Probabilistic evaluation of the water footprint of a river basin: Accounting method and case study in the Segura River Basin, Spain

Water resource sustainable use assessment methodology and an impact factor analysis framework for SDG 6-oriented river basins: evidence from the Yellow River basin (Shaanxi section) in China

The rapid growth of developing countries has placed unprecedented pressure on water resources, severely hindering the realization of sustainable development goal 6 (SDG 6) in river basins. In this study, sustainable water resource utilization (SWRU) in the Yellow River basin (Shaanxi section) from 2005 to 2019 is evaluated through an analysis of water resource overload combined with the water footprint (WF) and the water planetary boundary (WPB) and an analysis of water resource utilization quality combined with the WF and city development index (CDI) based on the coupled coordination model. Then, the results are incorporated into the drive-pressure-state-impact-response framework to analyze the impacts of the socioeconomic system on SWRU and the feedback effect of related policies. The results show that there were obvious differences in the spatiotemporal evolution characteristics of the WF in different geographical units. The WF of Guanzhong first increased and then decreased, and the WF of Northern Shaanxi grew continuously. The water deficit state is increasing. Although the coordination level between the WF and CDI in the basin increased by 500.31%, it was characterized by nonequilibrium and volatility. Compared to water resource endowment, socioeconomic development and government policies have greater impacts on SWRU; furthermore, the influencing factors demonstrate spatial variability, revealing the complexity of achieving SDG 6 in the basin. As policy implications, adaptive water resource policies should be formulated on the basis of strengthening the overall basin management. This study provides a scientific basis for promoting the realization of SDG 6 through watershed water management.

Water resources management of large hydrological basins in semi-arid regions: Spatial and temporal variability of water footprint of the Upper Euphrates River basin

The existing water accounts for large-scale, semi-arid and transboundary river basins are usually lack of sufficient spatial-temporal elements of water use, a prerequisite for identifying potential water savings and for sustainable management of scarce water resources. This study aims to demonstrate value of water footprint (WF) accounting framework for such river basins with the case study of the Upper Euphrates River basin which is not only used as major food and energy production resource in Turkey but also a focal point for international conflict, diplomacy and dialogue in Middle East. The methodology is based on Water Footprint Assessment Manual which is published by Water Footprint Network. The study maps spatial-temporal variations of sectoral water use in the study area for the agriculture, domestic water supply and industry for the period of 2008-2019. The water footprint of the Upper Euphrates River basin is calculated as 27.4 Gm³, most of which is related to the agricultural activities. The downstream and lower plains of the study area exhibited a considerably high blue and grey agricultural WF, reaching 2397 and 349 mm, respectively. Several crops have substantially large WFs in the region such as cotton, wheat, pistachio, and barley. The analysis given in this study revealed importance of spatial-temporal disaggregated information in water accounting for sustainable management of water resources. These accounts can provide insights that were not available to the decision makers before, such as water saving opportunities, potential water efficiency and productivity benchmarks, strategic planning for various climatic conditions etc. These are the major values that water footprint accounting can introduce in water management in a large scale, semi-arid transboundary river basins.

Variability in Population Traits of a Sentinel Iberian Fish in a Highly Modified Mediterranean-Type River

Human pressures on water resources have been suggested as a driver of biological traits that induce changes in native fish populations. This study highlighted the interplay between environmental stress factors, mostly related to flow regulation, and the longitudinal river gradient in biological traits such as the growth, size structure and somatic condition of a sentinel fish, Luciobarbus sclateri. We found an increase in size-related metrics and somatic condition at population levels associated with downstream reaches, although fragmentation and habitat alteration, flow regime alteration and the abundance of non-native fish were also significantly involved in their variability. Age-related parameters and growth were only explained by flow regime alterations and the abundance of non-native fish species. The high plasticity observed in L. sclateri population traits suggests that this is a key factor in the species adaptability to resist in a strongly altered Mediterranean river basin. However, the interplay of multiple stressors plays an important role in fish population dynamics and could induce complex responses that may be essential for long-term monitoring in sentinel species.

Water Footprint and Virtual Water Trade: The Birth and Growth of a New Research Field in Spain

The growth in the number of studies applying and expanding the concepts of the water footprint and virtual water trade in Spain has generated a wealth of lessons and reflections about the scarcity, allocation, productive use, and management of water from the viewpoint of a semi-arid country. This paper reviews the evolution of this research field in Spain since its introduction in 2005 and reflects on its main contributions and issues of debate. It shows how these concepts can be useful tools for integrated water accounting and raising awareness, when used with certain precautions: (1) Supply-chain thinking, taking into account value chains and the implications of trade, generally ignored in water management, can help to address water scarcity issues and sustainable water use. (2) Green water accounting incorporates land use and soil management, which greatly influences hydrological functioning. (3) The grey water footprint indicator analyzes pollution from an ecosystem point of view and facilitates the understanding of the water quantity and quality relationship. (4) Apparent water productivity analysis, innovatively incorporated into Spanish studies, considers the economic and social aspects associated with water use. However, the decision-making context should be broader, contextualizing and complementing water information with other indicators.

Functional response of fish assemblage to multiple stressors in a highly regulated Mediterranean river system

Mediterranean rivers are characterised by strong environmental constrains and species-poor, highly endemic fish fauna. In Europe, these systems are exposed to multiple stressors due to extensive human activities. Studies on the effects of some stressors on riverine fish are available but complex responses of fish assemblages to interplay of flow alteration with physical habitat changes and invasive species have not been evaluated up to date. This study analysed the response of functional diversity of fish assemblages to multiple stressors in the Segura River system in the southern Spain. Fish assemblages were sampled in 16 sites in two consecutive periods (2009-2010 and 2013-2015). Subsequently, we assessed the responses of functional specialisation, originality and entropy (based on nine functional traits and abundances) as well as species richness and abundance to interplay of flow regime alteration and ecological status, fragmentation as well as non-native species abundance across spatial and temporal scales. The governing role of flow regime in structuring fish assemblage was superimposed on physical habitat changes, water quality deterioration and fragmentation as well as the presence of non-native fish species. We found an increase of species richness and abundance but decrease of functional specialisation and originality in river reaches with high level of base flow and more stable hydrological conditions. Opposite pattern was observed in reaches with severe reduction of base flow and marked inversion in the seasonal pattern of high and low flows. We postulate that the use of tools that consider the functional identity of the species as method to assess the effects of environmental alterations on fish biodiversity could improve conservation measures for Mediterranean fish fauna. Furthermore, design flows that mimic natural flow regime patterns characteristic for Mediterranean rivers are a promising tool to provide environmental conditions that would favour native fish within the assemblage and benefit their conservation.

The Irrigation Cooling Effect as a Climate Regulation Service of Agroecosystems

Agroecosystems provide a range of benefits to society and the economy, which we call ecosystem services (ES). These services can be evaluated on the basis of environmental and socioeconomic indicators. The irrigation cooling effect (ICE), given its influence on the land surface temperature (LST), is an indicator of climate regulation services from agroecosystems. In this context, the objective of this study is to quantify the ICE in agroecosystems at the local scale. The agroecosystem of citrus cultivation in Campo de Cartagena (Murcia, Spain) is used as a case study. Once the LST was retrieved by remote sensing images for 216 plots, multivariate regression methods were used to identify the factors that explain ICE. The use of a geographically weighted regression (GWR) model is proposed, instead of ordinary least squares, as it offsets the spatial dependence and gives a better fit. The GWR explains 78% of the variability in the LST, by means of three variables: the vegetation index, the water index of the crop, and the altitude. Thus, the effects of the change in land use on the LST due to restrictions on the availability of water (up to 1.22 °C higher for rain-fed crops) are estimated. The trade-offs between ICE and the other ES are investigated by using the irrigation water required to reduce the temperature. This work shows the magnitude of the climate regulation service generated by irrigated citrus and enables its quantification in agroecosystems with similar characteristics.

Monthly Allocation of Water Resources and Pollutant Loads in a Basin Based on the Water Footprint and Fallback Bargaining

The refined allocation of water resources and pollutant loads in a basin according to seasonal changes is an important measure for sustainable management. This study proposes a monthly water resource and pollutant load allocation model that is based on the water footprint and fallback bargaining. First, the water utilization and pollutant discharge demand and allocable resources are accounted for by taking their water footprints as indicators. Subsequently, various initial allocation schemes are designed based on several typical bankruptcy rules. Finally, with the goal of resource sustainability, the initial schemes are optimized by applying the fallback bargaining approach. The Huangshui River basin, which is located in Qinghai, China, is a typical seasonal basin with water use conflicts and it is considered for verifying the proposed methodology. The results show that the monthly allocation framework can effectively balance the water use and pollutant discharge demand of regions upstream and downstream in different seasons, improve the overall resource utilization efficiency in the basin, and ensure that the allocation each month reaches the Pareto optimum.

Water Footprint of Food Consumption by Chinese Residents

Water shortages are a worldwide problem. Virtual water and the water footprint link water resources, human beings and agricultural products, and are effective tools to alleviate water-resources stress. The production of agricultural products consumes a large amount of water, and food is the most basic consumer good for human survival, so it is very necessary to study the water footprint of residents’ food consumption, which is also the weak point of current research on virtual water and the water footprint. This paper aimed to conduct a comprehensive analysis on the water footprint of food consumption in China from the perspectives of urban and rural residents, per capita water footprint, water footprint structure and food consumption structure. The results revealed that the average water footprint of residents’ food consumption was 605.12 billion m3/year, basically showing an upward trend. Guangdong residents had the highest water footprint for food consumption due to the highest population and higher consumption of water-intensive foodstuffs such as grain and meat in their diet. The water footprint of Xizang residents’ food consumption was the lowest followed by Ningxia and Qinghai due to having the least population. The water footprint of food consumption consumed by urban residents was on the rise while that consumed by rural residents was on the decline in China, which was consistent with the changing trend of population. On the whole, the rural population consumed more virtual water embedded in food than the urban population. From the water footprint structure point, the contribution rate of the green water footprint is the largest, reaching 69.36%. The second is the gray water footprint and then the blue water footprint, accounting for 18.71% and 11.93%, respectively. From the perspective of the food consumption structure, grain and pig, beef and mutton consumption contributed significantly to the total water footprint of residents’ food consumption, contributing 37.5% and 22.56%, respectively. The study is helpful for water management and water allocation in rural and urban areas, improving agricultural technology to reduce the gray water footprint and optimizing food consumption structure, such as reducing the consumption of grain and meat.

Understanding agricultural water footprint variability to improve water management in Chile

Understanding water consumption is crucial for sustainable management of water resources. Under climate change scenarios that project highly variable water availability, the need for public policies that assure efficiency and equity in water resources is increasing. This work analyzes the case of the Cachapoal River agricultural basin (34°S 71°W), which presents temperature increases and a precipitation deficit, with a drought period that began more than eleven years ago having significantly decreased water availability. Water consumption in the basin for food production was determined from the agricultural water footprint (WF_agricultural), using the green (WF_green), blue (WF_blue) and gray water footprint (WF_gray) indicators, which were measured in the upper, middle and lower basin under conditions of climate variability (dry, wet and normal years). The greatest WF_agricultural was established in the dry year, with a total of 18,221 m³ t^-1, followed by 15,902 m³ t^-1 in the wet year and 14,091 m³ t^-1 in the normal year. Likewise, the greatest WF_blue and WF_gray, of 12,000 m³ t^-1 and 4934 m³ t^-1, respectively, were also observed in the dry year. The greatest WF_green, 2000 m³ t^-1, was calculated for a normal year. The 63% of agricultural area of the basin was covered by avocado (Persea americana), olive (Olea europaea), corn (Zea mays) and grape (Vitis sp) crops, which presented the greatest WF_agricultural. This water footprint data provides a quantitative basis for the assessment of water consumption and degradation, considering agricultural production and its multiple variables. The success of the application of these results lies in the use of indicators to understand change processes and complement future water allocation plans with more rational water management models.

An academic analysis with recommendations for water management and planning at the basin scale: A review of water planning in the Segura River Basin

Water resources management is particularly challenging in water-scarce basins, where low water availability is combined with a potential water demand exceeding the supply capacity of the natural system. This is the case of the Segura River Basin in south-eastern Spain. This paper aims at analysing the usefulness of incorporating new hydrological data and perspectives to improve the understanding of water availability and management and help promote more integrated water planning in the Segura Basin. In this basin, agriculture amounts to approximately 1366 hm³/year and accounts for 80% of the total blue water use. The forest and agriculture use of soil water amounts to 3065 and 1962 hm³/year, respectively. The unaccounted virtual water trade is also relevant and helps in mitigating water scarcity in the basin. The basin is a net virtual water-exporting region, with an average export of 1598 hm³/year, mainly in the form of fruits and vegetables, and imports approximately 1253 hm³/year, mainly related to feed for pig farms. Virtual water imports are four times larger than the disputed water transfer rate to the Segura Basin from other river basins. Water productivity analyses by sub-sectors are useful in understanding the economic rationale of the basin activities. Two types of agriculture coexist in the basin, namely, intensive industrial agriculture and occupational farming, which maintain the territory and landscape. From a Mediterranean country perspective, the analysis recommends considering climate fluctuations and temporal variability and trends of water availability and use, moving beyond the average values considered in river basin management plans. Groundwater reserve depletion continues to occur at a rate of 231 hm³/year, as water from wells is currently cheaper than using desalinated water in farms, and it does not cause boron-related water quality problems for irrigation. If socially costly administrative measures are not taken, groundwater reserve depletion will continue.

How much water is required for coal power generation: An analysis of gray and blue water footprints

Although water resource shortage is closely connected with coal-based electricity generation, relevant water footprint analyses remain limited. This study aims to address this limitation by conducting a water footprint analysis of coal-based electricity generation in China for the first time to inform decision-makers about how freshwater consumption and wastewater discharge can be reduced. In China, 1 kWh of electricity supply obtained 1.78 × 10^-3 m³ of gray water footprint in 2015, and the value is 1.3 times the blue water footprint score of 1.35 × 10^-3 m³/kWh. Although water footprint of 1 kWh of electricity supply decreased, the national total gray water footprint increased significantly from 2006 to 2015 with increase in power generating capacity. An opposite trend was observed for blue water footprint. Indirect processes dominated the influence of gray water footprint, whereas direct freshwater consumption contributed 63.6% to blue water footprint. Ameliorating key processes, including transportation, direct freshwater consumption, direct air emissions, and coal washing could thus bring substantial environmental benefits. Moreover, phosphorus, mercury, hexavalent chromium, arsenic, COD, and BOD₅ were key substances of gray water footprint. Results indicated that the combination of railway and water transportation should be prioritized. The targeted transition toward high coal washing rate and pithead power plant development provides a possibility to relieve environmental burdens, but constraints on water resources in coal production sites have to be considered.

Blue and Green Water Footprint Assessment for China—A Multi-Region Input–Output Approach

Research on blue and green water footprints (WF) for China has typically been carried out based on bottom-up and top-down approach using a single-region input–output table. However, this research typically lacks detail on the sectoral interrelationships which exist between China and its trading partners in other countries/regions of the world. Here, a multi-region input–output approach using the WIOD database was applied to quantify the blue and green WF for China in 2009. The quantification was conducted from both production (WFP) and consumption (WFC) perspectives. The results show that the total WFP for China in 2009 was 1152.2 km3, second only to India. At 1070.9 km3, China had the largest WFC volume in the world. The internal WF was 953.5 km3, taking the substantial share for both the WFC and WFP. Overall, China’s trade resulted in a net export of 53.5 km3 virtual water. In contrast, the agricultural sector resulted in a net import of 70.6 km3 virtual water to China, with United States, Brazil, and Canada acting as major suppliers. This study suggests that quantifying the WF of China at global level through a MRIO framework is a necessary step towards achieving sustainability for China’s water management.

Pharmaceutical grey water footprint: Accounting, influence of wastewater treatment plants and implications of the reuse

Emerging pollutants, including pharmaceutical compounds, are producing water pollution problems around the world. Some pharmaceutical pollutants, which mainly reach ecosystems within wastewater discharges, are persistent in the water cycle and can also reach the food chain. This work addresses this issue, accounting the grey component of the water footprint (GWF_P) for four of the most common pharmaceutical compounds (carbamazepine (CBZ), diclofenac (DCF), ketoprofen (KTP) and naproxen (NPX)). In addition, the GWF_C for the main conventional pollutants is also accounted (nitrate, phosphates and organic matter). The case study is the Murcia Region of southeastern Spain, where wastewater treatment plants (WWTPs) purify 99.1% of the wastewater discharges and there is an important direct reuse of the treated wastewater in irrigation. Thus, the influence of WWTPs and reuse on the GWF is analysed. The results reveal that GWF_P, only taking into account pharmaceutical pollutants, has a value of 301 m³ inhabitant^-1 year^-1; considering only conventional pollutants (GWF_C), this value increases to 4718 m³ inhabitant^-1 year^-1. So, the difference between these values is such that in other areas with consumption habits similar to those of the Murcia Region, and without wastewater purification, conventional pollutants may well establish the value of the GWF. On average, the WWTPs reduce the GWF_C by 90% and the GWF_P by 26%. These different reductions of the pollutant concentrations in the treated effluents show that the GWF is not only due to conventional pollutants, and other contaminants can became critical, such as the pharmaceutical pollutants. The reuse further reduces the value of the GWF for the Murcia Region, by around 43.6%. However, the reuse of treated wastewater is controversial, considering the pharmaceutical contaminants and their possible consequences in the food chain. In these cases, the GWF of pharmaceutical pollutants can be used to provide a first approximation of the dilution that should be applied to the treated wastewater discharges when they are reused for another economic activity that imposes quality restrictions. For the case of agriculture in the Murcia Region, the dilution required is 2 (fresh water) to 1 (treated wastewater), taking into account the pollution thresholds established in this work.