Just a little toot here.
First of all you need to find the right superglue. Right meaning cheap and runny as hell. Mine was the consistency of water. Found at the pound store. Here is what I used.
Next you need your prepared surface for the sand runnel to be placed. These are rock spires made from foam and coated in guesso. The white is pollyfilla that I used as a filler between the foam spires and the foam hill. Basing for all the flat surfaces was done first to give the runnels something to hold onto while they were being set.
Once you are ready you pour sand into the area that will have a runnel. Let the sand flow naturally and then hold at an angle to keep it in place.
Next dribble the superglue onto the surface to lock it in place.
Since it is sand and will flow normally you can add more to the set runnels until you get the effect that you want.
A couple of things to keep in mind. The superglue must be incredibly thin in consistency so it is not glue you would normally use on miniatures since it would run. The next thing is try to drop onto a hard surface first (in this case I used the rock spire) so you do not cause the sand to create craters where the drops of glue hit. If you start from the top you can add drops to the already set sand and move down the slope. Another thing that can happen is small holes in your surface can form (while the superglue is setting) and the loose sand behind the glued surface will pour out. When this happens just let it setup, then add more sand into the hole until filled and re-glue. Last thing to remember is that superglue causes heat when setting up so you do not want to do too much at one time or you can damage materials like foam. I did one runnel at a time and alternated their placement between every other spire so it did not generate too much heat.
Hope that helps.
Snitchy sends.
