Extrap

[Sam Everitt]

Hi All,

What does the sub section in Extrap relate to? Is it a percentage of the length of a transect or of total ensembles ?

Cheers

Reply:

Hi. It is percentage of discharge. If you choose for instance 10/90 subsection, then Extrap will do its magic on the ensembles that contain the center 80% of the discharge. Screenshot showing 10/90 subsectioning

Topic

[Nick Everard]

Replying to add to the above (and to test out posting here!)

Also note that QRev has an option that allows you to set Extrap analysis to be discharge weighted. This means that each ensemble’s (sample) contribution to the extrapolation evaluation is weighted according to what proportion of the total Q is in that individual ensemble. This solves the problem where ensembles collected close to banks where water might be slow and shallow influence the extrapolation as much as those in the middle that usually contain many times as much flow.

It also largely eliminates the need to use the sub-sectioning method discussed above, certainly for regular discharge measurements.

Access this menu from QRev’s little cog icon, top left.

 

[Kristoffer Florvaag-Dybvik]

There should be a “Thumbs up”  button in the forum, but Thumbs up, Nick!

[Author]

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