Author(s): Edmond Y. M. Lo; Charng Ning Chen
Linked Author(s):
Keywords: Flood Simulation; Probabilistic Flood Events; Flood Risk; Inundation Hazard; Damage/Loss Assessment
Abstract: Rapid economic growth particularly in Asia’s developing countries is creating regions of high asset exposure to riverine and coastal flooding. Impacts of urbanization with corresponding increase in runoff peaks, land subsidence due to extraction of groundwater, population growth and economic expansion, and climate change (e. g. change in storm characteristics and potential sea level rise) will aggravate the future flood exposure. This is particularly evident in rapidly developing low-lying deltaic cities such as Jakarta, Indonesia and Bangkok, Thailand. Coastal cities, such as Manila in the Philippines, and Guangzhou in China, have an additional risk of flooding exposure due to the passages of typhoons. In an on-going study conducted at the Nanyang Technical University through its Institute of Catastrophe Risk Management, a fully integrated flood simulation and damage/loss assessment model is being developed and applied to the special capital region of Jakarta, or DKI Jakarta, in Indonesia. The region with its low-lying coastal area is invariably exposed to serious flood hazards, especially under high tides. The model will permit fast evaluation and assessment of potential flood state and damage/loss, at different flood risk levels. The model will be enhanced at a later stage to incorporate features for assessing the effects of storm surges, land subsidence, urbanization, and climate change on flood risk. The modeling work comprises the parallel development of modules for establishing probabilistic flood events, evaluating flood hazards, establishing building exposure/vulnerability, and assessing flood damage/loss. The development of these modules requires extensive databases of hydro-meteorological data on rainfall and runoff; topographic and dimensional data of the catchment terrain, drainage channels and stream-crossing structures; and spatial data on land use, ground cover and building/facility inventories. Upon completion of model calibration against major historic events, flood inundation maps associated with design floods with recurrence intervals of 2, 5, 10, 25, 50, and 100 year are generated. Corresponding flood damage/loss curves that depend on inundation depth and building stock and category are being developed and applied. Geographic Information System (GIS) tools are used to facilitate the interface between the risk simulation models and databases: ranging from digital terrain or topography data processing to digital representation of the hydrologic parameters, land use/cover, and soil types; as well as the geospatial data associated with flood damage assessment. We anticipate that the model can be extended for other cities, coastal or inland, with comparable general settings. With further enhancement for storm surge simulation, the model can also find use for the effective management and mitigation of the risks associated with rising exposure to coastal flooding, which could become a critical issue for governments and communities of the coastal urban centers.
Year: 2013