Where in the central valley??ÿ If you're close enough to the areas that are experiencing extreme subsidence, a project that monitors the movement on a daily or weekly basis might produce some interesting results.?ÿ?ÿ
It would be interesting to see what has transpired in and around the "El Nido Bowl" since it dropped at least 2 feet between January 2008 and January 2010. That sudden drop seemed to be induced by a change in the surface land use, rather than the drought, which didn't start until at least a year later. I would look for areas, even small ones (the El Nido bowl is only a few miles across at its deepest) where the surface land use has been changed from say grazing to some sort of thirsty ag use. Of course, one would need to look at the geology. If the subsidence prone geology isn't present, the potential subsidence will be minimal, at most.
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Despite that you should be since graduated and licensed, I will repond for future seniors.
You did not mention GPS, unless you consider that remote sensing. Since distance takes away your available time I suggest you confine yourself to your college campus. I suggest you subdivide off an area for a survey library, since the survey society providing the funding is a separate entity from the university. Make it classroom size with entry and rest rooms. See if you can do it within existing zoning and/or include all variances required. Include independent sewer and utility connections. Use all available survey methods, GPS to tie into the university boundary, traditional traverse to at least two known corners, traditional level to a benchmark. Locate adjacent buildings with transit and tape, using perpendicular or building face line offset shots and do the immediate construction area topo with a level and stadia rod. Include all field book work. Do not be concerned with large sheet sizes, letter, legal or ledger size plan set is easier. If you are simulating a board submission include on the cover sheet a "Waiver Request for Sheet Size". in PA a surveyor could design the minor road and utility extensions and calculate any additional stormwater runoff.
Paul in PA, PE, PLS
You could learn how to develop an LDP and do some surveying in the LDP to show its benefit or not.
I'd like to see someone publish carefully a done study (lots of averaging) of base-rover standard deviations for various short occupation?ÿ times at various small-to-moderate distances at various epoch rates. The data I've seen doesn't cover short times at those distances.
I'd like to see someone publish carefully a done study (lots of averaging) of base-rover standard deviations for various short occupation?ÿ times at various small-to-moderate distances at various epoch rates. The data I've seen doesn't cover short times at those distances.
Oregon DOT will be publishing a research project soon that will cover some of this.
Oregon DOT will be publishing a research project soon that will cover some of this.
The RTK elevation error report we did for DWR in 2011 covers some of Bill's interest.?ÿ Scott, any reason not to upload it here?
By all means, Jim. You probably can put your hands on it quicker than I can.
Thanks.
It's old, and the findings weren't exactly earth-shattering, but here it is.
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A cursory look at the report seems to indicate a minute got most of the improvement at distances of a few km, and 2 minutes at the larger distances.
Longer should always be statistically better, but quickly got into diminishing returns. The trends were not clear cut.
Also the effect subsidence has had on the vertical profile of the high speed rail project. Current ground elevations along the profile are not even close to the elevations used for design. This has also impacted the survey control established along the route for design and construction.
How do you incorporate and adapt? Fun stuff!?ÿ
I was consulted by the HSR team about 2011 as their control was falling apart and land surface elevations along the alignment were dropping rapidly from when they were mapped. They asked me what they should "do" about it? I told them that they either move the alignment (going almost right through the El Nido Bowl) or acquire a much wider right-of-way footprint than the original design called for because the profile of the rails had to be built where it was designed to be built, which meant they were going to have a much taller/wider base to reach the the ground surface when they finally build it. Of, course, that also meant huge change orders and wouldn't solve the problem going forward if the subsidence continued, which was likely. At that point it was about 2.5' in the worst areas, but across the valley to the west is where the "famous" picture of Dr. Joe Poland was taken standing next to a utility pole marking where the land surface had been 1925 and 1977. A total of about 29'.
The best option is to not build it at all, but I'll refrain.
https://www.usgs.gov/media/images/location-maximum-land-subsidence-us-levels-1925-and-1977
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