alone, the scenarios projected by the Millennium Ecosystem Assessment predict a 2.5–5-fold increase in livestock, from 200 million head in 2005, to 500–970 million head in 2050 (Cork et al. 2005). Recent studies suggest that increasing agricultural water productivity is an important pathway to improve rural livelihoods, increase food production and reduce water depletion (e.g. Molden et al. 2007; Peden et al. 2007). These studies emphasise the need to include livestock production in efforts to increase water productivity in irrigated and rainfed agriculture and especially in the context of river basins. Analysis by Kirby et al. (2006, 2007) indicates that livestock and mixed cropping livestock systems are the dominant consumers of water in most river basins of the tropics, hence provide vast scope for improvement of basin-level water productivity. The need for improved water productivity is caused by a combination of increased demand for food and increasing scarcity of water. We describe these below, paying particular attention to the demand from livestock systems. The concept of water productivity The effectiveness with which agricultural production systems convert water into beneficial product is called the water productivity (WP) (Kijne et al. 2003). The concept of water productivity developed initially from water use efficiency, that is, as a means of improving irrigation water use (Viets 1962). Water use efficiency is expressed as m3 of water consumed per kg crop yield. Water productivity expresses the benefit or value per m3 water consumed or depleted (noting that water depleted is not necessarily the same as water input) (Molden et al. 1998). Water productivity could be quantified in terms of physical and economic water productivity. Physical water productivity. The concept of physical water productivity has been used to quantify the contribution of different sectors of agricultural activity to overall well being, including irrigated crops (e.g. Ahmad et al. 2006; Liu et al. 2007), rainfed crops (Terrasson et al. 2009), livestock (Peden et al. 2003) and fish (Kirby et al. 2007). The physical WP on farms has been assessed for many different crops and roughly varies from <0.1 to ~1.0 kg grain product per m3 water depleted. The physical WP of livestock is usually lower than crop WP, and has been estimated to range from <0.1 (horse and beef meat) to ~0.29 kg (pork meat) or 0.79 kg (cow milk) per m3 water depleted (Chapagain and Hoekstra 2003). More recent estimates (e.g. Peden et al. 2007) show that in many cases, livestock WP are modified greatly by management. For example, WP increases greatly when animals are fed on crop residues. Economic water productivity. While physical WP is a useful concept for describing and comparing the productivity of single crops at the farm-scale and sub-catchment level, moving to the catchment and river basin scale requires a shift to economic WP concepts (Ahmad et al. 2009). The assessment and mapping of economic WP requires hydrological, spatial and economic analysis, and hence information on water use, land use, production and yields (crop, livestock, forests), and prices. Analysis will often be possible using secondary and remote sensing data. When expressing water productivity in terms of monetary value or net benefit per unit of water depleted, livestock products usually have a greater (economic) WP than primary crop products. This margin is expected to increase further in the future, due to the globally rising demand for livestock products. Assessing water productivity in multiple use systems that include livestock is much more complex than assessment of single-use irrigated or rainfed cropping systems. However, this may be necessary, since it is impossible to determine the water productivity of the whole system without it. We therefore attempt to look at water productivity of livestock in the context of multiple uses of water. What follows is an examination of the factors that need to be considered in order to make a complete assessment of the productivity of water in multiple use systems. The basic expression is as follows: WPr ¼ Benefit Consumption To identify opportunities and constraints for improving water productivity and achieving sustainability of food production in the long-term, a better understanding of the multiple uses of water in different basins and regions is mandatory. This endeavour is particularly useful to understand the full value derived from food systems in which livestock play a substantial role, because these systems tend to be more complex and multi-phased (Sileshi et al. 2003; Peden et al. 2007). Estimating water consumption of multi-component systems The uses of water in agricultural production systems are multiple, and often simultaneous in space and/or time. However, the total productivity of this use – expressed as gain per unit consumed by all agricultural uses – is not evaluated. What data exist, normally apply to single crop uses, where output, as kg/ha or $/ha is compared to estimates of the water consumed (Molden et al. 2003; Seckler et al. 2003; Bessembinder et al. 2005; Zoebl 2006). The measurement of water flow through all uses within basins provides a basic integrating measure of the relative activities of different agricultural sectors within the basin. Water flow through multiple use systems can be illustrated by the ‘finger’ diagrams presented by Molden et al. (2003) (Fig. 1). The finger diagram illustrates how much water is being consumed by the agricultural sector but does not distinguish between different types of land use beyond irrigated or rainfed. Kirby et al. (2008) partition water use in sub-basins according to the estimated area of four land uses – rainfed cropping, irrigated agriculture, grassland and forest – and estimates of actual evapotranspiration (ET) for each one. The volume of water consumed by each land use is estimated by means of the FAO CROPWAT model (Smith 1992). Total ET is constrained to be consistent with measured outflow for each sub-basin. While the estimate of total ET for a given land use may be correct at sub-basin level, estimates of total ET will contain many uncertainties which arise as a result of spatial and temporal Livestock water use in basins The Rangeland Journal 197 Process INFLOW Beneficial Depleted Available Net inflow Gross inflow Non-process Agriculture, cities, industry Waterlogging, fallow lands, flows to sinks Utilisable Uncommitted Outflow Surface and subsurface flows, precipitation Non-beneficial Forests, grasslands, water bodies, etc. Non-utilisable Environmental and legal requirements Addition to Removal from Committed Storage Fig. 1. Generalised water-accounting diagram, applicable to basin analysis and analysis at other scales. Source: Molden et al. (2003). redistribution of water and water products. Spatial redistribution of water will occur locally as a result of lateral flow processes. Spatial redistribution of water products will occur as feed and animal products being moved around the system. Temporal redistribution of water occurs as primary products are consumed, stored or recycled internally within the system (see section on ‘Value adding’ below). Estimating benefits of multi-component systems People derive a range of livelihood support from multiple use Farming systems evolve from ‘unimproved’, low input rangeland through more intensive market oriented systems using improved forages (e.g. production systems in Asia and parts of Latin America and the Caribbean using hays, silages and cut-and-carry fresh forages), mixed livestock–cropping systems towards high input farming systems in which cropping and livestock tend to be separated entirely. Research has mainly followed this trend for segregation, and the linkages between animal and arable components within the agricultural system as a whole are often not evident (Russelle et al. 2007). Nevertheless, linkages persist in which flows of biological material and energy (hence, the energy and water which is used to produce it) pass from part of the system through to the point at which goods and services are delivered. The classifications of Upton (2004) and Thornton et al. (2002) identify the importance of rainfed mixed farming systems, which house most of the world’s poor. One important component of these production systems is livestock, which is estimated to contribute to the livelihoods of at least 70% of the world’s rural poor (Ashley et al. 1999). Peden et al. (2007) illustrate the complexity of multiple water use within mixed livestock–cropping systems. The model stresses the parallel nature of multiple uses, by which people gain livelihood support through meat, milk, hide, draught power, or other support provided through livestock. Normally, it is the negative consequences of resource use that are sought in analysis. For example, Foran et al. (2005) attempt triple bottom line accounting to quantify the environmental costs of agricultural and other sectors in the Australian economy. Conversely, Mearns (1997, 1998) points out that in focusing on damaging aspects of livestock systems, analysis may omit significant natural resource stocks and flows attributable to livestock systems, when properly managed. Furthermore, focusing on the livestock systems in isolation of other sectors may omit significant transfers (e.g. direct values to society such as draught power, weeding, organic fertiliser, means of transport, household energy supplies) on which the functioning of the entire system depends. Putting volumes of flow into the different categories above has not been attempted for a geographic area. Therefore, we do not know the relative water productivity of constituents within a livestock–cropping system. However, some details of individual processes are appearing from plot and field scale measurement. Value adding While the ‘finger diagram’ is a convenient representation of parallel uses of water within a basin, this concept overlooks the serial use of water, in which the product of one activity is consumed by the next, to produce goods or services of greater complexity or value (Fig. 2). The incentive for assembling such chains is normally value adding. Foran et al. (2005) illustrate the use of input–output analysis of water productivity for the dairy industry, from dairy cattle, through dairy products, high value product and finally restaurant service. At each stage, value is added to conclude with a high value product that supports the production of relatively low value dairy cattle. The full benefit is accounted for only when the high value derived products are included in the assessment. Conversely, looking at only the economic benefits of water-consuming activities may overlook the high social or environmental costs with which they are associated. The tendency is to stress the 198 S. E. Cook et al. The Rangeland Journal Imported feed (virtual water) Water enabled outputs Beneficial Land evaporation Feed sourcing strategies for allocating transpired water Drinking Wild biodiversity, non-timber FP Meat, milk, eggs, hides, animal power, manure, wealth Exported water, hydropower. urban uses, fish Ground and soil water recharge Open water evaporation ltur e Non-beneficial Discharge Floods acu Grazing and watering strategies to reduce water depletion Ground water Food, fiber, wood Aqu Available water Rain Surface inflow Ma nu Plants re ,d ra ug An ht im al Trees fe ed Livestock Pasture, range and browse Crops Degraded water Fig. 2. Parallel and serial multiple water uses in agricultural production systems. Modified after Peden et al. (2007). simple gains from easily-defined sectors of economies while overlooking benefits and costs from more complex systems that include transfers between sub-sectors. The main purpose of identifying the value chain through which water flows is to account fully for the gains (or costs) associated with water consumption. Strictly speaking, it is not possible to account for the total gain without understanding the connectivity through the value chain of all products that derive from water use. Since farmers make decisions based on complete valuations, quantifying the value chain is necessary, if hazardous, to understand the motivation of land use decisions that influence water productivity. Estimating water productivity of livestock within systems In practice, the methods of estimating WP contain large assumptions about both the enumerator and denominator (see Cook et al. 2006). The denominator is intended to represent actual ET. This can be hard to estimate and is rarely attempted (see Ahmad et al. 2006 [cited in Masih et al. 2007] for an exception). People usually estimate water depleted as simple water balance [rainfall – runoff plus percolation], or even growing season rainfall. The enumerator is a measure of benefit or value per m3 water depleted. It can be expressed in terms of the mass (kg yield) or nutritional value (kCal) of agricultural output (physical WP) or as monetary value in $ (economic WP). Water productivity serves two functions: first, as an accounting variable (e.g. to help improve water allocation among different water consumers) but also as a diagnostic indicator of agricultural system performance. In the latter case, it can be used to evaluate, as fully as possible, the total livelihood support of water through multiple uses. A major drawback of simple methods of water productivity accounting is that – in selecting measurable inputs and production – methods are partial and do not acknowledge all benefits and costs of complex water-consuming systems. In agricultural systems that include components of crops and livestock (i.e. most agricultural systems at basin scale), the focus is usually on meat or milk while the multiple uses of the system components are ignored, thereby underestimating livestock water productivity. Moreover, non-marketable values associated with water use, such as livelihood support and values derived from ecosystem services, are normally not accounted for (Ward and Michelsen 2002; Turpie et al. 2008). Livestock systems differ from cropping systems in three critical ways that can be extremely important to the people who use them: first, through grazing, animals capture resources over large areas that might otherwise provide no food benefit to people; second, animals can sustain climate shocks of droughts and floods more effectively than crops and so provide a degree of risk protection to natural hazards; third, animals provide a wide range of goods and services, some of which are highly valued for nutrition or as a ‘bank’ for household needs and emergencies. There is a fourth dimension of benefits derived from livestock, related to the possibility of a continuous cash flow through for example milk (in contrast to revenues from crop production, which depend on specific harvest dates). Ignoring this conversion of water into value-added products and livelihoods in multipleuse systems would lead to a gross under-estimation of the role of water. Another important factor to consider when evaluating the contribution from livestock systems is the relative, or marginal, Livestock water use in basins The Rangeland Journal water productivity of different consumers (Molden et al. 2007). The absolute water productivity attributable to livestock (in kg or $/m3) is often low, particularly in rangeland systems. So it seems that total WP might improve if the water was used in other ways. However, if it is not possible to use the water in other ways, the marginal cost of using this water in livestock systems is effectively zero. In this case, livestock represents the ‘best’ use of this water, until an alternative becomes apparent. 199 São Francisco in South America, and Volta in West Africa) to provide – among others – a more comprehensive and integrated understanding of how basin water resources are allocated both within the basins and downstream. The results obtained from the Karkheh Basin Focal Project (Kirby et al. 2009) are used as example for illustrating the approach proposed to account for multiple uses of water in complex systems. Karkheh Basin example Basic concept In summary, it is the following characteristics, which make analysis very complex: 1. Water enters the system, is used, and leaves as ‘virtual water’ in goods or services. 2. Water is used in parallel sub-systems, each of which may contribute to overall wellbeing. Different streams apply to food production, environmental services, hydro-power etc. 3. Water is also used in series, the input of one water-consuming process may be the output of another (value adding). 4. Sequential processes interact to generate final goods and services (multiplier effect): for example, high quality animal feed provides greater nutritional value than low quality feed, but may consume the same volume of water. 5. The effectiveness of water use depends on several co-factors such as soil fertility and institutional effectiveness. 6. Transfers occur between activities. Sometimes these are measured as WP. Most transfers are ‘hidden’ within the system. Estimation of the complete water productivity of these systems, therefore, requires a method of analysis that can decompose the benefits and costs of water productivity throughout complex livelihood support systems. Without such a method, it is impossible to fully account for all interactive facets of such farming systems. Conventional approaches usually only estimate Gross WP: Total Water Input Benefit or sectoral WP of parallel uses: Water Input 1 Benefit 1 Water Input 2 Benefit 2 Water Input 3 Benefit 3 We propose that an integral approach for full accounting of water productivity needs to consider value adding through serial uses and transfers between sectors: Water Input 1 Benefit 1 1 Water Input 2 Benefit 2 1 Benefit 2 2 Water Input 3 Benefit 3 1 Benefit 3 2 Benefit 33 In the following, we try to field-truth the suggested approach as much as possible by using a concrete example. In the frame of the CGIAR Challenge Program on Water and Food (CPWF), Basin Focal Projects (BFPs) have been conducted in four selected benchmark basins (Karkheh in the Middle East, Mekong in Asia, Basin context The Karkheh Basin is one of the smallest basins among the nine CPWF benchmark basins. Its total area occupies 5.08 million ha and is located in Iran, bordering Iraq. A large part of the basin lies in a mountainous area, with altitudes between 1000 and 2500 masl. The Karkheh River and its tributaries rise in the high Zagros mountains in the northern part of the basin, at an altitude of 3500 masl. Near the downstream end of the Karkheh, a major dam has recently been constructed, which is used for hydropower generation and irrigation. Further downstream, the river drains into the extensive Hour-al-Azim (Al Azim Swamp) in the south, where most of the remaining water is consumed as evapotranspiration. The river water becomes progressively more saline in this part of the basin, with electrical conductivities exceeding 3 dS/m. The Karkheh Basin is also one of the driest of the nine CPWF benchmark basins. Its conditions range from semi-arid in the uplands (north) to arid in the lowland (south). The basin is considered a hydrologically closed basin, i.e. the only input of the system is the annual precipitation, which averages roughly 500 mm in the upper and 230 mm in the lower part. A significant amount of the surface and groundwater resources is replenished each winter in the form of snowfall (and rain). During most of the year, the annual evaporation exceeds precipitation and accounts for ~1500 mm in the upland, and more than 2000 mm in the lowland. In fact, the Karkheh is a water-stressed basin and showed a negative water balance of 144 Mm3 for the years 2000 and 2001. The difference is mainly due to over-exploitation of groundwater resources for irrigation (Ashrifi et al. 2004). In 2002, ~4 million people lived in the basin and 67% of them in rural areas. The average income of the rural population is estimated at 230 US$/capita. The industry sector in the basin is growing steadily, especially in the lower catchment. Although the majority of the population lives in rural areas there is an increasing demographic shift towards cities. The principal farming activities in the upper catchment are rainfed cropping and livestock rearing on rangelands, complemented by irrigation agriculture. In the lowland, the predominant activity is irrigation cropping, sourced from springs, rivers and more recently from the newly commissioned Karkheh Dam. Cereals (wheat, barley, maize and chickpea) account for >70% of the rainfed area, and >60% of irrigated land. The dominant crops are winter wheat and barley, which are grown for grain as well as fodder. Nomadic herding has a long tradition throughout the basin, and pastoralism is a crucial component for the livelihoods of most rural people in the Karkheh Basin (but it is not known to what extent). Livestock is integrated into both rainfed and irrigated farming systems, with a considerable (but not quantified) part of 200 S. E. Cook et al. The Rangeland Journal the wheat and barley area being used directly for stock grazing and fodder. In the upland, sheep and goats are predominant, and cattle in the lowland. Other agricultural uses include poultry production and fish farming. Water use accounting A first step towards better understanding the complexity of mixed farming systems is to characterise and quantify the multiple uses of water in these systems. The total water balance, or the total water moving through a basin or sub-basin, can be calculated using the IWMI (Molden 1997; Molden et al. 2001) water accounting framework, modified by Kirby et al. (2008), which distinguishes different water use categories through disaggregation of components. Water accounting provides information on how much water there is in a basin, where it goes and how it is used. Water accounting is done at the catchment level, where total catchment ET is estimated from potential evaporation and water supply from the surface store, and partitioned between rainfed and irrigated land uses based on the ratio of their areas. The rainfed component of ET is further disaggregated according to the different land uses/vegetation types (agriculture, forest/ woodland, grassland, other) based on the ratio of their areas and using crop factors to scale their ET relative to other land uses. The accounts are dynamic and reflect both spatial and temporal variation (seasonally, annually), with a monthly time-step. The methodology can be applied even when data are limited, and it is possible to construct a reasonable account based on data publicly available. Data requirements include monthly climate data (rainfall, temperature and other climate variables) distributed spatially across the basin, land use data, catchment areas and river flow data (Kirby et al. 2008). Water use Kirby et al. (2006, 2007) have applied the methodology to the nine benchmark river basins of the CPWF, including Karkheh. Results show that the basins are very different and vary from very ‘wet’ (Mekong) to very ‘dry’ (Karkheh). They also show that in most basins grassland is the most extensive land use, and consumes the greatest amount of water (Fig. 3). The water use accounting method for the Karkheh Basin is described in detail by Kirby et al. (2009). The simple account has two parts: an account of water flowing into a basin, flows, storages and outflows, and partitioning of evapotranspiration from each vegetation type or land use, including evapotranspiration from wetlands and evaporation from open water. Kirby et al. (2009) use a monthly time-step to represent flows in the Karkheh basin. Of the mean annual input of precipitation to the Karkheh basin (21.4 km3/year), most (93%) is utilised for agricultural production. The distribution of the different land and water uses across the basin is shown in Fig. 4. As in many of the world’s major basins (Fig. 3), grassland consumes the greatest amount of water (and land) in most parts of the basin, followed by irrigated agriculture (but occupying a smaller area). A considerable amount of the runoff water from the upper catchments is used as input for irrigation in the lower part of the basin. The evaporation and losses are mainly due to evapotranspiration in the lowland marshes. Water productivity Estimates of physical crop WP in the Karkheh Basin – based on field scale measurements and farmer surveys – are available at field and sub-catchment scale (Ahmad et al. 2004; Moayeri et al. 2007). Physical WP has also been estimated at the sub-basin and basin level (Ashrifi et al. 2004). In Table 1, an overview is given of the physical WP for the major crops in the Karkheh basin by irrigated and non-irrigated area. Land and water productivity Karkheh Indus Grassland Rainfed crops Irrigated crops Woodland etc. Net runoff Volta Yellow River Mekong Andean System of Basins Ganges Nile ~ Francisco Sao Limpopo Fig. 3. Major water uses in the nine CGIAR Challenge Program on Water and Food benchmark basins (annual averages 1990–2004). Woodland also contains other minor land uses. Source: Kirby et al. (2007). Livestock water use in basins The Rangeland Journal 201 N Basin boundary District boundary Water distribution, MCM/year Landuse Bare/urban Irrigated cropland Rainfed cropland Orchard Forest Rangeland Grassland Swamp Wet soil/seasonal wetland Water 700 Rainfed agriculture Irrigated agriculture Grassland Woodland Net runoff Evaporation and losses 0 25 50 100 km Fig. 4. Principal land (left) and water uses (right) in the Karkheh Basin (annual averages 1990–2004). Source: Ahmad et al. (2009). Table 1. Land productivity (LPr, kg/ha) and physical water productivity (WP, kg/m3) estimates for the major crops of the Karkheh Basin, 2006 (Source: Ahmad et al. 2009) Crop Rainfed LPr Wheat Barley Maize Chickpea Irrigated WP 1457 ± 577 0.46 ± 0.22 1411 ± 606 0.43 ± 0.19 – – 621 ± 213 0.70 ± 0.84 LPr WP 3315 ± 1513 0.55 ± 0.20 2638 ± 1525 0.470 ± 0.19 7438 ± 1557 0.84 ± 0.30 – – numbers are influenced by a complex mix of biotic and abiotic variables, such as quality of land and water, farm management, market prices and institutional arrangements to mention some [Ahmad et al. 2004, 2006 (cited in Masih et al. 2007)]. Hence, cross-country and -basin comparisons are problematic. Still, in general terms it can be said that the physical WP values in the Karkheh Basin are low in a global context, and there is scope for improvement. A more detailed discussion of the physical WP values in the Karkheh Basin as compared to other basins, and of the implications for improvement has been undertaken by CPWF (2008). The economic WP in the Karkheh Basin has been estimated at sub-basin and basin scale (Masih et al. 2007; Ahmad et al. 2009), mainly using secondary data from meteorological, hydrological and agricultural statistics. Separate calculations with and without livestock are presented in Fig. 5. It can clearly be seen that the inclusion of livestock in economic WP calculations has dramatic implications for the magnitude and distribution of agricultural economic WP across the basin. In sub-catchments where livestock are present, WP values are almost double whereas the opposite is true for subcatchments where livestock production is not significant. This analysis highlights the importance of including livestock – and other agricultural systems not traditionally included in WP estimates, such as fisheries and forestry – in WP calculation to account for value adding of benefits derived from multiples uses of water. It is a first step towards a more complete analysis of the costs and benefits of water use in mixed production systems. It should be noted, however, that this analysis only considers sectoral uses of water. To fully account for all benefits of multiple water uses, methodologies need to be developed that include transfers of water between sectors. For example, in the present case study the analysis would need to be extended to account for the extent (%) to which crops (wheat and barley) and crop residues S. E. Cook et al. The Rangeland Journal 0.004 0.022 0.408 0.359 0.398 0.360 0.193 0.163 Fig. 5. Economic water productivity (US$/m3) for vegetation (left) and vegetation and livestock (right) in the Karkheh Basin, 2002/2003. Source: Ahmad et al. (2009). Other evaporation and losses ET: 4.59 km3/year Woodland ET: 2.07 km 3 /year Total Basin Rainfall 24.5 km 3/year Total (vegetative) WP 0.097 $/m 3 Total (global) WP 0.129 $/m3 ?? Other grassland ET: 6.94 km3/year Irrigated ET: 2.68 km3/year Karkheh dam ET: 0.08 km 3/year Al-Azim swamo ET: 0.66 km 3/year Rainfed ET: 3.72 km3/year Fish WP: ?? Virtual water Biomass WP: ?? Biomass LP: 200–300 kg/ha WP: ?? Rangeland ET: 3.36 km 3/year Net runoff ET: 0.4 km 3/year 202 Livestock (cattle, goats, sheep, poultry) WP: ?? ? ? ?? ?? Crops WP: 0.5–0.6 kg/m3 or 0.22 $/m3 Crops WP: 0.3–0.6 kg/m3 or 0.051 $$/m 3 e.g. milk – WP: ?? e.g. meat – WP: ?? ? ? Wheat – WP: 0.55 kg/m3 Barley Barle – WP: 0.47 kg/m3 Ma Maize – WP: 0.84 kg/m3 e.g. flour – WP: ?? e.g. bread – WP: ?? e.g. beer – WP: ?? Wheat – WP: 0.45 kg/m 3 Barley – WP: 0.43 kg/m3 Chickpea – WP: 0.70 kg/m3 Virtual water Hydropower WP: ?? Fig. 6. Water accounting model for multiple water uses in the Karkheh Basin (see explanation in the text). ET, evapotranspiration; LP, land productivity; WP, water productivity. Source: Ahmad et al. (2009). Livestock water use in basins are used as livestock fodder (Fig. 6). Also, as outlined above, there are other costs and benefits currently not accounted for in this type of analyses, including virtual water transfers (e.g. imports of fertilisers and feed concentrates), and non-monetary goods and services such as livelihood support (e.g. livestock derived drought power, organic fertiliser, transport, store of wealth, etc.) and environmental benefits (e.g. ecosystem services). There is considerable scope for improving physical WP in rainfed, irrigated, livestock, and fisheries systems in this region. This can be obtained by adopting proven agronomic and water management practices because increasing land productivity (i.e. kg agricultural output per area of land) generally leads to improvements in physical water productivity. There is a wide array of options that can be applied, including better technologies (e.g. supplemental, deficit and drip irrigation), better land and water management practices (e.g. conservation agriculture to maintain or improve soil fertility, zero or minimum tillage, small-scale water management practices for improved water storage, delivery, and application), and better germplasm (e.g. better adapted crop and forage varieties and livestock breeds). The most appropriate approach for a specific situation and the actual land and water productivity gains are context dependent and need a thorough integrated assessment before taking decisions. Like physical WP, economic WP can be improved by several strategies, ranging from better technologies (improving the quality of produce), to better germplasm (better feed sources and better livestock races), and better management (better feeding strategies, integrating livestock and fisheries into farm production systems). Additional options include better marketing strategies, institutional linkages and policies, e.g. payments for environmental services. There is much more scope for increases in economic WP than in physical WP, which is becoming increasingly constrained. Furthermore, increasing economic WP has key implications for farmer decisions, economic growth, poverty reduction, equity, and the environment. Conclusions The evidence available indicates that livestock systems are large consumers of water in most river basin systems of the world. In Africa, they are the largest. Yet the fate of water passing through these systems is largely unknown. Methods of tracking water flux through extensive livestock systems do not yet exist. Their development is constrained by a lack of data for fluxes, stores and transfers of water that occur within such complex systems. Some recent advances in data availability and methodologies increase the possibilities of accounting for water flow through these systems. First, improved data on hydrology through water use accounting and other methods are available. These give us approximations of relative water flows through different land uses; second, we have improved information on livestock numbers and animal production, through the FAO livestock atlas (Wint and Robinson 2007) and other data sources; third, we see the application of analyticalmethodssuch asInput-Output analysis(Foran et al.2005; Karkacier and Goktolga 2005; Grêt-Regamey and Kytzia 2007; Guan and Hubacek 2007) or Ecological Network Analysis (Fath 2004; Fath et al. 2007) that can identify the outcomes from complex parallel and sequential (water) uses. The Rangeland Journal 203 Such analysis is difficult and produces at best, approximate results. So is it worthwhile? The potential uses suggest it is. First, analysis will indicate the full benefits and costs of water use as they affect the major water users within major basin systems. This will enable scientists to take stock of all major users of water for the first time. 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