Correct but the trend line needs to be based on measurements made with instruments of similar accuracy. If you look at the graph in the original post the difference between the high and low points of temperature is about 2 degrees. An error in reading the temperature buy even 0.2 degree is a 10 percent error. The people publishing this information need to be transparent and tell us the accuracy of their measurements (+ or - so many 0.1ths of a degree) so that an informed decision can be made.
When ever I make a measurement of anything (especially comparative measurements) I always use the same instrument to make the measurement. Whether that be a caliper, mil gauge or total station. Measuring material values versus measuring temperatures and distances are totally different. Temperatures, distances and other environmental and spacial measurements are totally dependent upon the accuracy of the instrument and the precision and training of the operator. Any one or a combination of errors can lead to false readings.
When looking at charts like this always look at the scale of the axes. You can emphasize a difference by adjusting the scale of the axes.
From Dave bakers YouTube channel
https://www.youtube.com/live/oP1Ozm3.8fjyuKKKEXFif_
I'm not aware of any area where new residential construction doesn't require Base Flood Elevation(BFE) +1 ft for the lowest level. That is the only way you can qualify for flood insurance which is a requirement for any federally backed mortgage (most of them).
Now you can certainly make the argument that BFE+1 is inadequate and I would agree. Latest stats I have is that 25% of all flooded structures are above the BFE+1.
I believe the disclosures to the general public regarding flood threats are misleading. Developers/ Real Estate agents are often times misleading or don't understand. The only thing they are concerned with is you are required to have flood insurance or not.
However there is a massive different in risk between BFE+1 and BFE+3. When I contracted my personal home 14 years ago the number one thing on my list was the BFE. I'm in southern Lafayette Parish near the river with a BFE+20. I've often been asked if I worry about flooding and have to explain no and why. Some have a hard time comprehending that you can be close to the river and much safer from flooding than someone who lives miles away.
one of the last things you want is for FEMA to rewrite your flood maps, look at the difference between bfe in Hancock county 18'+ and Harrison county right across the bridge bfe's of 16', the and that is with Hancock having higher elevations than much of coastal Harrison county, the difference was difference in tital surge in Hancock where Hurricane Katrina made landfall of 32' and then diminishing surge as you went east from the eye. The flaw is that they based the map off of surge which would have been greatest in Harrison county if the storm would have shifted as little as 30 miles east. Their flawed maps have cost Hancock county millions
Additionally any time the Corp of Engineers does anything it is for the benefit of the area with the most influential lobby, the levies that were put in to protect New Orleans only increased surges in Hancock County MS and the north shore of the Lake.
The Houston area has a subsidence district
https://hgsubsidence.org/
They found that all of the industrial plants in the area taking BILLIONS of gallons of ground water a year caused significant subsidence and flooding in the area. They put a surcharge on the water wells that was more than the cost of desalinization of gulf water. The original study was done many years ago and , if I remember correctly, the original surcharge was $3.00 a thousand gallons. You could still pump ground water as long as you wrote a check. It was quickly determined that it was chea6ti desalinate gulf if Mexico water.
After the Kat-Rita event the big question along the coast was "how high is high enough" to rebuild. USGS came through and checked all their benchmarks and found them lower than the published elevations some by as much as 2 feet. That's when it was decided that all future flood elevations were to be established by GPS observations.
It was also found that benchmarks in rice growing areas were one to one and half foot lower than published. They also found that there was some rebound when rice field flooding was over for the year.
We live on a sponge. It get dry we sink it get wet we rise. All in very slow rates but we still move. NOTHING resting on the ground in south Louisiana is stable.
Provided they are in a regulated flood zone. There is no requirement for minimum Finished floor or equipment elevations in zone x. Only Zone A, AE & AE FLOODWAY That being said, one needs to understand that we're are all in a flood zone, it's just a matter if it's regulated or not.
Having been involved in several flood studies allows me to make several comments,
1). Engineers will spend countless hours arguing over CN values, but I have made the argument that if an area is flooded then the CN goes through the roof because the the ground surface is water.
2) drainage basin areas will vary depending on whether adjacent basins are flooded and the basins communicate with each other.
3). If a ground surface has subsided does the BFE go down with the ground given that the water is on that ground. Fema says no. (Last I checked)
4,) Given that the government has control over the GEOID that is used then they can make water levels higher by adjusting were zero is.
5). I firmly believe that the eventual goal is to make it so expensive to live in a flood zone you will be forced to move.
6). The BFE +1 is from the floodway modeling. By forcing everyone in an A or AE flood zone to be BFE +1 . theoretically the natural flood zone could diminish to the flood way if everyone did BFE +1. That is where "No net fill" and "No net rise" comes from.
This is a very complex issue involving engineering, politics and government agencies each with their own agenda. I am certain it won't get solved any time soon.
so keep your flood insurance no matter what?
It is established fact that Louisiana is sliding into the gulf. There are hundreds of documented landslides due to the jello that is sediment built.
Don't think of it as subsidence directly above an aquifer.
Aquifer depletion causes an underground valley of sorts affecting the adjacent jelllo structure with the force of gravity.
It is silly to think the jello can only slide south when subsidence to the north has its own pull.
Erosion is not the only culprit.
There are currently 63 users browsing this thread. (3 members and 60 guests)