Alternatives to track relocation include the construction of seawalls or other coastal “armoring.” Currently, 38% of the Southern California coastline is armored. But these techniques can end up blocking the natural replenishment of sand and hastening beach disappearance — a phenomenon that’s brought waves perilously close to the Surf Line in several sites.  “You need a certain amount of sand in the system for it to work,” said Brett Sanders, a professor of civil and environmental engineering at UC Irvine. “It's like how you can’t run a car without oil in the engine.” Read More