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 Despite the close connection between urbanization and the ecology of rivers, the co‐constitution of rivers and urban space remains undertheorized. This advanced review asks how scholars across social science and humanities disciplines have understood the relationships between rivers and the cities they make possible. This review is aimed toward advancing an urban river research agenda that centers the mutual production of the urban nature space of rivers and the socially uneven geographies of the modern city. To this end, I draw from the literatures of environmental history, urban history, urban political ecology, and postcolonial studies. Urban and environmental history provide historical accounts of the role of rivers in the urbanization process. Urban political ecology usefully theorizes nature‐society relations as a dialectic wherein the metabolization of nature produces historically contingent forms of urban socio‐nature, always already imbued with asymmetrical power relations. More recent urban political ecology writing has incorporated insights from scholars of racial capitalism and settler colonialism, broadening the field for a deeper engagement with the role of social difference in the production of uneven urban natures. A postcolonial reading of the concept of the river‐as‐line highlights the continued imposition of colonial epistemologies upon both human and non‐human worlds. An engagement with Indigenous scholarship further troubles the epistemological basis for modern forms of social and environmental inquiry. An effective urban river research agenda will incorporate the insights of these literatures and center the historical, geographical, and social processes that constitute the urban river as both a material and discursive object. This article is categorized under: Human Water > Water as Imagined and Represented Human Water > Value of Water Engineering Water > Planning Water

ABSTRACT 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

ABSTRACT Water access is a fundamental part of the human right to water, water security, and a critical element of sustainable communities. This review describes and discusses the existing literature related to water access in Mexico City. In this study, water access is theorized as a multidimensional phenomenon related to the universal need for reliable, affordable, and clean water. Therefore, the analysis includes literature on the quantity, continuity, quality, health, acceptability, accessibility, and affordability of water and water services in this city. The literature on water access was divided into three domains: historical, sociospatial, and quantitative analyses. Each of these domains has contributed to the understanding of the transformation of this territory, the development of infrastructure, the socioenvironmental impacts of this transformation, and the contemporary inequalities in water supply, distribution, and consumption that characterize this city. Although these domains are characterized by a persistent interrelationship between technology and society, there is no unified approach to local urban water debates. The diversity of paradigms and theoretical frameworks in Mexican academic literature is a valuable asset for addressing the multidimensional nature of water access. Even when data gaps remain, taken together, these analyses provide a comprehensive understanding of water access in Mexico City, emphasizing the need for continued critical research in this area in the coming years. This article is categorized under: Human Water > Water Governance Human Water > Rights to Water Engineering Water > Planning Water

ABSTRACTIn recent years, numerous flood events have caused loss of life, widespread disruption, and damage across the globe. These devastating impacts highlight the importance of a better understanding of flood generating processes, their impacts, and their variability under climate and landscape changes. Here, we argue that the ability to better model flooding is underpinned by the grand challenge of understanding flood generation mechanisms and potential impacts. To address this challenge, the World Meteorological Organization‐Global Energy and Water Exchanges (GEWEX) Hydrometeorology Panel (GHP) aims to establish a Global Flood Crosscutting project to propagate flood modeling and research knowledge across regions and to synthesize results at the global scale. This paper outlines a framework for understanding the dynamics and impacts of runoff generation processes and a rationale for the role of a Global Flood Crosscutting project to address these challenges. Within this Global Flood Crosscutting project, we will establish a common terminology and methods to enable the global research community to exchange knowledge and experiences, and to design experiments toward developing actionable recommendations for more effective flood management practices and policies for improved resilience. This harmonization of rich perspectives across disciplines will foster the co‐production of knowledge primed to advance flood research, particularly in the current period of heightened climate variability and rapid change. It will create a new transdisciplinary paradigm for flood science, wherein different dimensions of mechanistic understanding and processes are rigorously considered alongside socioeconomic impacts, early warning communications, and longer‐term adaptation to alleviate flood risks in society.

ABSTRACTEnvironmental justice research has shown that people's experiences and perceptions of water differ because systematic inequalities shape the extent to which people access clean water and are exposed to water hazards. Q‐methodology is one technique that has been used to aggregate multifaceted subjective narratives and understand different perspectives on a topic. In this paper, we systematically review 77 case study articles applying Q‐methodology to water‐related topics, to inventory how people perceive their relationships with water. We create a classification system based on environmental justice theory to examine (1) distributive justice issues around alternative water sources and agricultural and urban water scarcity, (2) procedural justice issues around Integrated Water Resource Management (IWRM) and trust; and (3) recognition justice issues regarding misrecognition, underrecognition, and the intersectionality of the environmental justice principles. Notably, only eight articles in our dataset found just two factors on a topic, with most finding three or more factors, suggesting that most audiences are not polarized or opposed in a binary sense but range along a spectrum of perspectives on water issues. This finding means water conflicts are complex, but also that people may share core water values on disputed topics. Learning from people from various backgrounds can provide an understanding of the different relationships people have with water, which can help water managers predict where conflicts may occur, empathize with minority viewpoints, and innovate water solutions that could be used to advance environmental justice goals.

ABSTRACTGiven the extent of recent land use‐land cover changes and the consequences for hydrological effects, it is important to capture the role that land use‐land cover plays in hydrological model conceptualization. This need is amplified under a changing climate, as the hydrological sensitivity of catchments to climate change can vary depending on the land use‐land cover. Traditionally, model calibration has prioritized parameter adjustment rather than enhancing the representation of land use‐land cover processes. This practice—though useful in improving model fit—can lead to misinterpretations, especially when simulating under varying land use‐land cover and climate conditions. While airborne and satellite remote sensing technologies now allow for frequent, large‐scale monitoring of land surface parameters, their spatiotemporal complexities remain underutilized in hydrological models. By analyzing the conceptualizations of land use‐land cover related hydrological processes within models, this paper reviews the progress in the current state of modeling approaches and discusses future research needs and directions. The path ahead for land use‐land cover and hydrological modeling is one of embracing technological advancements and methodological rigor, focusing on representing the multifaceted reality.

ABSTRACTAs climatic extremity intensifies, a fundamental rethink is needed to promote the sustainable use of freshwater resources. Both floods and droughts, including water scarcity, are exacerbating declines in river biodiversity and ecosystem services, with consequences for both people and nature. Although this is a global challenge, densely populated regions such as Europe, East Asia and North‐America, as well as the regions most affected by climate change, are particularly vulnerable. To date mitigation measures have mainly focused on individual, local‐scale targets, often neglecting hydrological connectivity within catchments and interactions among hydrology, biodiversity, climate change and human wellbeing. A comprehensive approach is needed to improve water infiltration, retention and groundwater recharge, thereby mitigating the impacts of heavy rainfall and floods as well as droughts and water scarcity. We propose a holistic catchment‐scale framework that combines mitigation measures including conventional civil engineering methods, nature‐based solutions and biodiversity conservation actions. This framework integrates legislation, substantial funding and a governance structure that transcends administrative and discipline boundaries, enabling coordinated actions across multiple spatial and temporal scales. It necessitates the collaboration of local and regional stakeholders including citizens, scientists and practitioners. A holistic vision for the sustainable management of freshwater resources could have synergistic effects that support biodiversity and mitigate climate change within functional ecosystems that deliver benefits to people.

ABSTRACTIn needleleaf forests, up to half of annual snowfall may be returned to the atmosphere through sublimation of snow intercepted in the canopy. However, limited and sparse observations of snow interception and ablation processes have hindered the development of fundamental theories underpinning current estimates of snow accumulation in forests. Existing parameterisations for snow interception and ablation have been developed in locations with distinctive climate, tree species and forest structures, resulting in inconsistent and non‐comprehensive process representations. This variability limits the transferability of these parameterisations across diverse landscapes and climates. Moreover, difficulties in isolating individual processes in field‐based measurements has led to parameterisations that inadvertently coupled multiple processes, adding to uncertainty. Many studies have also simplified original parameterisations and do not include recent advances from observational studies. This review article aims to elucidate the theoretical foundations and assumptions underlying the current snow interception and ablation parameterisations to provide a better understanding of uncertainties in existing methods and identify priorities for future field‐based observational studies. The methods behind snow interception and ablation studies are also reviewed to provide necessary context for examining current parameterisations. Specific gaps in the literature include determining the canopy snow storage capacity, challenges in distinguishing snow throughfall measurements from canopy snow ablation, partitioning unloading rates and canopy snowmelt drainage, the assumption of vertical falling hydrometeor trajectories, the absence of wind resuspension parameterisations, and the limited testing of parameterisations in varied forests and climates.

Abstract Operational water management is a critical global challenge, and decision making can be improved by using mathematical optimization. This paper provides an overview of optimization techniques, both exact and heuristic, used in water management. It focuses on the use of optimization techniques in the short term: operational planning in reservoir management, control of open channels, hydropower scheduling, and operation of polder drainage pumps. Principles of model predictive control, methods for optimization under forecast uncertainty, and approaches for conflict resolution are explained with the help of educational examples and practical cases. Challenges and research questions to be addressed in the future are presented as an outlook.This article is categorized under: Engineering Water > Methods Science of Water > Water and Environmental Change Water and Life > Conservation, Management, and Awareness