My current pond is a spring fed / water table / significant runoff pond that stays pretty full all the time. I suppose there will be some watershed as well to the second pond, with the overflow pipe of the higher pond running down the overflow trench into the second pond.

I'm more concerned about what will happen to the water once it gets into the second pond. Will it regulate with the water table, or will it overflow and flood the whole area down there, in which case, I'm would be no better off than I am now...