That looks similar to a material that one of the guys in our Delaware Scale Modelers uses on his ocean bases. It's textured a little like fine waves, like ocean waves viewed from about 1000 feet in the air, and he uses it with his 1/700 scale ships. I believe it has an adhesive backing. Now, it's not like the sculpted bases you may have seen, made from a foam core with gesso or acrylic gel for surfacing. I will ask him what the product is and post it back here.
Prost!
Brad