Material from RGB colormap and water glitch

Hello everybody

I have just startet using Unreal Engine 4 and I recently I ran into some problems.

First of: I have a landscape map, which I generated using a heightmap of the earth. Everything went fine, until I noticed that when I zoom out too much, I get some nasty grafical glitches:

I still don’t know what’s causing this… I guess it’s because of the water material maybe?

As you can see my map hasn’t got any material. I wanted to know if there is any way to make a Material that lays textures based on a map I made earlier. It sounds a bit wierd, maybe I’m just not the best at explaining stuff :P.

I have a texture map that looks like this:

My idea was: every color on this map has an induvidual rgb code (for example: sand/desert rgb(39, 52, 81), plains/forest rgb(84, 78, 49) etc.). And based on the rgb value of every “biome” I wanted to put a texture on the map. So the desert rgb has a sand texture and so on.

Is there a way to make this possible? Or am I just wandering in the dark?

Thanks in advance

Has nobody an idea, how I could fix my problem?