Burradoo BU2 Catchment Assessment Study Stage 1 Flood Study Report

Brief description

#Objectives
The objective of this Study is to define the nature of the existing flood behaviour in the
Burradoo BU2 catchment.
To achieve the objective, the following tasks were undertaken:

* Collate available flood-related data,
* Define existing catchment condition flood behaviour for mainstream flooding in the
catchment,
* Define design flood levels, velocities and flow distributions for the catchment,
* Define the extent of flooding the 5 year, 20 year, 50 year, and 100 year ARI and PMF
events for the catchment,
* Define provisional flood hazard for the flood-affected areas,
* Define the hydraulic categories for the flood-affected areas,
* Assess impacts of climate change,
* Preliminary assessment of flood damages for the flood-affected areas,
* Identify preliminary remedial options.

#Methodology
This Study was carried out using computer-based hydrologic and hydraulic modelling.
Two numerical modelling tools were developed:

* A hydrologic model was utilised to convert rainfall on the catchment to runoff. The
hydrologic model RAFTS was used, which combines rainfall information with local
catchment characteristics to estimate runoff hydrographs.
* A hydraulic model was utilised to convert runoff hydrographs into water levels and
velocities in the study area. The model simulates the hydraulic behaviour of the water
within the study area by accounting for flow in the major channels as well as potential
overland flowpaths, which develop when the capacity of the channels is exceeded. It
relies on boundary conditions, which were the runoff hydrographs produced by the
hydrologic model and downstream boundary conditions from the creek into which it
discharges. The TUFLOW modelling system was used for this purpose.

The Study details are grouped together under the following sections of the report:

* __Section 3__ provides a general description of the catchment
* __ Section 4__ discusses the content and sources of relevant data, which were utilised for
the study. Historical rainfall and flood data used in the calibration of the established
hydrologic and hydraulic models and survey data used are detailed.
* __Section 5__ discusses the catchment characteristics and describes the hydrologic model
setup for the study.
* __Section 6__ describes the hydraulic model utilised for the study, its verification and
subsequent use for design rainfall events.
* __Section 7__ details results for the design flood events.
* __Section 8__ reviews the sensitivity of the model to the data used.
* __Section 9__ identifies the provisional flood hazard.
* __Section 10__ identifies the hydraulic categorisation.
* __Section 11__ reviews the impacts of climate change.