Objective

The primary goal of the project was to quantify the nature and extent of the existing flooding problem and evaluate options that could be potentially implemented to manage the existing, future and continuing flood risk.

Catchment Description

The catchments are significantly urbanised and many of the original creeks and gullies have been built over and replaced by stormwater pipes. A handful of open channels remain, including Saltwater Creek which also includes several detention basins that serve to reduce the impact of flooding across downstream properties.

Flooding

The capacity of the open channels, detention basins and stormwater pipes can be exceeded during heavy rainfall in the local catchments leading to “mainstream” flooding as well as “overland” flooding. Flooding has been experienced across both catchments on a number of occasions in the past including 1981 as well as more recently in 2007 and 2010. The 1981 flood, in particular, inundated multiple properties within the Saltwater Creek catchment and is onsidered to be larger than the 1% AEP design flood.

Flooding of the lower lying areas adjoining Tuggerah Lake can also occur during heavy rainfall in the broader Tuggerah Lake catchment. However, inundation from Tuggerah Lake across the foreshore areas was previously assessed as part of the ‘Tuggerah Lakes Floodplain Risk Management Study and Plan’ (WMAwater, 2014) and was not considered further in this study. Therefore, the ‘Tuggerah Lakes Floodplain Risk Management Study and Plan’ must be reviewed in conjunction with this report to understand the potential flood risk across the forehore areas. Council will ultimately consolidate the flooding information from the various interacting floodplains and associated reports to delineate the extent of the floodplain and the most appropriate flood risk management measures for particular locations.