Besides acoustic waves, fiber measures strain, pressure and temperature. One proposed application is to line a water ar oil pipeline to quickly locate a leak. Currently pressure sensors every few miles. The you have to visually inspect the segment for the leak. Harder to do for buried pipelines.
Just look for all of the dead grasses where the spill is occurring for oil pipelines or patches of lush grasses compared to the other areas for water pipes. Or is that too simplistic?
It's not always that easy to see. I'm on the board for my city's utilities and we recently had a leak in our 48" water main that was 380,000 gallons/day. We found out about it because of all the water coming up in someone's front yard.
After repairing it and doing pressure tests, we now know we have another leak in another part of the main. However, there's all sorts of roads and other things build along the way so it's hard to know where it is, especially if it's not as big of a leak.
That indeed works, but is a time consuming manual process, pipes arent always leaking clearly (visually), and that only works when a failure has occured. I built a few fibre based instruments three or four years ago that could detect and gauge changes in the pipe caused by wall thinning (before leaks have occured), small leaks (too small to notice soil changes) and also fouling. Longevity and robustness of the sensors was always an issue though
