Author(s): Diogo Costa; Senthil Gurusamy; Paolo Burlando; Shie-Yui Liong
Linked Author(s):
Keywords: Coupled models; Urban flooding; Transient pollution events; Emerging cities; Jakart
Abstract: Analysing the impact of a flood in densely urbanised areas is a rather challenging task as it often involves dealing with complex flood patterns that cannot be accurately modelled with a resolution other than of a few meters. The problem becomes even more difficult to address when the flooding water originates from particularly polluted rivers. This requires introducing additional considerations to the modelling of the typical flood-related variables (water levels, water velocities and inundated areas). With regard to pollution, the aspects of major concern are not only the potential contamination of the groundwater system connected to the river, but also the exposure of the affected communities to high levels of contamination. Evaluating the vulnerability of a particular urban area to the effects of flooding due to inherently polluted rivers requires therefore the use of a more comprehensive modelling approach. Two-dimensional hydrodynamic and transport surface models have been fully coupled to simultaneously compute the main flow variables and the dynamics of mixing and dilution, therefore enabling the investigation of the particular aspect of overbank pollution propagation during such events. Because understanding and modelling flow and transport processes in highly complex urban terrains is a difficult task, we have identified a set of hypothetical terrain and river configurations, which allow identifying the main features of flow and transporting process in the presence of plausible approximations of actual urban river corridors. These configurations have been designed particularly to investigate the impacts on flow and transport behaviour that characterise various contrasting river corridor landscapes, from strongly engineered to more natural-like, from rural to densely urbanised. Simulating the response of each hypothetical terrain configuration allowed speculating on the vulnerability of urban river corridors, the density of which is rapidly growing, in many cases irrespectively of any good design practice. We used these results as proxy for actual case studies, like that of Jakarta, Indonesia, which has motivated this study and is also modelled as comparison to the hypothetical configurations.
Year: 2014