Where can I find a system like this?

[Nherwyziant]

I saw this system before, it allows you to check if the terrain has deep or shallow water and detects the type of terrain on some place or stuff >.>. I think it has something like GetTerrainType.

 

[Ashlebede]

This is not a system, but you can check whether the terrain is walkable & floatable.

Floatable + walkable = shallow water
Only walkable = no water
Only floatable = deep water

To check this, you can use [ljass]IsTerrainPathable()[/ljass], which, if I remember well, returns [ljass]false[/ljass] if the terrain is pathable.

I think there is a GUI version of it.

if not IsTerrainPathable(x,y,PATHING_TYPE_WALKABILITY) and not IsTerrainPathable(x,y,PATHING_TYPE_FLOATABILITY) then
  //shallow
elseif not IsTerrainPathable(x,y,PATHING_TYPE_WALKABILITY) then
  //dry land
else
  //deep  
endif

By the way, this takes in account the pathing blockers & doodads which block pathing, so it might not always give the correct results (unpathable areas will return deep water, unless you use an [ljass]elseif[/ljass] instead of the last [ljass]else[/ljass]).