Evolving pathways towards water security in the Vietnamese Mekong Delta: An adaptive management perspective.

The interplay of climate change, upstream hydropower development, and local water engineering interventions for agricultural production contributes substantially to the transformation of waterscapes and water scarcity in the Vietnamese Mekong Delta. This paper aims to examine how these dynamics are linked to the paradigm shift in water management in An Giang and Ben Tre, the two ecologically distinct provinces that face serious water scarcity in the delta. We used the adaptive management concept to examine how state-led policy directions from food security towards water security enable change in water management that gives priority to water retention. While policy learning is evident, questions remain about how this ad-hoc solution could help address the presently acute water scarcity and water security over the long term. The paper advocates achieving water security should focus not only on diplomatic interventions into upstream climate-development complexities but also local water-livelihood politics.

Effects of landscape changes on water quality: A global meta-analysis.

Landscape changes resulting from anthropogenic activities and climate changes severely impact surface water quality. A global perspective on understanding their relationship is a prerequisite for pursuing equity in water security and sustainable development. A sequent meta-analysis synthesizing 625 regional studies from 63 countries worldwide was conducted to analyze the impacts on water quality from changing landscape compositions in the catchment and explore the moderating factors and temporal evolution. Results exhibit that total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) in water are mostly concerned and highly responsive to landscape changes. Expansion of urban lands fundamentally degraded worldwide water quality over the past 20 years, of which the arid areas tended to suffer more harsh deterioration. Increasing forest cover, particularly low-latitude forests, significantly decreased the risk of water pollution, especially biological and heavy metal contamination, suggesting the importance of forest restoration in global urbanization. The effect size of agricultural land changes on water quality was spatially scale-dependent, decreasing and then increasing with the buffer radius expanding. Wetland coverage positively correlated with organic matter in water typified by COD, and the correlation coefficient peaked in the boreal areas (r=0.82, p<0.01). Overall, the global impacts of landscape changes on water quality have been intensifying since the 1990s. Nevertheless, knowledge gaps still exist in developing areas, especially in Africa and South America, where the water quality is sensitive to landscape changes and is expected to experience dramatic shifts in foreseeable future development. Our study revealed the worldwide consistency and heterogeneity between regions, thus serving as a research roadmap to address the quality-induced global water scarcity under landscape changes and to direct the management of land and water.

Sustaining ex-mining lake-converted constructed wetlands as nature-based solutions: A comprehensive assessment of the carbon-water nexus in Paya Indah Wetlands, Malaysia.

Water and carbon, essential for Earth's well-being, face imminent threats from human activities that fuel climate change. This study investigates nature-based solutions, focusing on the carbon-water nexus of ex-mining lake-converted constructed wetlands, specifically in Malaysia's Paya Indah Wetlands (PIW). Addressing research gaps, it assesses the ecosystem services of these wetlands, emphasising integrated evaluations for informed land management and employing a top-down conservation approach. Methodologically, spatial assessments, soil and water sampling, carbon quantification, water quality index calculations, land cover classification and stakeholder surveys were conducted. Results underscore the significant carbon sequestration and water quality improvement potential of constructed wetlands, with soil and sediment carbon accumulation reaching 1553.11 Mg C ha-1 (equivalent to 5700 Mg CO2 ha-1), translating to an annual sequestration capacity of 67.5 Mg C ha-1 year-1. Water quality index values ranged from 58 to 81 (Classes II to III). PIW's establishment led to a reduction of over 90% in barren land, with increases in water bodies (36%) and vegetation-covered land (38%), boosting wildlife populations by 30%. Spatial variations in organic carbon density and water quality underscore the complexity of the carbon-water nexus and its impacts on ecosystem health and water security. Despite land use changes, PIW demonstrates resilience, contributing to climate change mitigation. Stakeholder perceptions vary, emphasising the need for adaptive strategies. The study proposes transdisciplinary conservation initiatives and adaptive plans, stressing the pivotal role of ex-mining lake-converted constructed wetlands in enhancing climate resilience.

A real-time simulation model of water quality with the impact of internal pollution for water source reservoir.

The water source reservoirs are the important urban water source in northern China. Although external pollution has been greatly improved, the internal pollutants in reservoirs continue to accumulate with the complex deposition and release processes, resulting in potential risks to water supply safety. To address the aforementioned issue, this paper proposed a simulation model of water quality named ECOlab EU1-WSR to simulate the spatio-temporal changes of water quality under the influence of internal pollution for the water source reservoirs. Based on the analysis of the water quality characteristics and the distribution of benthic vegetation in the reservoir, a three-dimensional hydrodynamic model was established based on MIKE3, the corresponding parameters and the related state variables were set, the ECOlab EU1-WSR model was established by secondly developing the original ECOlab EU1 template, and the real-time dynamic outputs of pollutant content in sediment were added to link the water quality index with sediment nutrition index for better revealing the impact of the internal pollution on the water quality. The performance of the model was evaluated by the case application on the water quality simulation of Daye reservoir and the optimization of the connection project between Daye reservoir and Xueye reservoir in Shandong Province China. The results showed that the model can accurately and simultaneously simulate the pollution in water and sediment by the comparative verification of hydrodynamics, water temperature, and water quality. Moreover, the model can effectively reflect the influence of the accumulation, deposition, and release of internal pollution on water quality by analyzing the correlation between the content of various pollution in water body and those in sediment, such as the total nitrogen and total phosphorus in the water body at the bottom of the water intake, were negatively correlated with the total nitrogen and total phosphorus in the sediments with correlation coefficients of 0.538 and 0.917, respectively. In addition, the optimal water inlet position and water flow rate of the connection project can be optimized and determined by using the model to effectively control water quality. The established model will be a useful tool for the design and management of a reservoir, the interconnection projects, and other water bodies by adaptively recoded.

Total environment sentinels: Dragonflies as ambivalent/amphibiotic bioindicators of damage to soil and freshwater.

Discerning the impact of anthropogenic impacts requires the implementation of bioindicators that quantify the susceptibilities and vulnerabilities of natural terrestrial and aquatic ecosystems to perturbation and transformation. Although legal regulations in Brazil recognize the value of bioindicators in monitoring water quality, the depreciation of soil conditions has yet to receive adequate attention. Thus, our study aimed to evaluate the potential of odonates (dragonflies and damselflies) as amphibiotic bioindicators to reflect the correlation between the degradation of aquatic and terrestrial habitats in pasture-dominated landscapes. We assessed the relationship between the biotic indices of Odonata and the conservation status of preserved riparian landscapes adjacent to anthropogenically altered pastures in 40 streams in the Brazilian savannah. Our results support the hypothesis that Odonata species composition may be a surrogate indicator for soil and water integrity, making them promising sentinels for detecting environmental degradation and guiding conservation strategies in human-altered landscapes. Importantly, while the Zygoptera/Anisoptera species ratio is a useful bioindicator tool in Brazilian forest, it is less effective in the open savannah here, and so an alternative index is required. Importantly, while the Zygoptera/Anisoptera species ratio is a useful bioindicator tool in Brazilian forest, it is less effective in the open savannah here, and so an alternative index is required. On the other hand, our results showed the Dragonfly Biotic Index to be a suitable tool for assessing freshwater habitats in Brazilian savannah. We also identified certain bioindicator species at both ends of the environment intactness spectrum.

Water Supply Interruptions Are Associated with More Frequent Stressful Behaviors and Emotions but Mitigated by Predictability: A Multisite Study.

Water supply interruptions contribute to household water insecurity. Unpredictable interruptions may particularly exacerbate water insecurity, as uncertainty limits households' ability to optimize water collection and storage or to modify other coping behaviors. This study used regression models of survey data from 2873 households across 10 sites in 9 middle-income countries to assess whether water supply interruptions and the predictability of interruptions were related to composite indicators of stressful behaviors and emotional distress. More frequent water service interruptions were associated with more frequent emotional distress (ß = 0.49, SE = 0.05, P < 0.001) and stressful behaviors (ß = 0.39, SE = 0.06, P < 0.001). Among households that experienced interruptions, predictability mitigated these respective relationships by approximately 25 and 50%. Where the provision of continuous water supplies is challenged by climate change, population growth, and poor management, water service providers may be able to mitigate some psychosocial consequences of intermittency through scheduled intermittency and communication about water supply interruptions. Service providers unable to supply continuous water should optimize intermittent water delivery to reduce negative impacts on users, and global monitoring regimes should account for intermittency and predictability in post-2030 water service metrics to better reflect household water insecurity experiences.

Analysis of the evolution of water culture and water security in the Weihe River Basin over a 100 year-period.

The significance of water culture in addressing water crises and ensuring water security has garnered considerable attention, emerging as a focal point in global change and water science research. Water culture is a societal adaptation to changes in hydrological systems. However, this needs to be acknowledged within contemporary discourse on water security governance. This study utilized historical policy document data from many sources, including local municipal records from Shaanxi and Gansu, and water conservancy records. It aimed to identify the significant nodes and stages of policy transformation in the Weihe River Basin (WRB) during the last century (1949-2020). This study employed a content analysis method to elucidate the evolutionary patterns of water culture in the study region during the previous century. Drawing on the co-evolution framework, our investigation delved into the reciprocal relationship between changes in water culture and the evolution of water security in the WRB. Our findings indicated that water culture transformation in the WRB has undergone four significant stages: the Disaster-Resistant Hydraulic (1949-1966), Irrigation Hydraulic (1967-1998), Resources Hydraulic (1999-2010), and Ecological Hydraulic (2011-2020) phases. Water security assessment showed that policy attention varied across the different stages. The disaster-resistant hydraulic phase primarily addressed water-related disaster concerns, whereas the irrigation hydraulic phase emphasized the scarcity of water resources. The resource hydraulic phase focused on ensuring the security of the water environment, while the ecological hydraulic phase placed emphasis on safeguarding water sustainability. Moreover, we found that prevailing water policies prioritize resolving isolated issues; however, water security is a multifaceted systemic matter that requires a comprehensive approach. This study has the potential to offer policy makers a more comprehensive and systematic perspective, enabling them to enhance their understanding of the underlying nature of the problems. Additionally, this study can assist in developing future water security policies.

Co-defining WASH (In)Security challenges among people experiencing homelessness. A qualitative study on the Human Right to Water and Sanitation from Bonn, Germany.

INTRODUCTION: Access to safe and affordable drinking water, sanitation and hygiene (WASH) for all is needed to safeguard human health, high on societal and political agendas. According to official estimates, populations in high-income countries (HICs) are well served. Vulnerable communities at the margins of rich societies, including people experiencing homelessness, however, are often underserved and overlooked. For them, safe WASH is often a dream rather than reality. To date, no study has been conducted in Germany - one of the countries most affected in Europe. METHODS: We chose a qualitative mixed-method approach to understand WASH (in)security challenges that people experiencing homelessness are facing. Data were collected in Bonn, Germany, from 25 people experiencing homelessness (in-depth interviews, arts-based workshops, group discussions), their service providers (social workers), and (un)available public infrastructure (inspections), in 2023. Data were analyzed following the dimensions of the Human Right to Water and Sanitation (HRTWS): availability; accessibility; affordability; acceptability; quality and safety. RESULTS: People experiencing homelessness largely lack available, accessible, affordable, acceptable and safe WASH. Open urination and defecation are often the only alternative, resulting in substantial health risks and diseases. Women face particular challenges, especially while menstruating. Extreme weather events complicate existing WASH insecurity further, creating additional hardships for unhoused people and their service providers. The missed realization of the HRTWS has far-reaching consequences, making it harder to transition out of homelessness. CONCLUSIONS: Much remains to be done to serve unhoused people in HICs better with WASH. Their experiences shed light on the underlying complexities, and the implications of different often interconnected challenges, including instability, mobility, preexisting diseases, mental health conditions and substance use disorder. Different insecurities exist among different sub-groups (e.g. women, people with limited mobility). They are valuable key informants for targeted health messaging and interventions.

Exploring the potential of bacterial-augmented floating treatment wetlands for the remediation of detergent-contaminated water.

Due to industrialization and urbanization, the use of detergents inadvertently led to contamination of aquatic environments, thus posing potential threat to aquatic organisms and human health. One of the main components of detergents is linear alkylbenzene sulfonate (LAS), which can cause toxic effects on living organisms, particularly aquatic life in the environment. In this study, floating treatment wetlands (FTWs) mesocosms were developed and augmented with LAS-degrading bacteria. The plant species, Brachiaria mutica (Para grass), was vegetated to establish FTWs and bacterial consortium (1:1:1:1) of Pseudomonas aeruginosa strain PJRS20, Bacillus sp. BRRH60, Acinetobacter sp. strain CYRH21, and Burkholderia phytofirmans Ps.JN was augmented (free or immobilized) in these mesocosms. Results revealed that the FTWs removed LAS from the contaminated water and their augmentation with bacteria slightly increased LAS removal during course of the experiment. Maximum reduction in LAS concentration (94%), chemical oxygen demand (91%), biochemical oxygen demand (93%), and total organic carbon (91%) was observed in the contaminated water having FTWs augmented with bacterial consortium immobilized on polystyrene sheet. This study highlights that the FTWs supported with immobilized bacteria on polystyrene sheets can provide an eco-friendly and sustainable solution for the remediation of LAS-bearing water, especially for developing countries like Pakistan.

This pilot-scale study provided insights to resolve the detergent-contaminated wastewater issue, using floating treatment wetlands (FTWs) augmented with bacteria. The FTWs augmented with bacteria immobilized on a polystyrene sheet and vegetated with Brachiaria mutica led to high degradation of LAS, a toxic compound of detergent, from the contaminated water.

Making waves: Promoting municipal water reuse without a prevailing scarcity driver.

The wealth of water reuse research in scarcity and/or rapid urbanisation contexts has underpinned significant change in many relatively water scarce contexts. Less progress has been achieved in water rich contexts; a fact illustrated by the lack of change on the ground. The Climate Emergency demands that all municipalities urgently contribute to more efficient resource management of water. Consequently, to advance municipal scale reuse projects in locations where scarcity is not forcing the issue, for example Scotland, there is a need to predicate water reuse on different drivers, specifically climate change and the circular economy. Moreover, greater contextual sensitivity needs to be applied when exploring barriers to reuse to more critically exploit opportunities, for example avenues to reform complex regulatory frameworks, different contingencies around trust, and different potential degrees of the yuck factor. To achieve this, new initiatives need to be urgently undertaken to consider the barriers to reuse that will not be swept aside by the imperative of  scarcity. The notion of a yum factor, whereby positive sentiments are nurtured to combat instinctive repugnance, coined as yuck by the bioethicist Arthur Caplan, is advanced as a strategic objective to promote more rapid expansion of municipal scale reuse.

Multi-taxon trends and the application of genotoxic biomarkers in the analysis of effluents from sewage treatment plant.

Sewage is a significant source of many contaminants, and the effectiveness of sewage treatment plants (STPs) is fundamental to ensure that the effluents produced by these plants have a minimal impact on aquatic environments and guarantee their long-term sustainability. The present study is based on a global scientometric survey of the published research on the application of genotoxicity biomarkers for the analysis of the effects of the contaminants found in the effluents and residues produced by STPs. The literature search focused on the Web of Science and Scopus databases. Research trends were investigated based on the year of publication of each study, the country in which it was developed, the type(s) of genotoxic assay applied, the model organism(s), the type of study (experimental or field study), the physicochemical parameters analyzed, and the principal findings of the genotoxic assays. A total of 134 papers, published between 1988 and April 2023, were selected for analysis. The studies were conducted in a total of 33 different countries, but primarily in Brazil, China, Germany. These studies employed 16 biomarkers to assess genotoxicity, of which, the micronucleus test was the most used. The studies reported on a number of genotoxic substances, such as pollutants, including pesticides, microplastics, metals, and drugs. The data produced by these studies provide important insights into the genotoxic effect of the xenobiotic agents found in STP effluents, which are capable of damaging the DNA of a range of different organisms.

Environmental impacts, exposure pathways, and health effects of PFOA and PFOS.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that have been widely utilized in various industries since the 1940s, and have now emerged as environmental contaminants. In recent years, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been restricted and replaced with several alternatives. The high persistence, bioaccumulation, and toxicity of these substances have contributed to their emergence as environmental contaminants, and several aspects of their behavior remain largely unknown and require further investigation. The trace level of PFAS makes the development of a monitoring database challenging. Additionally, the potential health issues associated with PFAS are not yet fully understood due to ongoing research and inadequate evidence (experimental and epidemiological studies), especially with regard to the combined effects of exposure to PFAS mixtures and human health risks from drinking water consumption. This in-depth review offers unprecedented insights into the exposure pathways and toxicological impacts of PFAS, addressing critical knowledge gaps in their behaviors and health implications. It presents a comprehensive NABC-Needs, Approach, Benefits, and Challenges-analysis to guide future strategies for the sustainable monitoring and management of these pervasive environmental contaminants.

"The people here knew how I used to live, but now I have to start again:" Lived experiences and expectations of the displaced and non-displaced women affected by the Thwake Multipurpose Dam construction in Makueni County, Kenya.

BACKGROUND: Dam construction and associated disruptive activities such as population displacement can have significant societal consequences, especially for those socially and economically disadvantaged. Though community-level health and social consequences of displacements have been documented, there is little understanding of the individual-level consequences and intra-household gendered dynamics. OBJECTIVE/METHODS: We sought to explore the experiences and expectations of displaced (n = 30) and non-displaced (n = 20) women in Makueni County, Kenya, where Kenya's second largest dam, Thwake Multipurpose Dam, is being constructed. We used qualitative techniques, including photo-elicitation interviews, go-along interviews, key informant interviews, and participant observation, to understand the lived experiences of women affected by the dam construction processes and their associated disruptions. RESULTS: We found that both displaced and non-displaced women experienced the impacts of dam construction in four areas, i.e., economic (income loss), health (hearing damage), social (disrupted social networks), and environmental (flooding) domains. Though both groups described adverse effects, the displaced women perceived worse economic and social outcomes than non-displaced ones. Further, older and married women in both groups had the worst lived experiences and negative perceptions about the consequences for social well-being, e.g., loss of cultural identity, land ownership, and access to important religious sites. Changes in livelihood also transformed gender roles as women assumed economic responsibilities to cushion their families from hunger. CONCLUSION: Development projects such as dams negatively impact the host community-displaced and the non-displaced experience adverse health, social, and environmental effects. However, poor women who are smallholder farmers bear the greatest burden. Assessment of individual-level experiences and intrahousehold dynamics might enhance our understanding of the biosocial outcomes of these consequences. Therefore, integrative biosocial approaches should be considered when examining the impacts of dam construction.

Economic attractiveness of domestic rainwater harvesting in Brazilian cities.

Brazil is the fifth largest country by area in the world, with a variety of climates in its territory. This work assesses the economic attractiveness of domestic rainwater harvesting direct feed systems, for the replacement of non-drinking water, in 148 locations of the Brazilian territory considering hourly rainfall data for the 14-year period between 2008 and 2021. The water tariff and consumption data for each location were also considered along with estimated hourly and monthly consumption patterns. With annual operating expenses at 1% of the capital expenditure and an annual discount rate of 8%, the net present value for the 14-year period is positive in only 15 locations, which are among those with the highest water tariffs in the country. The results of these base case simulations discourage the installation of domestic RWH systems in most of the Brazilian locations considered. However, the results also show that, depending on house occupancy, filtration equipment cost, water tariff, and catchment area, outcomes more favorable to the installation of RWH systems are obtained, especially in cities of Brazil's southern and southeastern regions.

A declaration on the value of experiential measures of food and water insecurity to improve science and policies in Latin America and the Caribbean.

BACKGROUND: Water security is necessary for good health, nutrition, and wellbeing, but experiences with water have not typically been measured. Given that measurement of experiences with food access, use, acceptability, and reliability (stability) has greatly expanded our ability to promote food security, there is an urgent need to similarly improve the measurement of water security. The Water InSecurity Experiences (WISE) Scales show promise in doing so because they capture user-side experiences with water in a more holistic and precise way than traditional supply- side indicators. Early use of the WISE Scales in Latin American & the Caribbean (LAC) has revealed great promise, although representative data are lacking for most of the region. Concurrent measurement of experiential food and water insecurity has the potential to inform the development of better-targeted interventions that can advance human and planetary health. MAIN TEXT: On April 20-21, 2023, policymakers, community organizers, and researchers convened at Universidad Iberoamericana in Mexico City to discuss lessons learned from using experiential measures of food and water insecurity in LAC. At the meeting's close, organizers read a Declaration that incorporated key meeting messages. The Declaration recognizes the magnitude and severity of the water crisis in the region as well as globally. It acknowledges that traditional measurement tools do not capture many salient water access, use, and reliability challenges. It recognizes that the WISE Scales have the potential to assess the magnitude of water insecurity more comprehensively and accurately at community, state, and national levels, as well as its (inequitable) relationship with poverty, poor health. As such, WISE data can play an important role in ensuring more accountability and strengthening water systems governance through improved public policies and programs. Declaration signatories express their willingness to promote the widespread use of the WISE Scales to understand the prevalence of water insecurity, guide investment decisions, measure the impacts of interventions and natural shocks, and improve public health. CONCLUSIONS: Fifty-three attendees endorsed the Declaration - available in English, Spanish and Portuguese- as an important step to making progress towards Sustainable Development Goal 6, "Clean Water and Sanitation for All", and towards the realization of the human right to water.

Rethinking terrestrial dissolved organic matter in dam reservoirs before mixing: Linking photodegradation and biodegradation and the phenanthrene binding behavior.

With the increased construction of dam reservoirs and the demand for water security, terrestrial dissolved organic matter (DOM) has received attention because of its role in regulating water quality, ecological functions, and the fate and transport of pollutants in dam reservoirs. This study investigated the transformations of soil DOM and vegetation DOM of dam reservoirs following photodegradation and biodegradation before conservative mixing, as well as the resultant effects on phenanthrene binding. Based on the results, terrestrial DOM could undergo transformation via photodegradation and biodegradation before conservative mixing in dam reservoirs. Although both processes resulted in substantial decreases in DOM concentrations, the changes in chromophoric DOM and fluorescent DOM depended on the original DOM sources. Furthermore, the photodegradation of terrestrial DOM resulted in more pronounced photobleaching than photomineralization. In addition, photodegradation of terrestrial DOM resulted in the generation of DOM-derived by-products with low molecular weight and low aromaticity, whereas the biodegradation of terrestrial DOM resulted in DOM-derived by-products with low molecular weight and high aromaticity. Subsequently, the photodegradation and biodegradation of terrestrial DOM substantially enhanced the binding affinity of phenanthrene. Soil DOM is prior to vegetation DOM when predicting the ecological risk of HOCs. These results indicate that the terrestrial DOM in dam reservoirs should be reconsidered before conservative mixing. Further studies on the coupling effects of both biogeochemical processes, as well as on the relative contributions of soil DOM and vegetation DOM after transformation to the aquatic DOM in dam reservoirs, are required. This study provides information on the environmental effects of dam construction from the perspective of biogeochemical processes.

Water chemistry poses health risks as reliance on groundwater increases: A systematic review of hydrogeochemistry research from Ethiopia and Kenya.

Reliance on groundwater is increasing in Sub-Saharan Africa as development programmes work towards improving water access and strengthening resilience to climate change. In lower-income areas, groundwater supplies are typically installed without water quality treatment infrastructure or services. This practice is underpinned by an assumption that untreated groundwater is typically suitable for drinking due to the relative microbiological safety of groundwater compared to surface water; however, chemistry risks are largely disregarded. This article systematically reviews groundwater chemistry results from 160 studies to evaluate potential health risk in two case countries: Ethiopia and Kenya. Most studies evaluated drinking water suitability, focusing on priority parameters (fluoride, arsenic, nitrate, or salinity; 18 %), pollution impacts (10 %), or overall suitability (45 %). The remainder characterised general hydrogeochemistry (13 %), flow dynamics (10 %), or water quality suitability for irrigation (3 %). Only six studies (4 %) reported no exceedance of drinking water quality thresholds. Thus, chemical contaminants occur widely in groundwaters that are used for drinking but are not regularly monitored: 78 % of studies reported exceedance of contaminants that have direct health consequences ranging from hypertension to disrupted cognitive development and degenerative disease, and 81 % reported exceedance of aesthetic parameters that have indirect health impacts by influencing perception and use of groundwater versus surface water. Nevertheless, the spatiotemporal coverage of sampling has substantial gaps and data availability bias is driven by a) the tendency for research to concentrate in areas with known water quality problems, and b) analytical capacity limitations. Improved in-country analytical capacity could bolster more efficient assessment and prioritisation of water chemistry risks. Overall, this review demonstrates that universal and equitable access to safe drinking water (Sustainable Development Goal target 6.1) will not be achieved without wider implementation of groundwater treatment, thus a shift is required in how water systems are designed and managed.

Water security assessment and driving mechanism in the ecosystem service flow condition.

Water resources are the foundation of human survival and development. Thus, it is essential to quantify the relationship between water supply and demand and assess water security to ensure sustainable use of water resources. In this study, we quantified the relationship between water supply and demand in the Yiluo River Basin (YRB) using the InVEST model, constructed a spatial flow model of water provision service at the sub-watershed scale, and analyzed the water security index (WSI) under static and dynamic conditions. Subsequently, we used geographic detectors to identify the explanatory power of the main influencing factors of the WSI. The results showed that (1) from 2005 to 2018, the water supply decreased continuously and the water demand first increased and then decreased in the YRB; (2) the spatial pattern of WSI showed that it was high in the southwest and low in the northeast, wherein the highest and lowest WSI values occurred in 2005 and 2018, respectively. From 2005 to 2018, the mean values of the static and dynamic WSI decreased from 0.77 to 0.60 and 1.56 to 1.20, respectively. (3) The precipitation factor from the supply dimension and the gross domestic product (GDP) factor from the demand dimension had the strongest explanatory power for the static WSI. For the dynamic WSI, the flow quantity of the water provision service flow had the strongest explanatory power. This study provided a reference for governments to formulate sustainable water resource management.

Integrated water security and coupling of social-ecological system to improve river basin sustainability.

The river basin sustainability depends on both the coordinated development of socio-ecological systems and resilience to water resources. However, the lack of integrating them on spatial and temporal scales compromises our capacity to develop precise interventions towards sustainable river basins. We developed an approach by integrating water security and social-ecological coupling to assess the river basin sustainability. We divided it into four categories including highly sustainable (secure and coordinated), insecure, uncoordinated, and low sustainable (insecure and uncoordinated). The middle reach of Heihe River (MHR) was taken as the study area with the sub-basin as the spatial analysis unit from 2000 to 2020. The results showed that there was heterogeneity and agglomeration in spatial distribution. 23.8 %, 38.8 %, and 11% of the sub-basins mainly clustered in the north and central areas were found in the state of water insecure and SES uncoordinated, or both respectively. The unsustainable areas (five sub-basins) and lose-lose areas (two sub-basins) should be the priority areas for management interventions. Our approach can provide an important reference for assessing and improving the river basin sustainability.

Toward understanding the interaction of shale gas-water-carbon nexus in Sichuan-Chongqing region based on county-level water security evaluation.

This study develops a comprehensive framework for understanding the interaction of shale gas-water-carbon nexus in Sichuan-Chongqing region. Within this framework, a county-level water security index (WSI) evaluation system is structured. Spatial autocorrelation model and spatial matching degree model are integrated to illustrate the spatial agglomeration characteristics of water security and the water-carbon relationship, respectively. The impacts of shale gas development on water security and carbon emissions are evaluated based on identification of shale well productivity. Results show that about 25.17% of counties with WSI < 0.4 (unsafe), especially in the eastern region. The central cities (such as Chengdu and Neijiang) should take active steps to reach a safety threshold (WSI ≥ 0.6). Population growth can accelerate water security deterioration through uncertainty analysis. Moreover, the spatial matching degree between WSI and carbon emissions in most cities is extremely poor (< 0.5), implying that these cities should optimize their energy structure and promote green transformation. Water used for shale gas extraction can hardly be ignored from a county-scale perspective, especially in Tongliang, Tongnan, and Jianyang. The future shale gas development would pose a threat to the regional climate.