Back when I worked as stress analyst I did a lot of “delta analysis”. The basic system was in place, but things change: a part might be built of a different material, a particular mission might have higher loads than the initial predictions…The question we were answering is “is it still okay?”
There isn’t a picture to go with that…but the beach where I spend a lot of time is also a delta for a creek. Over the years the silt has built up and the landscape and animals one sees have changed. One thing I find really cool is that every year the path of the creek through the delta shifts because of winter storms…so it is an example of both fast and slow changes, and yet when the tide is in it looks the same as ever.