explicit terrian height adjustment

I'm creating a map where the entire thing needs to be at a specific height, with a rivers running though it. I started with a shallow water map, and now i need to raise the entire map by the same value. is there any way I can do this? The tools don't seem to accomodate that very well. My other option was to use shallow water with ramps, but ramps seem to do some weird things sometimes, like not allow you to place them for no reason. Any help would be helpful.

raise one area to the height you want it to be with the raise, lower, and plateau tools, then just use the "plateau" tool and drag it across the whole map using the 8-square wide circle. Eventually you can start copy pasting the terrain across the map once you get a good sized area going.

start off with the smallest size map possible (64x64 or 32x32), shallow water. then use the raise tool (not the raise cliff, but the one that makes a hill) and raise the land to the height you want. then use the plateau tool to level off the entire area (click on a point on the raised land). once you've filled your map this way, increase the map size under map size and camera bounds. its faster this way than copy and pasting.

start off with the smallest size map possible (64x64 or 32x32), shallow water. then use the raise tool (not the raise cliff, but the one that makes a hill) and raise the land to the height you want. then use the plateau tool to level off the entire area (click on a point on the raised land). once you've filled your map this way, increase the map size under map size and camera bounds. its faster this way than copy and pasting.

oh yeah, make sure you raise the land to the very edges before increasing the size.