Taralga has a population of about 350 and is located on Corroboree Creek which flows in a north-easterly direction through the village area. It drains a small tributary catchment of the headwaters of the Wollondilly River of about 13 square kilometres at the village. Taralga is subject to main stream flooding from Corroboree Creek. Significant problems also originate from overland flows from the local sub-catchments situated within the developed part of the village. The principal overland flow paths, which originate in the sub-catchments on the western floodplain, flow eastwards to join Corroboree Creek.
The objective of the flood studies was to define flood behaviour in the villages in terms of flows, peak levels and extents for floods ranging between 20 and 200 years average recurrence interval, as well as for the Extreme Flood.
The flood study had three components:
- Preparation of the Data Collection Report – L&A, 2012. This component involved the collection and review of available data on historic flood behaviour, as well as available survey information and provided recommendations for the collection of additional data for preparation of the catchment and floodplain models.
- A hydrologic component which included preparation of the RORB hydrologic model of the study catchment, testing the sensitivity of model parameters for historic and design storms and adoption of model parameters for design flood estimation; derivation of design storm rainfalls and their application to the model to define design discharge hydrographs.
- A hydraulic component which comprised the preparation and testing of the TUFLOW hydraulic model of the main streams and floodplains and the application of historic and design discharge hydrographs to the model to define indicative extents and depths of inundation, water surface profiles, flows and velocities for the design floods.
