USC FloodStudyUpdate Report - Flipbook - Page 7
5.
HYDROLOGIC MODEL ............................................................................................ 25
5.1.
Introduction ............................................................................................... 25
5.2.
Sub-catchment Delineation ....................................................................... 25
5.3.
Sub-catchment Parameters ...................................................................... 26
5.3.1. Area and Slope ......................................................................................... 26
5.3.2. Impervious Fraction .................................................................................. 26
5.3.3. Surface Roughness .................................................................................. 28
5.4.
Sub-catchment Linking ............................................................................. 29
5.5.
Rainfall Losses ......................................................................................... 29
6.
HYDRAULIC MODEL ............................................................................................... 30
6.1.
Introduction ............................................................................................... 30
6.2.
TUFLOW Hydraulic Model Extent and Resolution .................................... 30
6.3.
Terrain ...................................................................................................... 31
6.3.1. Ongoing Development .............................................................................. 31
6.3.2. Roads ....................................................................................................... 31
6.3.3. Basins....................................................................................................... 32
6.3.4. Dams ........................................................................................................ 32
6.3.5. Creeks ...................................................................................................... 32
6.3.6. Upper Canal ............................................................................................. 32
6.4.
Surface Roughness .................................................................................. 33
6.5.
Buildings ................................................................................................... 34
6.6.
Pit and Pipe Network ................................................................................ 34
6.7.
Culverts and Bridges ................................................................................ 35
6.8.
Model Boundaries ..................................................................................... 35
6.8.1. Inflows ...................................................................................................... 35
6.8.2. Downstream Boundary ............................................................................. 35
7.
MODEL CALIBRATION ........................................................................................... 37
7.1.
Methodology ............................................................................................. 37
7.1.1. June 2016 Calibration ............................................................................... 37
7.1.2. February 2020 Verification ........................................................................ 38
7.2.
Rainfall Losses ......................................................................................... 38
7.3.
June 2016 Calibration Results .................................................................. 40
7.4.
Discussion of Calibration Results.............................................................. 41
7.5.
February 2020 Verification Results ........................................................... 42
7.6.
Discussion of Verification Results ............................................................. 44
8.
DESIGN FLOOD EVENT MODELLING.................................................................... 46
8.1.
Overview .................................................................................................. 46
8.2.
IFD ........................................................................................................... 46
8.3.
Temporal Patterns .................................................................................... 47
8.4.
Rainfall Losses ......................................................................................... 48
8.5.
Areal Reduction Factors ........................................................................... 49
8.6.
Initial Conditions ....................................................................................... 50
8.7.
Blockage................................................................................................... 50
8.8.
Critical Duration Assessment .................................................................... 52
8.8.1. Approach .................................................................................................. 52
8.8.2. WBNM Model ........................................................................................... 52
8.8.3. Critical Duration Analysis .......................................................................... 54