Hey there! I am currently trying to create a DEM from spot elevations on a small, coastal plain site. The max elevation range is no more than 10 feet. The ultimate goal will be to use this DEM to define drainage areas, so it's very important that I make it as hydrologically accurate as possible, especially because it's really flat. There is a small canal onsite and I know the invert elevation near the north and south site boundaries. I only know invert elevation at two points in the canal. I don't know how to represent the canal properly so it will be handled the right way when I go to create the DEM. My first though was to create a 3D polyline and input the Z values at those two points--but then I am not sure whether GIS interpolates the Z values between those two points along the polyline. I searched the documentation for that answer and didn't find anything.
I also have a lot of top of curb (TC) elevations that I'm not sure how to handle. If the TC elevations were the same, I'd probably create a polyline with an elevation field (like a contour line). I thought about creating points but wasn't sure how the points would affect the resulting DEM. I thought about using a 3D polyline with Z values defined at each TC, but then I don't know if/how GIS interpolates between the defined Z values for polylines.
I haven't worked with 3D in ArcGIS before so I may be totally off the mark regarding appropriate use of the feature. If there is a completely different, better way of handling the stream invert and TC elevations, I am very open to it.