ABSTRACT The ecotone connecting rivers with their riparian zones represents conditions where fluvial processes, abundant resources and reciprocal energetic subsidies have combined over evolutionary time to create multiple opportunities for niche development in a wide range of organisms. Among them, specialist riverine birds are diverse, conspicuous, and widespread globally, but they remain under‐researched by both river ecologists and ornithologists. Globally, we identify 69 bird species that have evolved specialized lifestyles along high‐gradient, fast‐flowing rivers and here we review (i) spatial patterns in their distribution to identify hotspots of diversity; (ii) major threats to their status and (iii) regions that are candidates for their conservation. Only a few species of specialist riverine birds are well known ecologically, hindering understanding of population trends, distribution, and conservation requirements at regional, continental or global scales. Multiple threats include habitat impairments through dams and other water resource infrastructure; land management for agriculture, forestry and urbanization; invasive non‐native species; pollution from well‐known and emerging sources; and the effects of climate change on flow patterns and thermal regimes. Neither the direct nor indirect effects involved—for example through prey availability or species interactions—have been adequately addressed by ecologists in contrast to birds in terrestrial or marine ecosystems. We identify two urgent needs respectively, (i) to expand interdisciplinary research to understand the ecology of river birds and (ii) to enhance their conservation both through catchment‐scale action and by protecting those regions that support threatened species and large species richness, notably in the tropics and sub‐tropics. This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Stresses and Pressures on Ecosystems Water and Life > Conservation, Management, and Awareness
ABSTRACT Atmospheric water harvesting (AWH) provides a decentralized means of producing water without reliance on conventional sources such as rivers, lakes, or aquifers. While traditionally applied in humanitarian and drinking water contexts, the high quality of AWH‐derived water also makes it attractive for industrial and ultrapure water (UPW) applications, where reducing water footprints is increasingly critical. This review examines three primary AWH technologies with emphasis on their energy requirements, water quality, and potential for integration into industrial systems. Fog harvesting is the lowest‐energy option but is restricted to regions with persistent fog and yields limited volumes. Dew‐point condensation systems are commercially available, supported by cost models, and perform best in high‐humidity environments. Desiccant‐based systems, though still emerging, are adaptable across climates and especially promising for arid or low‐humidity regions. Their energy demand can be significantly reduced by coupling sorbent regeneration with industrial waste heat. For industries such as semiconductors manufacturing, pharmaceuticals, beverage production, and energy, both water quality and energy use are central constraints. Compared to municipal tap water, which requires extensive desalting and chemical treatment for UPW, AWH‐derived water is nearly salt‐free, lowering pretreatment energy demands and cost. Significant challenges remain for AWH energy efficiency to reach an ambitious United States Defense Advanced Research Projects Agency (DARPA) target of 42 kWh/m 3 (~$2/m 3 ), but advances in sorbent materials, hybrid system designs, automation, and waste energy recovery provide realistic pathways. This review outlines a roadmap for AWH to evolve into a viable, scalable, and sustainable supplemental source of UPW, particularly in water‐stressed industrial regions. This article is categorized under: Engineering Water > Sustainable Engineering of Water
ABSTRACT The assessment of flood risk is crucial for sustainable planning, policymaking, and emergency management. Even with recent methodological advancements, flood risk assessment in data‐scarce regions still encounters significant uncertainties. Despite the multitude of available methods and data sources, no context‐specific guidance exists for selecting a suitable combination of methods to map risk in a given data‐scarce area of interest. To address this gap, we conducted a systematic review of 264 studies on flood risk assessment in data‐scarce regions. First, our study reveals diverse interpretations of “risk” and “data scarcity”, deviating from well‐established definitions. We highlight the use of a standardized definition of flood risk to enhance the comparability of findings and improve the reliability of assessments. Second, we conceptualize data scarcity in the flood risk context to support an informed selection of assessment methods. Third, we systematically compile risk indicators, methods, and data sources applied in the context of data scarcity, and we analyze the interplay between methods for mapping the three key risk components, that is, hazard, exposure, and vulnerability. This interplay enables the design of a three‐step approach for identifying an appropriate methodological combination for flood risk assessment in any data‐scarce application context. Through these three key contributions, our review paves the way for more reliable and consistent flood risk assessment and management in data‐scarce regions, facilitating the reduction and mitigation of flood impacts in vulnerable communities across the globe. This article is categorized under: Science of Water > Water Extremes Engineering Water > Planning Water
ABSTRACT Smart water meters (SWMs) are key to modern residential, industrial and agricultural water supply and management systems. enabling accurate real‐time data, timely leak detection, reduced water loss, and improved billing accuracy. High system performance enables better forecasting and optimization, especially in areas with aging infrastructure or growing populations, while resilience against cyber threats ensures safety and security. However, maintaining and managing these assets is challenging, due to data reliability and analytical issues, communication failures, and increasing system complexity This review synthesizes current literature on key challenges, recent innovations, and best practices for efficiently managing and maintaining smart water meter (SWM) assets. We highlight the potential of predictive and condition‐based maintenance supported by asset management, the plan‐do‐check‐act (PDCA) approach alongside tool such as root cause analysis (RCA), reliability‐centered maintenance (RCM), conditioning monitoring or failure modes and effects analysis (FMEA)) in accordance with ISO 55002 to enhance reliability and operational efficiency. We advocate for the adoption of machine learning and internet of things (IoT)‐enabled monitoring to facilitate a shift from reactive to predictive maintenance, which remains underexplored in traditional water management literature. The findings offer valuable insights for water utilities aiming to advance smart water infrastructure through strategic asset management, data frameworks, and capability development. This article is categorized under: Engineering Water > Sustainable Engineering of Water Engineering Water > Planning Water Engineering Water > Methods
ABSTRACT Hydrological, morphological and ecological processes can be used as nature‐based solutions to manage the movement of water, known as nature‐based flood management (NFM). NFM can contribute to flood resilience and adaptation, while also delivering multiple ecosystem service co‐benefits. However, a lack of evidence on the range, scale, and value of these benefits is a key barrier to NFM uptake. Quantifying the type and extent of ecosystem co‐benefits is therefore critical in communicating the opportunities that NFM provides to people and nature. We undertook a scoping review of the peer‐reviewed and grey literature to identify evidence for the co‐benefits and disbenefits of different types of NFM activities in the UK. The findings were categorized within a natural capital framework, and the quality of evidence was assessed using a bespoke critical evaluation tool that considered the reliability, validity, and relevance of the data collected. A total of 205 pieces of evidence from 27 sources were identified, describing the co‐benefits, disbenefits, or neutral outcomes of different NFM activities. Benefits for regulating services, water quality, and biodiversity were the most frequently measured. Although multiple benefits from NFM are often claimed from anecdotal observations, this review revealed evidence gaps across most categories of ecosystem services and a range of NFM activities. Future priorities for increased experimental quality, consistent use of indicators, and the appropriate spatial and temporal scale of monitoring NFM benefits and disbenefits are discussed, and will be critical to support the widespread implementation of nature‐based solutions for water management. This article is categorized under: Water and Life > Conservation, Management, and Awareness
ABSTRACT The Lower Mississippi River Basin (LMRB) is a crucial area known for its intensive agricultural production that is heavily dependent on the Mississippi River Valley Alluvial Aquifer (MRVAA) for irrigation. This region's agriculture relies extensively on this underlying aquifer to sustain its crop production needs. Extensive irrigation with groundwater, coupled with regional geology, has led to significant groundwater decline. The LMRB includes large areas of eastern Arkansas and Louisiana, western Tennessee and Mississippi, and the bootheel of Missouri, with the most severe overdraft of the MRVAA occurring in the Mississippi Delta region of Arkansas and Mississippi, which is therefore the regional focus of this paper. In parts of Arkansas, the decline has been so severe that these areas have been designated as Critical Groundwater Areas. This manuscript identified relevant literature that pinpoints challenges and the strategies used in response to the decline. Experimental strategies being explored to potentially increase groundwater levels include case studies of managed aquifer recharge (MAR) using infiltration galleries (IGs), riverbank filtration coupled with groundwater transfer followed by injection wells, and repurposed borrow pits, which are all techniques tailored to the region's hydrogeology. Strategies to transition irrigation from groundwater to surface water involve on‐farm reservoir‐tailwater recovery systems (R‐TWRS), which store and recycle irrigation runoff and excess precipitation to reduce groundwater dependence. Findings from this paper demonstrate how conservation strategies such as MAR and R‐TWRS are designed to mitigate the ongoing decline of the alluvial aquifer that is crucial for the economic and ecological sustainability of the LMRB. This article is categorized under: Engineering Water > Sustainable Engineering of Water Engineering Water > Planning Water Water and Life > Conservation, Management, and Awareness
ABSTRACT Groundwater temperature dynamics and spatial patterns influence aquifer biogeochemistry and the quality and ecosystem dynamics of receiving surface waters. Groundwater‐dominated streams are characterized by modulated diel and seasonal thermal regimes and can exhibit pronounced spatial thermal variability near focused groundwater discharge. Temporally modulated thermal regimes impose less thermal stress on aquatic biota than in thermally dynamic streams, and spatial thermal variability creates riverscapes with thermal refuges that sustain poikilotherms during extreme events. Thus, groundwater inflows can (1) lower ambient summer stream temperatures, with changes up to 8°C in past studies, and (2) create anomalous cold‐water plumes, with field studies showing plume temperature differences exceeding 20°C. Because groundwater temperatures are relatively insensitive to seasonal meteorological changes, they are often incorrectly assumed to be thermally resilient to long‐term changes in land cover or climate. However, global evidence reveals that shallow aquifers are warming up to several degrees Celsius in response to urbanization, deforestation, and climate change, which can influence the heat fluxes associated with groundwater discharge to surface waters and resultant stream temperatures. Properly accounting for the changing thermal impacts of groundwater discharge in process‐based stream temperature models is only possible through a rigorous understanding of subsurface thermal processes and how those processes alter spatiotemporal patterns of groundwater temperature. This review advances process‐based understanding of groundwater temperature and its thermal influence on streams and evaluates approaches for representing groundwater discharge impacts in stream temperature models. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Water and Environmental Change Water and Life > Stresses and Pressures on Ecosystems
ABSTRACT Irrigation systems are socio‐technical systems whose sustainability depends on social relations and governance systems. However, most of the irrigation sector and research has largely been guided by apolitical, masculine, and technical discourses. We argue that a feminist political ecology (FPE) approach could support in‐depth analyses of social and political dynamics and provide original perspectives on irrigation research and practice. We conducted a systematic literature review of FPE research on irrigation, examining how FPE is defined, framed, and applied to research on irrigation, and conversely how irrigation is defined and analyzed through an FPE lens. We identify 12 FPE themes to study power relations and social inequities in irrigation, resources, labor, land, and tenure struggles across 21 studies. Our review shows that FPE provides a multi‐scalar, politicized, and social justice‐oriented approach to differentiated access to, and the impacts of, irrigation. FPE studies bring fresh insights into: (i) embodied and emotional labor and everyday struggles over irrigation, (ii) effects of household, care, and community relations on irrigation access and control, and (iii) often overlooked topics such as water infrastructural violence, gendered vulnerability, intersectionality, and marginalized social groups in irrigation systems. We note a gap between the theoretical potential of FPE and its application in practice. Some studies apply FPE apolitically, and only a few studies reflect on a decolonial approach to science, self‐reflexivity, and positionality. We recommend that future research engage more with concepts of body/embodiment, emotions, and care, and the link between the fluidity of water resources and dynamic power relations. This article is categorized under: Human Water > Water Governance Human Water > Rights to Water Engineering Water > Planning Water
ABSTRACT Rapid recent expansion of artisanal and small‐scale gold mining (ASGM) globally has led to widespread impacts on water. ASGM often occurs within or adjacent to communities, directly impacting the people who live there. We performed an extensive review of scholarship to document the myriad ways ASGM impacts water and thus humans and ecosystem health. Drawing from > 300 peer‐reviewed articles, books, and government reports, we examine how ASGM uses water in both alluvial and hard rock mining. We report impacts of ASGM on water distribution and water quality. We also link ASGM‐water processes to human health, including impacts on disease dynamics, drownings and water‐related accidents, local water insecurity, and mental health. We conclude by identifying remaining gaps in the scholarship around ASGM and water, including the need for research on hard rock mining, household water insecurity, disease transmission beyond malaria, and fluvial geomorphology. Finally, we show that the short‐term and transient nature of many ASGM activities contrast with the resultant long‐term and widespread impacts. While gold mining is framed as being vital to national economies and employment, the long‐term implications (e.g., mercury contamination, increased malarial transmission, artificial lake formation, farm destruction) are profound. Policy makers, government officials, and others should consider the long‐term environmental, social, and health impacts of ASGM on water resources to fuel development and enforcement of more sustainable policies and regulations. This article is categorized under: Science of Water > Water and Environmental Change Engineering Water > Water, Health, and Sanitation Science of Water > Water Quality
ABSTRACT Isotope‐based Bayesian mixing models (BMM) are widely used in ecohydrology to infer where plants acquire water from the soil, yet clear guidance on their application to root water uptake (RWU) remains limited. This review synthesizes existing BMM applications for RWU estimation and critically examines three fundamental challenges that constrain their robustness and interpretability. First, RWU inference is often severely underdetermined because the number of isotopic tracers is far smaller than the number of potential soil water sources or depth layers, placing fundamental limits on parameter identifiability. Second, RWU estimates are sensitive to model configuration choices, particularly source grouping and prior specification. A key conceptual insight emerging from this review is that so‐called “non‐informative” Dirichlet priors can become strongly informative as the number of sources increases, leading to divergent uptake patterns inferred from the same dataset. Third, inappropriate specification of error structures can misrepresent how isotopic variability is propagated into the likelihood function, inflating posterior uncertainty or biasing inferred RWU proportions. Looking forward, we argue that further progress in BMM‐based RWU inference requires moving beyond discrete, depth‐resolved formulations toward physically grounded and vertically continuous inference frameworks with well‐justified error structures. Such developments, together with explicit consideration of identifiability and model dimensionality, are essential for the robust use of hydrogen and oxygen stable isotopes in quantifying root water uptake patterns. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Methods
Graphical methods are complementary tools to conventional statistical Performance Measures (PMs) for model evaluation. Despite their recognized value, a comprehensive understanding of how graphical methods can be applied and interpreted for water quality modeling remains lacking. In this overview paper, we describe typical usage of graphical methods, aspects of model performance they reveal, and the interpretation of visualization methods based on four categories, which include (1) temporal trend and variation in water quality data, (2) distribution of model outputs and parameters, (3) relationships between variables, and (4) spatial variation in water quality responses and performance. In addition, we highlight the capability of different graphical methods in terms of visually assessing performance in model fitting, addressing model limitations and predictive uncertainties. We also underscore their potential in uncovering key patterns reflecting relevant processes to inform whether the model is sensible in getting results that are consistent with relevant characteristics of observations. Graphical methods help in establishing a level of confidence with respect to the quality of the modeling process and especially its model evaluation exercises. Recommendations on the selection of methods, qualitative interpretation of model performance, and future research on graphical model evaluation and improvement are discussed. Two example studies featuring distinct water quality problem contexts and model structures are presented. They show how different graphical methods can be used to enhance assessment of model performance and sensibility, thereby identifying areas for model improvement.
ABSTRACT Recurrent flooding in the Brahmaputra River Basin has caused extensive loss of life and substantial economic damage. Despite its profound socio‐economic and environmental implications, a comprehensive understanding of how the basin's geomorphological and hydrometeorological characteristics shape flood occurrence and how these complexities constrain early warning and management systems remains limited. This review synthesizes current knowledge on the occurrence, drivers, and mitigation of floods in the Brahmaputra River Basin. The basin's distinctive geomorphology and hydroclimatic regime create inherently favorable conditions for flooding. Active river meandering, avulsion, and rapid channel migration across the middle and lower reaches enhance flood susceptibility, whereas glaciers and snowmelt dominate hydrological processes in the upper basin, and monsoonal rainfall governs the lower basin. Flood generation arises from the interaction of extreme precipitation, antecedent hydrological conditions, and large‐scale atmospheric dynamics. Although recent decades have witnessed basin‐wide warming alongside declining mean rainfall, increasing rainfall variability and shifting monsoon behavior continue to amplify flood unpredictability. Despite technological progress in flood forecasting and early warning systems, their effectiveness remains constrained by sparse observations, inadequate data sharing, and limited transboundary coordination. Overall, rising temperatures, accelerated glacier melt, geomorphological dynamism, and shifting precipitation patterns collectively heighten the challenges of flood prediction and management in the Brahmaputra River Basin. This article is categorized under: Science of Water > Water Extremes Science of Water > Hydrological Processes Science of Water > Water and Environmental Change
ABSTRACT Hydroclimate change is stressing dams and their management, altering the benefits, costs, and risks of built water infrastructure for people and the environment. Removing obsolete dams and barriers may hold promise as a nature‐based solution to adapt to climate change‐related events, including more severe droughts and floods. While most dam removal studies describe the impacts of dams on people and the environment, few studies directly connect removal with climate change, resilience, or adaptation. To explore the potential link between dam removal and climate resilience, we reviewed 50 studies and reports, including peer‐reviewed and gray literature. We interpret climate resilience broadly, encompassing environmental, economic, engineering, social, and cultural criteria. Removing dams and barriers enhances climate resilience by reconnecting rivers, enhancing fisheries, cooling stream temperatures, and providing access to stream temperature refuges, and reducing risk where changing hydrology exceeds dam design standards. We highlight several cases where dams and barriers have already been removed to improve climate resilience and identify over 70 unique metrics of climate resilience. There is no universal approach for measuring resilience, as river systems and objectives vary. Many dams are instrumental for flood risk reduction, water supply reliability, hydropower generation, water temperature management, novel ecosystems, and blocking dispersal of invasive species. Research linking dam removal to climate resilience is still emerging and is essential for prioritizing the removal of unsafe, underperforming, and obsolete dams, thereby directing funding for maintaining and rehabilitating valuable water infrastructure to withstand extreme climate events. This article is categorized under: Science of Water > Water and Environmental Change Engineering Water > Sustainable Engineering of Water
Streamflow droughts pose recurrent threats to societies and freshwater ecosystems. These events span time scales from short (a few weeks) to long (multiple years), with varying impacts and management challenges depending on their duration. Streamflow droughts arise from the interaction between atmospheric anomalies in precipitation and temperature, and hydrological processes, such as actual evapotranspiration, snow and sub‐surface storage, and human activities. Therefore, they are subject to global changes in climate, water and land management. Thorough understanding and modeling of streamflow droughts are needed to cope with these extreme events under current and future conditions. Still, syntheses of the growing body of literature on the processes governing streamflow droughts of various durations and their simulation are lacking. Here, after briefly recalling definitions and methods for drought identification and characterization, we extensively review recent findings on the generation and simulation of streamflow droughts. We develop the review along two lines: (1) the main hydro‐climatic processes involved (i.e., atmospheric, land‐surface, sub‐surface, and anthropogenic processes) and (2) the time scales over which streamflow droughts can take place, by bringing together findings for events of varying durations. We then summarize the main findings that emerged from this literature review and their implications for drought monitoring, management, and adaptation. Finally, we suggest moving toward (i) large‐scale analyses at multiple temporal scales, (ii) considering event‐specific, compound drivers of streamflow droughts, and (iii) their improved simulation, as three main pathways for future research. Advancing along these directions will improve forecasting and prediction of streamflow droughts under changing conditions. This article is categorized under: Science of Water > Water Extremes
Delta regions increasingly suffer from both biodiversity loss and the effects of climate change. In response, many conservationists, ecologists, and urban designers have called for infrastructural models that restore rather than undermine natural systems. Yet, efforts to implement such pro‐environmental transformations often face pushback due to competing normative frameworks about what deltas are for and who they should serve. Drawing on recent developments in the anthropology of infrastructure, we argue that infrastructural transformation can be complicated due to how existing infrastructural arrangements articulate with different “moral ecologies,” or sets of moral ideas regarding how and for whom to organize relationships between human and nonhuman actors and environments. While the concept of “moral economy” has previously been used to examine normative claims in environmental disputes, it falls short in addressing infrastructural contexts where economic, ecological, and moral logics intersect. We propose moral ecology as a complementary analytical framework that better captures how just relations are understood among particular sets of actors. Moral ecologies, we argue, entail three elements: (1) commonly held understandings of appropriate human–nonhuman relations; (2) forms of participation in environmental processes influenced by those understandings; and (3) mechanisms by which pressure can be applied to those who violate them. Through a review of emerging literature in archaeology, environmental anthropology, and human geography, we outline the conceptual foundations of moral ecologies and illustrate their relevance for understanding infrastructural inertia, contestation, and how change can be better strategized in deltaic regions. We conclude that while the framework offers powerful tools for analyzing normative conflict in hydrosocial systems, further work is needed to theorize how change occurs within and between moral ecologies, as well as how they interrelate. This article is categorized under: Human Water > Water as Imagined and Represented Human Water > Value of Water Human Water > Methods
The conventional approach to urban stormwater system design is deemed unsatisfactory, primarily due to its narrowly defined objective. Such a design approach is limited due to the amplified variability of stressors resulting from climate change, urbanization, and ecologically harmful resource use. Additionally, recent technological advancements are not yet adequately utilized. In this perspective piece, we aim to introduce and summarize design paradigms that are gaining traction within the context of next‐generation stormwater infrastructures. Each paradigm offers its own set of vision and goals. Here, we consider common values, trends, ideas, and real‐world practices in the stormwater management field. We first highlight the limitations of the conventional paradigm—it falls short of effectively addressing the increasing challenges associated with the planet's uncertain hydroclimatic future and the new integrated objectives of urban stormwater systems. To address these challenges, this paper presents a summary of paradigms, offering an expanded vocabulary that enables urban stormwater system designers to recognize future uncertainties in stormwater systems and extend their functionality. This encompasses concepts that deal with design in the face of uncertainties: stormwater systems' (1) robustness & resilience, (2) adaptability, and (3) characteristics of antifragility. Additionally, some paradigms recognize urban stormwater systems as an integral component of a comprehensive and integrated urban environment, encompassing concepts such as (4) sustainability and (5) multi‐functionality. Compiling the vocabulary of paradigms in one place and amplifying the discussion can potentially assist researchers, system designers, and decision‐makers in meaningfully broadening the scope of their design goals. This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water and Environmental Change
Reforestation and afforestation on China's Loess Plateau have more than doubled vegetation cover since the late 1990s, yet mounting evidence shows that these gains often come at the cost of long‐term ecohydrological resilience. The region's thick loess vadose zone acts as a deep but finite reservoir of soil water, storing legacy rainfall that current vegetation continues to exploit. This desiccation process is not instantaneous, but unfolds over decadal timescales as deep soil moisture—recharged during wetter periods decades earlier—is gradually depleted. Four lines of evidence reveal the hydrological tradeoffs of large‐scale greening: (1) bomb‐peak tritium archives indicate that 1960s precipitation is still migrating through the subsurface 7–14 m belowground, confirming piston flow infiltration and decades‐long residence times; (2) roots of afforestation species routinely extend 5–15 m, drawing on this paleo moisture; (3) stand‐age trajectories show that deep soil water is predictably exhausted within 15–25 years of planting, forming chronic dried soil layers; and (4) drought‐driven collapse of hydrological niche separation among species increases competition and ecological risk. Together, these dynamics constrain the water balance and reveal an accumulating hydrological debt. Adaptive strategies—thinning, rotation, spatial mosaics, and rainwater harvesting—can slow desiccation and better align vegetation structure with water availability. The Loess Plateau offers globally relevant lessons for dryland restoration: greening must account for rooting depth, recharge rates, and the vertical architecture of water storage. Sustaining ecological function requires harmonizing surface vegetation with the subsurface memory of water. This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Hydrological Processes Science of Water > Water and Environmental Change
Empirical research on households' flood risk adaptation behavior has gained significant attention. While several reviews have already summarized the general progress in this research domain, no study has systematically assessed the progress toward addressing identified research gaps in this field over time and across geographic regions. Therefore, we conducted a systematic review ( n = 352) to assess the distribution and scope of empirical studies over time and across regions. Applying content and statistical analyses, we assess the distribution of case studies across countries, regions, and flood risk levels, and the share of studies addressing key research gaps related to methods, theoretical frameworks, behavioral drivers, and adaptation behaviors. We find that the number of studies on drivers of households' flood risk adaptation has significantly increased over the last two decades. However, relevant studies are still rare in many countries, particularly in those facing the highest flood risks located in the Global South, with some exceptions in South and Southeast Asia, Latin America, and Western Africa. In addition, general research progress toward addressing key research gaps is low, particularly concerning the rare application of mixed‐method approaches and longitudinal data collection. In contrast, significant progress is observed for the use and adaptation of theoretical frameworks over the last two decades. Furthermore, the research scope significantly differs across regions, without clear regional patterns. Our findings thus highlight that future research on household flood risk adaptation behavior should be progressively conducted in countries most at risk and strongly build on identified research gaps to ensure accelerated progress. This article is categorized under: Human Water > Water Governance Science of Water > Water and Environmental Change Water and Life > Conservation, Management, and Awareness
Climate change increasingly shapes how groups share—or fight over—water‐dependent resources. Synthesizing 235 peer‐reviewed studies published between 1980 and 2022, this article clarifies when water scarcity fuels communal conflict and when it sparks cooperation. Rather than treating water scarcity as a purely physical condition, the review conceptualizes it as a socially and politically mediated process that shapes, and is shaped by, access, governance, and inequality. Evidence is concentrated in farmer–herder settings across 30 countries, yet more than half of all work focuses on five African nations and relies on single‐case designs. The analysis shows that water scarcity alone rarely drives violence. Instead, outcomes depend on how water and water‐dependent resources are accessed, governed, and contested across social and institutional settings. Water governance thus emerges as a central arena of power and social justice, shaping whether environmental stress produces conflict or cooperation. The same shocks foster negotiation over water resources when customary rules remain legitimate and include marginalized users. For practitioners and policymakers, strategies like conflict‐sensitive adaptation, fostering institutional pluralism, and implementing early‐warning systems that integrate climate forecasts with social indicators may transform water stress into opportunities for collaboration rather than sources of confrontation. This article is categorized under: Human Water > Water Governance Human Water > Methods Water and Life > Conservation, Management, and Awareness
The family of per‐ and polyfluoroalkyl substances (PFAS) includes thousands of artificial compounds with a wide range of applications in industrial and consumer goods, many preceding statutory controls and commercialized with an implicit assumption about safety with respect to environmental and human health. In recent years, emerging concern about PFAS contamination has led to studies of prevalence in the environment and in the human body. Drinking water has been established as a significant exposure route for humans. Epidemiological studies have found associations between some PFAS compounds in drinking water and human health impacts including neonatal impacts, metabolic syndrome, thyroid dysfunction, and certain cancers. However, understanding of causal mechanisms is not yet definitive. This review of over one hundred peer‐reviewed scientific papers and government documents synthesized the state of current knowledge as of late 2025, focusing on evidence regarding: firstly, prevalence of PFAS in drinking water and the human body; secondly, demonstrated associations with human health impacts; and, thirdly, how regulatory authorities in different parts of the world are attempting to address emerging concerns about risks to human and environmental health. This article is categorized under: Engineering Water > Water, Health, and Sanitation Science of Water > Water Quality Human Water > Water Governance
