Sub metric elevation surveying equipment for water systems in refugee camps

https://positioningservices.trimble.com/services/rtx/fieldpoint-rtx/

I have used the Centerpoint RTX service with Trimble R10 receivers for water supply projects in Ecuador, but it is higher accuracy (and more $$$) than you require.?ÿ

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https://www.waterworld.com/drinking-water/distribution/article/14276477/mapping-in-the-mountains

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You could use SBAS corrections, if they were available in the region your working in, which I don't believe includes Africa or the Middle East. I could be wrong.

https://en.wikipedia.org/wiki/GNSS_augmentation

Honestly? Nobody doing the work is a surveyor? Conventional level runs. Decidedly low tech, easy to learn, no whiz-bang flashy light electronics to raise suspicion. It's been done this way for a long time.?ÿ

The other option involves resource grade GPS and post processing and some body familiar with processing to apply the corrections. One unit collects GPS data as a base station and a second unit acts as a rover storing observation along the route. The roving data is combined with the base data to apply the necessary corrections to achieve desired accuracy.?ÿ

Good luck!

An X-90 OPUS static receiver and a used total station for trig levels based on the OPUS points.

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@half-bubble?ÿ

I doubt they care about actual elevation - only differences across the project, so trig levels would be sufficient.

Posted by: @half-bubble

An X-90 OPUS static receiver and a used total station for trig levels based on the OPUS points.

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AUSPOS or Trimble RTX post processing would be the way to go rather than OPUS.?ÿ

@bill93 That is true. We used ITRF2014 positions at the current epoch, and EGM08 geoid model.

The nice thing about using RTX is that the elevations are displayed right away, no comps necessary. I would assume that those decimeter solutions can be obtained using something less than a fully capable data collector, maybe even a cell phone, and be able to apply EGM08. But, I am not familiar with the non-survey grade Trimble receivers.?ÿ

Could be that something like the Lidar function on an Iphone 13 would answer the low cost / easily transportable portion of your needs. Not so sure about the easy to learn part, at least for the data resolution portion. Check out this Youtube on the process.

Honestly? Nobody doing the work is a surveyor? Conventional level runs. Decidedly low tech, easy to learn, no whiz-bang flashy light electronics to raise suspicion. It's been done this way for a long time.?ÿ

The other option involves resource grade GPS and post processing and some body familiar with processing to apply the corrections. One unit collects GPS data as a base station and a second unit acts as a rover storing observation along the route. The roving data is combined with the base data to apply the necessary corrections to achieve desired accuracy.?ÿ

Good luck!

@ Williwaw Sorry for the language barrier and the tech barrier.

What would be conventional level runs? These with an optical theodolite?

I am certainly hoping I am not the one doing these surveys :), but find a solution that can be rolled out. Refugee camps are usually in remote locations where contracting is complicated.

@john-hamilton What would be the rough cost of equipment and subscription?

@bill93 Yes, we only need relative elevations but speed and ease of training would be nice to have.

Any particular equipment you could point to/recommend?

@santiago?ÿ

Topo surveying by stadia methods, which was discussed just last week in another thread, might be a low cost/low tech answer to your problem.?ÿ ?ÿ?ÿ

My understanding of your messages is that you want to determine heights of points in a water distribution system at refugee camps. If that is the case, you should be able to determine relative heights with a basic level, tripod and rod like this set:

BTW, the equipment shown above is illustrative of a low-cost option. I have not used them.?ÿ

I assume that you are talking about remote sites where equipment would be transported over bad roads and the like. This requires periodic checks to insure the level remains in adjustment.

Look on the web for ƒ??leveling peg testƒ? or ƒ??Forster methodƒ? or ƒ??Kukkamaki method.ƒ??ÿ

Setting or choosing stable and recoverable points at or near the sites of interest is important.?ÿ

I do not know how much you know about leveling. I recommend that all leveling begin and end on stable and recoverable points.

Establishing ƒ??permanentƒ? monuments will expedite future expansion to new sites.

All leveling should be done in closed loops meaning that the summation of rod readings should equal zero with the difference being errors in your observations. Distances between the level instrument and rod should be consistent and with these distances limited by the ability of the instrument person to clearly read the rod. Intermediate sites observed between monumented points (turning points) should be use clear and distinct points (like a screwdriver driven into soil).

Note that my comments assume that you want to establish relative heights with respect a point on a relatively compact site and are not attempting to tie your work to a national datum

Make sure the tripod is firmly set and stable (check clamps and the tripod head and feet for any play. Keep the base of the rod (and face) clear of anything that would alter the rodƒ??s direct contact with the point of interest.?ÿ

There are a number of samples of leveling notes on the web, I would look at examples from surveying programs at universities. Clearing labeling points and keeping track of them certainly helps.

With respect to GNSS, remember that physically meaningful heights like orthometric heights (H) are approximated by the combination of GPS-derived ellipsoid heights (h) and a geoid model (N). Their relationship is h - H - N = 0 (ideally). While both the UNAVCO and NGA sites have on-line tools reporting N they provide different numeric results. These sites require geographic coordinates for the point of interest.

The NGA tool is available from this link: https://earth-info.nga.mil/#tab_data

Good luck,

DMM

GNSS technology is the appropriate tool to connect distant sites together. Long leveling runs accumulate error and take a lot of time. ?ÿ?ÿ

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Thank you everybody for the replies, it was very helpful ???? .