How would you change the pond surface to that of another pond?

[RoF 240]

I want to change the water surface of "zr_dam_04_ep1" to the water effect of "Nagara_pond_2" (They can both be found in the cup pack). How easy would it be to do that? I've never done any modeling, so a noob at it lol, The only reason I want to use zr_dam is, it's square and easier to put together in x-cam.