Flood hazard mapping – Surface Water Solutions: Consulting and Software Training

This video on the RAS Solution YouTube channel presents new capabilities in HEC-RAS 6.0 beta for developing flood hazard maps. Below are some sample scripts for copying and pasting into the RASter calculator. View the video on YouTube to submit your comments to suggest any additional scripts to be incorporated here.

The raster calculator script below matches the ARR flood hazard mapping which draws from Smith et al 2014 as referenced in the Australian Rainfall and Runoff guidelines.

‘——————————————————-
‘ rasscript for Flood Hazard mapping based on
‘ WRL Technical Report 2014/07 Flood Hazard
‘ by G P Smith, E K Davey and R J Cox
‘ UNSW Water Research Laboratory
‘ https://knowledge.aidr.org.au/media/2334/wrl-flood-hazard-techinical-report-september-2014.pdf
‘ As cited in ARR 2019 Book 6: Flood Hydraulics Chapter 7: Safety Design Criteria
‘ http://book.arr.org.au.s3-website-ap-southeast-2.amazonaws.com/
‘ Figure 5-5 and Table 5-2
‘ Requirements: Terrain, Depth, ‘d’ and Velocity, ‘v’
‘——————————————————-

If d = NoData OrElse v = NoData Then
Output = NoData
ElseIf d > 4 Or v > 4 Or d*v > 4 Then
Output = 6 ‘H6 unsafe for people, vehicles & all buildings
ElseIf d > 2 Or v>2 Or d*v>1 Then
Output = 5 ‘H5 unsafe for people, vehicles & some buildings
ElseIf d > 1.2 Or d * v > 0.6 Then
Output = 4 ‘H4 unsafe for people & vehicle
ElseIf d > 0.5 Then
Output = 3 ‘H3 unsafe for vehicle and vulnerable people
ElseIf d > 0.3 Or d * v > 0.3 Then
Output = 2 ‘H2 unsafe for small vehicles
Else
Output = 1 ‘H1 generally safe for people, vehicles, & buildings
End If

Here are some suggested colours:

6: 250,189,166,255
5: 255,231,166,255
4: 217,232,173,255
3: 191,220,183,255
2: 190,229,233,255
1: 150,185,225,255
0: 255,255,255,0

Feel free to submit palettes for other colour schemes through the YouTube comments and we’ll add them to the list.

We’ll be adding other categories, including ZUK0, ZUK1, FD2321. If you have codes for any of these in the meantime, please submit them:

Table 4 Hazard to People Classification using Hazard Rating (HR= d x (v + 0.5) + DF) for (Source Table 13.1 of FD2320/TR2 – Extended version)

SUPPLEMENTARY NOTE ON FLOOD HAZARD RATINGS AND THRESHOLDS FOR DEVELOPMENT PLANNING AND CONTROL PURPOSE – Clarification of the Table 13.1 of FD2320/TR2 and Figure 3.2 of FD2321/TR1

Some might be more challenging to script due to the nature of the curves – anyone want to give these a shot?

USBR downstream hazard classification