Also on the chance that (like many other people recently) you've added beaches in an attempt to find Wiglett in Pokemon GO, you might be better off taking a day trip to somewhere like this:
https://www.openstreetmap.org/way/286195927

This beach feature has been on the map for 10 years. It almost certainly should create a beach biome. Niantic uses old map data in their games, so the beaches you've added here might not have an impact for months or even years.