The first example "augment the meat notes" is good. However, I would use "increase" when talking about the tensions and the floodwaters.
Generally, "increase" is much more common than "augment." "Augment" usually refers to increasing something that is desirable, whereas "increase" can be used in all contexts. The dictionary definition you quote gives you some technical uses of the term in music and linguistics, where we cannot use "increase."
In your first example, you could also use the word "enhance."