Water Footprint Calculation Research Articles

Towards improvement of grey water footprint assessment: With an illustration for global maize cultivation

The grey water footprint refers to the volume of water that is required to assimilate polluted water. It reflects the intensity of water pollution caused by water use for human activities. This study aims to address some major shortcomings associated with grey water footprint accounting in the literature and discuss several ways towards its improvement. Global maize production is used for illustration. The study specifically tackles three issues: the appropriate water quality standards for grey water footprint assessment; grey water footprint for multiple pollutants; and the influence of spatial resolution of the assessment on the level of grey water stress. A biophysical crop model is applied to quantify nitrogen and phosphorus losses to water in maize production on a global scale with a 0.5-degree spatial resolution. The study shows that the grey water footprint calculation is highly sensitive to the water standards applied. The results also suggest that the grey water footprint relating to nitrogen and phosphorus pollution caused by maize production alone has already exceeded their local water availability in many parts of the world. Grey water stress shows a more critical situation at the grid level than at the watershed level for maize cultivation because the former represents the local concentration whereas the latter gives the average situation of the whole watershed. This study highlights the need for standardizing the setting of water quality standards for a consistent grey water footprint assessment taking into consideration the diverse aquatic ecosystems and ambient water quality requirements across regions, as well as the presence of multiple pollutants in water bodies.

Water Footprint of Industrial Tomato Cultivations in the Pinios River Basin: Soil Properties Interactions

Industrial tomatoes are cultivated in about 4000 ha of the Pinios river basin (central Greece), providing significant income to the farmers. In this study, the water footprint (WF) of industrial tomatoes between planting and harvest was estimated in 24 different farms for three consecutive years. The selected farms were representative of the main agro-climatic zones and soil textural classes within the river basin. Green, blue and grey WF calculations were based on datasets of the experimental plots for each farm, including irrigation water volume, meteorological, soil, and crop yield data. The results showed that the WF of tomatoes ranged from 37 to 131 m3 water/ton tomatoes with an average of 61 m3/ton. The WF variation depended mainly on crop yield, local agro-climatic and soil conditions. The green, blue, and grey WF components averaged 13, 27 and 21 m3/ton, respectively. The results reveal the importance of WF in understanding how tomato production relates to the sustainable use of freshwater and pollution at local level.

Water Footprint Calculation on the Basis of Input–Output Analysis and a Biproportional Algorithm: A Case Study for the Yellow River Basin, China

In the Yellow River basin, China, ecosystems suffer from the overexploitation and utilization of water resources, resulting in various environmental impacts. Consideration must be given to both human and ecosystem water requirements in water resources management. A water footprint (WF) is a tool for estimating industrial, agricultural, commercial and household water requirements and for examining the impact of consumption on water resources. The study attempts to establish an approach to analyse the dynamic processes and driving forces that result in certain WFs. Using input–output tables for provinces and municipalities, we calculate water use coefficients, the total WF and the net external WF of consumption in China’s Yellow River Basin. A biproportional algorithm is employed to revise the input–output tables for analysing the temporal dynamics of the WF. The factor analysis and linear regression were used to analyse the main influencing factors of WF. Results indicate that the coefficient for water use by primary industries is highest and that coefficients for provincial water use differ significantly. Second, household consumption and residuals from capital accumulation constituted approximately half of the total WF of the Yellow River basin in 2002 and also differed significantly among provinces. Third, the ratio of the net external WF to the total WF increased, and the ratio of final consumption to the total WF declined during the period examined. Fourth, output by secondary industries correlated most strongly with the WF, followed by area under irrigation, per capita meat consumption, water consumption per 10,000-yuan increase in added value and population.

Water footprint calculation: application to urban water cycle

Water use impact assessment, also named water footprint, has an increasing interest and thus methodologies are quickly evolving within the frame of life cycle assessment. In this work, we proposed to apply an adaptation of Ridoutt and Pfister (Int J Life Cycle Assess 18(1):201–207, 2013) methodology to address both consumptive and degradative use of water for several options of urban water cycle management. We implemented several new endpoints such as ecotoxicity and human toxicity from USEtox, and aquatic acidification from IMPACT2002+. The assessment encompassed the life cycle of three urban water cycle scenarios. The functional unit was the distribution of one cubic meter of water to users.

Agronomic concepts in water footprint assessment: A case of study in a fertirrigated melon crop under semiarid conditions

This paper compares the assessment of previous methodologies to calculate blue and gray water footprint and includes agronomic concepts that reflect the semiarid scenarios of fertirrigated crops with low water quality. We describe how we have employed these methodologies in a three-year field experiment. The latter involves a fertirrigated melon crop under mineral fertilization, using eleven different N rates ranging from 11 to 393kgha−1N in semiarid conditions, where irrigation is necessary to maintain production. We found that the different methodologies do not consider the scenario where green water footprint is zero, because the effective rainfall is negligible, and the irrigation water has high salt content, requiring the application of larger volumes of water to avoid salt accumulation in the soil and consequent loss yield. We propose modifications to the calculation of water footprint to consider this scenario. In our calculation the blue water footprint includes: (i) the extra consumption of irrigation water that the farmer has to apply to compensate the lack of uniformity in drips discharge; (ii) the water requirement to consider percolation losses and salts leaching, which depends on the salt tolerance of the crop, soil and quality of irrigation water, needed to ensure the fruit yield. With respect to gray water footprint, all N sources susceptible to being lost were considered, the N fertilizer rate and N content in the irrigation water and in the soil (mineral N and mineralized N during the crop period). Therefore, besides considering all these parameters, our proposal takes into account the drained water, given with a water balance, and the nitrates amount below the roots and susceptible to being washed. The methodologies of previous studies underestimate the water footprint resulted in our experiment. With the new considerations proposed, the treatments with the optimum N dose obtained a total water footprint between 127.8 and 151.7m3t−1. Higher values than those were presented in the treatments with the least N dose (145.7 and 158.4m3t−1), although the highest values of water footprint were obtained in treatments with a N excess (226.0 and 355.0m3t−1).

The Importance of Individual and Territorial Differences on Water Footprint Calculations

The Importance of Individual and Territorial Differences on Water Footprint Calculations

Water Footprint in paddy rice systems. Its determination in the provinces of Santa Fe and Entre Ríos, Argentina

In the context of social responsibility and, of the directives aimed at an integral management of natural resources, the Water Footprint (WF) has been widely spread as an indicator that contributes to a safe and sustainable use of water. The purpose of this study was to determine the WF for rice production (WFR) in two rice-growing areas in Argentina: central-east Entre Ríos and Santa Fe. The calculation was made using the methodology proposed in The Water Footprint Assessment Manual, according to which the WF of a crop, in this case rice, represents the relation between the amount of water satisfying the evapotranspiration demand (CWU) and the field productivity. The WF has three components: green (WFgreen), associated with rain used by the crop (CWUgreen); blue (WFblue), related to underground or surface water that fulfils the evapotranspiration demand (CWUblue); and grey (WFgrey), related to the volume of water required to dilute the residues of pollutants generated from the crop production. To estimate the CWUblue and CWUgreen, a rice water balance model (RWM), specifically developed for continuous flooding irrigation, was applied. Based on daily data of precipitation, crop evapotranspiration and soil variables the model allows calculating gross irrigation depth, surface runoff due to precipitations, variation of water stored in the soil, and deep percolation. Four agricultural seasons were assessed: 2009/2010, 2010/2011, 2011/2012, and 2012/2013. In Entre Ríos, WF was 987m3ton−1 (44% WFgreen and 56% WFblue), whereas in Santa Fe it was 846m3ton−1 (36% WFgreen and 64% WFblue). In accordance with related work in the region, WFgrey was not considered. Although only CWU is part of the WF calculation, the other components of the water balance are necessary for rice production. The RWM model determined the consumptive use of the crop and distinguished blue water from green water, besides calculating the other parameters of the water balance. This made possible to show the inefficiencies in the system since precipitations are not fully used. The WFR, together with these components, is useful to make comparisons between different regions and it is a tool to promote water saving, provided that it is complemented with specific policies, such as the differential application of irrigation taxes or electric power rates.

Calculation of water footprint of the iron and steel industry: a case study in Eastern China

China is the largest producer of iron and steel in the world. This heavy industry is characterized by significant water consumption and numerous water-related hazards. In this study, we propose the use of water footprint instead of conventional indicators (fresh water consumption (FWC) per tonne of steel or water consumption (WC) per tonne of steel) for the iron and steel industry. Using an iron factory in Eastern China as an example, we develop a water footprint calculation model that includes direct and virtual water footprints. A system boundary analysis method is then proposed to develop a common and feasible industrial water footprint assessment methodology. Specifically, we analyze the characteristics of the iron and steel industry from a life cycle assessment perspective. A water risk assessment was performed based on the results of the water footprint calculations. The selected iron factory has a water consumption (blue water) footprint of 2.24 × 107 m3, including virtual water, and a theoretical water pollution (gray water) footprint of 6.5 × 108 m3 in 2011, indicating that the enterprise poses a serious risk to the water environment. The blue water and gray water footprints are calculated separately to provide more detailed water risk information, instead of adding these two indicators, which has less environmental significance.

Application of data quality indicator of carbon footprint and water footprint

To mitigate the impact of global warming on the environment, many governments, non-profit organizations, and enterprises have formulated relevant standards to assist enterprises in promoting carbon management, and to encourage the design and popularization of low-carbon products. These standards include: PAS 2050, ISO/TS 14067 and so on. Under these initiatives, enterprises try to disclose the carbon and water footprints of the products based on the life cycle. Some enterprises argue and debate that there exists uncertainty of the footprints calculation since the data collection is not systematically. To solve this problem, in this research, the calculation of carbon footprint and water footprint are evaluated with the data quality indicator (DQI) management system. The collected data is evaluated based on the footprint calculation methods. Also the pedigree matrix is constructed as an aide to solve the data uncertainty that included reliability, completeness, times, geography, and technologies differences. Through the DQI, the carbon footprint and water footprint are not only calculated simultaneously, but also correctly. The results could be the reference for products’ environmental improvement.

사과의 지역별 물발자국 비교와 물 리스크 대응 -충주와 거창 지역을 중심으로-

According to 2012 OECD environmental report, Korea was ranked as the first country of water stress. Water footprint is a method to calculate water usage during the life cycle of a product from material procurement through production to disposal to recycle and to quantify the load to water resources. In water footprint calculation, water consumption unit is used. Agricultural water use is over 48% so it is urgent to mange that area Korea needs to spread the discussion about water footprint as quickly as possible, for the study to prevent social and environmental problems due to water shortage. This paper, through water footprint calculation and comparison in Chungju and Geochang areas, looks to counter measures for water risk, targeting domestically-produced apple.

An environmental approach for the management and protextion of heavily irrigated regions

In this paper the results of a preliminary study that investigates water footprint (WF) concept, as a useful tool to address water management problems in cultivated areas are presented. The two basic methodologies reported in the literature, their applicability, benefits and challenges were previously analyzed and evaluated by Tsoukala et al. (2011). A WF calculation for the crops of Messara valley in Crete is presented, so as to examine its contribution to achieving effective agricultural policies. Messara is one of the most important agricultural regions in Greece that faces serious problems in order to meet crop irrigation demand. The conclusions drawn from this analysis showed that WF can provide a transparent framework for the identification of potentially optimal alternatives for efficient water use at river basin catchment level.

Calculation and Analysis of Water Footprint in Shunyi District of Beijing

The water footprint and consumption pattern is an effective tool for quantitifying the volume of water resources consumption in certain region [ ].Shunyi’s water footprint in the period 2006-2010 is calculated in this article from the view of virtual water. The general water footprint in Shunyi District at the year 2010 reached 790 million m3 and water footprint per capita was 536.48 cubic meters. Shunyi 's water resource quantity per capita was 501.27 m3 in the same year and the Water Scarcity Index was 1.98. The result of calculation shows that the water resource volume of exploitation in Shunyi District of Beijing has been beyond the water resources carrying capacity.

The Water Footprint Assessment of Ethanol Production from Molasses in Kanchanaburi and Supanburi Province of Thailand

This study aims to assess water footprint of ethanol production from molasses in Kanchanaburi and Suphanburi Provinces of Thailand, based on the water footprint concept methodology.The water footprint of ethanol from molasses can be calculated into three parts: sugar cane, molasses, and ethanol production. The green, blue, and grey water footprints of ethanol production from molasses in the Kanchanaburi Province are 849.7, 209.6, and 45.0 (m3/ton), respectively, whereas those of ethanol in the Suphanburi Province are 708.3, 102.9, and 64.8 (m3/ton), respectively. Study results depend on several factors such as climate, soil, and planting date. These are related and effective to the size of water footprint. Especially, if schedule of planting and harvest date are different, which causes the volume of rainfall to be different; these affect the size of water footprints. A limitation of calculation of grey water footprint from crop process has been based on a consideration rate of nitrogen only. Both provinces in the study area have their respective amount of the grey water footprint of molasses, and ethanol production is zero. The wastewater in molasses and ethanol production have a very high temperature and BOD, whereas the grey water footprint in this study is zero because the wastewater may be stored in pond, or it may be reused in area of factory and does not have a direct discharge into the water system. However, there is a risk for soil and ground water pollution.

Water footprint in Hungary

More and more news report on water-related extreme environmental phenomena. Some of these are natural, which are often beyond the human race. But others are definitely due to anthropogenic effects. I think the water footprint index is able to highlight national and international water-use processes and gives us the opportunity of organizing a sustainable, consumer-, environmental- and governancefriendly management. 81% of the fresh water withdrawal is from surface water bodies in the EU. In Europe as a whole, 44% of abstraction is used for energy production, 24% for agriculture, 21% for public water supply and 11% for industry. Public water supply is confined to ground waters. To the water resources related human activity caused qualitative and quantitative amortisation will grow worse in the foreseeable future due to the climate change. Beside seasonal differences the sectoral differences are increasingly becoming critical between different areas, such as Southern and Western Europe. The former, wrong agricultural support system has worsened the situation since it gave financial aid for the used improper techniques of water-intensive crop cultivation. By today, this seems to be solved. Public water abstraction is affected by manyfactors, of which mostly are based on social situation and habits, but technological leakage receives a big role as well. Interesting, that for example the residents’water consumption in Eastern Europe decreased because price were raised and regular measurements were introduced. But in Southern Europe it increased due to tourism in the past period. Industrial water withdrawal decreased across Europe because of the decline of industry and the development of technologies. According to the European Environment Agency (EEA), the Union needs a sustainable, demand-driven leadership which focuses on the preservation and use efficiency. This have already appeared in politics and legal administration as well. Current research calls the attention to the significance and difficulties of this kind of domestic estimation presented trough the water footprint calculation of bread and pork in Hungary. The received data indicate the domestic water consumption trends in a modern approach. There is no doubt for me about the urgent necessity of water footprint calculation because as a result innovative, sustainability supported environmental, social, economical, and political relationships can be created – not just on local, regional or national level, but on interregional, European and even global stage.

Water balance of global aquifers revealed by groundwater footprint

Groundwater is a life-sustaining resource that supplies water to billions of people, plays a central part in irrigated agriculture and influences the health of many ecosystems. Most assessments of global water resources have focused on surface water, but unsustainable depletion of groundwater has recently been documented on both regional and global scales. It remains unclear how the rate of global groundwater depletion compares to the rate of natural renewal and the supply needed to support ecosystems. Here we define the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services) and show that humans are overexploiting groundwater in many large aquifers that are critical to agriculture, especially in Asia and North America. We estimate that the size of the global groundwater footprint is currently about 3.5 times the actual area of aquifers and that about 1.7 billion people live in areas where groundwater resources and/or groundwater-dependent ecosystems are under threat. That said, 80 per cent of aquifers have a groundwater footprint that is less than their area, meaning that the net global value is driven by a few heavily overexploited aquifers. The groundwater footprint is the first tool suitable for consistently evaluating the use, renewal and ecosystem requirements of groundwater at an aquifer scale. It can be combined with the water footprint and virtual water calculations, and be used to assess the potential for increasing agricultural yields with renewable groundwaterref. The method could be modified to evaluate other resources with renewal rates that are slow and spatially heterogeneous, such as fisheries, forestry or soil.

A new water footprint calculation method integrating consumptive and degradative water use into a single stand-alone weighted indicator

Purpose A complete assessment of water use in life cycle assessment (LCA) involves modelling both consumptive and degradative water use. Due to the range of environmental mechanisms involved, the results are typically reported as a profile of impact category indicator results. However, there is also demand for a single score stand-alone water footprint, analogous to the carbon footprint. To facilitate single score reporting, the critical dilution volume approach has been used to express a degradative emission in terms of a theoretical water volume, sometimes referred to as grey water. This approach has not received widespread acceptance and a new approach is proposed which takes advantage of the complex fate and effects models normally employed in LCA.

Considerations on methodological challenges for water footprint calculations

We have investigated how different approaches for water footprint (WF) calculations lead to different results, taking sugar beet production and sugar refining as examples. To a large extent, results obtained from any WF calculation are reflective of the method used and the assumptions made. Real irrigation data for 59 European sugar beet growing areas showed inadequate estimation of irrigation water when a widely used simple approach was used. The method resulted in an overestimation of blue water and an underestimation of green water usage. Dependent on the chosen (available) water quality standard, the final grey WF can differ up to a factor of 10 and more. We conclude that further development and standardisation of the WF is needed to reach comparable and reliable results. A special focus should be on standardisation of the grey WF methodology based on receiving water quality standards.

基于投入产出方法的甘肃省水足迹及虚拟水贸易研究

随着社会化进程的加快,地处西北内陆的甘肃省正面临日益严峻的水资源短缺危机,社会经济发展受到一定程度的制约,水生态环境也呈现出恶化的趋势。水足迹是近年来提出的衡量人类活动对于水生态系统影响的指标,能够帮助决策者制定水资源管理及保护的政策,从而实现地区水资源的可持续利用。运用单区域投入产出方法计算并分析了甘肃省1997、2002和2007年第一产业、第二产业和第三产业部门的虚拟水强度、水足迹以及虚拟水贸易情况。结果显示:(1)甘肃省第一产业的虚拟水强度最高,但呈现出逐年下降的趋势,水足迹也因此有所下降;(2)虚拟水贸易方面,甘肃省以虚拟水净出口为主,尤其是第一产业,每年虚拟水净出口量约全省总水资源量的10%。建议甘肃省继续巩固已有的节水成果,调整产业结构,大力发展节水型产业和高新技术产业。同时建议适当调整贸易格局,合理控制虚拟水出口,以缓解当地水资源短缺危机,保障地区水安全与生态安全。;In recent decades, China's fast economic and social development has put a heavy burden on its water demand. Located in the northwest of China, Gansu Province is facing more and more serious water crisis. Waterfootprint is an indicator that is used to measure the water use derived from the consumed products. The water footprint concept will help the policymakers to make more rational policies for water resources management.Another relevant concept is the virtual water, which measures the embodied water in the traded products. For water scarce regions, the virtual water import of water intensive products will relieve the local pressure for water supply. Four methods can be used for the water footprint calculation, in which an input-output model provides a reliable and constantly updated framework for the disaggregated sectors. The quantification results are ready for the local government to carry out a better water resource management practice. This paper presents a framework of calculating and evaluating the water footprint and the virtual water trade of three sectors in Gansu Province with a single regional input-output model. <br> The results showed that the virtual water intensity (water use per final demand, m³/Yuan) for the primary sector is the highest among the three sectors. However, the primary sector contributes most to the decrease of the total virtual water intensity in 2007. The primary sector also has the highest direct water use rate (80%), which is calculated as the proportion of direct virtual water intensity to the total virtual water intensity. While the direct water use rate of the second and third sectors is under 20%. The above mentioned results indicate that reducing the agricultural water use is one of the key measures to the water foot print reduction.Compared to the water footprint in 1997, the water footprint of the three sectors all increased in 2002 (from 11.9billion m³ to 14.5 billion m³). However, the water footprint has seen a sharp decrease in 2007. It can be concluded that the main reason of the water footprint decrease is the successful water saving practice in agriculture.<br> As for a region suffering from water scarcity, externalizing the water footprint is one of the methods to alleviatethe region's pressure for water supply. The proportion of the external water footprint to the total water footprint has been increasing for the three years considered in Gansu Province. However, the external water footprint of the primary sector only accounts for 10% of the water footprint of the primary sector, which means that the food demand in Gansu Province largely depends on its own production. In addition, Gansu Province continuously exported its agricultural virtual water to other regions for the three years considered. In 2007, the virtual water export of the primary sector amounts to 10% of the total water resource and 25% of the total water use in the Province.The paper finally suggests that the policymakers in Gansu Province should keep reinforcing the water saving achievement, adjusting the industrial structure and trade patterns, as well as seeking for the possibility of the virtual water strategy for the province.

Calculation and analysis of water footprint in Beijing City

Individual or community water footprint(WF) is defined as the total volume of water used to produce goods and services consumed by the individual or community.Virtual water content of a product(a commodity,good or service) is the volume of water used to produce the product.It is the sum of water used in the various stages of the production chain.Total water footprint(TWF) includes real water consumption,and more importantly virtual water consumption.By analyzing the volume and structure of WF,the consumption of water resources in any given region in terms of finished products can be determined.This paper calculated TWF of Beijing City for 2002 based on water input-output table.It also analyzed TWF composition in the city.The analysis showed that Bei-jing's TWF in 2002 was 8.626 billion m3.About 70% of TWF was used in resident consumption and 30% in government consump-tion.The per capita average WF of Beijing was 606.208 m3,that of urban residents was 537.690 m3 and the per capita average WF of rural residents was 197.123 m3.Real water consumption accounted for 8% of TWF,whereas virtual water consumption accounted for 92% of TWF.Virtual water net inflow was 1.498 billion m3,which accounted for 17.4% of TWF.The results illustrated that virtual water accounts for the bulk in the water consumption structure.Percent of entity water of Beijing was very small.Because of differ-ences in production chains and trades,the content of virtual water in commodities and services varied significantly.Virtual water import reduced possessed water resources in Beijing.However,the volume of water consumption did not reduce the pressure on wa-ter resources,which just was transferred to the surrounding regions.This paper provided valuable modes of water-saving and water recourses management in Beijing.

The real water consumption behind drinking water: The case of Italy

The real amount of drinking water available per capita is a topic of great interest for human health and the economic and political management of resources. The global market of bottled drinking water, for instance, has shown exponential growth in the last twenty years, mainly due to reductions in production costs and investment in promotion.This paper aims to evaluate how much freshwater is actually consumed when water is drunk in Italy, which can be considered a mature bottled-water market. A Water Footprint (WF) calculation was used to compare the alternatives: bottled and tap water. Six Italian brands of water sold in PET bottles were inventoried, analysed and compared with the public tap water of the city of Siena, as representative of the Italian context.Results showed that more than 3 L of water were needed to provide consumers with 1.50 L of drinking water. In particular, a volume of 1.50 L of PET-bottled water required an extra virtual volume of 1.93 L of water while an extra 2.13 L was necessary to supply the same volume of tap water. These values had very different composition and origin. The WF of tap water was mainly due to losses of water during pipeline distribution and usage, while WF of bottled water was greatly influenced by the production of plastic materials. When the contribution of cooling water was added to the calculation, the WF of bottled water rose from 3.43 to 6.92 L. Different strategies to reduce total water footprint are discussed.