Compound Hydro-Climatic Extremes and Water Sustainability: Understanding Cascading Risks and Adaptation Pathways

Hydro-climatic extremes — including droughts, floods, heatwaves, and extreme precipitation events — are increasing in frequency and intensity due to climate change. Their impacts on water systems are further amplified by concurrent environmental degradation: land-use change and deforestation reduce evapotranspiration buffering and infiltration capacity; soil degradation lowers moisture retention and accelerates runoff generation; urbanization increases imperviousness and peak flows; and the loss of wetlands, floodplains and riparian vegetation erodes the natural attenuation of hydrological extremes. These degradation processes do not generate extremes themselves, but they reshape the catchment response so that a given climatic forcing translates into a more severe or longer-lasting hydrological extreme than it would in a less degraded system.While individual extreme events have received significant research attention, there is growing recognition that some of the most severe impacts on water systems arise from compound and cascading extremes: events that occur simultaneously, in close succession, or in combinations that amplify overall risk beyond what any single hazard would produce. Examples include drought-to-flood transitions, concurrent heat and drought stress on water supply, sequential flooding events that overwhelm recovery capacity, and the compounding effects of land-use change on hydrological response to climatic extremes. These compound dynamics pose distinct challenges for water sustainability, yet they remain poorly understood, insufficiently monitored, and inadequately represented in risk assessment and adaptation planning, where single-hazard framings still dominate operational practice even where multi-hazard concepts are acknowledged in principle.This Research Topic aims to advance scientific understanding of compound and cascading hydro-climatic extremes and their implications for sustainable water management. It seeks to bring together interdisciplinary contributions that investigate how multiple extremes interact, how their combined impacts propagate through hydrological, ecological, and socio-economic systems, and how adaptation strategies can be designed to address multi-hazard risk rather than single-event responses. By consolidating emerging evidence on compound extreme dynamics with methodological advances in detection, attribution, modelling, and risk assessment, this collection aims to support a shift toward more integrated and resilient approaches to water management under increasing climatic uncertainty.For the purposes of this collection, a submission qualifies as addressing compound, cascading, or interacting hydro-climatic extremes if it meets at least one of the following criteria:• Concurrent extremes: two or more hydro-climatic hazards (e.g., heat and drought, extreme precipitation and storm surge, drought and wildfire-driven hydrological change) co-occurring in space and time, with quantified joint dependence or joint impact.• Sequential or temporally clustered extremes: two or more hazards occurring in close succession such that the system response to the second is conditioned by the first (e.g., drought-to-flood transitions, back-to-back floods overwhelming recovery, post-fire flood response).• Spatially compounding extremes: spatially distributed hazards whose combined footprint affects shared water infrastructure, supply systems, or ecosystems (e.g., simultaneous basin-wide droughts across connected supply regions).• Preconditioned or interacting extremes: a single hazard whose severity, duration or impact is conditioned by a preceding hydro-climatic state or by environmental degradation acting as a non-climatic preconditioner (e.g., antecedent soil-moisture deficits amplifying heatwaves; degraded catchments amplifying flood response).Submissions must explicitly invoke and quantify the compound, cascading or interacting nature of the events analysed; single-hazard studies that merely reference compound framing in the introduction fall outside the scope.We invite papers addressing, but not limited to, the following themes:• Characterization and classification of compound hydro-climatic extremes meeting the criteria above, including drought-to-flood transitions, concurrent extremes, and sequential multi-hazard events.• Detection, attribution, and trend analysis of compound extreme events under climate change.• Cascading impacts of interacting extremes on water availability, water quality, ecosystems, and socio-economic systems.• Modelling frameworks for representing compound and cascading extremes in hydrological and water resource systems.• Multi-hazard risk assessment and early warning approaches that account for interacting extremes.• Adaptation strategies and water management frameworks designed for compound rather than single-event risks.• Remote sensing, data fusion, and data-driven approaches — including statistical, machine-learning and deep-learning methods — for detecting, attributing, monitoring, and forecasting compound hydro-climatic events across scales.Studies focused on single-hazard analysis (e.g., flood modelling or drought monitoring in isolation), general climate-change impacts on hydrology, or broad nature-based solutions without a compound-extremes dimension fall outside the scope of this Research Topic. Topic editors: Md Anarul Haque Mondol, Balqis Mohamed Rehan, Mohammad Kamruzzaman, David Dunkerley Source: https://www.frontiersin.org/research-topics/80489/compound-hydro-climatic-extremes-and-water-sustainability-understanding-cascading-risks-and-adaptation-pathways