Dungog is a country town of approximately 2,100 people (2011 census) located at the junction of Myall Creek and the Williams River in the Hunter Valley, NSW. It was severely impacted on the 20th and 21st of April, 2015 by flooding in both of these watercourses. This report presents the findings of a short post-disaster damage survey undertaken by Geoscience Australia on 13 May, 2015. It includes an analysis of the survey data and makes comparisons with existing models for building damage in high velocity flow regimes. Comparisons were made with the most current flood study for the town, both in depth of inundation and predicted flow velocities.
The town is situated on undulating topography which rises from quite flat countryside close to Myall Creek and the Williams River to become quite steep terrain at the southern end of the town. Like many Australian country towns, Dungog's building stock consists of a core of older buildings, many predating World War 1, surrounded by residential buildings of all ages up to the present day. Most commercial retail buildings are located on Dowling Street, the main north-south thoroughfare, and are of unreinforced masonry construction. Light industrial buildings are generally steel portal frame construction with a variety of cladding materials. Some light industrial buildings are located on low terrain around the north end of town while the more modern light industrial buildings are located in a new part of town at the north-west corner of the urban area. There were 1015 private residential dwellings in Dungog recorded in the 2011 census. Residential buildings range from older, clad timber frame houses on low stumps to more modern construction styles such as brick veneer and cavity brick houses with slab on grade foundations.
The floodwaters damaged approximately 46 houses and directly impacted five businesses. Six of the impacted houses exhibited velocity-related damage for which video footage taken at the time of the flood was available and enabled an estimate of water velocity to be made. Hence, although only a small survey was undertaken, the flood afforded the opportunity to gather some data on velocity related flood damage to Australian house types for use as validation points on velocity-depth fragility curves for one Australian house type. Typically such validation data is difficult to obtain due to paucity of information relating to estimates of water velocity accompanying building loss.
