"I really like the idea about stacking ponds to get cleaner water. one question though, how do you manage the sediment buildup in the top pond?"
Essentially all ponds start collecting sediment and/or organic matter from Day 1. An upstream settling pond allows you to have some control of where the sediment infilling occurs.
The biggest advantage is that it will be much easier to muck out a small pond with an excavator every 10(?) years, than it is to clean out your large pond.
Of course, the upper pond can be multi-use for anything else you would like in your plans.
It looks like the land to the east of your property transitions to grassland. It that is true, then you should have relatively clean surface run-off water to fill your ponds.
