The site sits entirely within the Maroochy River floodplain and experiences flooding to significant depths and tidal inundation. It is understood the storage capacity of the Maroochy River lower estuary floodplain has already been exceeded by the ’priority fill’ of current lots in the Twin Waters, Marcoola, Pacific Paradise and Mudjimba localities.
The role and vulnerability of the Maroochy River catchment and floodplain have been recognized by the Queensland State Government when it endorsed the inclusion of fluvial processes in the development of the Coastal Hazard Adaptation Strategy (CHAS) for SCRC. Flood related planning issues:
- Flood Hazard Area under the planning scheme (the entire site is subject Current Climate Riverine Flooding)
- The most limiting factor is compliance with the Flood Hazard Overlay Code.
- The Overall Outcomes of the Flood Hazard Overlay Code are:
- development does not occur on land subject to flooding except in specified circumstances and only where the impacts of flooding can be effectively ameliorated such that there is no foreseeable risk to life or property;
- development protects floodplains and the flood conveyance capacity of waterways;development in areas at risk from flood and storm tide inundation is compatible with the nature of the defined flood or storm tide event;
- the safety of people is protected and the risk of harm to property and the natural environment from flood and storm tide inundation is minimised; and
- development does not result in a material increase in the extent or severity of flood or storm tide inundation.
It will be difficult to achieve the Performance Outcome (PO1) for Floodplain Protection under the Flood Hazard Overlay Code:
Development is undertaken in a manner that ensures:-
- natural hydrological systems are protected;
- natural landforms and drainage lines are maintained to protect the hydraulic performance of waterways; and
- development integrates with the natural landform of the floodplain rather than modifying the landform to suit the development.