Abstract
Abstract. Floods are one of the most destructive natural disasters that threaten communities and properties. In recent decades, flooding has claimed more lives, destroyed more houses and ruined more agricultural land than any other natural hazard. The accurate prediction of the areas of inundation from flooding is critical to saving lives and property, but relies heavily on accurate digital elevation and hydrologic models. The 2011 Brisbane floods provided a unique opportunity to capture high resolution digital aerial imagery as the floods neared their peak, allowing the capture of areas of inundation over the various city suburbs. This high quality imagery, together with accurate LiDAR data over the area and publically available volunteered geographic imagery through repositories such as Flickr, enabled the reconstruction of flood extents and the assessment of both area and depth of inundation for the assessment of damage. In this study, approximately 20 images of flood damaged properties were utilised to identify the peak of the flood. Accurate position and height values were determined through the use of RTK GPS and conventional survey methods. This information was then utilised in conjunction with river gauge information to generate a digital flood surface. The LiDAR generated DEM was then intersected with the flood surface to reconstruct the area of inundation. The model determined areas of inundation were then compared to the mapped flood extent from the high resolution digital imagery to assess the accuracy of the process. The paper concludes that accurate flood extent prediction or mapping is possible through this method, although its accuracy is dependent on the number and location of sampled points. The utilisation of LiDAR generated DEMs and DSMs can also provide an excellent mechanism to estimate depths of inundation and hence flood damage
Highlights
1.1 Queensland FloodsDuring December 2010 to February 2011, the State of Queensland experienced a series of damaging floods which caused billions of dollars in damage and the loss of over 20 lives
This paper examines some of the information that was volunteered by citizens during the flood events in Queensland as part of the social networking and media activities
The flood inundation area was determined by subtracting the original ground surface DEM from the flood surface model using a cut/fill algorithm
Summary
1.1 Queensland FloodsDuring December 2010 to February 2011, the State of Queensland experienced a series of damaging floods which caused billions of dollars in damage and the loss of over 20 lives. Prior to 1860, three major floods were reported for the Brisbane/Ipswich regions, with the January 1841 flood having the highest recorded level of 8.43m at Brisbane (Bureau of Meteorology, 2011b). A further five major floods inundated Brisbane and Ipswich between 1885 and 1900 In this time period, the Brisbane River peaked at 8.3m, and the Bremer River at 24.5m – its highest recorded level (Centre for the Government of Queensland, 2010). The Brisbane River peaked at 8.3m, and the Bremer River at 24.5m – its highest recorded level (Centre for the Government of Queensland, 2010) It was not until 1974 that Brisbane and Bremer Rivers flooded to 5.45m and 20.7m respectively – the highest levels since 1893 (Bureau of Meteorology, 2010). The 2011 Brisbane flood reached a level of 4.46m, well below the 1891 levels, but still inundating over 14,000 properties
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