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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Water-gas shift: Characterization and testing of nanoscale YSZ supported Pt catalysts

Nano-scale Y-doped zirconium oxide materials were prepared with high surface areas (150-200 m(2)/g) and small nano-crystallites (<8 nm). A combination of XANES and EXAFS was used to show that ZrO2 exhibited the tetragonal phase, while the Zr0.5Y0.5O1.75 support displayed the cubic phase. A comparison with undoped zirconia suggests that the Zr0.9Y0.1O1.95 support was tetragonal in structure. A slight increase in d-spacing observed in HR-TEM for the Zr0.9Y0.1O1.95 support relative to undoped ZrO2, along with a shift to lower 2 theta in XRD, provide evidence that Y-doping caused macrostrain. STEM imaging confirmed that the Pt clusters ranged from 0.5 to 2 nm over all three supports. Catalyst reducibility was explored by H-2-TPR, XANES at the Zr K-edge, and TPR-XANES at the Pt L-III edge. A higher concentration of surface defects for the 0.5%Pt/Zr0.9Y0.1O1.95 catalyst relative to 0.5%Pt/ZrO2 was confirmed by DRIFTS of adsorbed CO, while a greater surface mobility of surface formate was suggested based on forward formate decomposition experiments in steam. The Y-doped Pt promoted catalysts displayed higher water-gas-shift activity relative to the 0.5%Pt/ZrO2 catalyst when the Y content was at or below 50%, with the best catalyst being 0.5%Pt/Zr0.9Y0.1O1.95. (C) 2015 Elsevier B.V. All rights reserved.

Pt/YSZ↗
DOE OSTI2016

Balancing global water availability and use at basin scale in an integrated assessment model

Water is essential for the world’s food supply, for energy production, including bioenergy and hydroelectric power, and for power system cooling. Water is already scarce in many regions of the world and could present a critical constraint as society attempts simultaneously to mitigate climate forcing and adapt to climate change, and to provide for a larger and more prosperous human population. Numerous studies have pointed to growing pressures on the world’s scarce fresh water resources from population and economic growth, and climate change. This study goes further. We use the Global Change Assessment Model to analyze interactions between population, economic growth, energy, land and water resources simultaneously in a dynamically evolving system where competing claims on water resources from all claimants—energy, land, and economy—are reconciled with water resource availability—from renewable water, non-renewable groundwater sources and desalinated water—across 14 geopolitical regions, 151 agriculture-ecological zones, and 235 major river basins. We find that previous estimates of global water withdrawal projections are overestimated. Model simulations show that it is more economical in some basins to alter agricultural and energy activities rather than utilize non-renewable groundwater or desalinated water. This study highlights the importance of accounting for water as a binding factor in agriculture, energy and land use decisions in IAMs and implications for global responses to water scarcity, particularly in the trade of agricultural commodities and land-use decisions.

basin↗
DOE OSTI2016

Drivers of Change in Managed Water Resources: Modeling the Impacts of Climate and Socioeconomic Changes Using the US Midwest as a Case Study

A global integrated assessment model including a water-demand model driven by socio-economics, is coupled in a one-way fashion with a land surface hydrology – routing – water resources management model. The integrated modeling framework is applied to the U.S. Upper Midwest (Missouri, Upper Mississippi, and Ohio) to advance understanding of the regional impacts of climate and socio-economic changes on integrated water resources. Implications for future flow regulation, water supply, and supply deficit are investigated using climate change projections with the B1 and A2 emission scenarios, which affect both natural flow and water demand. Changes in water demand are driven by socio-economic factors, energy and food demands, global markets and prices. The framework identifies the multiple spatial scales of interactions between the drivers of changes (natural flow and water demand) and the managed water resources (regulated flow, supply and supply deficit). The contribution of the different drivers of change are quantified regionally, and also evaluated locally, using covariances. The integrated framework shows that water supply deficit is more predictable over the Missouri than the other regions in the Midwest. The predictability of the supply deficit mostly comes from long term changes in water demand although changes in runoff has a greater contribution, comparable to the contribution of changes in demand, over shorter time periods. The integrated framework also shows that spatially, water demand drives local supply deficit. Using elasticity, the sensitivity of supply deficit to drivers of change is established. The supply deficit is found to be more sensitive to changes in runoff than to changes in demand regionally. It contrasts with the covariance analysis that shows that water demand is the dominant driver of supply deficit over the analysed periods. The elasticity indicates the level of mitigation needed to control the demand in order to reduce the vulnerability of the integrated system in future periods. The elasticity analyses also emphasize the need to address uncertainty with respect to changes in natural flow in integrated assessment.

climate change, water resources management, socio-↗
DOE OSTI2017

Effect of Leaf Water Potential on Internal Humidity and CO 2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure

The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2 , thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Here, our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. Lastly, the omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange measurements. Manufactures of leaf gas exchange measurement systems should incorporate leaf water potentials in measurement set-ups.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

A review of water valuation metrics: Supporting sustainable water use in manufacturing

In the manufacturing sector, water has been often considered too cheap to conserve. Such thinking relies on water valuations that limit the value of water to the price paid. Using such simple methods, the share of water cost to total manufacturing cost is significantly small, <3%. As a result, conserving water and enabling technology uptake is difficult to justify economically and slow to advance, hindering progress toward sustainable water use. However, the value of water to a manufacturer is far greater than the price paid. Valuations such as the true cost of water consider the additional in-plant treatment and energy costs and have been gaining greater traction in the manufacturing sector. However, true cost alone still undervalues water by not accounting for economic and social costs related to scarcity and environmental externalities. This paper makes the case and presents a framework for valuing manufacturing water beyond the price paid and the true cost. The proposed fuller valuation of manufacturing water takes into account the internal and opportunity costs associated with the realization of water risks. The paper follows with a review of a wide range of water valuation metrics, both at the specific industry level and regional/economy-wide level. The use of various valuation metrics incorporating the relationship between the change in value with change in water use, such as marginal value of water, shadow price, and elasticity at the specific industry level, has been limited in the U.S. manufacturing sector. Further, a limited number of studies exist on data-intensive subjective evaluation techniques such as computable general equilibrium modeling and input-output modeling for regional water valuation. After reviewing water value metrics, several recent case studies from manufacturers from the literature are presented to illustrate both the promise and challenges of a fuller valuation of water as proposed here. Some large multinational corporations have moved toward assessing the value of water via supply chain sustainability initiatives, environmental profit and loss accounting, estimating risk-adjusted values of water, hydro-economic modeling, natural capital asset valuation, and developing value chain indices. This paper provides policymakers and technology developers a framework for monetizing water value beyond its true cost and current metrics. If adopted, such fuller water valuations can help make the business case for the development and deployment of cost-effective water-conserving technologies, thereby improving the sustainability of the manufacturing sector with respect to water.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

U.S. Manufacturing Water Use Data and Estimates: Current State, Limitations, and Future Needs for Supporting Manufacturing Research and Development

Water is essential to manufacturing operations; without it, many facilities could not operate or meet production demands. Physical, reputational, and regulatory risks to water supplies compounded by climate change-induced impacts on hydrological conditions threaten the adequacy of water supplies for manufacturing. Manufacturing water use has not been a major focus of either water or manufacturing-related research. Research and development (R&D) aimed at helping manufacturers use water more sustainably and adapt to changing water conditions is needed to ensure a thriving sector and economy. However, the ability to identify R&D needs is severely limited due to a lack of current, statistically representative data on manufacturing water use and its environmental implications. In this Perspective, we outline four key questions to inform R&D on manufacturing use and highlight how the current state of water data in the United States does not support the adequate investigation of these questions. We make recommendations for the water data characteristics needed to explore the research questions and knowledgeably inform R&D on manufacturing water use.

McCall, James↗
DOE OSTI2017

Basic Research Needs for Energy and Water: Report of the Office of Basic Energy Sciences Basic Research Needs Workshop for Energy and Water

Water is precious; it has no substitute as a vital resource. It is essential not only for life, but also for practically all forms of economic activity. The food we eat, the clothes we wear, the goods we use, and the electricity we consume all require water. Water — in both quantity and quality — is one of the world’s most critical resources. The global importance of water presents enormous opportunity for innovation spurred by basic science to better understand at a fundamental level energy, water, and their interrelationship. Energy-water systems, whether manufactured or part of the natural world, exhibit extraordinary dynamics and complexities. To make possible a transformation to a future where fundamental processes underlying energy-water systems are quantified and harnessed for societal benefits, understanding of the chemical processes and materials underlying the interdependence of energy and water must be advanced. These interdependent energy and water issues (energy-water issues) intersect with national and international priorities. The challenges we face for energy-water systems are, in fact, an opportunity to shape a sustainable future for the nation and the world and present an enormous opportunity for fundamental energy science. Basic research — spanning chemistry, physics, geosciences, biosciences, and materials sciences — is essential to answering many questions related to energy and water systems. It is now clear that ensuring robust and secure energy and water systems will require a significant basic scientific research effort. Science questions that underpin water resiliency and water-energy systems span 12 orders of magnitude in length scale, from the nature and implications of hydrogen bonding, to the state and movement of water through aquifers. Addressing challenging questions requires advances and integration of basic chemical, geological, biological, material, and computational sciences. Recognizing the tremendous scope and scale of basic research needs in the energy-water domain, the U.S. Department of Energy’s Office of Science, Office of Basic Energy Sciences (BES), sponsored a workshop on “Basic Research Needs for Energy and Water,” which was held near Washington, D.C., January 4–6, 2017. Attended by more than 100 leading national and international scientific experts in chemistry, physics, materials sciences, biosciences, and geosciences related to the energy-water system, the workshop addressed basic research necessary to improve water use for industrial applications and energy production and to increase fit-for-purpose water availability and energy efficiency as well as crosscutting scientific research needs. The workshop identified four Priority Research Directions (PRDs) that will lay the foundation to better understand materials and processes relevant to energy-water issues and harness their potential for technological impact.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Plant Water Profiler: A Tool for Understanding Water Use, Cost and Savings Potential for Manufacturing Plants

In the 1746 Poor Richard’s Almanack, Benjamin Franklin published “When the well’s dry, we know the worth of water” (Franklin, 1746); industrial water users have begun to see the truth in these words as they examine the potential and reality of water scarcity becoming a significant business risk. Through the authors’ interactions with manufacturers via the U.S. Department of Energy’s Better Plants program and Strategic Analysis projects, they realized that manufacturing facilities often do not fully understand the risks to the water supply and the consequential risks to their business. The authors’ also noticed that many facilities do not know how their water is used (baselining), how they compare with their peers (benchmarking), the actual cost impacts of water use (true cost of water), and potential areas for water savings. This results in a lack of motivation and ability to identify and implement effective water-efficiency measures.The Plant Water Profiler Tool (PWP) was created to help manufacturing plant management address these issues by identifying and accounting for water use in manufacturing operations, helping determine the true cost of water, and providing some high-level estimates for peer comparison. The PWP uses a water mass balance and common engineering equations to estimate water use by each of the facility’s systems (e.g., differentiating process water use from cooling and restroom water use), even when no submetering data is available. This new tool also helps users identify possible areas for water savings and associated water and energy cost savings, making it a potentially useful resource for corporations conducting water assessments. Additionally, governments and private organizations can use the methodology behind this tool to design a survey to help build a database of industrial water use. This paper and corresponding presentation provide an overview of current industrial water use practices and tools, as well as the value of determining the true cost of water. It also briefly describes the methodology behind the tool, then focuses on its functionality through an industrial case study and lessons learned from implementing the case study.

Armstrong, Kristina O.↗
DOE OSTI2022

Desalinating a Real Hyper-Saline Pre-Treated Produced Water via Direct-Heat Vacuum Membrane Distillation

Membrane distillation (MD) is an emerging thermal desalination technology capable of desalinating waters of any salinity. During typical MD processes, the saline feedwater is heated and acts as the thermal energy carrier; however, temperature polarization (as well as thermal energy loss) contributes to low distillate fluxes, low single-pass water recovery and poor thermal efficiency. An alternative approach is to integrate an extra thermal energy carrier as part of the membrane and/or module assembly, which can channel externally provided heat directly to the membrane-feedwater interface and/or along the feed channel length. This direct-heat delivery has been demonstrated to increase single-pass water recovery and enhance the overall thermal efficiency. We developed a bench-scale direct-heated vacuum MD (DHVMD) process to desalinate pre-treated oil and gas "produced water" with an initial total dissolved solids of 115,500 ppm at a feed temperature ranging between 24 and 32 degrees C. We evaluated both water flux and specific energy consumption (SEC) as a function of water recovery. The system achieved a 50% water recovery without significant scaling, with an average flux >6 kg m-2 hr-1 and a SEC as low as 2,530 kJ kg-1. The major species of mineral scales (i.e., NaCl, CaSO4, and SrSO4) that limited the water recovery to 68% were modeled in terms of thermodynamics and identified by scanning electron microscopy and energy-dispersive X-ray spectroscopy. In addition, we further developed and employed a physics-based process model to estimate temperature, salinity, water transport and energy flows for full-scale vacuum MD and DHVMD modules. Model results show that a direct-heat input rate of 3,600 W can increase single-pass water recovery from 2.1% to 3.1% while lowering the thermal SEC from 7,800 kJ kg-1 to 6,517 kJ kg-1 in an unoptimized module. Finally, the scaling up potential of DHVMD process is briefly discussed.

brine↗
DOE OSTI2020

Changes in water vapor adsorption and water film thickness in clayey materials as a function of relative humidity

Abstract Soil water, with adsorbed water being an important component, plays an important role in fluid flow and chemical movement in the unsaturated zone. The adsorbed water consists of water film and interlayer water, and its content is related to the relative humidity (RH). This study theoretically and experimentally focuses on the variation in adsorbed water content in clayey materials as the RH changes. Based on a slit‐pore model, three types of water (water film, interlayer water, and capillary water) could be present in the water vapor adsorption process. The variation of water film is obtained from the analysis of interfacial forces, and then the total water content can be quantitatively subdivided into these three types of water for different RH values. The slit‐pore adsorption model was used with experimental measurements (water vapor adsorption and N 2 physisorption) to quantify the amounts and interrelationships of these three different types of water to six clayey materials, namely three clay minerals (kaolinite, montmorillonite, and illite–smectite mixed layer) and three clay‐rich sediments from the Jianghan Plain in China. The main results are that (a) the volumes of water vapor adsorption are much greater than those of N 2 adsorption except for kaolinite; (b) interlayer water largely dominates the growth of total water content in montmorillonite and results in a concentration of 0.090 ml g −1 at 95% RH; and (c) the minimum thickness of water film is calculated to be 0.23 nm, and the maximum value is one‐third of the pore width by considering the interfacial forces.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Every apple has a voice: using stable isotopes to teach about food sourcing and the water cycle

Abstract. Agricultural crops such as fruits take up irrigation and meteoric water and incorporate it into their tissue ( fruit water ) during growth, and the geographic origin of a fruit may be traced by comparing the H and O stable isotope composition ( δ 2 H and δ 18 O values) of fruit water to the global geospatial distribution of H and O stable isotopes in precipitation. This connection between common fruits and the global water cycle provides an access point to connect with a variety of demographic groups to educate about isotope hydrology and the water cycle. Within the context of a 1-day outreach activity designed for a wide spectrum of participants (high school students, undergraduate students, high school science teachers) we developed introductory lecture materials, in-class participatory demonstrations of fruit water isotopic measurement in real time, and a computer lab exercise to couple actual fruit water isotope data with open-source online geospatial analysis software. We assessed learning outcomes with pre- and post-tests tied to learning objectives, as well as participant feedback surveys. Results indicate that this outreach activity provided effective lessons on the basics of stable isotope hydrology and the water cycle. However, the computer lab exercise needs to be more specifically tailored to the abilities of each participant group. This pilot study provides a foundation for further development of outreach materials that can effectively engage a range of participant groups in learning about the water cycle and the ways in which humans modify the water cycle through agricultural activity.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

California Trees Seasonally Use Augmented Water Sources: Water Isotope Tracking in a Groundwater‐Dependent Ecosystem

Sustainable groundwater management must account for the needs of groundwater dependent ecosystems. To understand the relationship of ecosystems and seasonal water use, we studied the stable isotope composition (δ 18 O and δ 2 H) of water in streamside trees in a semi-arid streamside environment (Livermore, California, USA). We sampled seven trees at two sites every other month from April 2024 through April 2025 for tree xylem stable water isotope signatures. These data were compared to potential source waters: precipitation, imported surface water, soil water and regional groundwaters. Large daily precipitation events were found to be isotopically similar to regional groundwater and were thus treated as one water source. A Bayesian mixing model using stable water isotopes was used to determine the ratios of these three potential source waters (small daily precipitation events, groundwater/large daily precipitation events and imported water) present in tree xylem water. On average, tree water sources include 32% imported water (SD = 9%), 35% small daily precipitation events (SD = 10%) and 33% groundwater (SD = 3%), with significant seasonal variation (t summer-winter = 30.8, p < 0.01), particularly drawing more imported water (more than 55%) in the summer. While small daily precipitation events contribute only 10% of the total precipitation in our dataset, it represents a third of water used by trees. In addition, while these ecosystems are designated as groundwater dependent ecosystems, the trees use approximately one third imported water and even more during dry summer months. This approach provides water managers with a practical tool for quantifying ecosystem water needs, supporting data-driven decisions and regulatory compliance. While California's Sustainable Groundwater Management Act emphasizes supporting groundwater dependent ecosystems, it allows flexibility in demonstrating benefits. In conclusion, our methodology provides a way to document that management actions (such as managed aquifer recharge with imported water) deliver measurable co-benefits to GDEs.

Geosciences↗
DOE OSTI2021

The many-body expansion for aqueous systems revisited: III. Hofmeister ion – water interactions

We report a Many Body Energy (MBE) analysis of aqueous ionic clusters containing anions and cations at the two opposite ends of the Hofmeister series, viz. the kosmotropes Ca2+, SO42- and chaotropes NH4+ and ClO4- with 9 water molecules to quantify the how these ions in altering the interaction between the water molecules in their immediate surrounding. The current results are contrasted to the ones reported earlier for water clusters as well as for alkali metal and halide ion aqueous clusters of the same size, which lie in the middle of the Hofmeister series. Through this analysis, noteworthy differences between the MBE of kosmotropes and chaotropes were identified. The MBE of kosmotropes is dominated by ion-water interactions that extends beyond the 4-body term, the point at which the MBE of pure water converges. The percentage contribution of the 2- B to the total cluster binding energy is noticeably larger. The disruption due to the dominant ion results in weak, unfavorable water-water interactions. The MBE for chaotropes, on the other hand, was found to converge more quickly as it more closely resembles that of pure water clusters. Chaotropes exhibit weaker overall binding energies and ion-water interactions with more favorable water-water interactions, somewhat recovering the pattern of the 2-4 body terms exemplified by pure water clusters. More importantly, both kosmotropic and chaotropic ions exhibit an anticorrelation between the 2-B ion-water (I-W) and water-water (W-W) interactions as well as between the 3-B (I-W-W) and (I-W) interactions. The consideration of two different structural arrangements (ion inside and outside of a water cluster) suggests that fully solvated (ion inside) chaotropes disrupt the hydrogen bonding network in a similar manner as partially solvated (ion outside) kosmotropes and offer useful insights into the modeling requirements of bulk vs. an interface. Finally, the 2-B contribution to the total Basis Set Superposition Error (BSSE) correction for the kosmotropic and chaotropic ions follows the previously reported erf profile vs. intermolecular distance. When scaled for the corresponding dimer energies and distances, a single profile fits the current results together with all previously reported ones for the pure water and halide water clusters.

Herman, Kristina M.↗
NASA NTRS1999

Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water

The ability of West Indian manatees (Trichechus manatus) to move between fresh and salt water raises the question of whether manatees drink salt water. Water turnover rates were estimated in captive West Indian manatees using the deuterium oxide dilution technique. Rates were quantified in animals using four experimental treatments: (1) held in fresh water and fed lettuce (N=4), (2) held in salt water and fed lettuce (N=2), (3) acutely exposed to salt water and fed lettuce (N=4), and (4) chronically exposed to salt water with limited access to fresh water and fed sea grass (N=5). Animals held in fresh water had the highest turnover rates (145+/-12 ml kg-1 day-1) (mean +/- s.e.m.). Animals acutely exposed to salt water decreased their turnover rate significantly when moved into salt water (from 124+/-15 to 65+/-15 ml kg-1 day-1) and subsequently increased their turnover rate upon re-entry to fresh water (146+/-19 ml kg-1 day-1). Manatees chronically exposed to salt water had significantly lower turnover rates (21+/-3 ml kg-1 day-1) compared with animals held in salt water and fed lettuce (45+/-3 ml kg-1 day-1). Manatees chronically exposed to salt water and fed sea grass had very low turnover rates compared with manatees held in salt water and fed lettuce, which is consistent with a lack of mariposia. Manatees in fresh water drank large volumes of water, which may make them susceptible to hyponatremia if access to a source of Na+ is not provided.

Trichechus/metabolism↗
NASA NTRS2000

Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi)

Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2+/-0.1 l d(-1) and 123.0+/-6.8 ml kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na(+), K(+), and Cl(-) decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na(+):K(+) ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals.

Non-programmatic↗
NASA NTRS2016

Water Stress in Global Transboundary River Basins: Significance of Upstream Water Use on Downstream Stress

Growing population and water demand have increased pressure on water resources in various parts of the globe, including many transboundary river basins. While the impacts of upstream water use on downstream water availability have been analyzed in many of these international river basins, this has not been systematically done at the global scale using coherent and comparable datasets. In this study, we aim to assess the change in downstream water stress due to upstream water use in the world's transboundary river basins. Water stress was first calculated considering only local water use of each sub-basin based on country-basin mesh, then compared with the situation when upstream water use was subtracted from downstream water availability. Wefound that water stress was generally already high when considering only local water use, affecting 0.95-1.44 billion people or 33%-51% of the population in transboundary river basins. After accounting for upstream water use, stress level increased by at least 1 percentage-point for 30-65 sub-basins, affecting 0.29-1.13 billion people. Altogether 288 out of 298 middle-stream and downstream sub-basin areas experienced some change in stress level. Further, we assessed whether there is a link between increased water stress due to upstream water use and the number of conflictive and cooperative events in the transboundary river basins, as captured by two prominent databases. No direct relationship was found. This supports the argument that conflicts and cooperation events originate from a combination of different drivers, among which upstream-induced water stress may play a role. Our findings contribute to better understanding of upstream-downstream dynamics in water stress to help address water allocation problems.

Water↗