scholarly journals Appendix I: Analytical Framework for the Assessment of Virtual-Water Content, Virtual-Water Flows, Water Savings, Water Footprints, and Water Dependencies

2008 ◽  
pp. 147-156
Keyword(s):  
Water Content ◽  
Virtual Water ◽  
Analytical Framework ◽  
Water Savings ◽  
Water Flows

The virtual water content of major grain crops and virtual water flows between regions in China

2012 ◽  
Vol 93 (6) ◽  
pp. 1427-1437 ◽  
Author(s):  
Shi-Kun Sun ◽  
Pu-Te Wu ◽  
Yu-Bao Wang ◽  
Xi-Ning Zhao
Keyword(s):  
Water Content ◽  
Virtual Water ◽  
Grain Crops ◽  
Water Flows

scholarly journals Analysis of virtual water flows associated with the trade of maize in the SADC region: importance of scale

2009 ◽  
Vol 13 (10) ◽  
pp. 1967-1977 ◽  
Author(s):  
J. M. Dabrowski ◽  
E. Masekoameng ◽  
P. J. Ashton
Keyword(s):  
South Africa ◽  
Water Use Efficiency ◽  
Water Content ◽  
Water Use ◽  
Water Scarcity ◽  
Virtual Water ◽  
Blue Water ◽  
Maize Production ◽  
Water Flows ◽  
Use Efficiency

Abstract. The concept of virtual water encourages a country to view agricultural crops in terms of the amount of water required to produce those crops, with a view to implementing trading policies that promote the saving of scarce water resources. Recently, increased attention has focussed on partitioning the virtual water content of crops into green and blue water (derived from rainfall and irrigation, respectively) as the latter has higher opportunity costs associated with its use and therefore impacts directly on scarcity. Maize is the most important crop traded within the SADC region. South Africa is the largest producer and exporter of maize, with the majority of its exports destined for other SADC countries. In comparison to other SADC countries, South Africa produces maize relatively efficiently, with a low virtual water content and a high green (868 m3 t−1) to blue (117 m3 t−1) water ratio. The blue water content is however higher than for maize produced in all other SADC countries, with the exception of Namibia (211 m3 t−1). Current trade patterns therefore result in a net expenditure of blue water (66×106 m3), almost all of which is exported by South Africa (65×106 m3). South Africa is one of the most water scarce countries in the region and analysis of virtual water flows indicates that current SADC maize trading patterns are influenced by national productivity as opposed to water scarcity. The virtual water content of maize was estimated for each of South Africa's nineteen Water Management Area's (WMA) and used as a proxy to represent water use efficiency for maize production. The virtual water content varied widely across all of the WMAs, ranging from 360 m3 t−1 in the Ustutu Mhlatuze to 1000 m3 t−1 in the Limpopo. A comparison of the virtual water content and production of maize (expressed as a percentage of the total national production) identified those WMAs where maize production is highly water inefficient (e.g. Lower Orange and Limpopo WMAs). Results suggest that, while a national estimate of the virtual water content of a crop may indicate a relatively efficient use of water, an analysis of the virtual water content at smaller scales can reveal inefficient use of water for the same crop. Therefore, analysis of the virtual water content of crops and trading of agricultural products at different spatial scales (i.e. regional, national and WMA) could be an important consideration within the context of water allocation, water use efficiency and alleviation of water scarcity.

scholarly journals Analysis of virtual water flows associated with the trade of maize in the SADC region: importance of scale

2008 ◽  
Vol 5 (5) ◽  
pp. 2727-2757 ◽  
Author(s):  
J. M. Dabrowski ◽  
E. Masekoameng ◽  
P. J. Ashton
Keyword(s):  
South Africa ◽  
Water Use Efficiency ◽  
Water Content ◽  
Water Use ◽  
Water Scarcity ◽  
Virtual Water ◽  
Blue Water ◽  
Maize Production ◽  
Water Flows ◽  
Use Efficiency

Abstract. The concept of virtual water encourages a country to view agricultural crops in terms of the amount of water required to produce those crops, with a view to implementing trading policies that promote the saving of scarce water resources. Recently, increased attention has focussed on partitioning the virtual water content of crops into green and blue water (derived from rainfall and irrigation, respectively) as the latter has higher opportunity costs associated with its use and therefore impacts directly on scarcity. Maize is the most important crop traded within the SADC region. South Africa is the largest producer and exporter of maize, with the majority of its exports destined for other SADC countries. In comparison to other SADC countries, South Africa produces maize relatively efficiently, with a low virtual water content and a high green (868 m3 tonne−1) to blue (117 m3 tonne−1) water ratio. The blue water content is however higher than for maize produced in all other SADC countries, with the exception of Namibia (211 m3 tonne−1). Current trade patterns therefore result in a net expenditure of blue water (66×106 m3), almost all of which is exported by South Africa (65×106 m3). South Africa is one of the most water scarce countries in the region and analysis of virtual water flows indicates that current SADC maize trading patterns are influenced by national productivity as opposed to water scarcity. The virtual water content of maize was estimated for each of South Africa's nineteen Water Management Area's (WMA) and used as a proxy to represent water use efficiency for maize production. The virtual water content varied widely across all of the WMAs, ranging from 360 m3 tonne-1 in the Ustutu Mhlatuze to 1000 m3 tonne−1 in the Limpopo. A comparison of the virtual water content and production of maize (expressed as a percentage of the total national production) identified those WMAs where maize production is highly water inefficient (e.g. Lower Orange and Limpopo WMAs). Results suggest that, while a national estimate of the virtual water content of a crop may indicate a relatively efficient use of water, an analysis of the virtual water content at smaller scales can reveal inefficient use of water for the same crop. Therefore, analysis of the virtual water content of crops and trading of agricultural products at different spatial scales (i.e. regional, national and WMA) could be an important consideration within the context of water allocation, water use efficiency and alleviation of water scarcity.

scholarly journals Evaluation of Physical and Economic Water-Saving Efficiency for Virtual Water Flows Related to Inter-Regional Crop Trade in China

2018 ◽  
Vol 10 (11) ◽  
pp. 4308
Author(s):  
Jing Liu ◽  
Yu Zhang ◽  
Zhongbo Yu
Keyword(s):  
Water Productivity ◽  
Virtual Water ◽  
High Water ◽  
Water Saving ◽  
Trade Patterns ◽  
Water Savings ◽  
Cropping Patterns ◽  
Water Flows ◽  
Water Right ◽  
Water Compensation

If products were traded from regions with relatively high water productivity to regions with relatively low water productivity, water saving could be achieved. In this study, two indices—physical water-saving efficiency (volume of water savings per cubic meter of virtual water flows) and economic water-saving efficiency (value of water savings per cubic meter of virtual water flows considering water right trading)—were proposed to analyze the efficiency of inter-regional virtual water flows related to crop trade in China. Results indicated that the volume of inter-regional virtual water flows was 1.61 × 109 m3, more than 90% of which was occupied by oil-bearing crops, cereals, and beans. In terms of physical efficiency, only cereals and vegetables presented negative values. All kinds of crop trades were economically efficient, while most crops’ economic water-saving efficiency was less than 10 × 103 Yuan/m3. The application of advanced water-saving technologies, the cultivation of new crop varieties, the adjustment of regional cropping patterns, or consumption and trade patterns, could contribute to more water savings and higher physical water-saving efficiency, while the possible social, economic, and environmental tradeoffs should be considered simultaneously. Water right trading and virtual water compensation could contribute to sustainable water consumption, and full-cost pricing should be adapted in the future.

Estimation of the virtual water trade between two Spanish regions: Castilla-la Mancha and Murcia

2010 ◽  
Vol 10 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Ángel De Miguel ◽  
Eloy García ◽  
Irene De Buestamante
Keyword(s):  
Water Flow ◽  
Food Processing ◽  
Virtual Water ◽  
Water Transfer ◽  
Water Efficiency ◽  
International Context ◽  
Water Flows ◽  
Spanish Regions ◽  
La Mancha ◽  
Virtual Water Flow

Virtual water is defined as the water needed to produce a product. We can use virtual water flow calculations to estimate the water efficiency of a country, as well as its economic dependence on water resources. Former studies on this area have focused on quantifying the virtual water flows between countries, in an international context. In this study we reduce the action framework to regions within a country, determining the virtual water balance between two Spanish regions: Castilla-La Mancha and Murcia. In 2004, Castilla-La Mancha exported to Murcia 2,453,442 tons of commercial products, from which 1,191,628 tons were agricultural goods. In terms of virtual water, it means 1,365 hm3, including food-processing, and industrial products. It is necessary to add 350 hm3 to the result, because of the water transfer (Tajo-Segura transfer) between the rivers basins of these regions, so the final virtual water number, in 2004, was 1,715 hm3. The other way round, Murcia exported in 2004 2,069,000 tons of products, from which 490,351 tons were agricultural goods. That supposes 712 hm3 of virtual water. Virtual water flow is unbalanced and displaced towards Murcia with a difference of 1,003 hm3.

scholarly journals Evaluating Cryospheric Water Withdrawal and Virtual Water Flows in Tarim River Basin of China: An Input–Output Analysis

2021 ◽  
Vol 13 (14) ◽  
pp. 7589
Author(s):  
Yang Yang ◽  
Shiwei Liu ◽  
Cunde Xiao ◽  
Cuiyang Feng ◽  
Chenyu Li
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Socioeconomic Development ◽  
Virtual Water ◽  
Water Withdrawal ◽  
Tarim River ◽  
Tarim River Basin ◽  
Input Output ◽  
Output Analysis ◽  
Water Flows

In Tarim River Basin (TRB), the retreat of glacier and snow cover reduction due to climate warming threatens the regional economy of downstream basins that critically depends on meltwater. However, the quantitative evaluation of its impact on multiple sectors of the socioeconomic system is incomplete. Based on compiled regional input–output table of the year 2012, this study developed a method to analyze the relationships between economic activities and related meltwater withdrawal, as well as sectoral transfer. The results show that the direct meltwater withdrawal intensity (DMWI) of agriculture was much higher than other sectors, reaching 2348.02 m3/10,000 CNY. Except for A01 (agriculture) and A02 (mining and washing of coal), the embodied meltwater withdrawal (EMW) driven by the final demand of other sectors was greater than direct meltwater withdrawal, and all sectors required inflows of virtual water (72.45 × 108 m3, accounting for 29% of total supply from cryospheric water resources) for their production processes in 2012. For sectors with high DMWI, improving water-use efficiency is an effective way to reduce water withdrawal. To some extent, the unbalanced supply of cryospheric water resources due to geographical segregation can be regulated by virtual water flows from water-saving to water-intensive sectors. Such decisions can affect the balance between socioeconomic development and environment conservation for long-term sustainability.

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