Autodesk InfraWorks

[#1]

So, if you have a .shp file representing the flowlines of rivers and streams, what's the best way to display that? Water areas don't work, right? They have to have an enclosed area and all I have is the flowline of the streams. Create a road style that looks like a river? Any other ideas?

[#2]

You are correct.  You  have to have a closed area for the water style.  And you are also correct in that you could create a road with a "water" surface.  You can grab a picture of water off the internet and assign it as a material.  Should work for you.

[#3 · Accepted solution]

There is an easier solution to this: when importing the data and after selecting the target type "Water area" there is this field "Buffer width": this can be used to turn the line string/polyline into a polygon. This field can be either mapped from the imported data or set to a constant value. and then you can chose an appropriate water style.

And a remark to the water surface: you can also use the special "water shader material" (dynamically animated and reflective) as material for the different street track materials; there should be no need to import your own water texture.

[#4]

The buffer width works like a charm! Now if only my dataset had the width of the stream in it.