3 ms·

Does that 100 year rule apply to undeveloped areas? My neighborhood is 20 years old and before it existed, it was wilderness in the middle of nowhere. I wonder

by city41 6y ago

Does that 100 year rule apply to undeveloped areas? My neighborhood is 20 years old and before it existed, it was wilderness in the middle of nowhere. I wonder how well flood data is tracked for that type of land.

kemiller2002 6y ago
From what I remember (where I am obviously), the Department of Water division of the Department of Natural resources surveys pretty much all of the area of the state. When someone builds something in a new place, there is quite a bit of research that goes into water tables, flood zones, etc. I would assume they map that out, but honestly I can't say for certain. I do know that it's occurred on occasion that rules get "bent" to make certain things happen. It's politics and money, and permitting is a high visibility job.
- to11mtm 6y ago
  It depends! I used to do permitting for construction of aerial and buried fiber networks. Typically if you're doing some sort of thing where floodplain data is needed, you'll start by finding the dataset from USGS/FEMA/USGIS/etc. Import that in, you'll get a whole bunch of data that depending on package (i.e. if you are doing stuff in AutoCAD instead of working with real GIS software) you might have to shape to get more proper information; floodplain data looks like a bunch of contoured lines (often semiparallel to each other.) based on the survey, and have different embedded metadata accordingly. So you'll do your drawing based on that, and ideally at some point, a Surveyor goes out and will Verify the map. They'll do this by probably re-pulling the original survey data, going out to the site, and basically making sure you didn't lie in your map. This last part BTW is an important check&boundary, and IMO the more important one than municipal approval. A good professional surveyor knows that if he does the wrong (i.e. potentially harmful) thing, he could lose his license and livelyhood forever. Professional Seals are something that I have a lot of respect for. FWIW, this is often the easier part of getting a permit as long as you are building sanely. The city is where politics, money, and process gets broken.
peterwoerner 6y ago
It's also based on simulations. They army corp of engineers runs simulations to figure out where the flood planes are and also where they can dump water in the case of flooding. Saved new orleans about 10 years ago from being completely underwater.
flurben 6y ago
There is no 100 year rule. To the extent that "N-year floods" exist, or their hypothetical water levels, that is all more of an arbitrary label than a scientifically-valid designation. realistically they're measuring "big floods" and "bigger floods" in a way that is consistent, however the stated time frequency with which they supposedly occur is so extremely inaccurate that it does not rise to the level of 'science.'

by city41 6y ago

kemiller2002 6y ago

From what I remember (where I am obviously), the Department of Water division of the Department of Natural resources surveys pretty much all of the area of the state. When someone builds something in a new place, there is quite a bit of research that goes into water tables, flood zones, etc. I would assume they map that out, but honestly I can't say for certain. I do know that it's occurred on occasion that rules get "bent" to make certain things happen. It's politics and money, and permitting is a high visibility job.

to11mtm 6y ago
It depends! I used to do permitting for construction of aerial and buried fiber networks. Typically if you're doing some sort of thing where floodplain data is needed, you'll start by finding the dataset from USGS/FEMA/USGIS/etc. Import that in, you'll get a whole bunch of data that depending on package (i.e. if you are doing stuff in AutoCAD instead of working with real GIS software) you might have to shape to get more proper information; floodplain data looks like a bunch of contoured lines (often semiparallel to each other.) based on the survey, and have different embedded metadata accordingly. So you'll do your drawing based on that, and ideally at some point, a Surveyor goes out and will Verify the map. They'll do this by probably re-pulling the original survey data, going out to the site, and basically making sure you didn't lie in your map. This last part BTW is an important check&boundary, and IMO the more important one than municipal approval. A good professional surveyor knows that if he does the wrong (i.e. potentially harmful) thing, he could lose his license and livelyhood forever. Professional Seals are something that I have a lot of respect for. FWIW, this is often the easier part of getting a permit as long as you are building sanely. The city is where politics, money, and process gets broken.

peterwoerner 6y ago

It's also based on simulations. They army corp of engineers runs simulations to figure out where the flood planes are and also where they can dump water in the case of flooding. Saved new orleans about 10 years ago from being completely underwater.

flurben 6y ago

There is no 100 year rule. To the extent that "N-year floods" exist, or their hypothetical water levels, that is all more of an arbitrary label than a scientifically-valid designation. realistically they're measuring "big floods" and "bigger floods" in a way that is consistent, however the stated time frequency with which they supposedly occur is so extremely inaccurate that it does not rise to the level of 'science.'