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Global flood management is a major issue for most cities which have to deal with worsening factors such as climate change and fast urban growth. Computer models have been used to model and understand urban flooding on a local scale in cities (25–50 km2). It has been practically impossible to model bigger cities in one go in sufficiently high resolution due to the heavy computations involved. The present paper describes a new modelling approach for urban flooding which allows modelling on large city scale (1000 km2) while keeping sufficient resolution, e.g. 5 m or 10 m grid. The multicell approach is applied for the city of Beijing for July 21st, 2012 flood event. Model results are compared to testimonials from the 2012 event. Comparison to traditional 2D urban flood computations shows that the multicell approach is much faster than standard detailed models while keeping a suitable level of precision. [ABSTRACT FROM AUTHOR]

In many tropical island settings in the world and as a result of human activities and tropical weather conditions, urban areas have been vulnerable to special kinds of hazards. The most common and the most widely experienced hazard events for these localities are tropical cyclones and accompanying storm surges, flash floods and landslides. Such events can cause serious damages to the drainage systems, roads, properties, receiving environment and even the loss of human lives. Given the threats of climate change, such natural disasters are likely to strengthen this trend in the coming years. In many situations, it is the population living in low-lying urban areas that are most exposed to these disasters. From this, it follows that the scientific and professional communities have a responsibility to evolve better stormwater management approaches directed to minimizing hazard risks owing to urban flooding, even while addressing different climatic conditions. Although, the physics, chemistry and biology of processes related to water are universal, some of the processes and implementation of measures to manage water vary in terms of the climate conditions, geographical location, availability of resources and local culture. In tropical island conditions, where flash floods occur frequently, alongside the obvious structural measures, effective non-structural measures, such as better hazard mitigation and prevention, improved preparedness and introduction of warning systems, well organised pre-emptive action and emergency response activities, have to be coupled together in order to minimize damages. Furthermore, as the management of urban flooding is an emerging subject, it is necessary to understand that such a topic needs to be treated holistically, and so in a multi-disciplinary manner. This implies that the public, town planners, economists, lawyers, emergency services, and many other groups need to be involved, along with the engineers, surveyors and contractors, in developing strategic plans for hazard reduction, operational management and post-event recovery. Thus the stakeholders have to be involved in the decision-making processes (e.g., Abbot 2007, available at www.eiil.net). The present paper describes an integrated stormwater management approach oriented towards the small islands in tropical climates which continuously tend to suffer from flash floods. The approach outlined here draws on the work experiences gained in the Caribbean. [ABSTRACT FROM AUTHOR]