Working on my layout aisle being a river or bay

I have a concept of the walk-in aisle of my layout being a river or small bay, so I am making my scenery (rocky banks etc.) all come down to a common level as it would be meeting a bay.

Series of shots, showing rocky banks coming to a common level.

Bank by the concrete arch bridge

Continuation of banks at bay level

Further along the bank

This showing my suspended edge, not yet fully built up with scenery

This shot from a low level showing the way the edge is built

My thought is to build a rolling cart with an area of bay level water that can be raised into position anywhere along the walk in aisle, for photography of the layout, with extended water.