You have to give the water somewhere to go that doesn't wash away the fill. Some kind of drain that routes the water somewhere safe. Or redirecting the water from its source.
You should also have something that holds the fill. A terrace or wall or something similar. It looks like you have a partial wall, but you'll need a full wall or it will keep washing away.
And what were you trying to do with that fill? A patio or something similar?
