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Darlington Point - Levee Gradient Sensitivity Analysis

Darlington Point is located on the banks of the Murrumbidgee River about 40 kilometres south of Griffith. The town has a population of about 900 and is becoming increasingly popular for residential living for those who work in Griffith and surrounding areas. The town is effectively broken up into two precincts that are separated by the Murrumbidgee River. The main centre of Darlington Point is located on the southern bank of the Murrumbidgee River and is protected from flooding by an earth levee system that surrounds the town. The main centre of Darlington Point includes commercial and industrial precincts and residential areas.

North Darlington Point is a small residential precinct located on the northern bank of the Murrumbidgee River. It is situated on the floodplain opposite Darlington Point and extends either side of the main road north to Griffith. North Darlington Point is currently not protected from floodwaters by a levee system. The Darlington Point Levee was constructed in the aftermath of the notorious 1956 flood. The levee has a total length of 5.8 kilometres and follows the alignment shown in Figure 3. Part of the existing levee extends along the southern banks of the Murrumbidgee River and along the western bank of Waddi Creek. The remaining sections traverse open and treed sections of the floodplain to form a ring around the entire town.

The following conclusions can be drawn from the results of the modelling, which assumes that the levee does not fail once the design flood (1956 event) or the imminent failure flood is exceeded:

  • Existing design floodwater levels indicate that the existing Darlington Point levee will be overtopped in the 200 year recurrence flood event.
  • The hydrograph shape (i.e., peaky or flat) does not alter the floodwater gradient. It does, however, slightly alter the peak floodwater level around the existing Darlington Point levee.
  • A ‘flat’ hydrograph will cause overtopping of the levee once the peak discharge of the Murrumbidgee River reaches approximately 1,730 m3/s. This corresponds approximately to the 200 year recurrence flood.
  • A ‘peaky’ hydrograph will cause overtopping of the levee at a slightly higher peak discharge;
  • Changes in hydrograph shape resulted in no overall alterations to the flood gradient. As such, changes in hydrograph shape do not alter the location where the levee is overtopped;
  • Regardless of the hydrograph shape, the levee always overtops first near the northern limit of the levee at a point immediately west of Ryan Street. This would appear to be an ideal location for construction of an emergency spillway.

Additional Information

Field Value
Title Darlington Point - Levee Gradient Sensitivity Analysis
Publication Date 22 May 2009
Themes Land and Resource Management
Spatial Extent
Map data © OpenStreetMap contributors
Council/LGA Murrumbidgee Council
Author/ Prepared by WorleyParsons Resources & Energy; Patterson Britton & Partners Pty Ltd
Publish date 28 May 2020
Update date 28 May 2020
Approval State Approved
Submitted for approval 29 May 2020
Submitted by Julia Muniz de Miranda Sa
Approved 29 May 2020
Approved by dstazic
Identifier e1e3824f-00c3-4fb0-bb75-3e85c7d3fedb