Currambene Creek and Moona Moona Creek Flood Studies

Brief description

__1.3 Overview of Report__

This Report (Volume 1) summarises the investigations and presents plans showing water surface
profiles and the indicative extents of flooding. The Report is supported by three Appendices,
which provide additional details on flooding patterns and are bound in Volume 2.
Section 2 of the Report contains background information including a description of the
catchments, a review of the data base available for the study and a discussion on the history of
flooding in the two catchments. This led to the selection of the historic floods for calibration and
testing of the RORB hydrologic model of Currambene Creek.
Streamflows recorded at The Falls gauging station, together with pluviographic data recorded at
the RAN Air Station at HMAS Albatross and daily rainfall data were used for this purpose.
Appendix A provides further details of the calibration process.
Section 3 deals with the derivation of design runoff hydrographs from the study catchments. The
RORB runoff-routing program was adopted for this study. Models of the catchments of
Currambene and Moona Moona Creeks were developed.
This step involved the determination of design storm rainfall depths over the catchments for a
range of storm durations, and conversion of the rainfall hyetographs to discharge hydrographs.
Further details of this phase of the investigation are presented in Appendix B.
Section 4 deals with the development of the hydraulic models of the main streams and their
estuarine surrounds. The unsteady flow version of the HEC-RAS software was used for this
purpose. There were no historic flood level data available for calibration of the hydraulic models.
Accordingly, selection of model parameters required a detailed review of the engineering
literature and previous studies of a similar nature undertaken by the Study Team, supplemented
by sensitivity analysis. The results of model testing are presented in the first part of Appendix C.
Section 5 details the results of the hydraulic modelling of the design floods using HEC-RAS.
Results are presented as water surface profiles and plans showing indicative extents of
inundation. Appendix C presents further details on the derivation of design flood information and
contains diagrams showing zones of provisional high and low hazard on the floodplain for
selected design floods events, categorisation of the floodplain into floodway and flood storage
areas and tabulations of peak levels and flow velocities at each cross section in the hydraulic
models.
Section 6 summarises the flood study investigations and identifies several flood related issues
on the tributaries of Currambene Creek which will require further study during the Floodplain Risk
Management Study and Plan.
Section 7 contains a list of References.