Emerging trends in global freshwater availability

Exacerbated anthropogenic water pollution under climate change and urbanization

Anthropogenic water pollution severely threatens human society worldwide, yet the water pollution induced by combined sewer overflow (CSO) remains unclear within climate change and urbanization. Hence, this study integrated the general circulation model (GCM) and shared socioeconomic pathway (SSP) projections with water quality modeling, to analyze spatiotemporal patterns and future trends of CSO-induced water pollution under changing environments. Results demonstrated that the given area (Dresden, Germany) encountered significant CSO-induced pollution, with 14,860 kg (95 % confidence interval, CI: 9,040-15,630 kg) of particulate matter (SS), organic compounds (COD, TN, TP), and pharmaceuticals (Carbamazepine, Gabapentin, Ciprofloxacin, Sulfamethoxazole) being discharged annually. Climate change and urbanization exacerbated the severity of CSO-induced pollution, causing the discharged pollutants to reach a maximum annual load of 34,900 kg (CI: 21,400-44,100 kg), with up to 82.19 % of organic compounds and 75.28 % of pharmaceuticals being discharged by the top 25 % of extreme CSOs. GIS-based spatial analysis indicated the regional heterogeneities of CSO-induced pollution, the high-frequency CSOs were predominantly located in highly-impervious areas, while the high-load discharges mainly occurred in densely-populated areas. Scenario analysis revealed stronger temporal variabilities of CSO-induced pollution in the future, with the seasonal anomalies of discharged loads ranging from -86.18 % to 76.89 %. In addition, pharmaceutical pollution exhibited significant uncertainties under changing environments, and the CI of discharged load expanded by up to 131.71 %. The methods and findings herein yielded further insights into water quality management in response to changing environments.

Sustainable water allocation under climate change: Deep learning approaches to predict drinking water shortages

Addressing sustainable urban water supply has become one of the most critical challenges for modern megacities, particularly in arid and semi-arid regions where rapid urbanization and climate change converge to exacerbate resource scarcity. Tehran, a metropolis under mounting water stress, exemplifies this global crisis. With population pressures, migration, poor urban planning, and inadequate environmental management intensifying the demand for water, reliance on groundwater surged to over 51 % of the city's total supply by 2021. This unsustainable dependence is compounded by severe aquifer depletion, now declining at an alarming rate of 32 cm annually. This study adopts advanced machine learning approaches to provide a forward-looking, integrative approach to understanding and mitigating the impacts of urban centralization, land-use mismanagement, and climate variability on Tehran's water resources. By leveraging hybrid simulation models, combining Recurrent Neural Networks (RNN) and Long Short-Term Memory (LSTM) models with three optimization techniques (i.e. Fire Hawk Optimizer (FHO), Whale Optimization Algorithm (WOA), and Horse Optimization Algorithm (HOA)) this research offers a powerful tool for managing water allocation across five critical dam reservoirs and the Tehran aquifer. Our analysis reveals that the RNN-FHO model demonstrates superior performance in predicting dam inflows, while the RNN-WOA model excels in forecasting groundwater table fluctuations, providing a vital roadmap for water resource planners. We developed a robust conceptual model to address anticipated drinking water shortages by supplementing surface water with groundwater resources. To simulate future conditions, we employed three state-of-the-art climate models (MRI-ESM2, CNRM-CM6-1, and BCC-CSM2) across three emission pathways (SSP1.26, SSP2.45, and SSP5.85) for the period 2021-2050. The projections indicate a troubling trend: dam inflows could decline by 8% in the most optimistic scenario and by 11 % in the worst case. Furthermore, by 2030, water demand in Tehran is expected to exceed 2.2 BCM, intensifying pressure on groundwater resources and necessitating large-scale water transfers. Excessive groundwater extraction, ranging from 100 to 300 MCM, would result in drastic aquifer drawdowns of 46-171 cm, threatening both hydrological stability and environmental health. This study highlights the critical need for a paradigm shift in water management practices. A strategic approach, encompassing reductions in per capita water consumption, extensive recycling, improved use of treated effluent in urban landscapes, and optimized water allocation, is essential to avert a looming water crisis. The methodologies and insights presented in this study offer transformative solutions for water-stressed urban environments worldwide.

Transformations in a hypersaline lake: Examining the linkages between water level changes and Aeolian dust generation

The decline of hypersaline lakes, such as Maharloo Lake, presents significant ecological challenges. That highlights the need to comprehensively analyze the changing dynamics driven by human activities and climate change. Satellite imagery analysis from 1987 to 2022 reveals that the surface area of Maharloo Lake has decreased from 270 to 252 square kilometers due to land use changes. Moreover, the water level of the lake has declined by 30% during the wet season (May) and 90.2% during the dry season (October). The primary factors contributing to this decline include changes in temperature, potential evapotranspiration, excessive groundwater extraction, and the diversion of surface water for agriculture and urban development. These changes have transformed Maharloo Lake from a permanent to a seasonal lake, leading to an increase in the overall extent of barren, saline lands. The lake sediments are predominantly composed of fine-grained, destructive deposits with chemical salts, with over 90% being silt and clay. The average maximum wind speed and threshold erosion velocity indicate a reduced role of wind in eroding the lake's surface sediments, and the low levels of fine particulate matter (PM2.5) and Total Suspended Particulates (TSP) particles around the lake suggest the sediments are resistant to wind erosion and have not been a significant source of dust storms thus far. Understanding the nature of the sediments and their sensitivity to wind erosion, as well as the influence of the erosive wind factor in the occurrence of dust storms, is crucial. One cannot uniformly consider all lakes or dried lake beds as sources of dust storms based solely on changes in water levels.

Efficient direction-independent 3D spiral fog collector

Inspired by the natural structures of cacti and desert beetles, a novel three-dimensional (3D) high-efficiency fog collector is proposed. This design integrates a unique macro-structural configuration with a surface wettability gradient that remains independent of the fog flow direction. The fog collector adopts an integral spiral structure, with superhydrophilic triangular protrusions uniformly distributed across its surface. Under optimized design conditions, with a folding angle of 60 degrees, the collector features 23 superhydrophilic protrusions, each measuring 2.5 × 5 mm. Under these conditions, the fog collection efficiency reaches 0.5057 g cm-2 min-1. Furthermore, to assess the practical feasibility of the fog collector, a series of experiments, including sand impact and chemical resistance tests, were conducted. The experimental results show that the contact angle of the fog collector's surface remains high, indicating its excellent stability and durability. The fog collector not only uses a low-cost aluminum plate as the base material but also incorporates a simple and efficient preparation process, significantly enhancing its design feasibility and practicality. The results presented in this study offer a novel approach to designing high-efficiency fog collectors that are unaffected by the direction of fog flow.

A novel generative adversarial network and downscaling scheme for GRACE/GRACE-FO products: Exemplified by the Yangtze and Nile River Basins

The coarse spatial resolution of about 300 km in Total Water Storage Anomalies (TWSA) data from the Gravity Recovery And Climate Experiment (GRACE) and its follow-on (GRACE-FO, hereafter GRACE) missions presents significant challenges for local water resource management. Previous approaches to addressing this issue through statistical downscaling have been limited by the reliance on the scale-invariance assumption, residual correction, hydrological models, and a lack of consideration for spatial correlations among the TWSA grids. This study introduces the DownGAN generative adversarial network, which downscales GRACE TWSA to 25 km, as exemplified in the Yangtze River Basin (YRB) and the Nile River Basin (NRB). Additionally, we propose a novel downscaling scheme to address the above limitations. DownGAN receives static and dynamic variables as inputs while considering their potential time-delay effects. The downscaled TWSA is validated using a synthetic example, in-situ runoff, groundwater levels, and two hydrological models. The potential benefits of the downscaled TWSA in closing the water balance budget and monitoring hydrological droughts in the YRB and NRB are explored. The synthetic example indicates that DownGAN trained using the proposed downscaling scheme can downscale the YRB and NRB's TWSA from 1° to 0.5° and 0.25°, respectively. DownGAN outperforms RecNet, a fully convolutional neural network, producing continuous, consistent, and realistic downscaled TWSA. The downscaled TWSA exhibits high correlations with the runoff and groundwater levels in the YRB and NRB, respectively. In addition, DownGAN demonstrates better performance in closing the water balance budget and monitoring drought events in both the YRB and NRB than HR GRACE mascon products, as evidenced by its higher correlations with the total water storage changes derived from the water balance equation and two drought indices, respectively. DownGAN is adaptable to other downscaling tasks and regions, offering a flexible downscaling factor, minimal assumptions, cost-effectiveness, and realistic predictions.

Health and Environmental Impacts of Cyanobacteria and Cyanotoxins from Freshwater to Seawater

Cyanobacterial harmful algal blooms (cyanoHABs) are a natural phenomenon produced mainly by the interaction between natural and anthropogenic events. CyanoHABs are characterized by the production of cyanotoxins that can have harmful effects on different species within the food web and even affect human health. Among the most prevalent toxin groups worldwide are microcystins (MCs), anatoxins (ATXs), cylindrospermopsins (CYNs) and nodularins (NODs), which are characterized as toxins with hepatotoxic, neurotoxic, and cytotoxic effects. This review summarizes and analyzes research on the influence of cyanoHABs, the main toxin-producing cyanobacteria and the most prevalent cyanotoxins in freshwater and marine bodies, highlighting their global occurrence, toxicology, and bioaccumulation dynamics in vectors of the food web, and the main cases of acute and chronic intoxications in humans. This review is useful for understanding the dynamics of cyanoHABs' interaction with the ecosystem and their impact on human health, and how the implementation of a surveillance and management framework for cyanobacteria and cyanotoxins could generate vital information for stakeholders to establish health guidelines on the risks and hazards of cyanoHABs for the ecosystem and humans.

Constructing interconnected hierarchical porous structures and nitrogen-doped carbon nanofibers for superior capacitive deionization

Capacitive Deionization (CDI) has emerged as a sustainable and efficient method for desalinating low-salinity water sources. However, CDI materials are often limited by insufficient surface area, slow electron/ion transport, and suboptimal electrolyte wettability, which restrict desalination capacity and rate. Herein, we simultaneously construct interconnected hierarchical porous structures and nitrogen-doping in carbon nanofibers by pyrolyzing polymer nanofiber precursors embedded with Zeolite Imidazolate Framework-8 (ZIF-8) nanoparticles. ZIF-8 nanoparticles serve not only as precise pore-forming templates but also act as a rich source of nitrogen for doping the carbon nanofibers. We optimize the pore structure and nitrogen content of the carbon nanofibers by tuning the diameter of ZIF-8 nanoparticles within the polymer nanofiber precursor, thereby achieving superior CDI performance. This unique structure not only substantially increases the specific surface area and significantly enhances mass transfer processes, but also introduces abundant nitrogen into the porous carbon fibers. This improves their hydrophilicity, adjusts their electronic structure, increases active sites, and greatly boosts the electrodes' adsorption capacity and desalination efficiency. An electrode constructed from the optimized porous nanofibers with a larger specific surface area (LPCNF) achieves a peak desalination capacity of 68.11 mg/g. Furthermore, the electrode maintains a high salt adsorption capacity (SAC) retention of 93.4 % after 50 cycles, significantly outperforming conventional materials such as activated carbon, graphene, and carbon nanotubes. Overall, the developed method optimizes both the pore structure and enhances the nitrogen content, providing a novel strategy for developing high-performance CDI electrode materials.

Significant expansion of small water bodies in the Dongting Lake region following the impoundment of the Three Gorges Dam

Small water bodies (SWBs) are vital for freshwater biodiversity and ecosystem services, yet they remain underrepresented in research compared to larger water bodies, despite being particularly vulnerable to anthropogenic activities and climate change. Advances in satellite remote sensing, particularly the Joint Research Centre's Global Surface Water (JRC-GSW) dataset derived from Landsat imagery, provide an unprecedented opportunity for high-resolution and long-term analysis of SWBs spatio-temporal dynamics. This study leverages the JRC-GSW dataset to assess the impacts of the Three Gorges Dam (TGD) on SWBs in the Dongting Lake region, focusing on maximum and minimum water extents during wet and dry seasons pre- and post-dam impoundment. Results reveal significant shrinkage and fragmentation of water bodies post-TGD, particularly during the dry season and predominantly in the northwest region. The number and total area of SWBs increased post-TGD by 16%-83% and 17%-28%, respectively, accompanied by intensified seasonal variability. Enhanced fragmentation was especially pronounced during the dry season. Weak correlations between water body dynamics and hydrometeorological factors highlight the dominant influence of anthropogenic activities, particularly dam operations, in shaping these patterns. These findings emphasize the importance of high-resolution, long-term satellite data in monitoring SWBs dynamics and inform sustainable water resource management and biodiversity conservation in regions affected by large-scale infrastructure projects.

Organic Micropollutants in Waterways of a Large-Scale Water Diversion Project: Insights from Nontarget Screening and "Community" Analysis

Large-scale water diversion projects are essential for meeting the needs of water-stressed regions, necessitating an evaluation of their impact on water quality and aquatic ecosystems. This study provides the first snapshots of organic micropollutants (OMPs) along the 1466 km Eastern Route of China's South-to-North Water Diversion Project. Using nontarget analysis with ultrahigh-performance liquid chromatography and high-resolution mass spectrometry, we identified and quantified 357 OMPs from water samples collected during the water diversion period (WDP) and the nonwater diversion period (NWDP). The OMPs included 136 household compounds, 112 agricultural compounds, 102 industrial compounds, and 7 traffic markers. Significant regional variations in OMP concentrations and compositions were observed during the NWDP due to diverse local pollution sources along the route. However, such differences were reduced during the WDP, likely due to water transfer. OMP diversity varied substantially during the NWDP but was more stable with less distance decay during the WDP. Network analysis indicated closer relationships between the OMPs during the WDP, suggesting a more consistent spatial distribution. The source water overwhelmingly influenced the water quality along the diversion route. These findings underscore the need for ongoing assessments of the impact of water diversion on regional water quality and ecosystems.

ABA-auxin cascade regulates crop root angle in response to drought

Enhancing drought resistance through the manipulation of root system architecture (RSA) in crops represents a crucial strategy for addressing food insecurity challenges. Abscisic acid (ABA) plays important roles in drought tolerance; yet, its molecular mechanisms in regulating RSA, especially in cereal crops, remain unclear. In this study, we report a new mechanism whereby ABA mediates local auxin biosynthesis to regulate root gravitropic response, thereby controlling the alteration of RSA in response to drought in cereal crops. Under drought conditions, wild-type (WT) plants displayed a steep root angle compared with normal conditions, while ABA biosynthetic mutants (mhz4, mhz5, osaba1, and osaba2) showed a significantly shallower crown root angle. Gravitropic assays revealed that ABA biosynthetic mutants have reduced gravitropic responses compared with WT plants. Hormone profiling analysis indicated that the mhz5 mutant has reduced auxin levels in root tips, and exogenous auxin (naphthaleneacetic acid [NAA]) application restored its root gravitropic defects. Consistently, auxin reporter analysis in mhz5 showed a reduced auxin gradient formation in root epidermis during gravitropic bending response compared with WT plants. Furthermore, NAA, rather than ABA, was able to rescue the compromised gravitropic response in the auxin biosynthetic mutant mhz10-1/tryptophan amino transferase2 (ostar2). Additionally, the maize ABA biosynthetic mutant viviparous5 (vp5) also showed gravitropic defects and a shallower seminal root angle than WT plants, which were restored by external auxin treatment. Collectively, we suggest that ABA-induced auxin synthesis governs the root gravitropic machinery, thereby influencing root angle in rice, maize, and possibly other cereal crops.

Assessing the ecological effects of the World's Largest Forestry Eco-engineering: Three-North Protective Forest Program within the initially scheduled range from 1978 to 2022

China's Three-North Protective Forest Program (TNP) is the world's most ambitious afforestation project (ongoing from 1978 to 2050), which aims to increase forest coverage through afforestation and reforestation, protect agriculture, reduce soil erosion, and control desertification. Although TNP has been ongoing for 45 years, its rationales and effects remain uncertain. Here, we conducted a range-wide assessment of TNP by analyzing data from >10,000 scenes of satellite images and >50,000 field survey plots. The TNP range and definitions of shelterbelts, arboreal forests, and shrublands were changed during the study period, but we used the initial TNP range (4.07 million km2) and the definitions in 1978 for keeping the consistency, comparability, and comprehensiveness. The TNP increased forest coverage from 5.05% in 1978 to 9.69% in 2022, with arboreal forests, shrublands, and shelterbelts increasing by 42.5%, 184.4%, and 53.6%, respectively. However, only 40.1% of the 471,113 km2 afforested area was established between 1978 and 2022. The well-established shelterbelts improved crop yield by 4.3%-9.5%, but only 10.2% of all the farmlands in TNP regions (TNR) were protected. The total area of soil erosion due to hydraulic forces was reduced by 447,363 km2, with 61% of this reduction attributed to TNP. TNP contributed to the reduction of desertification by 15%, largely due to the low rate of afforestation success and the largely decreased grasslands. The total carbon sequestration from TNP was 1.96 Pg C. Moreover, water storage in TNR showed a decreasing trend, but the contribution rate of TNP was only 7.8%. Our results illustrate that forestry eco-engineering projects are feasible in the management and restoration of arid and semi-arid degraded lands, but attention must be paid to fully considering the ecological carrying capacity of water resources, matching the species to sites, strengthening the post-afforestation management, as well as keeping the balances between composite ecosystems.

Global water gaps under future warming levels

Understanding the impacts of climate change on water resources is crucial for developing effective adaptation strategies. We quantify "water gaps", or unsustainable water use - the shortfall where water demand exceeds supply, resulting in scarcity. We quantify baseline and future water gaps using a multi-model analysis that incorporates two plausible future warming scenarios. The baseline global water gap stands at 457.9 km3/yr, with projections indicating an increase of 26.5 km3/yr (+5.8%) and 67.4 km3/yr (+14.7%) under 1.5 °C and 3 °C warming scenarios, respectively. These projections highlight the uneven impact of warming levels on water gaps, emphasizing the need for continued climate change mitigation to alleviate stress on water resources. Our results also underscore the unequal adaptation needs across countries and basins, influenced by varying warming scenarios, with important regional differences and model variability complicating future projections. Robust water management strategies are needed to tackle the escalating water scarcity caused by global warming.

Reversible Sol-Gel Transitions Mediated Organics Selective Uptake and Release for Simultaneous Water Purification and Chemicals Recovery

The separation and recovery of useful organics from wastewater have been a promising alternative to tackling water pollution and resource shortages, while strategies that truly work have rarely been explored. Herein, a reversible CO2 triggered sol-gel state transformation mediated selective organics uptake-release system using a surface modified carbonitride (S-CN) is proposed and exhibits remarkable organics recovery performance from wastewater. Results show that CO2 can serve as a cross-linker for linking S-CN particles to form a hydrogel by electrostatic interaction and hydrogen bonding, which can be recycled to the pristine sol state simply by removing the cross-linked CO2 with Ar purging. The reversible sol-gel transformation achieves nearly complete uptake of valuable organics from wastewater with high selectivity at the first sol-to-gel stage through electrostatic interaction, hydrogen bonding, and π-π interactions together, and it recovers 90% of the organics uptaked by releasing them into a concentrated solution at the second gel-back-to-sol stage.

GRAiCE: reconstructing terrestrial water storage anomalies with recurrent neural networks

The Gravity Recovery and Climate Experiment (GRACE) and its follow-on (GRACE-FO) missions have provided estimates of Terrestrial Water Storage Anomalies (TWSA) since 2002, enabling the monitoring of global hydrological changes. However, temporal gaps within these datasets and the lack of TWSA observations prior to 2002 limit our understanding of long-term freshwater variability. In this study, we develop GRAiCE, a set of four global monthly TWSA reconstructions from 1984 to 2021 at 0.5° spatial resolution, using Long Short-Term Memory (LSTM) and Bidirectional LSTM (BiLSTM) neural networks. Our models accurately reproduce GRACE/GRACE-FO observations at the global scale and effectively capture the impacts of climate extremes. Overall, GRAiCE outperforms a previous reference TWSA reconstruction in predicting observed TWSA and provides reliable water budget estimates at the river basin scale. By generating long-term continuous TWSA time series, GRAiCE will offer valuable insights into the impacts of climate variability and change on freshwater resources.

Spatiotemporal nonlinear characteristics and threshold effects of China's water resources

China faces shortage of water resources, particularly in the context of rapid population growth and accelerating urbanization, making the changes in its water resources among the most pronounced globally. Additionally, the complex interplay between climate change and human activities leads to nonlinear and non-stationary patterns in China's water resources. This study utilizes high-resolution water storage monitoring data to comprehensively analyze the nonlinear changes in water storage and its relationships with human footprint, precipitation, and temperature, revealing the complex dynamics of water storage changes across China. This study used advanced data analysis techniques to identify the turning points where water storage undergoes nonlinear changes, with categories of nonlinear changes that first decrease then increase and those that first increase then decrease together accounting for 55.62% of the observations. The northeastern and western fringe areas of China are hotspots for these nonlinear changes, and the analysis identifies 2019 as a year with a high frequency of turning points. The piecewise linear regression analysis found that when the human footprint exceeds a specific threshold, its negative impact on water storage significantly intensifies; when precipitation and temperature exceed certain thresholds, their impact on water storage shifts from negative to positive. These findings not only reveal the complex spatiotemporal distribution characteristics of water storage change turning points across China but also emphasize that water resource management strategies in China and globally need to adopt more comprehensive and dynamic approaches in the context of global climate change. To meet future challenges, it is essential to integrate multiple variables and develop flexible, adaptive management strategies to ensure the sustainable use and effective management of water resources.

Improving future agricultural sustainability by optimizing crop distributions in China

Improving agricultural sustainability is a global challenge, particularly for China's high-input and low-efficiency cropping systems with environmental tradeoffs. Although national strategies have been implemented to achieve Sustainable Development Goals in agriculture, the potential contributions of crop switching as a promising solution under varying future climate change are still under-explored. Here, we optimize cropping patterns spatially with the targets of enhancing agriculture production, reducing environmental burdens, and achieving sustainable fertilization across different climate scenarios. Compared with current cropping patterns, the optimal crop distributions under different climate scenarios consistently suggest allocating the planting areas of maize and rapeseed to the other crops (rice, wheat, soybean, peanut, and potato). Such crop switching can consequently increase crop production by 14.1%, with accompanying reductions in environmental impacts (8.2% for leached nitrogen and 24.0% for irrigation water use) across three representative Shared Socio-economic Pathways from 2020 to 2100. The sustainable fertilization rates vary from 148-173 kg N ha-1 in 2030 to 213-253 kg N ha-1 in 2070, significantly smaller than the current rate (305 kg N ha-1). These outcomes highlight large potential benefits of crop switching and fertilizer management for improving China's future agricultural sustainability.

Interactive effects of aridity and local environmental factors on the functional trait composition and diversity of macroinvertebrate assemblages in dryland rivers

Drought and local habitat alteration are major environmental stressors shaping the aquatic biota in dryland rivers. However, the combined effects of these factors on aquatic biodiversity remain poorly understood. We collected macroinvertebrate data from Central Asian dryland rivers in Xinjiang, China, from 2012 to 2022, to investigate the individual and interactive effects of drought (as indicated by increasing values of Aridity, AI) and local habitat conditions (fine sediments, velocity and pH) on aquatic macroinvertebrate functional trait composition and diversity. We found that interactions of the selected environmental stressors exhibited more frequent additive than synergistic or antagonistic effects, leading to shifts in macroinvertebrate functional trait composition and diversity accordingly. Interaction of AI and fine sediments showed more pronounced synergistic effects (positive or negative) compared to others and had positive influences on traits like small body size, ovoviviparity, etc. Functional diversity metrics responded differently to stressor interactions, with FRic and FDis being negatively affected, whereas FEve was positively correlated to stressor interaction, suggesting the complementary roles of functional diversity metrics to diagnose impacts of stressor interactions. Overall, our study provides new insights into macroinvertebrate assemblage-stressor relationships in dryland rivers and can help better assess, predict and manage aquatic biodiversity in these rivers under ongoing environmental change.

Corroboration of arsenic variation over the Indian Peninsula through standardized precipitation evapotranspiration indices and groundwater level fluctuations: Water quantity indicators for water quality prediction

The contamination of groundwater with arsenic (As) as a result of geo-morphological and hydrogeochemical factors has been the subject of comprehensive research. However, there has been limited exploration of the spread of As under the influence of dynamic elements such as floods, droughts, and rapidly declining groundwater levels. Moreover, the utilization of rapidly changing natural forces, including hydroclimatic extremes and declining groundwater levels, in conjunction with standard climate indices such as the Standard Precipitation Index (SPI) and the Standard Precipitation Evapotranspiration Index (SPEI), for the purpose of elucidating As distribution has been minimal. Accordingly, this study specifically addresses these water quantity indicators, along with Gravity Recovery and Climate Experiment (GRACE) derived groundwater levels, to expound on As contamination at a Pan-Indian scale. Significant correlations were delineated between SPI, SPEI, GRACE-derived groundwater levels, and arsenic concentrations. Clustering results unveiled the grouping of states according to agro-climatic zones, thereby underscoring the similarities in water quantity dynamics across the Indian peninsula. The study additionally computed the Saturation Index (SI) for aragonite and deliberated on the potential future saturation of this pivotal mineral. The primary contribution of this study lies in the successful demonstration of a methodology for prognosticating As distribution based on available precipitation and climatic indices, groundwater withdrawal, and the geological prospects of agroclimatic zones. The insights derived from the analysis of SPI, GRACE data, and As concentrations furnish valuable input for water resource management vis-à-vis strategies for mitigating As contamination.

Widespread potential for streamflow leakage across Brazil

River-aquifer interactions play a crucial role in water availability, influencing environmental flows and impacting climate dynamics. Where groundwater tables lie below river water levels, stream water can infiltrate into the underlying aquifer, reducing streamflow. However, the prevalence of these "losing" rivers remains poorly understood due to limited national-wide in situ observations. Here we analyze water levels in 17,972 wells across Brazil to show that most of them (55%) lie below nearby stream surfaces, implying that these nearby streams are likely seeping into the subsurface. Our results demonstrate the widespread potential for stream water losses into underlying aquifers in many regions of the country, especially in areas with extensive groundwater pumping. Our direct observations underscore the importance of conjunctively managing groundwater and surface water, and highlight the widespread risk of streamflow losses to aquifers, which could impact global water access and ecosystems that rely on rivers.

GRACE based groundwater drought evaluation of Ganga Basin and analysis of drought propagation using wavelet based quantitative approach

The Ganga River Basin which is the home of almost half a billion people have plunged into groundwater drought due to anthropogenic activities. Hence groundwater drought assessment and its propagation from the meteorological drought is highly required for the Ganga River Basin. This paper focuses on the evaluation of historical groundwater drought using Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) dataset, further to obtain the drought propagation times. Traditionally the drought propagation time is obtained from the correlation between groundwater drought time series and various scales of meteorological time series. However, the GRACE-derived groundwater drought index (GGDI) showed lesser correlation with the Standardized Precipitation Index (SPI) / Standardized Precipitation Evapotranspiration Index (SPEI) due to the presence of consistent trend in the GGDI series. Hence, a novel quantitative approach using Cross Wavelet Transform (XWT) is introduced to determine the drought propagation time which can devoid of the contribution of anthropogenic activities. Extracting the significant power area of XWT of GGDI with SPI/SPEI of different scales led to the determination of groundwater drought propagation time. The results showed Groundwater Storage Anomaly (GWSA) has a steep downtrend for Upper Gangetic Basin (UGB) (-26.2 mm/year) and Yamuna Chambal Basin (YCB) (-21.8 mm/year). It was observed that UGB and YCB faced groundwater drought from 2017 to 2022. The wavelet analysis showed that the drought propagation time of YCB is 14 months, UGB is 17 months, and the Lower Gangetic Basin (LGB) is 21 months. The frequency domain analysis of the drought signals suggested YCB had a faster response to the meteorological forcing, and LGB had the slowest response.

Environmental and economic assessment of urban wastewater reclamation from ultrafiltration membrane-based tertiary treatment: Effect of seasonal dynamic

This study aimed to assess the environmental and economic performance of an ultrafiltration (UF) tertiary treatment of effluent from an urban wastewater treatment facility. Data from a UF demonstration plant composed of commercially available equipment, including industrial hollow-fiber membranes was used to project a full-scale facility. The results from the demonstration plant recommended different ranges of transmembrane fluxes and sparging air demands under summer and winter conditions to prevent excessive fouling. The energy balance of the full-scale facility would be 0.308 ± 0.112 kWh·m-3 in summer and 0.140 ± 0.040 kWh·m-3 in winter, with blowers' being the main consumers (86-93 %). CAPEX accounted for €0.030 ± 0.002·m-3 in summer and €0.027 ± 0.002·m-3 in winter and membrane acquisition represented 66-69 % of the investment cost. Energy expenditure was the major OPEX cost (66-79 %), with a total operating cost of €0.077 ± 0.023·m-3 and €0.042 ± 0.008·m-3 in summer and winter, respectively. The final average value obtained for the TAC was €0.107 m-3 in summer and €0.068 m-3 in winter. The environmental assessment confirmed optimizing energy consumption and membrane requirements as the main factors influencing environmental sustainability. Specifically, summer and winter emissions of 0.079-0.175 and 0.043-0.079 kgCO2eq·m-3 (Global warming potential); 8.1 · 10-4-1.7 · 10-3 and 4.8 · 10-3-8.1 · 10-3 m3·m-3 (water consumption); 0.019-0.041 and 0.010-0.019 kg oileq·m-3 (fossil fuel scarcity); and 1.4 · 10-4-2.9 · 10-4 and 7.7 · 10-4-1.4 · 10-4 kg Cueq·m-3 (mineral resource scarcity) were calculated, respectively. The obtained permeate quality complied with the most stringent Spanish and EU regulations.

Floods of Egypt's Nile in the 21st century

Extreme precipitation and flooding events are rising globally, necessitating a thorough understanding and sustainable management of water resources. One such setting is the Nile River's source areas, where high precipitation has led to the filling of Lake Nasser (LN) twice (1998-2003; 2019-2022) in the last two decades and the diversion of overflow to depressions west of the Nile, where it is lost mainly to evaporation. Using temporal satellite-based data, climate models, and continuous rainfall-runoff models, we identified the primary contributor to increased runoff that reached LN in the past two decades and assessed the impact of climate change on the LN's runoff throughout the twenty-first century. Findings include: (1) the Blue Nile subbasin (BNS) is the primary contributor to increased downstream runoff, (2) the BNS runoff was simulated in the twenty-first century using a calibrated (1965-1992) rainfall-runoff model with global circulation models (GCMs), CCSM4, HadGEM3, and GFDL-CM4.0, projections as model inputs, (3) the extreme value analysis for projected runoff driven by GCMs' output indicates extreme floods are more severe in the twenty-first century, (4) one adaptation for the projected twenty-first century increase in precipitation (25-39%) and flood (2%-20%) extremes is to recharge Egypt's fossil aquifers during high flood years.

Nonstationarity in the global terrestrial water cycle and its interlinkages in the Anthropocene

Climate change and human activities alter the global freshwater cycle, causing nonstationary processes as its distribution shifting over time, yet a comprehensive understanding of these changes remains elusive. Here, we develop a remote sensing-informed terrestrial reanalysis and assess the nonstationarity of and interconnections among global water cycle components from 2003 to 2020. We highlight 20 hotspot regions where terrestrial water storage exhibits strong nonstationarity, impacting 35% of the global population and 45% of the area covered by irrigated agriculture. Emerging long-term trends dominate the most often (48.2%), followed by seasonal shifts (32.8%) and changes in extremes (19%). Notably, in mid-latitudes, this encompasses 34% of Asia and 27% of North America. The patterns of nonstationarity and their dominant types differ across other water cycle components, including precipitation, evapotranspiration, runoff, and gross primary production. These differences also manifest uniquely across hotspot regions, illustrating the intricate ways in which each component responds to climate change and human water management. Our findings emphasize the importance of considering nonstationarity when assessing water cycle information toward the development of strategies for sustainable water resource usage, enhancing resilience to extreme events, and effectively addressing other challenges associated with climate change.

An Abrupt Decline in Global Terrestrial Water Storage and Its Relationship with Sea Level Change

As observed by the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow On (GRACE-FO) missions, global terrestrial water storage (TWS), excluding ice sheets and glaciers, declined rapidly between May 2014 and March 2016. By 2023, it had not yet recovered, with the upper end of its range remaining 1 cm equivalent height of water below the upper end of the earlier range. Beginning with a record-setting drought in northeastern South America, a series of droughts on five continents helped to prevent global TWS from rebounding. While back-to-back El Niño events are largely responsible for the South American drought and others in the 2014-2016 timeframe, the possibility exists that global warming has contributed to a net drying of the land since then, through enhanced evapotranspiration and increasing frequency and intensity of drought. Corollary to the decline in global TWS since 2015 has been a rise in barystatic sea level (i.e., global mean ocean mass). However, we find no evidence that it is anything other than a coincidence that, also in 2015, two estimates of barystatic sea level change, one from GRACE/FO and the other from a combination of satellite altimetry and Argo float ocean temperature measurements, began to diverge. Herein, we discuss both the mechanisms that account for the abrupt decline in terrestrial water storage and the possible explanations for the divergence of the barystatic sea level change estimates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10712-024-09860-w.

Synergistically Utilizing a Liquid Bridge and Interconnected Porous Superhydrophilic Structures to Achieve a One-Step Fog Collection Mode

Conventional fog collection efficiency is subject to the inherent inefficiencies of its three constituent steps: fog capture, coalescence, and transportation. This study presents a liquid bridge synergistic fog collection system (LSFCS) by synergistically utilizing a liquid bridge and interconnected porous superhydrophilic structures (IPHS). The results indicate that the introduction of liquid bridge not only greatly accelerates water droplet transportation, but also facilitates the IPHS in maintaining rough structures that realize stable and efficient fog capture. During fog collection, the lower section of the IPHS is covered by a water layer, however due to the effect of the liquid bridge, the upper section protrudes out, while covered by a connective thin water film that does not obscure the microstructures of the upper section. Under these conditions, a one-step fog collection mode is realized. Once captured by the IPHS, fog droplets immediately coalesce with the water film, and are simultaneously transported into a container under the effect of the liquid bridge. The LSFCS achieves a collection efficiency of 6.5 kg m-2 h-1, 2.3 times that of a system without a liquid bridge. This study offers insight on improving fog collection efficiency, and holds promise for condensation water collection or droplet manipulation.

Environmental effects and spatial inequalities of paddy field utilization are increasing in China

Understanding the spatiotemporal dynamics of the environmental effects associated with paddy field utilization (PFU) is imperative for safeguarding the availability of food while preserving the environment. While thorough investigations have been carried out on the individual environmental effects of PFU, study on comprehensive environmental effects of PFU and the spatial inequity issues stemming from the transfer of these effects are scarce. This study aims to quantify the greenhouse gas emissions (GHGE), nitrogen emissions (NE), and water consumption (WC) linked to PFU in China from 2000 to 2020. Additionally, it evaluates the transference of environmental effects through the inter-provincial rice flow and examines the resultant spatial inequity issues. The intensity of GHGE has demonstrated a consistent increase, while the intensity of NE has shown a fluctuating yet generally decreasing trend. Provinces with high water footprints are predominantly located in the northern regions. Specifically, GHGE increased by 3.54 Mt, primarily due to intensified agricultural inputs. NE decreased by 0.08 Mt, largely influenced by the enforcement of sustainable agricultural practices. WC escalated by 3.49 billion m3, chiefly as a result of heightened groundwater dependence. Significant increases in environmental effects were observed in Northeast China Plain (NECP) and Middle-lower Yangtze Plain (MLYP), whereas Yunnan-Guizhou Plateau (YGP), Southern China (SC), and Sichuan Basin and surrounding regions (SBSR) experienced reductions. The volume of inter-provincial rice flow initially surged before witnessing a decline, with a net increase of 15.59 Mt in rice outflow from NECP. The transferred volumes of GHGE, NE, and WC within China surged by 123.87%, 105.26%, and 119.05%, respectively. Huang-Huai-Hai Plain (HHHP) and SC emerged as principal outflows of environmental effects, while MLYP and NECP became the main inflows, exacerbating regional environmental disparities. Lorenz curves for GHGE, NE, and WC indicate a growing deviation from the line of absolute equality, highlighting a substantial increase in spatial inequality regarding the environmental effects of PFU in China. Moving forward, it is crucial to optimize PFU and rice flow patterns to mitigate the specific regional environmental effects, enhance the spatial efficiency of rice production, and promote spatial equity in environmental effects.

Harnessing Holey MXene/Graphene Oxide Heterostructure to Maximize Ion Channels in Lamellar Film for High-Performance Capacitive Deionization

2D Ti3C2Tx MXene-based film electrodes with metallic conductivity and high pseudo-capacitance are of considerable interest in cutting-edge research of capacitive deionization (CDI). Further advancement in practical use is however impeded by their intrinsic limitations, e.g., tortuous ion diffusion pathway of layered stacking, vulnerable chemical stability, and swelling-prone nature of hydrophilic MXene nanosheet in aqueous environment. Herein, a nanoporous 2D/2D heterostructure strategy is established to leverage both merits of holey MXene (HMX) and holey graphene oxide (HGO) nanosheets, which optimize ion transport shortcuts, alleviate common restacking issues, and improve film's mechanical and chemical stability. In this design, the nanosized in-plane holes in both handpicked building blocks build up ion diffusion shortcuts in the composite laminates to accelerate the transport and storage of ions. As a direct outcome, the HMX/rHGO films exhibit remarkable desalination capacity of 57.91 mg g-1 and long-term stability in 500 mg L-1 NaCl solution at 1.2 V. Moreover, molecular dynamics simulations and ex situ wide angle X-ray scattering jointly demonstrate that the conductive 2D/2D networks and ultra-short ion diffusion channels play critical roles in the ion intercalation/deintercalation process of HMX/rHGO films. The study paves an alternative design concept of freestanding CDI electrodes with superior ion transport efficiency.

Planetary boundaries transgressions: A review on the implications to public health

This literature review systematically examines the impacts of violating planetary boundaries from 2009 to 2023, emphasizing the implications for human health. Planetary boundaries define safe operational limits for Earth's systems, and their transgression poses significant threats to environmental stability and public health. This paper reviews extensive research on the health effects of breaches in these boundaries, including climate change, biodiversity loss, freshwater use, and aerosol loading. The review integrates findings from numerous studies, providing a critical overview of health impacts across various global regions. The analysis underscores the intricate links between planetary boundaries breaching impacts, highlighting urgent policy and governance challenges. The study's outcomes aim to inform policymakers, businesses, and communities, promoting sustainable development and resilience in the face of escalating global challenges.

Advancing groundwater quality predictions: Machine learning challenges and solutions

Machine learning (ML) is revolutionizing groundwater quality research by enhancing predictive accuracy and management strategies for contamination. This comprehensive review explores the evolution of ML technologies and their integration into environmental science, assessing 230 papers to understand the advancements and challenges in groundwater quality research. It reveals that a substantial portion of the research neglects critical preprocessing steps, crucial for model accuracy, with 83 % of the studies overlooking this phase. Furthermore, while model optimization is more commonly addressed, being implemented in 65 % of the papers, there is a noticeable gap in model interpretability, with only 15 % of the research providing explanations for model outcomes. Comparative evaluation of ML algorithms and careful selection of evaluation metrics are deemed essential for determining model fitness and reliability. The review underscores the need for interdisciplinary collaboration, methodological rigor, and continuous innovation to advance ML in groundwater management. By addressing these challenges and implementing solutions, the full potential of ML can be harnessed to tackle complex environmental issues and ensure sustainable groundwater management. This comprehensive and critical review paper can serve as a guiding framework to establish minimum standards for developing ML in groundwater quality studies.

Spatial consistency of co-exposure to air and surface water pollution and cancer in China

Humans can be exposed to multiple pollutants in the air and surface water. These environments are non-static, trans-boundary and correlated, creating a complex network, and significant challenges for research on environmental hazards, especially in real-world cancer research. This article reports on a large study (377 million people in 30 provinces of China) that evaluated the combined impact of air and surface water pollution on cancer. We formulate a spatial evaluation system and a common grading scale for co-pollution measurement, and validate assumptions that air and surface water environments are spatially connected and that cancers of different types tend to cluster in areas where these environments are poorer. We observe "dose-response" relationships in both the number of affected cancer types and the cancer incidence with an increase in degree of co-pollution. We estimate that 62,847 (7.4%) new cases of cancer registered in China in 2016 were attributable to air and surface water pollution, and the majority (69.7%) of these excess cases occurred in areas with the highest level of co-pollution. The findings clearly show that the environment cannot be considered as a set of separate entities. They also support the development of policies for cooperative environmental governance and disease prevention.

Long-term trends in human-induced water storage changes for China detected from GRACE data

Terrestrial Water Storage (TWS) plays a pivotal role in water resource management by providing a comprehensive measure of both surface water and groundwater availability. This study investigates changes in TWS driven by human activities from 2003 to 2023, and forecasts future TWS trends under various climate change and development scenarios. Our findings reveal a continuous decline in China's TWS since 2003, with an average annual decrease of approximately 1.36 mm. This reduction is primarily attributed to the combined effects of climate change and human activities, including irrigation, industrial water use, and domestic water consumption. Notably, TWS exhibits significant seasonal and annual fluctuations, with variations ranging ±10 mm. For the future period (2024-2030), we project greater disparities between water resource supply and demand in specific years for the Songliao, Southwest, and Yangtze basins. Consequently, future water resource management must prioritize water conservation during wet seasons, particularly in years when supply-demand conflicts for limited water resources intensify. This study is valuable for effective planning and sustainable utilization of water resources.

Groundwater sustainability in India through nonrice-dominated cropping pattern

Over-exploitation of groundwater for irrigation caused rapid groundwater depletion in north India, leading to food and water security challenges. However, the crucial role of changing cropping patterns on groundwater savings under the observed and projected warming climate remains unexplored. Here, we show that altering the existing rice-dominated cropping systems in India can be a potential solution for groundwater sustainability under the current and future climate. Satellite and model-based estimates show that north India lost ∼336 and 297 km3 of groundwater, respectively during 2002-2022. We developed optimized crop switching scenarios for groundwater savings considering nutritional requirements, farmers' profit, and crop production. Crop switching considering all the three targets (crop switch one: CSI) and allowing rice replacement with alternate crops (crop switch two: CSII) could save 45 and 91 km3 groundwater, respectively in north India during the observed climate (2002-2022) compared with the current cropping pattern. Altering the current cropping pattern can lead to substantial groundwater savings under the projected future climate without comprising nutritional targets and farmers' profit at the state level. Replacing 37% area of rice with other crops (CSII) can recover 61 to 108 km3 groundwater compared with -13 to 43 km3 with current cropping pattern under the 1.5-3 °C global warming levels. Similarly, under the CSI scenario, 36 to 86 km3 groundwater can be recovered in the future warming world. Moreover, the benefits of crop switching in groundwater saving are higher during the prolonged dry periods compared with the baseline under the warming climate. Therefore, crop switching offers substantial benefits for groundwater sustainability under the current and projected future climate in India.

Dual-Interface Solar Evaporator with Highly-Efficient Thermal Regulation via Suspended Multilayer Design

Facing the increasing global shortage of freshwater resources, this study presents a suspended multilayer evaporator (SMLE), designed to tackle the principal issues plaguing current solar-driven interfacial evaporation technologies, specifically, substantial thermal losses and limited water production. This approach, through the implementation of a multilayer structural design, enables superior thermal regulation throughout the evaporation process. This evaporator consists of a radiation damping layer, a photothermal conversion layer, and a bottom layer that leverages radiation, wherein the bottom layer exhibits a notable infrared emissivity. The distinctive feature of the design effectively reduces radiative heat loss and facilitates dual-interface evaporation by heating the water surface through mid-infrared radiation. The refined design leads to a notable evaporation rate of 2.83 kg m-2 h-1. Numerical simulations and practical performance evaluations validate the effectiveness of the multilayer evaporator in actual use scenarios. This energy-recycling and dual-interface evaporation multilayered approach propels the design of high-efficiency solar-driven interfacial evaporators forward, presenting new insights into developing effective water-energy transformation systems.

Comparison of groundwater storage changes over losing and gaining aquifers of China using GRACE satellites, modeling and in-situ observations

Groundwater depletion in intensively exploited aquifers of China has been widely recognized, whereas an overall examination of groundwater storage (GWS) changes over major aquifers remains challenging due to limited data and notable uncertainties. Here, we present a study to explore GWS changes over eighteen major aquifers covering an area of 1,680,000 km2 in China using data obtained from the Gravity Recovery and Climate Experiments (GRACE), global models, and in-situ groundwater level observations. The analysis aims to reveal the discrepancy in annual trends, amplitudes, and phases associated with GWS changes among different aquifers. It is found that GWS changes in the studied aquifers represent a spatial pattern of 'Wet-gets-more, Dry-gets-less'. An overall decreasing trend of -4.65 ± 0.34 km3/yr is observed by GRACE from 2005 to 2016, consisting of a significant (p < 0.05) increase of 47.28 ± 3.48 km3 in 7 aquifers and decrease of 103.56 ± 2.4 km3 (∼2.6 times the full storage capacity of the Three Gorges Reservoir) in 10 aquifers summed over the 12 years. The annual GWS normally reaches a peak in late July with an area-weighted average annual amplitude of 19 mm, showing notable discrepancy in phases and amplitudes between the losing aquifers (12 mm in middle August) in northern China and gaining aquifers (28 mm in early July) mostly in southern China. GRACE estimates are generally comparable, but can be notably different, with the results obtained from model simulations and in-situ observations at aquifer scale, with the area-weighted average correlation coefficients of 0.6 and 0.5, respectively. This study highlights different GWS changes of losing and gaining aquifers in response to coupled impacts of hydrogeology, climate and human interventions, and calls for divergent adaptions in regional groundwater management.

Groundwater-dependent ecosystem map exposes global dryland protection needs

Groundwater is the most ubiquitous source of liquid freshwater globally, yet its role in supporting diverse ecosystems is rarely acknowledged1,2. However, the location and extent of groundwater-dependent ecosystems (GDEs) are unknown in many geographies, and protection measures are lacking1,3. Here, we map GDEs at high-resolution (roughly 30 m) and find them present on more than one-third of global drylands analysed, including important global biodiversity hotspots4. GDEs are more extensive and contiguous in landscapes dominated by pastoralism with lower rates of groundwater depletion, suggesting that many GDEs are likely to have already been lost due to water and land use practices. Nevertheless, 53% of GDEs exist within regions showing declining groundwater trends, which highlights the urgent need to protect GDEs from the threat of groundwater depletion. However, we found that only 21% of GDEs exist on protected lands or in jurisdictions with sustainable groundwater management policies, invoking a call to action to protect these vital ecosystems. Furthermore, we examine the linkage of GDEs with cultural and socio-economic factors in the Greater Sahel region, where GDEs play an essential role in supporting biodiversity and rural livelihoods, to explore other means for protection of GDEs in politically unstable regions. Our GDE map provides critical information for prioritizing and developing policies and protection mechanisms across various local, regional or international scales to safeguard these important ecosystems and the societies dependent on them.

Achieving Exceptional Volumetric Desalination Capacity Using Compact MoS2 Nanolaminates

Capacitive deionization (CDI) has emerged as a promising technology for freshwater recovery from low-salinity brackish water. It is still inapplicable in specific scenarios (e.g., households, islands, or offshore platforms) due to too low volumetric adsorption capacities. In this study, a high-density semi-metallic molybdenum disulfide (1T'-MoS2) electrode with compact architecture obtained by restacking of exfoliated nanosheets, which achieve high capacitance up to ≈277.5 F cm-3 under an ultrahigh scan rate of 1000 mV s-1 with a lower charge-transfer resistance and nearly tenfold higher electrochemical active surface area than the 2H-MoS2 electrode, is reported. Furthermore, 1T'-MoS2 electrode demonstrates exceptional volumetric desalination capacity of 65.1 mgNaCl cm-3 in CDI experiments. Ex situ X-ray diffraction (XRD) reveal that the cation storage mechanism with the dynamic expansion of 1T'-MoS2 interlayer to accommodate cations such as Na+, K+, Ca2+, and Mg2+, which in turn enhances the capacity. Theoretical analysis unveils that 1T' phase is thermodynamically preferable over 2H phase, the ion hydration and channel confinement also play critical role in enhancing ion adsorption. Overall, this work provides a new method to design compact 2D-layered nanolaminates with high-volumetric performance for CDI desalination.

Control approach and evaluation framework of scaling in drinking water distribution systems: A review

The United Nations Sustainable Development Goals call for innovative proposals to ensure access to clean water and sanitation. While significant strides have been made in enhancing drinking water purification technologies, the role of drinking water distribution systems (DWDS) in maintaining water quality safety has increasingly become a focal point of concern. The presence of scale within DWDS can impede the secure and efficient functioning of the drinking water supply system, posing risks to the safety of drinking water quality. Previous research has identified that the primary constituents of scale in DWDS are insoluble minerals, such as calcium and magnesium carbonate. Elevated levels of hardness and alkalinity in the water can exacerbate scale formation. To address the scaling issue, softening technologies like induced crystallization, nanofiltration/reverse osmosis, and ion exchange are currently in widespread use. These methods effectively mitigate the scaling in DWDS by reducing the water's hardness and alkalinity. However, the application of softening technologies not only alters the hardness and alkalinity but also induces changes in the fundamental characteristics of water quality, leading to transition effects within the DWDS. This article reviews the impact of various softening technologies on the intrinsic properties of water quality and highlights the merits of electrochemical characteristic indicators in the assessment of water quality stability. Additionally, the paper delves into the factors that influence the transition effects in DWDS. It concludes with a forward-looking proposal to leverage artificial intelligence, specifically machine learning and neural networks, to develop an evaluation and predictive framework for the stability of drinking water quality and the transition effects observed in DWDS. This approach aims to provide a more accurate and proactive method for managing and predicting the impacts of water treatment processes on distribution system integrity and water quality over time.

Watching the Grand Ethiopian Renaissance Dam from a distance: Implications for sustainable water management of the Nile water

Increased demands for sustainable water and energy resources in densely populated basins have led to the construction of dams, which impound waters in artificial reservoirs. In many cases, scarce field data led to the development of models that underestimated the seepage losses from reservoirs and ignored the role of extensive fault networks as preferred pathways for groundwater flow. We adopt an integrated approach (remote sensing, hydrologic modeling, and field observations) to assess the magnitude and nature of seepage from such systems using the Grand Ethiopian Renaissance Dam (GERD), Africa's largest hydropower project, as a test site. The dam was constructed on the Blue Nile within steep, highly fractured, and weathered terrain in the western Ethiopian Highlands. The GERD Gravity Recovery and Climate Experiment Terrestrial Water Storage (GRACETWS), seasonal peak difference product, reveals significant mass accumulation (43 ± 5 BCM) in the reservoir and seepage in its surroundings with progressive south-southwest mass migration along mapped structures between 2019 and 2022. Seepage, but not a decrease in inflow or increase in outflow, could explain, at least in part, the observed drop in the reservoir's water level and volume following each of the three fillings. Using mass balance calculations and GRACETWS observations, we estimate significant seepage (19.8 ± 6 BCM) comparable to the reservoir's impounded waters (19.9 ± 1.2 BCM). Investigating and addressing the seepage from the GERD will ensure sustainable development and promote regional cooperation; overlooking the seepage would compromise hydrological modeling efforts on the Nile Basin and misinform ongoing negotiations on the Nile water management.

Repurposing Sewage and Toilet Systems: Environmental, Public Health, and Person-Centered Healthcare Applications

Global terrestrial water supplies are rapidly depleting due to the consequences of climate change. Water scarcity results in an inevitable compromise of safe hygiene and sanitation practices, leading to the transmission of water-borne infectious diseases, and the preventable deaths of over 800.000 people each year. Moreover, almost 500 million people lack access to toilets and sanitation systems. Ecosystems are estimated to be contaminated by 6.2 million tons of nitrogenous products from human wastewater management practices. It is therefore imperative to transform toilet and sewage systems to promote equitable access to water and sanitation, improve public health, conserve water, and protect ecosystems. Here, the integration of emerging technologies in toilet and sewage networks to repurpose toilet and wastewater systems is reviewed. Potential applications of these systems to develop sustainable solutions to environmental challenges, promote public health, and advance person-centered healthcare are discussed.

Water Scarcity Assessment of Hydropower Plants in China under Climate Change, Sectoral Competition, and Energy Expansion

Hydropower plays a pivotal role in low-carbon electricity generation, yet many projects are situated in regions facing heightened water scarcity risks. This research devised a plant-level Hydropower Water Scarcity Index (HWSI), derived from the ratio of water demand for electricity generation to basin-scale available runoff water. We assessed the water scarcity of 1736 hydropower plants in China for the baseline year 2018 and projected into the future from 2025 to 2060. The results indicate a notable increase in hydropower generation facing moderate to severe water scarcity (HWSI >0.05), rising from 10% in 2018 to 24-34% of the national total (430-630 TWh), with a projected peak in the 2030s-2040s under the most pessimistic scenarios. Hotspots of risk are situated in the southwest and northern regions, primarily driven by decreased river basin runoff and intensified sectoral water use, rather than by hydropower demand expansion. Comparative analysis of four adaptation strategies revealed that sectoral water savings and enhancing power generation efficiency are the most effective, potentially mitigating a high of 16% of hydropower risks in China. This study provides insights for formulating region-specific adaptation strategies and assessing energy-water security in the face of evolving environmental and societal challenges.

Assessing the impact of agriculture, coal mining, and ecological restoration on water sustainability in the Mu Us Sandyland

Balancing water demand for socio-economic development and ecosystem stability presents a challenge for regional sustainable management, especially in drylands. Previous studies have indicated that large-scale ecological restoration projects (ERPs) lead to a decline in terrestrial water storage (TWS) in the Mu Us Sandyland (MUS). However, the effects of other human activities (e.g., cropland reclamation, coal mining) on water resources remain unclear, raising concerns regarding water crisis and human-natural system sustainability. Through the utilization of coal mine location data, we found that the impact of coal mass loss on the Gravity Recovery and Climate Experiment (GRACE) products cannot be ignored in MUS, especially in the coal-rich northeastern part. Combining these data with auxiliary datasets, we observed a significant (p < 0.05) decrease in TWS (-0.85 cm yr-1) and groundwater storage (GWS, -0.95 cm yr-1) in the MUS, with human activities accounting for 79.23 % of TWS and 90.45 % of GWS reductions, primarily due to increased agricultural and industrial water consumption. Agricultural water consumption increased 2.23 times from 2001 to 2020, attributed to enhanced water use intensity (62.6 %) and cropland expansion (37.4 %). Industrial water consumption in Shenmu, a representative coal county, experienced a 4.16-fold rise between 2001 and 2020. Despite these challenges, local governments have alleviated water stress, ensured food security, and increased household income by comprehensive management strategies, such as enhancing water-saving technology and enforcing stringent policies. Previous studies have overestimated the amount of water resources consumed by ERPs. However, ERPs has played a critical role in stabilizing the regional ecological environment and ensuring the region as a vital food and energy supplier. Our findings can guide for socio-economic development and water management policies in similar regions.

Assessing future intra-basin water availability in madagascar: Accounting for climate change, population growth, and land use change

The Major River Basins in Madagascar (MRBM) play a crucial role in providing water to the Malagasy population as well as the ecosystem. Little is known about the impact of climate change on these basins, and it is not clear what factors have the most significant impact on them. There are two central objectives of this study: 1. To assess the future potential water available for daily life and agriculture use across the MRBM. 2. To compare the projected change within the MRBM with the historical trends analysis and identify the water-stressed basins. In this paper, a new method for assessing the future available Intra-basin water resources combined with the impacts of climate change, land use, and population is proposed. Three imbalance indicators are introduced to quantify the spatial availability (indicator N°1), distribution (indicator N°2), and variability (indicator N°3) of the Potential Water Resources (PWR) available and have been applied to the MRBM. Under the SSP2-4.5 scenario, results showed a decreasing trend of the PWR in most of the basins by 2050 with a rise in evapotranspiration and a decline in precipitation. The increasing trend and uneven distribution of the population and agricultural land upstream/downstream are found to cause the reduction of the PWR available per capita (by 37 %) and agriculture area (by 69 %) across the MRBM. This study predicts water scarcity for most of the basins by 2050, especially in the Mangoro and Onilahy Basins. Upstream populations are expected to grow in Mahajamba, Mahavavy, Betsiboka, Manambolo, Tsiribihina, Mangoro, Onilahy, Mananara, and Mandrare basins, along with an expansion of the downstream agricultural land in Sofia, Betsiboka, Manambolo, Mangoky, and Mandrare basins. These findings enhance the cause-effect relationship between climate change, land use change, population growth, and water scarcity in the MRBM. Urgent action is therefore needed for an efficient and sustainable management of these water-stressed basins.

Polyelectrolyte Hydrogel-Functionalized Photothermal Sponge Enables Simultaneously Continuous Solar Desalination and Electricity Generation Without Salt Accumulation

Technologies that can simultaneously generate electricity and desalinate seawater are highly attractive and required to meet the increasing global demand for power and clean water. Here, a bifunctional solar evaporator that features continuous electric generation in seawater without salt accumulation is developed by rational design of polyelectrolyte hydrogel-functionalized photothermal sponge. This evaporator not only exhibits an unprecedentedly high water evaporation rate of 3.53 kg m-2 h-1along with 98.6% solar energy conversion efficiency but can also uninterruptedly deliver a voltage output of 0.972 V and a current density of 172.38 µA cm-2 in high-concentration brine over a prolonged period under one sun irradiation. Many common electronic devices can be driven by simply connecting evaporator units in series or in parallel without any other auxiliaries. Different from the previously proposed power generation mechanism, this study reveals that the water-enabled proton concentration fields in intermediate water region can also induce an additional ion electric field in free water region containing solute, to further enhance electricity output. Given the low-cost materials, simple self-regeneration design, scalable fabrication processes, and stable performance, this work offers a promising strategy for addressing the shortages of clean water and sustainable electricity.

Leisure-Time Physical Activity as a Pathway to Sustainable Living: Insights on Health, Environment, and Green Consumerism

In the aftermath of the COVID-19 pandemic, the intricate relationship between health and the environment has emerged with unparalleled significance. This investigation examines the effect of leisure-time physical activity (LTPA) on health and environmental consciousness and its influence on attitudes towards green/sustainable products among 533 individuals. Utilizing linear structural modeling and regression analysis, the findings reveal that participation in sports and leisure activities significantly mediates the connection between individual well-being and eco-responsible consumer behaviors. Highlighting LTPA's crucial role in enhancing environmental awareness, this study offers invaluable perspectives for the green product sector. It advocates for the development of strategies that align with consumers' environmental values, underscoring the essential function of sports and leisure in fostering sustainable consumer practices. Crucially, this underscores the intertwined nature of environmental sustainability and individual health, highlighting their mutual dependence.

Uncovering the impacts of depleting aquifers: A remote sensing analysis of land subsidence in Iran

Intensive groundwater pumping, previously unrecognized in its full extent, is blamed for aquifer degradation and widespread land subsidence in Iran. We use a 100-meter resolution satellite survey from 2014 to 2020 to assess the recent implications of groundwater usage across the country. Results indicate that approximately 56,000 km2 (3.5%) of the country's area is subject to land subsidence, primarily linked to irrigation; 3000 km2 of this area experiences subsidence rates greater than 10 cm/year. The central plateau catchment hosts two-thirds of the country's depleting aquifers, with locations sinking at rates higher than 35 cm/year. The results suggest an annual groundwater depletion of 1.7 billion cubic meters (BCM) from confined and semiconfined aquifers, with the long-term inelastic compaction for most aquifers being approximately one order of magnitude larger than their seasonal elastic response. This underscores the permanent loss of aquifers that jeopardizes the sustainability of water resources across Iran.

A unifying modelling of multiple land degradation pathways in Europe

Land degradation is a complex socio-environmental threat, which generally occurs as multiple concurrent pathways that remain largely unexplored in Europe. Here we present an unprecedented analysis of land multi-degradation in 40 continental countries, using twelve dataset-based processes that were modelled as land degradation convergence and combination pathways in Europe's agricultural (and arable) environments. Using a Land Multi-degradation Index, we find that up to 27%, 35% and 22% of continental agricultural (~2 million km2) and arable (~1.1 million km2) lands are currently threatened by one, two, and three drivers of degradation, while 10-11% of pan-European agricultural/arable landscapes are cumulatively affected by four and at least five concurrent processes. We also explore the complex pattern of spatially interacting processes, emphasizing the major combinations of land degradation pathways across continental and national boundaries. Our results will enable policymakers to develop knowledge-based strategies for land degradation mitigation and other critical European sustainable development goals.