The influence of flooding risk on infrastructure development in Western Sydney

The city of Sydney boasts one of the greatest natural harbors in the world, and perception of the city tends to center on the business and harbor areas. However, the city limits are bounded to the west by the Blue Mountains, and to the north by the Hawkesbury river which flows out into the Tasman sea through a narrow opening between tall cliffs some 40 Km north of the central business district. Rapid expansion has led to development of the western areas and in particular the vast flood plains that were previously used as arable or farming land. It has recently become apparent that the risks to the new populations were rising to unacceptable levels, and various limits on development were initiated. As part of the New South Wales government's strategy for disaster mitigation, in the event of a flood, great emphasis was placed on informing residents of areas likely to suffer inundation, and to prepare them for safe evacuation. The safe development of the Greater Western Sydney relies on the success of such plans. In this study the authors have investigated the effect of the government initiatives on the local population, and have re-analysed the flood data for the last 200 years using the Lieblein Best Linear Unbiased Estimator (BLUE) technique. The results obtained have established more reliable estimates of the yearly flood probabilities and have highlighted the need for a greater effort from the New South Wales authorities to inform the residents of the area of the hazards posed by likely floods.