Good job.
Unfortunately there are a few possible issues with the design as it as.
-
The heightmap includes a flat altitude where the ocean/water would be.
This is not correct realistically or naturally.
So now there may be issues integrating a water plane into the scene.
The water plane will have to be above the heightmap’s water plane altitude.
If the water plane is not high enough above the terrain, it may result in poly-fighting in the distance.
The player will be able to walk way out into the ocean at only foot deep or knee deep water.
If the ocean water plane is partially transparent/translucent, then the ocean floor will look like just be one big long flat region instead of proper underwater terrain that also includes bumps and dips and such. -
The coastal erosion procedure often results in a vertical altitude bump at the seam.
This is quite noticeable in your last screenshot.
This will be very noticeable when walking on the terrain.