A scoping review of flash floods in Malaysia: current status and the way forward

Flash floods are not only the deadliest weather-related hazard but also one of the leading challenges with which governments and societies need to cope. Flash floods occur within a very limited time, which is insufficient to enable effective warnings and preparedness. Flash floods have become, for many reasons, the most frequent form of natural disaster in Malaysia, considerably affecting humans, property, and the economy. Modeling flash flood phenomena in the tropics is challenging due to the high topographic and meteorological complexity of these regions. The uncertain definition boundary of the monsoon flood and the multidisciplinary nature of flash flood studies also increase the challenge of the reviewing process. In this study, a systematic methodology was developed to review flash floods in Malaysia by considering all the possible related issues. This study revealed a gap in the data analysis of flash floods and that related studies in Malaysia are still not highly developed. Accordingly, the creation of a comprehensive Malaysian flash flood dataset is recommended to advance flash flood studies, modeling, and forecasting. Rainfall analysis based on Global Precipitation Measurement and Tropical Rainfall Measuring Mission data of different intensities also confirmed the high variability of rainfall in Malaysia. The highest variability in the hourly-based rainfall dataset was observed in the central region. The information and findings presented here will be useful for interested hydrologists and decision-makers by enabling better water management. Additionally, the proposed recommendations for future research could pave the way for a better understanding of flash floods in Malaysia, and the method could be applied in different river basins worldwide.