I was talking about a topo in a steep ravine with one of my engineering clients and we were viewing it on google and discussing how accurate a google topo would be, he showed me an interesting feature in google earth and I just had to apply it to a FEMA job(zone A, no BFE's) I'm doing.
This is what the area looks like in google, the engineer had showed me the terrain function in google and how you can get a better idea of contours by playing with it(elev. exaggeration set at 2). As the picture shows the stream climbing up and down the sides of the draw it becomes pretty apparent how a topo would be "off" using google:
You don't think it's ...
just a severe gravity anomaly?
The computer & the Internet did it.
It must be correct!
You don't think it's ...
The geoid model is odd out there.
Also just might explain how the flood plain got built so "unusually" there:-(
on a side note..
I am truly amazed at the amount of time and trouble our entire geographically-aware civilization has spent in avoiding a ground survey.
We use to look at quadrangle maps with 10' contours (maybe)...if you wanted to know what happens in between the two contours...get a survey. I bet there's folks out there that are highly-educated and still unaware about how much precise data is available from a relatively inexpensive ground survey.
It's just too easy to double-click on somethin', then run with it. :pinch:
on a side note..
> I am truly amazed at the amount of time and trouble our entire geographically-aware civilization has spent in avoiding a ground survey.
>
> We use to look at quadrangle maps with 10' contours (maybe)...if you wanted to know what happens in between the two contours...get a survey. I bet there's folks out there that are highly-educated and still unaware about how much precise data is available from a relatively inexpensive ground survey.
>
> It's just too easy to double-click on somethin', then run with it. :pinch:
Time is more valuable than precision:clock:
hey Roadhand
El Paso, huh?
One of the things on my bucket list is to visit the least travelled "legal" border xings about 130 miles west of Ciudad Juarez between Antelope Wells, NM and El Berrendo, Mexico. It's actually just a little sw of Hachita, NM. It looks like it would be easier to get to from Juarez than El Paso. Antelope Wells has a population of 2. Both are US Customs. They live in a trailer out back...
No paper work is processed there, so you have to have all your paper in order before you get there. Only vehicle and pedestrian (?!) traffic.
Just one of those out-of-the-way places where no one ever goes..
on a side note..
I am truly amazed at the amount of time and trouble our entire geographically-aware civilization has spent in avoiding a ground survey
We've got a little bet in the office about just how far "off" the new fema map is for this house, I'm at 13', which would put it about 8' above the BFE. Our ground survey should save the landowner a boat load of money over time, well worth it to him, just sad he needs to spend so much on it.:-(
hey Roadhand
> El Paso, huh?
First impressions tells me.....not too bad.
We rented a house in Santa Teresa NM. I am flying back tommorrow afternoon to meet the movers,and say our goodbyes to everyone and we should be all settled in here by the first.
hey Roadhand
> We rented a house in Santa Teresa NM. I am flying back tomorrow afternoon to meet the movers, and say our goodbyes to everyone and we should be all settled in here by the first.
Cool. Isn't Santa Teresa technically on the south side of the Rio Grande (even though the Frontera Internacional turns west south of S. Teresa)?
Desert Sky Airpark has the War Eagles Museum, if you're into old recip fighters. And the Transmountain Highway needs to be traversed on two wheels to be appreciated, I understand.
Good luck and don't work too much.
hey Roadhand
I have been to a few out-of-the way places while working along the various borders. We surveyed all the crossings (and did photo control in between) from the Gulf of Mexico to Presidio, TX. And also did 4 crossings in Alaska and several more in NY/NH/VT.
Here is Los Ebanos, TX which I recently saw on one of the border reality shows, they were pursuing a smuggler in a pickup and he drove into the river at Los Ebanos and swam back to Mexico.
And another fun place, Poker Creek, AK. We got there after they had closed for the winter, but still got our work done. Long drive from there to the AlCan highway. Me on the left in the photo.
If I recall correctly, the GE surface is based on LandSat. You can download the landsat data and a bunch of other GISsy products from the Earth Explorer.
Use it to supplement your survey and not to replace the ground survey.
Has FEMA run the LiDAR in that area yet? Are there other sources of close enough GIS data that can supplement your survey?
I had a project atop a steep coastal bank overgrown with briers and poison ivy. I had the crew locate the top of the bank, then I used a 40-scale, 2' contour to identify the bottom of the bank. Contoured in between and it was all good enough. Had a check as we located the at grade stairway and it was close enough.
hey Roadhand
> Good luck and don't work too much.
I'll try not to. We still have about 5 mos of design, I hope I dont get bored before the fun stuff starts. Yes Santa Teresa is across the river but i would call it more west of than south of at that point. Our project will actually bridge over the border fence in two places and run between the fence and the river. I say its going to be a fun job, but I usually say that on all of them at the start.
Has FEMA run the LiDAR in that area yet? Are there other sources of close enough GIS data that can supplement your survey?
No idea how FEMA came up with their flood plain, just know it makes no sense. We have the survey done now, the engineer will come up with a BFE which I'm guessing is at least 5' below the LAG probably will be more. We will see:-)
A community to the northwest of this site has panels done, but they appear to be four feet or more low, so even though there are BFE's they in no way match up to the flood plain, that one is a job by job re calculation. Otherwise, even though there is a river, almost nothing would be in:-/
Doing a subdivision in that food zone now and it will be a complete redo of the brand new flood plain in that area.
hey Roadhand
> I have been to a few out-of-the way places while working along the various borders. We surveyed all the crossings (and did photo control in between) from the Gulf of Mexico to Presidio, TX. And also did 4 crossings in Alaska and several more in NY/NH/VT.
>
John,
Did you work for Michael Baker at some point? Back just after 9/11 I surveyed the crossing from Cut Bank, MT west to the Pacific for them.
hey Roadhand
I just assume Kevlar gear is a standard item in your truck. And don't forget to oil up that swivel you need to keep your head on. Don't want that getting hung up, it can help you more than..... oh, just fill in the blank. 😉
Sound's like an interesting project nonetheless. Enjoy.
