Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 10
Narellan Creek Catchment
Flood Study
3.3.1 Model Extent .............................................................................................. 22
3.3.2 Grid Size and Topography ....................................................................... 23
3.3.3 Roughness Coefficients ........................................................................... 23
3.3.4 Building Representation ........................................................................... 23
3.3.5 Watercourses ............................................................................................. 25
3.3.6 Culverts and Bridges ................................................................................ 25
3.3.7 Stormwater System................................................................................... 26
4
COMPUTER MODEL CALIBRATION .................................................................... 28
4.1 Overview ........................................................................................................... 28
4.2 June 2016 Flood .............................................................................................. 28
4.2.1 WBNM Modelling....................................................................................... 28
4.2.2 TUFLOW Modelling .................................................................................. 30
4.3 March 2022 Flood ............................................................................................ 33
4.3.1 WBNM Modelling....................................................................................... 33
4.3.2 TUFLOW Modelling .................................................................................. 33
4.4 July 2022 Flood ................................................................................................ 35
4.4.1 WBNM Modelling....................................................................................... 35
4.4.2 TUFLOW Modelling .................................................................................. 36
5
DESIGN FLOOD ESTIMATION .............................................................................. 38
5.1 General .............................................................................................................. 38
5.2 Hydrology .......................................................................................................... 38
5.2.1 Rainfall ........................................................................................................ 38
5.2.2 Areal Reduction Factors .......................................................................... 39
5.2.3 Rainfall Losses .......................................................................................... 39
5.2.4 Temporal Patterns .................................................................................... 41
5.2.5 Results ........................................................................................................ 41
5.3 Hydraulics ......................................................................................................... 42
5.3.1 Boundary Conditions ................................................................................ 42
5.3.2 Blockage ..................................................................................................... 44
5.4 Results ............................................................................................................... 45
5.4.1 Design Flood Envelope ............................................................................ 45
5.4.2 Presentation of Results ............................................................................ 45
5.4.3 Peak Depths, Levels and Velocities ....................................................... 45
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