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Combined Critical Events Envelope

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I am trying to present the overall peak floodplain at a number of ARI's in a township. 

1. What is the best way to determine the critical storm?
I have run various duration storms at each ARI. I have currently chosen the event which shows the maximum floodplain extent for the majority of locations. However, I know there could be some locations which peak in different duration events. 

2. I am wondering if it possible to present a single flood map which is an envelope of peak flood depths from a combination of peak storms?
This follows on from my first query. If I can't determine a single critical duration, I could present an envelope of multiple duration events. 

Any tips would be great. 


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Hi Lucy,


The 'maximum' function in the Asc_to_Asc utility is the one that you need to achieve both of these

Steps for both points:

Set up a batch file similar to the one in the first image. You need to link to the utility and, using the '-max' flag, link to the H max grids you need to combine. You can also use the optional '-out' flag to set the final filename, else the utility names it for you.

From this step you will get three outputs.

1) a maximum grid that has combined all the WSL to get the maximum. This is what you wanted in point 2.

2) a classified grid that details the source file for each of those maximums. See the second picture I've attached. This is the map that you will need for your first point. This classified grid references the order of the files you put into the batch file.  For example, if the maximum WSL in one area of my catchment came from the 15min duration, my classified grid would have the value 1 in this area, because it was first in the batch file.

3) a csv that links the integers in the classified grid to your file names. This is so you don't lose track of what each number means if you change the batch file. 

Hope that helps. 




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