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Flood study

Nattai River Flood Study

The Nattai River catchment is located in the Southern Highlands of New South Wales and occupies a total area of 6.75 km2. The extent of the catchment is shown in Figure 1 (refer Flood Study: Volume 2).

Nattai River originates near the intersection of Range Road and Old South Road at Mittagong and drains in a northerly direction through the eastern sections of Mittagong. The catchment comprises a variety of land uses including rural, residential, commercial, industrial and open space/recreational facilities. The catchment is drained primarily by natural watercourses. The urbanised sections of the catchment are also drained by a stormwater system which carries local catchment runoff into the watercourses via a network of stormwater pipes, pits, open channels and culverts.

During periods of heavy rainfall, there is potential for the stormwater system to become overwhelmed and for water to overtop the banks of the natural watercourses and inundate the adjoining floodplain. Accordingly, there is potential for inundation of properties located in close proximity to the creeks and drainage lines. Flooding has been experienced on several occasions in the past, particularly across properties fronting Evans Street.

Although some flooding investigations have been completed at isolated locations across the catchment, a comprehensive flood study of the entire Nattai River catchment has not previously been prepared. Therefore, with the exception of isolated flooding complaints from residents, the extent of the existing flooding problem is not well understood.

In recognition of this, Wingecarribee Shire Council decided to prepare a Floodplain Risk Management Plan for the Nattai River catchment.

The first stage in the development of a Floodplain Risk Management Plan involves the preparation of a Flood Study. The Flood Study provides a technical assessment of flood behaviour.

This report forms the Flood Study for the Nattai River catchment. It documents flood behaviour across the catchment for a range of design floods for existing topographic and development conditions. This includes information on peak discharges, flood levels, flood extents, flood depths and flow velocities for a range of design floods. It also provides provisional estimates of the flood hazard and hydraulic categories across the catchment.

The Flood Study comprises two volumes:

  • Volume 1: comprises the report text and appendices.
  • Volume 2: contains all accompanying figures.

This is Revision 2

Additional Information

Field Value
Title Nattai River Flood Study
Publication Date 1 January 2014
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Wingecarribee Shire Council
Author/ Prepared by Catchment Simulation Solutions
Publish date 22 May 2017
Update date 22 May 2017
Place Name Mittagong
Approval State Approved
Submitted for approval 23 May 2017
Submitted by John Silk
Approved 27 June 2017
Approved by dstazic
Data Comment

Report only; no other data. Legacy data; may have been superseded.

2 Volume dataset. This is Revision 2

Identifier 234c3252-1cb7-4c60-be01-026f380573ac