1. ARR : 2D Direct Rainfall Testing
Rob Swan
Rhys Thomson

2. Supported By 2
2/05/2019

3. Overview The Questions:
How does current best practice hydrological modelling for urban catchments compare with FFA?
How do the results compare for models established independently?

4. Overview Background on the Catchments WA Vic Sensitivity Testing
Assumptions
Results
Vic
Sensitivity Testing

5. Study Areas

6. Study Area - WA
Area = 8.2 ha TIA = 2.9ha

7. Area = ha
TIA = ha
Study Area - Vic

8. Available Information
Data Set
Victoria WA
Pits and Pipes
Only the trunk drainage system available, minimum 450mm diameter pipes
The majority of pit and pipe data is available.
Terrain
LiDAR
Aerial Photo
Yes
Flow gauge record length
1977 to 2012 (35yrs)
1983 to 1993 (10yrs)

9. WA – FFA Analysis

10. Vic – FFA Analysis

11. 2D Direct Rainfall Testing
Three modellers
2 based in NSW
1 Based in Victoria
Their Mission:
To create a Direct Rainfall model for each catchment, using best practice parameters
Testing undertaken using 1987 IFDs

12. Assumptions - WA Parameter Modeller 1 Modeller 2 Modeller 3 Software
Tuflow
SOBEK
Grid Size 2m
Buildings
Buildings “nulled”, rainfall increased to compensate
Buildings raised (by 3m)
Buildings “raised” (by 3m)
Roughness
Roads
0.018
0.015
Urban/ Residential
0.08
0.05
0.03
N/A
0.02
Open Space

13. Assumptions - WA Traditional Hydrology XP-SWMM model RORB model
Both single catchment
Losses
Modeller 1
Modeller 2
Modeller 3
Tuflow
XP-SWMM
RORB
SOBEK
Scenario 1
Scenario 2
IL – imp (mm) 1
10 (1.5)
1.5
CL – imp (mm/hr)
2 (0)
IL – per (mm/hr) 20
N/A (20) 30
CL – per (mm/hr) 3
N/A (5)

15. Results

16. WA-Results

17. Modeller 3
Currently looking for a good home
Has computer, will model

19. Assumptions - Vic Allocated micro-sub areas Parameter Modeller 1
Scenario 1
Scenario 2
Software
Tuflow
SOBEK
Grid Size 2m 3m
Buildings
Modelled with property roughness
Buildings “raised” (by 3m)
Buildings “nulled”
Roughness
Roads
0.018
0.015
Urban/ Residential
0.1
0.05
0.04
Medium Veg
N/A
0.06
Open Space
0.035
0.03
Commercial
Car Park
0.02

20. Assumptions - Vic Traditional Hydrology RORB model
Used a previous established model, but converted to use IL/CL
Losses
Modeller 1
Modeller 2
Modeller 3
Tuflow
RORB
SOBEK
Scenario 1
Scenario 2
IL – imp (mm)
7 (1.5)
1.5
CL – imp (mm/hr)
2 (0)
IL – per (mm/hr) 15
N/A (15)
CL – per (mm/hr)
2.5
N/A (4)

22. Results - Vic

23. Results - Vic

25. Sensitivity - Vic Modeller 3 Scenario 3 Scenario 4
Pre-wetted catchment to account for depression storage
Scenario 4
Initial losses adjusted to account for depression storage

27. New IFDs Typical Changes Vic WA
For less 1 hour duration, generally less than 5% difference (reduction) WA
For 30min, less than 10% generally (reduction)

28. Contacts
Website: