The village of Crookwell has a population of about 2,200 and is located about 45 km north of Goulburn on the Crookwell Road. The village is located in the headwaters of the Crookwell River catchment at the confluence of its principal tributary Kiamma Creek. The Crookwell River is a significant tributary of the Lachlan River and joins that stream upstream of Wyangala Dam. The extent of the Crookwell River catchment has a total area of 66 square kilometres at the Carrington Street bridge, including the catchment of Kiamma Creek which contributes runoff from its 23 square kilometre catchment upstream of the bridge.
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.
