6' Groundwater Level Meter

Hey all! Really excited to have discovered Arduino and am still trying to wrap my head around its potential uses. I am starting a directed study in school -- I am a biology student -- and I will be designing, building, programming, and installing a 6 foot tall (mostly buried), wireless groundwater meter at the UBC Farm.

I'd really love a bit of guidance regarding what products I might need as I know next to nothing about electronics or programming. That said, I am not looking to get spoon-fed! :) The project is still in its preliminary stages, but it looks as though the thing will be housed in a 4in (diameter) x 6' PVC pipe. The pipe will be buried, but its top will be accessible for maintenance and the electronics, etc.

It will be outdoors in a marshy area; it will need to read with an accuracy of approx. 5mm; it will measure a range of approx. 6 feet; it will relay data to a computer in the farm centre (about 150 meters away); it will be powered by a small solar panel. As one may imagine, the water won't be the cleanest. I'm not quite sure what kind of filtration we'll be able of putting together, but it definitely won't be the purest water. Temperature of the water may also fluctuate given outdoor temps, though it will likely only be used during the summer.

I've looked into different types of sensors: sonar and a capsense-type sensor stand out as the most useable given the aim of the project, but I'm really not all that sure. I'd be more than happy to provide further detail (!!), but the project is just starting so there may not be much more to say at this point :).

A push in the right direction would be great! For instance, I was perusing through the products section and have no idea what the difference is between all the Arduino products... I've only ever seen the starter kit!

Many thanks in advance! Super excited!

I have been reasonably successful measuring water level in a 100mm ABS tube using a parallax ping style sensor like this one: http://www.seeedstudio.com/depot/ultra-sonic-range-measurement-module-p-626.html http://www.parallax.com/product/28015

I would say that that accuracy is closer to +/- 15mm than the 2mm some models claim. There are dozens of versions of these things. I've seen them as cheap as $3 on ebay.

For a permanent installation in a humid/damp location, you might want to try a weatherproof sensor. Those will cost a bit more. There are tons to choose from. Here's a supplier for a range of options: http://www.robotshop.com/en/ultrasonic-range-finders.html

Thank you for the reply, Gardner!

These look great. I was thinking of ultrasonic, but wasn’t sure where to look. The more expensive weather-resistant ones appear to be very suitable for my application :slight_smile: Do you think that they’d work properly if inserted into a ±2" PVC pipe aimed downwards? The sensor will be ‘reading’ a sandy substrate (the bottom of the pit) or water.

Assuming that I can get a small solar panel and power storage set up, would it be preferable to power this device through the Arduino (if possible?) or via the battery, forwarding its data to the Arduino, a wifi shield, to a weather station.

I’ve got a final tomorrow so I can’t really immerse myself in the project quite yet, but will provide a clearer, more put-together description later on… once I’ve done considerably more work.

I originally got started after reading this: http://www.robotshop.com/media/files/PDF/water-level-with-the-ping-28015.pdf
They reported that a 50mm (2-inch) pipe resulted in limited range. I only needed 1,000 mm range or so, but I went with a 100mm pipe, mostly because that was available. My sensor is a seeed studio one that operates the same as the parallax ping.

The parts you’d need to have to just experiment a bit are pretty cheap. I would recommend buying a couple of the cheaper ones and just see how it all works.

In my application I run the sensor, an Arduino pro, a 433MHz radio and some other electronics from a 7Ah gel cell. It draws about 25mA on average, reading the water level every 15 secs or so.

For out doors use, you might want to confirm things will work consistently with the humidity and temperature extremes.

I ws playing around with an HC-SR04 (low cost ping sensor). I also ordered some waterproof 40KHz ultrasonic transducers.

I replaced one of the HC-SR04 transducers with one of the waterproof ones, and it works fine at short range. I only needed a short range (about 30 cm), so I didn't try any distance tests.

The waterproof transducers can be found on eBay with the search "10MM 40KHZ Waterproof Ultrasonic Sensor" (without the quotes).

They can be had for as little as $2.30 or so each, if you buy 10, or about $3.50 each if you buy 2.

It's worth experimenting.

Was anyone else able to replace transducers with waterproof ones like lar3ry ?

5 year old thread ?

That just proves the sensor is evergreen :)

Actually, I searched a bit but all other links such as below said replacing transducers wont work, so wanted to know if anyone really accomplished the task of replacing transducers?

https://forum.arduino.cc/index.php?topic=349192.0

https://forum.arduino.cc/index.php?topic=404646.0

https://forum.arduino.cc/index.php?topic=252162.0

https://forum.arduino.cc/index.php?topic=337938.0

you have 3 choices.
#1) buy the waterproof with driver board designed for that sensor
#2) swap sensors and get results, please post results
#3) get just the sensor and build your own driver board

cjiaac2c: Was anyone else able to replace transducers with waterproof ones like lar3ry ?

Yes. My original setup with the parallax ping style sensor failed due to humidity and consequent corrosion on the sensor board.

I thought I could directly substitute a JSN-SR04T, and while it worked initially, I found that this sensor is very sensitive to condensation on the front surface of the sensor. In order to get reliable readings from it, I had to eliminate the tube to allow free air circulation and limit condensation on the sensor. I then had to build a short cone around the sensor in order to provide enough directionality to avoid reading other fittings inside the tank.

The diameter of the tube has a major effect on the max distance as well as junk on the inside of the tube, probably a way to clean the inside of the tube will be needed. Maybe have a tube inside a tube so the inner sensor tube can be pulled out and cleaned and easily replaced.

A bubbler could also be used, a small tube submerged to the bottom of the pipe, air from a small pump to force all the air out of the small tube - LOW air flow then read the air pressure and the water height can be calculated. NOAA uses this method for some of their tide height measurements.

Do NOT buy the JSN SR04T sensor since it has many reliability and accuracy problems.

See this video where 1000s of others are facing the same issue

https://www.youtube.com/watch?v=N42Y-QOqwtA

I bought that sensor and made a big mistake.

After searching for a better sensor

I found this sensor

https://www.ebay.com/itm/253978673298

It has 2 transducers instead of 1 and there fore has a smaller minimum distance as compared to JSN SR04T.

It is also sealed from all sides making it fully waterproof.