RFT 2023-1690 - BYRON SHIRE OVERLAND FLOOD STUDY

Summary and scope

This Byron Shire Overland Flood Study involves conducting a flood study, which is a comprehensive technical investigation of flood behaviour that provides the main technical foundation for the development of a robust floodplain risk management plan. It aims to provide an understanding of the full range of flood behaviour and consequences in the study area. It involves consideration of the local flood history, available collected flood data, and the development of hydrologic and hydraulic models. Where possible, models are calibrated and verified against historic flood events and then extended to estimate the full range of flood behaviour. The study area covers the whole Byron Shire Local Government Area (LGA) which includes a mix of rural and urban catchments, and the modelling approach shall apply a coarser regionalised ‘broad brush’ approach across the extensive rural areas and a more refined, focused approach in the following urban footprint of towns where flooding in the built environment occurs: • Ocean Shores, New Brighton, South Golden Beach and Billinudgel • Brunswick Heads • Mullumbimby • Ewingsdale and Byron Bay. • Bangalow and Federal Village Council’s preference is to model overland flooding using combined 1D- 2D TUFLOW model applying rain on grid. Alternative approaches proposed by tenders will be considered on their technical merits in line with current best practice. The hydraulic model is to be able to represent all hydraulic processes and topographic features that significantly affect flood behaviour, including waterways, overland flow paths, trunk drainage systems structures, and entrance berms. The modelling shall include minor streams and creeks extending downstream to the confluence with major watercourses already mapped in the regional flood studies in Brunswick River, Marshalls Creek, Tallow Creek and Belongil Creek. Scope of Work The proposal is to outline a methodology that will achieve the objectives of the study, listed in Section 2 of the Technical Project Brief for the identified key end users (Table 1). The proposed methodology is to be developed to meet the scope of work and to produce the required deliverables (Section 7) and comply with the guidelines and best practices (Section 5) in consideration of the available information. See Section 6 RFT2023 - 1690 - Technical Project Brief for Scope of Work and Deliverables.