Brief description

BMT WBM was commissioned by Bankstown City Council to prepare a Flood Study for the Cooks
River stormwater catchment. Similar studies were simultaneously commissioned for the Punchbowl,
the Georges Hall, the Lansdowne and the Miller Road stormwater catchments. The location of the
Cooks River stormwater catchment is shown in Figure 1-1.

The study has been undertaken under the direction of Bankstown City Council and their Floodplain
Management Committee. The Committee includes Councillors and Council staff, officers from the
Office of Environment & Heritage (OEH), the State Emergency Service and community
representatives.
The study investigates flood behaviour throughout the Cooks River stormwater catchment for existing
catchment conditions as at 2012. This includes the analysis of:

* Flows within the underground pipe drainage network; and
* Surface runoff across the catchment.

A two-dimensional computer model was established for the catchment to analyse stormwater flood
behaviour under existing catchment conditions. The model provides information on the extent of flood
inundation, flood depths and flood velocities throughout the catchment for design floods ranging from
relatively frequent events to more extreme floods. Full details are outlined in the Cooks River
Catchment Flood Modelling Report, which is included as Appendix C.

Results from this study will form the technical basis for the Floodplain Risk Management Study. The
Floodplain Risk Management Study will identify areas of high flood risk and investigate options to
manage and reduce this risk. Assistance will be sought from the community to help identify these
areas and to derive appropriate solutions during the subsequent study.

The flood model developed during this study will provide Council with a valuable tool to assess the
future development in the catchment.

The main outcomes from this study include:

* A database of all public drainage assets within the study area;
* Establishment of a computer model capable of assessing flood behaviour;
* Information on flood behaviour under existing catchment conditions;
* Indicative information on drainage asset performance for various storm events;
* A property database including surveyed floor levels, flood levels and the resulting floor level
immunity, expressed in the magnitude of a storm event;
* Predicted change in flood behaviour due to the potential impacts of climate change; and
* A model that can be used to assess flood mitigation options and future development proposals.