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Converting Datums, NAVD88 (CGG2013) to match 1965 survey – Manitoba, Canada
Hi there,
I am surveying in Manitoba, CAN. UTM 14 North. I surveyed a creek a couple weeks ago, using my own BM that I corrected on CSRS PPP. I cannot find original BM information. On CSRS PPP I can use CGVD2013 or CGVD28(HT2_0), I used CGVD28 in this case. I brought my survey into Leica Infinity and applied the corrections to my two benchmarks, and converted the survey to feet. I need to compare my elevations to an original survey taken in 1965 in DATUM: GEODETIC in feet. When I convert everything in the way I have explained, i get elevations around 260.000 m or 875.00 – 876.00 ft. The elevations on the original survey are around 876.00… in theory my elevations should be higher as the drain has collected sediment, but they are around 2 ft lower.
I was told to try switching from NAVD88 (which I can get my benchmarks in using CSRS PP) to NGVD29, but I am not familiar with NGVD29, is this a United States thing? How different is it from CGVD28? Would It work for my area? If so, can you suggest some ways I could convert my benchmarks into NGVD29? I tried the https://www.ngs.noaa.gov/NCAT/ website but it doesn’t seem to want to work for.
Or maybe there’s something else I’m doing wrong, or some other trick to this? Or maybe I’m not doing anything wrong and this difference of 2 feet is just due to accuracy changes from 1965 to now.
Any suggestions would be greatly appreciated, thank you!
As an example, I have a corrected BM in UTM 14 North, CGVD28, with the following data:
Northing: 5635603.602 m
Easting: 505547.122 m
Elev (orthometric): 267.447 m
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