We didn't have survey grade mm accuracy GPS 50 years ago. Maybe 20 years ago we did? The elevation is value is also less precise than the XY.
Also, land can subside without sinking roadways. You can see this all over California in the farming areas where groundwater pumping sinks the ground on both sides of the road, and the road stays elevated.
Again- not saying sea level rise isn't happening but it is not as catastrophic as we have been led to believe and there are other factors at play.
yes, all of this is true.
edit: hit submit before I was done…
Im not going to say anything about anything I haven’t seen firsthand. And, if I get motivated enough, I’ll take some pictures next time I’m in thinking about this during my commute up A1A.
There may be some subsidence in the land, but the area (in South Florida) I’m talking about is 4-5 counties, and not all built on sand. The aquifer here does get drained, but it is also suffering from saltwater intrusion, so that argument is not supported fully (no pun)
what i see most is the ocean overtopping seawalls that were obviously designed at a height to prevent that, and saltwater filling up the storm drainage and flowing into the streets causing flooding.
as I said before, the building code here now stipulates a minimum elevation for participation in the national flood insurance program. It is also part of your homeowners policy - your elevation certificate. This is partially driven by the private sector having to pay out for flooding.
it gets so bad in some areas that there was a local news report from one of the big money neighborhoods in Miami that because of sea level rise, the real estate market was down because the rich folk couldn’t get there yachts under the bridge.
so, no, it is not a Noahs Ark moment. But it is indeed happening at the moment and will continue.