I have two terrain layers loaded of a coastal area. The first one is very detailed, but only includes above water elevations. The second one is not as detailed, but includes below water elevations. What I would like to do is keep all of the first (detailed) elevations except where the first is below 0.1 (water areas). In those areas I would like to use the second (less detailed) elevations, but only if they are below 0. I can't clip the second to areas below 0 because it is a tidal marsh, and it gets really messy with all the variation, so I need some sort of automated method.
I am wondering if there is a multiple step process that would accomplish this?
I think I need some sort of custom if-and statement like; keep second if first is less than (0.1) and second is less than (0).