Erode around an object

Hello, looking for some advice for eroding around objects. Examples: premade rocks that I have in a scene, I would like to erode AROUND them and maybe even build up sediment that it would be blocking. I have tried maskinging but havnt gotten very good results. Thanks!

I think that there are several ways to go about this. I think even masking might just be the solution but just in conjunction with other techniques.

Anyways, here’s my quick go at a solution. I made this example file to show how you might can go about this. This isn’t perfect, and I produced this rather quickly, but it might start to give an idea of what you can try. I’m sure more (better) solutions will surface here over time.

Hope this helps!