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Dear Samuel,
Within Wateraid, I am not aware of anybody using this. Even outside Wateraid, I doubt the usefulness, as most of the public available DEM have poor resolution (e.g. grid of 1x1km).
GPS are much more commonly used. The normal ones are notoriously inaccurate in the third dimension (height), but more sophisticated have barometers. If these are used properly, these can be sufficiently reliable for preliminary surveys.
However, to accurate calculate pipes needed, breakage tanks, bending of pipes etc, nothing beats a theodolite and if the investment is considerable, a theodolite should be used.
On another note: at least as important is to monitor the source over at least a full year (preferably much longer) to be certain that there is enough water also during the dry season. Failure due to sources running dry is more common than incorrect height measurements.
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Dear Samuel,
Within
Wateraid,
WaterAid,
I am not aware of anybody using this. Even outside
Wateraid,
WaterAid,
I doubt the usefulness, as most of the public available DEM have poor resolution (e.g. grid of
1x1km).
GPS are much more commonly used. The normal ones are notoriously inaccurate in the third dimension
(height),
(height)
but more sophisticated have barometers. If these are used properly, these can be sufficiently
reliable for preliminary surveys.
However, to
accurate
accurately
calculate pipes needed, breakage tanks, bending of pipes
etc,
etc.,
nothing beats a theodolite and if the investment is considerable, a theodolite should be used.
On another note: at least as important is to monitor the source over at least a full year (preferably much longer) to be certain that there is enough water also during the dry season. Failure due to sources running dry is more common than incorrect height measurements.
Arjen