虚拟水贸易在解决中国和全球水危机中的作用

水资源短缺已经威胁到中国一些地区的社会经济发展和生态安全,经济的发展将会进一步加剧水危机。近年来,农产品贸易中的虚拟水引起了全世界的关注,被看做是一种缓解水资源压力的手段。本文利用虚拟水的概念和方法分析了中国1996～2001年间的粮食贸易,发现:这些年间中国通过粮食贸易净进口了3.28×1 010m3虚拟水;通过粮食进口,中国相当于节省了1.86×1011 m3的水资源;中国的粮食贸易由于基本符合水利用效率的比较优势,因而给全球节省了1.01×1011m3的水资源。中国通过虚拟水贸易不能完全解决国内水危机问题,但是可以节省国内水资源,缓解农业区的水危机状况,提高全球水资源利用效率。尽管当前中国采取虚拟水进口策略会遇到很多问题,但是虚拟水的概念给我们理解粮食贸易和调水工程提供了全新的角度。     

虚拟水及其在缓解区域水资源短缺中的应用研究

虚拟水是指生产商品和服务所需要的水资源数量。虚拟水战略是指贫水国家或地区通过贸易的方式从富水国家或地区购买水密集型农产品(粮食)来获得本地区水和粮食的安全。本文在综述前人对虚拟水研究的基础上,计算了2002年甘肃省及不同地区主要农产品虚拟水含量,并对甘肃省加强虚拟水贸易的战略进行了探讨。     

The water footprints of Morocco and the Netherlands: Global water use as a result of domestic consumption of agricultural commodities

The volume of international trade in agricultural commodities is increasing faster than the global volume of production, which is an indicator of growing international dependencies in the area of food supply. Although less obvious, it also implies growing international dependencies in the field of water supply. By importing food, countries also import water in virtual form. The aim of the paper is to assess the water footprints of Morocco, a semi-arid/arid country, and the Netherlands, a humid country. The water footprint of a country is defined as the volume of water used for the production of the goods and services consumed by the inhabitants of the country. The internal water footprint is the volume of water used from domestic water resources; the external water footprint is the volume of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country. The study shows that both Morocco and the Netherlands import more water in virtual form (in the form of water-intensive agricultural commodities) than they export, which makes them dependent on water resources elsewhere in the world. The water footprint calculations show that Morocco depends for 14% on water resources outside its own borders, while the Netherlands depend on foreign water resources for 95%. It is shown that international trade can result in global water saving when a water-intensive commodity is traded from an area where it is produced with high water productivity to an area with lower water productivity. If Morocco had to domestically produce the products that are now imported from the Netherlands, it would require 780 million m³/year. However, the imported products from the Netherlands were actually produced with only 140 million m³/year, which implies a global water saving of 640 million m³/year.     

Are virtual water “flows” in Spanish grain trade consistent with relative water scarcity?

Virtual water adds a new dimension to international trade, and brings along a new perspective about water scarcity and water resource management. Most virtual water literature has focused on quantifying virtual water “flows” and on its application to ensure water and food security. Nevertheless, the analysis of the potential gains from international trade, at least from a water resources perspective, needs to take into account both spatial and temporal variations of blue (groundwater and stream flow) and green (soil moisture) water, as well as the socioeconomic and policy conditions. This paper evaluates whether Spanish international trade with grains is consistent with relative water scarcity. For this purpose, the study estimates the volume and economic value of virtual water “flow” through international grain trade for the period 1997-2005, which includes 3 years with different rainfall levels. The calculations show that Spain is a net virtual water “importer” through international grain trade. The volume of net virtual water “imports” amounts to 3420, 4383 and 8415 million m³ in wet (1997), medium (1999) and dry (2005) years, respectively. Valuing blue water at its shadow price or scarcity value, blue water “exports” oscillate between 0.7 and 34.2 million Euros for a wet and dry year, respectively. Overall, grain trade is apparently consistent with relative water scarcity as net imports increase in dry years. However, the evolution of grain exports, expressed as a variation in quantity and volume, does not match the variations in resource scarcity. A disaggregated crop analysis reveals that there are other factors, such as quality, product specialization or the demand for a standardized product, which also influence trade decisions and are not included in the notion of virtual water. These facts, among others, can therefore create potential distortions in the application of virtual water to the analysis of specific trade patterns. Nevertheless, from a water resources perspective, virtual water can bring important insights across countries for improving water and land management globally, fostering adaptation strategies to climate change and to transboundary resource management.     

基于投入产出法的浙江省虚拟水贸易实证分析

基于"虚拟水"理论,利用2005年和2007年浙江省的投入产出表(延长表)和各产业部门的用水数据,采用投入产出分析法构建价值型-实物型水资源投入产出模型,计算并分析了2005年和2007年浙江省各产业部门的虚拟水贸易量。结果表明:浙江省通过商品贸易向他省和国外输出的虚拟水主要集中在纺织、缝纫及皮革产品制造业和机械设备制造业;通过商品贸易向省内输入的虚拟水集中在农业、化学工业、金属冶炼及加工制造业、采掘业和食品制造和烟草加工业;从虚拟水贸易结构来看,农业和重工业为净输入虚拟水贸易行业,轻工业为净输出虚拟水贸易行业。     

The water footprint of coffee and tea consumption in the Netherlands

A cup of coffee or tea in our hand means manifold consumption of water at the production location. The objective of this study is to assess the global water footprint of the Dutch society in relation to its coffee and tea consumption. The calculation is carried out based on the crop water requirements in the major coffee and tea exporting countries and the water requirements in the subsequent processing steps. In total, the world population requires about 140 billion cubic metres of water per year in order to be able to drink coffee and tea. The standard cup of coffee and tea in the Netherlands costs about 140 l and 34 l of water respectively. The largest portions of these volumes are attributable to growing the plants. The Dutch people account for 2.4% of the world coffee consumption. The total water footprint of Dutch coffee and tea consumption amounts to 2.7 billion cubic metres of water per year (37% of the annual Meuse runoff). The water needed to drink coffee or tea in the Netherlands is not Dutch water. The most important sources for the Dutch coffee are Brazil and Colombia and for the Dutch tea Indonesia, China and Sri Lanka. The major volume of water to grow the coffee plant comes from rainwater. For the overall water need in coffee production, it makes hardly any difference whether the dry or wet production process is applied, because the water used in the wet production process is a very small fraction (0.34%) of the water used to grow the coffee plant. However, the impact of this relatively small amount of water is often significant. First, it is blue water (abstracted from surface and ground water), which is sometimes scarcely available. Second, the wastewater generated in the wet production process is often heavily polluted.     

Looking backward to look forward: water use and economic growth from a long-term perspective

Recent research has examined the relationship between natural resources and economic growth. Considered vitally important, not only for humanity’s well-being but also for the integrity of the ecosystem, the relationship between water use and economic growth has nevertheless traditionally attracted little attention by analysts. This article studies water use trends from 1900 to 2000 throughout the world and their relationship to the main determinants of economic growth. To do this, we first analyse water use trajectories. Second, to proceed with the determinants of water use, we reformulate the Ehrlich and Holdren’s impact, population, affluence, technology (IPAT) equation (1971), decomposing water use trends into changes in economic demands and in water use intensity on the basis of a decomposition analysis. Finally, a simple scenario analysis is conducted, to project future water use trends under different economic, demographic and technological assumptions.

?The empirical evidence shows that economic and population growth have been crucial in explaining the increase in water use over the past 100 years, with significant regional differences. Nevertheless, the decline in water use intensity has been responsible for a significant reduction in the growth of total water use.     

Human appropriation of natural capital: A comparison of ecological footprint and water footprint analysis

The water footprint concept introduced in 2002 is an analogue of the ecological footprint concept originating from the 1990s. Whereas the ecological footprint (EF) denotes the bioproductive area (hectares) needed to sustain a population, the water footprint (WF) represents the freshwater volume (cubic metres per year) required. In elaborating the WF concept into a well-defined quantifiable indicator, a number of methodological issues have been addressed, with many similarities to the methodological concerns in EF analysis. The methodology followed in WF studies is in most cases analogous to the methodology taken in EF studies, but deviates at some points. Well-reasoned it has been chosen for instance to specifically take into account the source and production circumstances of products and assess the actual water use involved, thus not taking global averages. As a result one can exactly localise the spatial distribution of a water footprint of a country. With respect to the outcome of the footprint estimates, one can see both similarities and striking differences. Food consumption for instance contributes significantly to both the EF and the WF, but mobility (and associated energy use) is very important only for the EF. From a sustainability perspective, the WF of a country tells another story and thus at times will put particular development strategies in a different perspective. The paper reviews and compares the methodologies in EF and WF studies, compares nation's footprint estimates and suggests how the two concepts can be interpreted in relation to one another. The key conclusion is that the two concepts are to be regarded as complementary in the sustainability debate.     

Endogenous trade policy in general equilibrium: An interaction of redistribution rule,trade openness,and labor market condition

Using a general equilibrium framework, the paper derives trade policy endogenously for a small country. It shows that, contrary to the existing literature, a lobbying industry is not guaranteed trade protection; it may even face trade taxes. Besides lobbying, trade policy depends on other factors such as the trade revenue distribution rule, income distribution across groups, trade openness, factor substitutability in production, industry employment size, and labor market flexibility. The paper also shows that the observed phenomenon of government preference for import tariffs over export subsidies—a long overdue puzzle—is an inherent outcome of lobbying equilibrium. It also shows that trade policies such as import tariffs and export taxes that have the same impact on economic market—Lerner symmetry (1936)—are driven by the same forces in the political market.     

The water market in Israel: An example for increasing the supply

In this study we search for solutions to the problem of Israel's water shortage. To illustrate the shortage, we first model the water market in Israel, i.e., the corresponding supply and demand of water, and from it the dynamics of water prices. A direct way to solve the shortage problem and to reduce the high equilibrium price can be found via a different way of sharing water among the Levant countries, or by bringing more water from outside the region. The latter can take the form of conveying Nile water or water from Turkey or by constructing desalination plants along the shores. In this study we concentrate on the importing of Nile water.The costs of most of the solutions are too high compared to the returns to water in agriculture. This relation is continuously changing with the increasing demand for water for domestic and agricultural use. Our analysis shows that within 5–10 years the marginal value product of water in the area west of the Jordan river would equal the marginal costs of water from the Nile, $0.40m³.     

The long-run decline in the share of agricultural and food products in international trade: a gravity equation approach to its causes

The objective of this study is to determine the causes of the loss of share of agricultural products and food in international trade. The article compares, using a gravity model, the impact of various factors upon bilateral trade in agricultural products, in manufactures and in total trade, between 1963 and 2000 for a representative sample of 40 countries. The results clearly demonstrate how the low demand elasticity for agricultural products and food, the high degree of protectionism to which they were subjected and their meagre share in intra-industrial trade are the principal causes of their relatively slow growth.     

An empirical investigation of the balance of embodied emission in trade: Industry structure and emission abatement

By constructing the world panel dataset for the pollution emission embedded in international trade of 132 countries for the period between 1988 and 2008, we investigate whether the balance of embodied emission in trade (BEET) is consistent with the implication of pollution haven hypothesis (PHH). By using two differently constructed datasets, we are able to distinguish between the composition (i.e., changes in industry structure of international trade) effect and the technique (i.e., improvement in emission abatement) effect. We find that the composition effect is neither related with the income level nor the democracy level of countries. However, the empirical evidence, with consideration for the technique effect, provides a partial support that income level is negatively related with the BEET. Therefore, the BEET in fact has worsened for developing countries, but not by the composition effect assumed in the PHH.     

The water footprint of energy from biomass: A quantitative assessment and consequences of an increasing share of bio-energy in energy supply

This paper assesses the water footprint (WF) of different primary energy carriers derived from biomass expressed as the amount of water consumed to produce a unit of energy (m³/GJ). The paper observes large differences among the WFs for specific types of primary bio-energy carriers. The WF depends on crop type, agricultural production system and climate. The WF of average bio-energy carriers grown in the Netherlands is 24 m³/GJ, in the US 58 m³/GJ, in Brazil 61 m³/GJ, and in Zimbabwe 143 m³/GJ. The WF of bio-energy is much larger than the WF of fossil energy. For the fossil energy carriers, the WF increases in the following order: uranium (0.1 m³/GJ), natural gas (0.1 m³/GJ), coal (0.2 m³/GJ), and finally crude oil (1.1 m³/GJ). Renewable energy carriers show large differences in their WF. The WF for wind energy is negligible, for solar thermal energy 0.3 m³/GJ, but for hydropower 22 m³/GJ. Based on the average per capita energy use in western societies (100 GJ/capita/year), a mix from coal, crude oil, natural gas and uranium requires about 35 m³/capita/year. If the same amount of energy is generated through the growth of biomass in a high productive agricultural system, as applied in the Netherlands, the WF is 2420 m³. The WF of biomass is 70 to 400 times larger than the WF of the other primary energy carriers (excluding hydropower). The trend towards larger energy use in combination with an increasing contribution of energy from biomass will enlarge the need for fresh water. This causes competition with other claims, such as water for food.     

An investigation into the interdependence of global water indices: a VAR analysis

We investigate the extent and manner of equity price interdependence among four water indices – World Water Index, S-Network Global Water index (S-Net), S&P Global Water Index (S&P) and MSCI ACWI Water Utilities Index (MSCI ACWI) using the vector autoregression (VAR) framework for the period 2004–2014. We also employ methods of Granger causalities, variance decomposition and impulse responses. We find Granger causality significance between S-Net and MSCI ACWI and S-Net and S&P indices at the 1% level of significance, suggesting that the indices are significantly linked. Further, S-Net is the most influential index amongst them in the forecast variance that can be accounted by S-Net at level of 55.75%. Our study indicates that the four water indices are interdependent and related, so the water indices are influenced by movements in the other water indices.     

Economic Benefits Resulting From Irrigation Water Use: Theory and an Application to Groundwater Use

Traditional economic analysis using a crop production function approachhas assumed that all variable factors, including irrigation water, arefully employed in the crop production process. However, this paper firstdemonstrates that economic benefits of irrigation water areoverestimated when the crop production function, and therefore theirrigation water demand function, is expressed in terms of irrigationwater supplied, rather than consumptive irrigation water use. Second,the paper demonstrates that the magnitude of the estimation bias isproportional to the rate of irrigation water losses through leaching,runoff and evaporation. Consequently, the model misspecification problemwould lead to increased irrigation water use and reduce incentives forfarmers to adopt improved irrigation technologies.     

Tariffs and non-tariff barriers to trade in Hungary: The impact of the Uruguay Round and EU accession

International trade has featured prominently in Hungary's rapid transition to a market economy. This paper reports some relatively simple summary and complementary indicators for tariffs and non-tariff barriers (NTBs) to trade, which are designed to reflect the level and structure of tariffs and the scope of NTBs in Hungary. The existence of tariff 'spikes' and highly pervasive NTBs in certain sectors constitutes prima facie evidence that the domestic dead-weight efficiency and net welfare losses caused by tariff and non-tariff protection as well as the costs to consumers could be high. The indicators are used to highlight several key developments associated with Hungary's transition to a market economy, implementation of the Uruguay Round (UR) agreements and possible accession to the EU.     

Areal differentiation of virtual water for agricultural products and its effect on regional agricultural structure adjustment in China： 1995-2007

With a vast territory, the space-time distribution of water resources is uneven in China. There is a great dif ference in natural conditions and farmland management of agricuttural production in different regions. The areal differentiation of agricultural products virtual water is obvious. Comparison with the agricultural products virtual water from 1995 to 2007 in China shows an increase in the first ten vears and a little decrease in recent years. There has been a tendency of increase all the time in Northeast and Northwest. but a decrease after an increase firstly in other regions. The virtual water offood crops is the maximum which accounts for more than 70% in China. and that of vegetables is in a fast growth. The proportion of agricultural products virtual water to the total water resources in each region has a large difference, showing the imbalance of agricultural water in different regions, which accounts for 50%-90% in Northeast, and 125%-185% in North China. Under the guidance of virtual water strategy, based on the differences of resource endowment, each region should adjust agricultural structure, decide production by water, and select water suitable crops. In water-rich region, agricultural produets of high water consumption should be planted appropriately, which will make full use of the abundant local water resources. In water-shortage region the crop production of high water consumption and low efficiency should be depressed, and that of low water consumption and high efficiency should be supported and increased. It will achieve reasonable disposition of water resources, promote ecological restoration and environmental protection, as welt as ensure food security.     

What level of decentralization is better in an environmental context? An application to water policies

This paper analyses the optimal division of environmental policymaking functions among the different levels of government. Using fiscal federalism theory, we identify the most appropriate level of decentralization in each case. The paper focuses on water resources policies, with an application to Spanish regions during the 1996–2001 period. A simulation allows the implementation of more efficient policies in the context of water resources. The results of the empirical exercise show that a decentralized scenario is preferred under strong differences among preferences.      

Complementarity between water pricing, water rights and local water governance: A Bayesian analysis of choice behaviour of farmers in the Krishna river basin, India

To ensure efficient water allocation and use, policy designers have adopted various strategies, including price setting, decentralising irrigation water management or improving water rights. Most of these strategies have been applied individually, without considering the complementary relationships between them. This paper uses a discrete choice model to analyse the scope for combinations of tools for irrigation water demand management and farmers' acceptance of these. In terms of local irrigation water governance, the presence or absence of collective irrigation water management, in the form of a Water Users Association, is considered. Water rights are specified in terms of the duration and quality of the entitlement and its transferability. Finally, four types of water pricing methods (area, crop, block and volumetric pricing) are considered. Using a choice experiment, we elicit the most preferred water pricing method, under different water rights situations, at different price levels and under various contexts for local irrigation water governance. Our results indicated that under conditions of improved water rights, preference for volumetric pricing increases, whilst the presence of a Water Users Association reduces this preference. Furthermore, it was found that using an appropriate combination of water demand management tools considerably increases the willingness to pay for a change in scenario.     

推进可持续发展水利是解决我国严重缺水问题的根本出路

我国水资源短缺,供需矛盾突出,水污染严重,水生态环境安全面临挑战,已经成为经济社会可持续发展的瓶颈。近些年,我国在推进可持续发展方面做了许多工作,取得了一定成绩,但仍然任重道远。我们必须深入学习贯彻科学发展观,深刻把握可持续发展水利的内涵。当前特别要抓好三项迫切的工作:一是保障饮水安全,维护人民群众的生命健康;二是坚定不移地推进节水型社会建设;三是正确处理资源开发和生态保护关系,担负起水利建设和生态保护的重任。