http://www.latimes.com/local/california/la-live-powerful-storms-moving-l-area-strongest-storm-in-years-taking-aim-at-1487305729-htmlstory.html

Now's a good time to mention a book that I learned about on HN. The Control of Nature by John McPhee. It has chapters on: The lower Mississippi food control structures, Iceland's fight against flowing lava and Los Angeles's efforts to control raging water flowing down thru ravines.

Here's an excerpt:

String out along the San Gabriel front are at least a hundred and twenty bowl-shaped excavations that resemble football stadiums and are often as large. Years ago, when a big storm left back yards and boulevards five feet deep in scree, one neighborhood came through amazingly unscathed because it happened to surround gravel pit that had filled up instead.

Jeff Masters has a great blog about the Old River Control structure. It prevent the Mississippi from flowing off toward Baton Rouge (an 150 mile shorter route) and forming a new delta. The Mississippi pushes so much sediment down stream, that short of this control, it would build a mound in front of itself, then just tumble off to the right.

https://www.wunderground.com/blog/JeffMasters/americas-achilles-heel-the-mississippi-rivers-old-river-control-st