The Kingston Beach Flood Study “defines the flood behaviour under existing and future potential climate conditions in the Browns River catchment for a full range of design catchment flood, coastal flood and coincident flood events”. A copy of this Flood Study is can be found at the bottom of this page.
It is necessary to ensure that this detailed modelling and mapping is used when assessing future development proposals within the potentially affected area. This is technical information and it will be necessary to consult a flood risk specialist to assist in its interpretation.
The modelling within the Kingston Beach Flood Study indicates that:
most of the Kingston Beach residential and commercial areas are subject to between 2.6 m AHD to 3.3m AHD water levels during the peak 1% AEP coincident flood in the Year 2100. The resultant flood risk varies across the study area with lower lying areas backing onto Browns River being exposed to relatively high velocities and flood depths compared to the higher ground adjacent to Osborne Esplanade i.e. the flood risk decreases across Kingston Beach from Browns River to the beach. The results indicate that for the design coincident flood event catchment (fluvial) flood is the dominant factor affecting flood risk in Kingston Beach, compared with storm surge. The influence of catchment flooding on coincident flood risk in Kingston Beach increases in scenarios that incorporate a lower than design storm tide. Conversely, the dominance of the catchment flood is expected to reduce as sea level rise increases throughout the 21st century.
The Flood Study provides the following commentary in regard to land use planning and development implications:
All levels of government have recognised that land use planning can help mitigate the threat from natural hazards. The Council of Australian Governments’ National Strategy for Disaster Resilience recognised that “responsible land use planning can prevent or reduce the likelihood of hazards impacting communities”, especially for new development. It is well understood across Australia that land use planning and building controls are generally more cost effective than flood mitigation infrastructure, flood warning systems, education programs or emergency responses. Because it is possible to predict which land is likely to be flooded, it is prudent to regulate development and building in those areas to ensure any impacts are known and managed. In so doing, the aim is to avoid or minimise the increase in future flood risks.
The relevant Code within the Kingborough Interim Planning Scheme 2015 is the E15.0 Inundation Prone Areas Code. This Code would normally apply to any area that is shown on the planning scheme maps within the High, Medium and Low Hazard Area overlays. As well as this, Clause E15.2.1(c)(ii) states that the Code applies to “land not within the Riverine Inundation Hazard Area but nevertheless subject to risk of flooding of 1% AEP or more”.
This means that Council must apply the Inundation Prone Areas Code for areas that are susceptible to this level of risk. This is defined within the Kingston Beach Flood Study. That is, the Riverine Inundation Hazard requirements in the Code do apply to land not within the overlay but which are at risk of riverine flooding of 1% AEP or more – which is the case for the whole of the low-lying areas of Kingston Beach by the year 2100. It will be necessary to relate the expected life of buildings or structures to the information provided within the Flood Study. The application requirements under E15.5.2 are also relevant in that Council may require further information on inundation risks to determine compliance with performance criteria.
Prospective developers should also be aware that the National Construction Code and the requirements under the Building Act 2016 will also need to be met, if the particular building site is within a known flood hazard area.