| 03 Mar 2026
Review article: Flash Floods in Mountainous Regions: Global Research Trends, Process Mechanisms, and Control Measures
Abstract. Flash floods in mountainous regions are becoming more frequent and destructive under climate warming, yet cross-regional understanding of their triggering mechanisms, cascading impacts, and governance remains fragmented. This review synthesises 1,967 studies published during 2000–2025 to establish a globally comparable baseline of mountain flash-flood research. By integrating bibliometric and topic analyses with qualitative synthesis, we reveal pronounced geographical and thematic imbalances, with research concentrated in Europe and Asia. At the same time, many high-risk mountain regions in Africa and South America remain overlooked. Across regions, flash-flood initiation and impacts are shown to be strongly state-dependent and coupled, emerging from interactions between storm intensity, duration and spatial concentration, antecedent hydrological conditions, and hillslope-channel connectivity. This coupling helps explain why fixed rainfall thresholds are difficult to generalise and highlights the need for dynamic, multi-source early-warning approaches. Comparing evidence on early warning, structural protection, and Nature-Based Solutions, the review shows that cascading processes dominate risk management challenges. We therefore propose an adaptive governance framework that links monitoring and forecasting, spatial planning, grey-green integration, and basin-scale risk sharing under non-stationary climate conditions. Overall, this synthesis consolidates fragmented evidence into a cross-regional knowledge base to support flash-flood risk reduction in mountainous regions, where data and capacity are limited.
The presented article has a very broad scope and considerable synthetic value. It attempts to combine physical mechanisms, environmental conditions, social and economic impacts, risk management, as well as technical measures and nature-based solutions. This is fully justified given the interdisciplinary nature of the problem. The extensive literature base of 1,967 publications provides potential for identifying global trends. The paper describes well the problem of non-stationarity, highlighting the limited transferability of rainfall thresholds, emphasizing the initial state of the catchment, and pointing out the non-stationarity of climate. The causes of flash floods are correctly presented as a combination of rainfall, soil moisture, topography, hillslope–channel connectivity, sediment, and anthropogenic changes. The article also successfully links science and practice by emphasizing the importance of warning systems, spatial planning, catchment management, and hybrid retention solutions.
However, the excessively broad scope of the analyzed problem comes at the expense of conceptual precision and clarity. The authors use the terms hazard, disaster, risk, impact, vulnerability, and resilience in a manner that is not fully differentiated. In a study of this type, clearer conceptual structuring would be expected. The criteria for selecting bibliometric cases are also unclear, and there is no discussion of their representativeness. The study covers the years 2000–2025, yet some conclusions regarding publication trends, risk growth, and climate change are formulated as if all periods had equal data quality. In reality, the increase in the number of publications may also reflect the development of science rather than solely the growing importance of the problem, and the rise in the number of documented events may partly result from improved reporting.
There is also some lack of clarity in the presentation of the analyzed regions. Examples are drawn from China, India, and Europe, but there is no systematic comparison between areas with similar climate, geomorphology, or levels of urbanization. The article also lacks discussion on uncertainty propagation, input data errors, model validation in poorly monitored regions, and the issue of overfitting in machine learning models. Furthermore, there is no analysis of costs, cost-effectiveness, trade-offs between objectives, or institutional and political constraints.
The article strongly promotes integrated, hybrid, and multi-scale approaches; however, greater integration does not always necessarily lead to better outcomes. The intention to include events of different origins that may trigger flash floods—such as classical flash floods, flood cascades, dam-break floods, and glacial lake outburst floods—is understandable. Nevertheless, this approach tends to blur the main object of the study.