FTPro - River export & size

Master TMO

I am working with a map in FTPro, generating and exporting rivers using different River Length criteria. Is there any way I can do it all in one export, and tell the difference in the exported maps between streams and major rivers?

In a related note, what exactly does the River Length number stand for? Is it water flow, or just a random value with no real relation to anything measurable?

jslayton

Sadly, FT Pro provides only a single color for the output, meaning that there's no way to distinguish flow amount in a river without multiple exports.

River length is the value threshold for flow to be considered a river.

Master TMO

I had suspected there wasn't any way other than exporting multiple layers of rivers. Oh well.

Does the value threshold tell me anything about the river? As an example, is there any way I can use the values to compare them in size to real-world rivers? I'm currently exporting using a threshold of 5, calling them 'major rivers'. Am currently thinking of doing a 2, a 0.5 and a 0.1.

jslayton

The value really only tells you that an area of flow has more rainfall falling on more cells cells upstream of it than another (it's just the number of cells if Potential River Flow is checked).

The flow threshold doesn't correspond reasonably to real-world values due to some projection and connectivity issues (that is, a cell on the map isn't the same size all over the image and cells aren't connected in the way that they would be in the real world).

Master TMO

Thanks, I appreciate the info.