Malaysia, being a tropical country located near the equatorial doldrums, experiences the annual occurrence of flood hazards due to monsoon rainfalls and urban development. In recent years, environmental policies in the country have shifted towards sustainable flood risk management. As part of the development of flood forecasting and warning systems, this study presented the urban flood simulation using InfoWorks ICM hydrological−hydraulic modeling of the Damansara catchment as a case study. The response of catchments to the rainfall was modeled using the Probability Distributed Moisture (PDM) model due to its capability for large catchments with long-term runoff prediction. The interferometric synthetic aperture radar (IFSAR) technique was used to obtain high-resolution digital terrain model (DTM) data. The calibrated and validated model was first applied to investigate the effectiveness of the existing regional ponds on flood mitigation. For a 100-year flood, the extent of flooded areas decreased from 12.41 km² to 3.61 km² as a result of 64-ha ponds in the catchment, which is equivalent to a 71% reduction. The flood hazard maps were then generated based on several average recurrence intervals (ARIs) and uniform rainfall depths, and the results showed that both parameters had significant influences on the magnitude of flooding in terms of flood depth and extent. These findings are important for understanding urban flood vulnerability and resilience, which could help in sustainable management planning to deal with urban flooding issues.

Coupled with climate change, the urbanization-driven increase in the frequency and intensity of floods can be seen in both developing and developed countries, and Malaysia is no exemption. As part of flood hazard mitigation, this study aimed to simulate the urban flood scenarios in Malaysia’s urbanized catchments. The flood simulation was performed using the Personal Computer Storm Water Management Model (PCSWMM) modeling of the Damansara catchment as a case study. An integrated hydrologic-hydraulic model was developed for the 1-D river flow modeling and 1-D–2-D drainage overflow modeling. The reliability of the 1-D river flow model was confirmed through the calibration and validation, in which the water level in TTDI Jaya was satisfactorily predicted, supported by the coefficient of determination (R²), Nash–Sutcliffe model efficiency coefficient (NSE), and relative error (RE). The performance of the 1-D–2-D model was further demonstrated based on the flood depth, extent, and risk caused by the drainage overflow. Two scenarios were tested, and the comparison results showed that the current drainage effectively reduced the drainage overflow due to the increased size of drains compared to the historic drainage in 2015. The procedure and findings of this study could serve as references for the application in flood mitigation planning worldwide, especially for developing countries.

Tsunamis have received increased worldwide awareness since their unprecedented occurrences in the Indian Ocean and Tohoku in 2004 and 2011, respectively. In this study, the impact of tsunami on a building with an elevated floor slab was investigated at a reduced scale of 1:100 and compared with that of a slab-on-grade building. Three nominal wave conditions were tested to study the effects of tsunamis on each building model type. The tsunami-like wave forces and pressures on the building model were measured in the experiment. Results showed that the existence of an elevated floor slab significantly reduced the horizontal force on building upon the impingement of the initial wave. When the nominal wave height was higher than the building model height, the wave-induced horizontal force was overestimated by the Japanese design method. The maximum vertical resultant force on the elevated building model manifested a linear trend with increasing wave-exposed height up to a maximum force of approximately 3.8 N when the building model was fully submerged. This study also presented a proposed methodology for tsunami force estimation of the front and back faces of a building with an elevated floor slab.

The tsunami is one of the deadliest natural disasters, responsible for more than 260,000 deaths and billions in economic losses over the last two decades. The footage of the devastating power of the 2004 Indian Ocean tsunami perhaps remains vivid in the memory of most survivors, and Malaysia was one of the countries affected by the unprecedented 2004 tsunami. It was the first time the Malaysian government had managed such a great disaster. This review, therefore, gathers the relevant literature pertaining to the efforts undertaken following the event of the 2004 tsunami from Malaysia’s perspective. A compilation of post-event observations regarding tsunami characteristics is first presented in the form of maps, followed by building damage, including damage modes of wall failure, total collapse, debris impact and tilting of structures. In addition, hazard assessments and projections regarding a hypothetical future tsunami towards vulnerable hazard zones in Malaysia are reviewed. It is observed that future tsunami risks may originate from the Indian/Burma Plate, Andaman Island, Sunda Trench, Manila Trench, Sulu Trench, Negro Trench, Sulawesi Trench, Cotabato Trench and Brunei slide. A rundown of post-2004 measures and tsunami research undertaken in the country is also included in this review, serving as a reference for disaster management globally. Overall, the outcomes of this review are important for understanding tsunami vulnerability and the resilience of coastal infrastructures, which will be crucial for continued progress in the future.