Flow arrows

Flow arrows get put in every triangle from the terrain - the screenshot does not (to me) show what you are trying to change, unless you mean the style of the arrow. That is not the same as the density of flow arrows.

Please give further detail.

By density i mean the arrows getting so crowded such that they lose meaning. My suggestion/wish is to have a way where the arrows can be edited/deleted/moved etc graphically (like the way triangles are edited using terrain tools).

Below is a location on my terrain model where the arrows get unusable.

I need to show them on sw3p sheets so if i reduce the scale on the cell, they will not be legible in the sheets.

Below is how they appear on the sheets. 

As they are placed in every triangle, and the stroking of the elements means extra triangles around curves, I cannot see a way to 'de-densify' the flow arrows - without changing the accuracy of the model.

You could have a feature definition for the curves where the stoking interval is larger and use this purely for the flow arrow display.

Would a Scalable Terrain work instead?