Dry Creek Bed Construction

[VO Landscape Design]

Trying this in a different forum.
A client wants a dry creek bed in their yard. It starts out about 6' at the top and 10' at the end and 41' long. I know the basics of design but am having problems with the amount of rocks for it. With the different size on the bottom building up to larger on the top is there a easy way to figure out approx. how much of each? It will be about 12" deep at the deepest part.
I am thinking Rock A (the smallest) at about 300 sq.ft. X 2" depth = 600sq.ft. Plus another 82sq.ft. X 10" depth = 820sq.ft.for the deepest part. Rock B (larger) at 208sq.ft. X 3" depth = 624sq.ft. Rock C (largest) at 129sq.ft. X 2" depth = 252sq.ft.
I hope this is clearer than it sounds to me.
Here is a picture of the area. The shaded area is where they would like it.
Thank you
VO

[wurkn with amish]

will water ever flow this route?

[VO Landscape Design]

will water ever flow this route?

Yes. Some will be coming off the porch above but not much.
VO

[wurkn with amish]

Well to start you off 300ft2 x 2" doesn't equal 6ooft2 . It equals 50ft3 so that would be roughly 3ton ( I always round up)
Here's what I came up with in amounts.
A. 7tons
B.3-4tons
C.2tons
What I would do is have 10-12 nice size boulders planted in and out of the stream and run a 3"-4" size gravel mixed with #4 gravel down thru the stream. Hope that makes sense.

[VO Landscape Design]

Well to start you off 300ft2 x 2" doesn't equal 6ooft2 . It equals 50ft3 so that would be roughly 3ton ( I always round up)
Here's what I came up with in amounts.
A. 7tons
B.3-4tons
C.2tons
What I would do is have 10-12 nice size boulders planted in and out of the stream and run a 3"-4" size gravel mixed with #4 gravel down thru the stream. Hope that makes sense.

Thanks. With limited space didn't want a lot of extra rock. This is in a nice area so this could be my "in"
VO