Yes have heard of it. I suspect they are trying to wait it out as the droughts come in cycles and then comes the floods.. Which is another reason to have better drainage systems. What they do has to be thought of by people in construction that know and Can do but again like you say the cost. Yet people still build their homes on cliffs. Someone told me when she was young her parents rented a house in down town Sac and the driveway sloped down towards the house so when the rains came the front would flood but luckily not in the house. Same for some houses where the back yard would slope down toward the house as well as the cement around it. something to really pay attention to when buying a home as well as how prevalent quakes are as well as the surrounding area. Sac has elevated mid town only about 5 feet and it’s said the first floor of the Gov house is left empty for flood reasons.
When the superstorm does come thousands are going to perish. Perhaps hundreds of thousands. There’s no doubt about that. It would be like a Dam breaking above you. Why there trying to figure out warning system.that isn’t good enough.