Lake Water Level AND Ice thickness, capacitive electrodes?

Hello,

I was originally looking to measure the water level in a lake in the summer, but I now realize the ability to also detect ice and the ice thickness in the winter will also be incredible useful.

I suppose ultrasonic is out, unless I placed one above water and one below water, but I don't think weatherproofing them will be reliable and waterproof units are too expensive.

I read it was possible to detect the difference in capacitance between ice, water, and air using an electrode. furthermore, by using MANY electrodes you can detect the level of the water and ice. However, the document I read had what seemed like a overly complicated setup and did not provide pictures.

Assuming an arduino connected to an electrode can detect the difference between water, air, and ice (I am going to try it on a small scale), I am more interested on advice for how to construct such a probe with a range of about 1 yard/meter. It will have many electrodes, and will be in the water year-round. The area is protected from the elements, but the structure is not heated. I am ok with replacing it every few years if needed.

For a basic proof of concept, I was thinking a small PVC pipe for the main structure of the probe, ignoring the fact that the ice may crush it. Every inch along the pipe, 1/2" wide metal hose clamps would be evenly spaced to serve as electrodes. The wires would run down the inside of the pipe and connect to each clamp through a small hole near each clamp. Finally, I could try and then fill the pipe when completed with concrete to counteract the expanding ice.

I need the probe to detect water level in the summer, the presence of frozen water on the surface, and the thickness of the ice.

Any help would be appreciated!

Thanks -Mike

This is an CapacitiveSensor library for the Arduino.
http://playground.arduino.cc/Main/CapacitiveSensor
I don't know if the Arduino will result into good accuracy to detect ice.
There are also special chips for capacitive sensing.

I think that hose clamps are too small for capacitive sensing.
Perhaps a PVC pipe with copper foil attached to it. Seal the outside with another PVC pipe or strong lacker or something like that.
Or pieces of a metal tube stacked on top of each other with some isolated spacer (for example ms-polymer sealant) between them. That would result in something very strong.

What if twigs and dirt gather around the pipe ?

My first thought was a row of ultrasonic sensors or sonar, waterproof of course.

At least measure also the temperature of the water. Perhaps a row of DS18B20. If the top part is freezing a lot (cold wind) and the lower part freezing a little (water), there could be ice :wink:

You might find This document. Quite interesting.

Could make an interesting project.

I’m interested in doing the same thing. I live on the Great Sacandaga Lake, and have built a very simple web page which can be bookmarked on a smartphone which provides the current conditions and some lake level information.

During the summer I have a probe which constantly reports the water temperature, but I would love to be able to report the ice thickness for winter.

I found this old thread which was not very encouraging: http://forum.arduino.cc/index.php?topic=137901.0

It seems like ultrasonic pulse is a dead end?

My original idea was based on the fact that water should be a different temperature than ice. I was thinking I could mount a water proof temperature probe every inch on a stick and then determine the ice thickness by finding the section that is colder than 32 degrees, but I do not know if this would actually work. The probes would all have to be perfectly calibrated and have high sensitivity, and this doesn’t take into consideration what the sun will do to the readings.