Hydraulic Assessment 29 August 2024

1.2         Project Purpose and Scope
The purpose of this Local Hydraulic Assessment (LHA) is to complete an assessment of the catchment hydrology and anticipated design flows
through the dam spillway, and identify any upgrades required to ensure that a minimum dry freeboard of 1 m is maintained beneath the
embankment crest. Additionally, the assessment is to identify works required to accommodate future flows during flood events, not allowing
the embankment crest or discharge channels to overtop.

A specification for a rock-lined chute has been provided based on the anticipated stormwater velocities and other flow characteristics in the
channel downstream of the dam spillway in the hydraulic model results.


1.3         Project Data and Guidelines
The following data has been utilised for this assessment:

•   Design inputs for hydrologic and hydraulic modelling from the Australian Rainfall and Runoff Data Hub;

•   Rainfall and Meteorological Data by Australian Bureau of Meteorology (BoM); and,

•   Aerial LiDAR data of the ANZLIC Committee on Surveys and Mapping (ELVIS, https://elevation.fsdf.org.au/).

•   Site Survey (CadCon – 8 May 2024).

The guidelines, standards, and codes considered during the assessment were as follows:

•   Noosa Plan 2020;

•   Planning Act 2016 and the associated State Planning Policy (DILGP, 2017);

•   Rock Sizing for Small Dam Spillways (Catchments and Creeks, 2014);

•   Queensland Urban Drainage Manual 2017 (QUDM); and,

•   Australian Rainfall and Runoff 2019 (ARR) 2019 (Ball, et al, 2019).

Reference documents relevant to the assessment are:

•   Noosa Council Decision Notice (ref: RAL22/0034 dated 24 April 2024).

•   Approved RAL Plan prepared by CadCon (Drawing Number: 219101-03-01).

•   Geotechnical investigation of Existing Dam prepared by Tectonic (Project No. 22244-002-Rev1).




38 BARINA COURT, POMONA I BBNE00000_0020-REP-001-0                                                                                         2