Measuring Depth of water with lasers

[pseudoabdul]

I'm a bit confused as to what you want to measure as well.

If it is the water level at some static point (in a river, a well, lake etc) just driving a pole into the bottom and putting a scale on that would be the simplest solution by far.

If you want to measure water depth, such as from a boat so you can assure you'll not run into sandbanks and such, ultrasonic solutions are the industry standard, and work pretty well in murky water as well (but not always when the floor is really muddy so the transition between murky water and dilute mud is vague).

These things are available commercially for $100-ish (for the the display system and transducer in one package), fairly reliable and not that hard to install. Range is usually limited to something like 50 meters, but then again, if you need a depth of over 50 meters you don't generally care about $10.000 more or less on equipment to secure your vessel worth millions not running aground

There are deep holes, some filled with a bit of water. I need to find out the depth to the bottom of the hole, not just to the top of the water. Cost isn't really an issue. Could maybe go up to $1000. How they do it with aircraft is short pulses, I'm looking for something like that.

 

[Radim]

Well, this is complicated. Maybe info might be found here:
https://www.ngdc.noaa.gov/mgg/announcements/announce_predict.html

You might try to combine ultrasonic (for water depth) and laser (for depth without water). You just need to get ultrasonic sensor there on rope or better with drone (much faster and convenient). Not sure if that is fast enough for you. I do not think you would find device up to 1k bucks able to do what you wish.

 

[dden4012]

There are deep holes, some filled with a bit of water. I need to find out the depth to the bottom of the hole, not just to the top of the water. Cost isn't really an issue. Could maybe go up to $1000. How they do it with aircraft is short pulses, I'm looking for something like that.

Hundred or two hundred foot cloth tape and a weight secured to the end, piece of rebar and some zip ties or duct tape.

 

[Cyparagon]

You might try to combine ultrasonic (for water depth)

The word you're looking for is SONAR.

 

[Radim]

The word you're looking for is SONAR.

I know, since I used it many times over many many years. Still just ultrasonic depth meter is enough.

 

[Encap]

Hundred or two hundred foot cloth tape and a weight secured to the end, piece of rebar and some zip ties or duct tape.

Exactly or a 5lb diving weight on an appropriate length of rope--many ways to do--easily

 

[lasersbee]

There are deep holes, some filled with a bit of water. I need to find out the depth to the bottom of the hole, not just to the top of the water. Cost isn't really an issue. Could maybe go up to $1000.

How deep ???
Range of hole diameters ???

To date the simplest method is a flexible graduated
cable with a weight to sink it to the bottom of a
hole. I subscribe to the KISS way of doing things.

Jerry

 

[Radim]

How deep ???
Range of hole diameters ???

To date the simplest method is a flexible graduated
cable with a weight to sink it to the bottom of a
hole. I subscribe to the KISS way of doing things.

Jerry

This is the easiest way, how even on old sailing ships it was done. In addition they took a sample of bottom material to see if it is suitable to anchor. For OP it might not be usable due to sloped profile of hole - some construction might be needed to move measuring rope to desired position (it is therefore not quick as required). I suggested drone carrying measuring aparatus (laser and ultrasonic depth meter) to access measuring spots easily and fast. Two measurment only are needed - one for air part, one for water part.

 

[lasersbee]

What actually does he want to know ???
1) The total depth of a hole from the surface ??
2) The distance from the surface of the hole
to the water surface ??
3) The distance from the Water Serface to the
bottom of the hole ??
4) are the hole vertical or slanted ??

It is not really clear as to what he is looking for
or what type and sizes of holes he is talking about.

Jerry

 

[Radim]

Jerry, I think you are right - these questions should be answered first by OP. Without more precise description of task to be done, we cannot find out working and easiest solution for him. Even it is fun to think about how we would do it, it might not be helpful as we do not know enough about the problem to be solved. Even some photos and drawings of holes as examples would be nice to imagine what we are trying to approach.

BTW: OP already stated he wants total depth of hole, which is partially flooded by water (sometimes dirty). Even there was some 10 m (hole diameter or air part depth?) and 1 m of water in it. Cost even 1K USD is ok. But still this input is not sufficient to find complex solution. Even I do not think my proposal with drone will fit the budget to be reliable enough.

As my teacher of programming (or statistics?) during my university studies at mathematical-physics faculty said: Garbage in, garbage out.

The task might be even that complicated like measuring depth of abyss not far from my home (none solutions posted above would work here - underwater robots are needed):

https://m.phys.org/news/2016-09-explorer-deepest-underwater-cave.html

 

[lasersbee]

Hmmmm...
I guess our questions were too much
to respond to...
No reply from the OP.

Jerry

 

[Radim]

Hmmmm...
I guess our questions were too much
to respond to...
No reply from the OP.

Jerry

True. It's a pitty we do not have some feedback from OP. At least how he solved it. Maybe email notification of a new post here will bring this to his attention...

 

[GillRios]

Hi...i have tested a LIDAR to detect the surface of water. It turned out the water needs to be dirty; i.e, there needs to be particles in the water which can reflect the laser beam of the LIDAR. For clear water, the laser beam went straight through.
If you want to test if your water will work with a LIDAR, you can guess it by using a small laser pointer. If you can see the laser dot on the surface of the water, there is a good chance LIDAR will work too.