Study Location

The Manning River catchment drains to the Tasman Sea on the New South Wales mid-north coast. The townships of Gloucester, Wingham, Taree, Harrington and Old Bar are the largest communities within the Manning River catchment. Taree is the largest of these and has a population of around 20 000. This study will investigate floodplain risk management for low-lying, expansive Manning River floodplain area downstream of Wingham.

Study Objectives

The objectives of the Manning River Floodplain Risk Management Study and Plan are to: * identify and assess measures for the mitigation of existing flood risk * identify and assess planning and development controls to reduce future flood risks * present a recommended floodplain management plan that outlines the best possible measures to reduce flood damage to the small number of residential and industrial properties, and sections of public road with an identified flooding hazard.

Catchment Description

The Manning River basin encompasses an area of just over 8100 km2 and drains to the Tasman Sea on the NSW mid-north coast. The Gloucester River, Barnard River and Nowendoc River join the Manning River upstream of Mount George. The lower Manning River floodplain is some 2060 km2 in size and includes the catchments of Dingo Creek and the Lansdowne River. The upper catchment is predominantly densely vegetated forest and the lower floodplain is occupied by rural pasture lands.

The Great Dividing Range forms the upper limit of the Manning River catchment, where elevations of around 1200 m AHD are typical. The Barrington Tops, located in the south-west of the catchment, peak at just below 1600 m AHD. The Manning River spills onto a vast, low-lying (elevated to less than 2 m AHD) floodplain area downstream of Taree. This study focuses on flood behaviour in the lower Manning River catchment area, downstream of Wingham and Lansdowne. Downstream of Taree, the Manning River splits into two arms and enters the ocean at two locations – the principal outlet being at Harrington with a secondary outlet at Farquhar Inlet, which is located just north of the Old Bar township. Both entrances are dynamic. Farquhar Inlet can become severely restricted and is known to have closed on many occasions historically. The entrance at Harrington is permanently open but can become significantly shoaled, particularly in periods between large floods. A break wall was constructed along the northern channel bank in 1884 to offer protection to shipping.

The topography of the Manning River catchment is shown in Figure 2-1. Land use within the catchment consists largely of forested areas or pastureland and other cultivated areas. There is little urban development within the catchment.

The townships of Tinonee, Taree, Cundletown, Croki, Coopernook, Harrington and Manning Point are located within the study area. The towns of Wingham, Taree, Harrington and Old Bar are the largest communities, with Taree the largest of these, having a population of around 20 000.

There are several major transport routes through the catchment including the Pacific Highway, Thunderbolts Way, Bucketts Way and the North Coast Railway Line. The Pacific Highway Taree Bypass was constructed between 1993 and 2000. It crosses both the north and south arms of the Manning River just downstream of Cundletown.

History of Flooding

There is a long and relatively frequent history of flooding within the lower Manning River catchment. The three largest floods on record occurred in 1866, 1929 and 1978. In more recent years, large flood events have occurred in 1990 and 2011, with a smaller event in 2013.

Flooding in the catchment is known to cause extensive flood damages and considerable disruption to residents. Access roads readily become inundated, isolating people and properties. Helicopters have been required to assist in the safe evacuation of residents in the past. Flooding has resulted in significant damage to residential properties and commercial businesses, with substantial loss of livestock a major impact of past flood events. Two lives were lost in the Manning River catchment during the 1929 flood.

Due to the large size of the catchment and spatial variation in rainfall, the relative magnitude of historical flood events is not necessarily the same across the whole catchment area. At Taree (Macquarie Street), the 1929 event resulted in the highest flood on record, with a peak level of 5.6 m AHD. Peak flood levels of 5.45 m AHD and 5.15 m AHD were recorded during the 1978 and 1866 events respectively and make up the second and third highest levels on record.

In addition to the anecdotal evidence of previous flooding, Council records provide several flood levels throughout the catchment. Further data has also been sought through questionnaires as part of the community consultation for the study.

The major events for which most of the collected data relates to include February 1929, March 1978, February 1990, June 2011 and March 2013.