[neilh20]

Hi Ben
Thanks for posting and the links. Fascinating and thanks for the status.
I was wondering, does the “Distance sensor” have a memory, can it report all readings if the gateway goes down for a couple of days.
I was wondering is there a schematic of the “Distance sensor ” https://github.com/OxFloodNet – I couldn’t find it to ask the above question 🙂
Neil

[neilh20]

Sensors for continuous monitoring are challenging, see this for nutrients

Nutrient Sensor Challenge aims to coax market for next generation instruments

which is an EPA initiate to develop real-time sensors under $8K!!
http://www.epa.gov/innovation/examples-epa-prize-competitions
On the other end of the spectrum for low key community orientated “learning” projects
https://publiclab.org/wiki/open-water
My 2cents for reclaimed water is to look first at your local jurisdiction legal requirements you need to meet, then break it into components. Practically speaking its dependent on the source of the reclaimed water, and what your base load of pollutants might be
1) for volume of irrigation water it may be relatively easy to sense
2) for other nutrients you may start with determining best practices, manual sampling, and on to continuous monitoring.
I don’t think there is a one solution fits all easy answer.

[neilh20]

Hi All
I was visiting the ArmTechCon/Santa Clara last week and a friend was on the ARM stand showing their CalPoly university project.
It had the basic same concept – using ultra-sonic to measure the depth of trash in a street side trash can, and then with a map displaying potentially multiple locations of monitored trash cans.
I asked if they would be OK if it was posted on this board, and he updated the links for it. The actual CalPoly project description seems to have expired.

The hardware they used was
https://developer.mbed.org/platforms/u-blox-C027/

Corey says:

Feel free to share the code if you think others would find it useful.
I’ve just published the latest to:
https://developer.mbed.org/teams/Garbage-Collectors/code/SLOTrashHTTP/
https://github.com/coyotebush/trash-map

It uses Flask, and a previous quote about this was

Flask was nice for handling the HTTP bits of the server. I’ve used it in other projects before and found it straightforward. Fairly popular in
the Python community, I think, as an alternative to larger application
frameworks like Django.

So while the project should be considered a “prototype” the components might be useful.

[neilh20]

Hey kevin, great to see a sketch.
Some thoughts
1) I would ensure a standard measuring tape on the outside of the tube – make it easy for any site visits by anybody the waterdepth and time of measurement can be recorded and used to validate/calibrate that electronic measurements
2) I personally have no experience with the ultrasonic transducer method – so I would think you want to be pretty clear that it works, and also to define what accuracy of measurement you are looking for. A simple way is to make the equipment and then leave it with a known stable water column for a couple of weeks. Possibly even allow water to evaporate and verify the readings as the water drops.
3) Might be better to move the senors at the bottom into their own protective shielded pipe so that if they ever need maintenance you don’t risk moving the pipe with the water column in it.
4)I would think for your flood location, you want to be aware of the velocity of the water and whether or not the top of your standpipe needs tying into the bank. A visual examination of local conditions for a low velocity location is always best.
Here is a link with some pictures of people installing a pipe in tidal marsh area.
http://tidalmarshmonitoring.org/monitoring-methods-hydrology-continuous-water-level.php
Usually with any electronic sensor the quality of the recordings – errors is the most challenging. Be great if you report on what you find if you do any managed “soak” testing.
Good luck

[neilh20]

Wow thanks for the details. Great to see the Sodaq Mbili/GprsBee and hear its good piece of equipment.
When it comes to attaching in the stream be, depends on stream conditions, soil type and vegetation. In the US concrete in the stream channel probably would require a permit – but I’ve seen hydrologist working for the NOAA that will pound a stake into the stream bed, tie it into roots if available. These have been for pressure sensor based equipment. The attached picture is in a channel with the stake pounded into the bed and then a secondary stake tying it into the top of the bank. This was installed in 2007 and flooded to bank height in 2008.

Attachments:

1. 

   LDSR-LCC46-01b-small.jpg
   

2. 

   080104-0940-LCC46standpipe800x600.jpg
   

[neilh20]

Hi Rene
Thanks for the reference on the FDC1004 – there is an App Report
http://www.ti.com/tool/tida-00317
Capacitive-Based Liquid Level Sensing Sensor Reference Design

I’ve attempted some custom PCB electrode for measuring water depth. The discussion is excellent. The challenge is field calibration – if looking for a 0-1m (for example) change – how to know when installing in the field and measuring capacitance, that the specific numbers being measured represent 1m of length.
The reference electrode design is a bit un-wieldy – but useful for discussion and experimentation.
The holy grail is a simple wire.
I found some unusual properties of the capacitive field.
I had the Aquaplumb in a column (3″/8cm dia pipe) of water, and varied the height.
I got useful readings. However, even with a full pipe – the wire in a reasonably large volume of water, when I brought my hand (a relatively small volume of water) to about 10-30cm away, it did cause an effect on the reading. The only explanation I had was there was a really extended field effect, but something really interesting.

From the reference design idea – perhaps some aluminium (or copper) tape could be used.

[neilh20]

Hi Rene
Yes the Aquaplumb is capacitve sensor based, tried it and tested it.
Then I took the basics and applied them to the Teensy-LC which has capacitive inputs and tried the same on that.
So I was interested in what your results are – the capacitive water depth measurement does produce numbers … so it worked but I came across some issues with calibration …..
I tried solving the calibration issues by generating three capacitive depth sensors in parallel, but finishing at different heights – with the idea of detecting when the water level exceeded one capacitive sensor it would indicate one known height was exceeded and could be used to calibrated the other heights.
So I was interested to see what you came up with. 🙂

The issue is I’m looking for a tight specification of changes in water depth over 24hours – monitoring the hydrograph over a diuranal cycle.
Easy/low cost simple Measurement traceability – managing/verifying no sensor drift – is also a requirement

[neilh20]

Rene, I got the bare bones Aqua Plumb when they kickstarted it:
http://www.vegetronix.com/Products/AquaPlumb/
They filed off all the numbers on the chips, so not clear how they are doing it.
Be interested to hear how you got on and compare notes.

[neilh20]

Hey interesting thread here.
Seems like a lot of people have some great ideas on this. My 2cents is its a really difficult area – specifically for what Rene has pointed out – the quiescent current.
Unfortunately Arduino does not cultivate a low power paradigm – Arduino core has said dealing with low power event based software is too difficult, but PRJC.com is a step beyond the core.

I’ve got a solution for stream monitoring that I’m working up –
http://www.meetup.com/Nerds-For-Nature/photos/26131259/#437612397 which I talked about at this years San Mateo Maker’s faire – see the poster to the left of guy/me – “Wireless Stream Sensor Road Map”

For anybody who is interested in a working on a Specific Conductance probe I created this as a starter.
https://makerspace.com/projects/specific-conductance-probe
The electrodes could be titanium – the challenge is how to plan to clean the electrodes of the ever prevalent slime build up.

Some instruments have a wiper, but I haven’t figure out how to easly do this.
Slime is often watershed dependent but a physical cleaning seems to be the most obvious solution.
http://priede.bf.lu.lv/grozs/HidroBiologjijas/FieldGuideAquaticPhenomena.pdf
http://www.gov.pe.ca/environment/whats-in-the-water

I could produce some hardware using the Teensy-LC to aid in prototyping if anybody is interested.

What is taking most of my time right now is a low-cost water depth probe, with a place holder here
https://makerspace.com/projects/water-depth-sensor-gauge-wireless-solar-powered-for-remote-streams
which can run by itself data collecting, or plug in to a low cost
Wireless Sensor Network
It uses a basic processor, Teensy-LC
low power MKL26Z with LiFePO4 battery, solar charging and RS485/SDI12 –
initially with a water depth measurements,
and can fit into a 2″ PVC pipe for protection and sealing in a stream.
There is a few places discussing this … so I’m wondering whats a good way of promoting the evolution of specifications for instruments.

with plug’n’play – it will fit into a 3″ plastic pipe for easy protection, solar powered/LiFePo4 and based on a Kinetis Arm (similar to the Teensy3.1 but because of hardware port limitations actually another processor with 128Kram)

So the challenges can be broken into smaller challenges – then they can be solved one-at-a-time.
I wonder if anyone is trying the Teensy3.1/TeensyLC (with Freescale ARM M0 processors) ~ solidly Arduino in a workable footprint.
See also
https://forum.pjrc.com/threads/23660-Low-Power-quot-Green-quot-Battery-Operation-Solutions-For-The-Teensy-3
http://publiclab.org/notes/donblair/08-25-2015/turbidity-001#c12460
http://publiclab.org/notes/neilh20/07-22-2014/water-quality-instrumentation-quality-gottchas

[neilh20]

Hi Dave
Sounds like you have a good idea of what you want to do and the technologies, but to start with the basics.
1) I’d suggest a plan with cost options including what ever time its going to cost in time billing. If there is team install project time with two people per visit for safety and x hours traveling time – the costing analysis changes. If you expect to visit the site regularly and can absorb the wireless network planning then it is a different cost structure.
2) First is to identify locations on the ground (sorry sounds basic but sometimes this step gets missed) and the wireless telemetry options.
2) a cellular radio-site survey – probably first on paper, and then if there is the possibilty of a specific cell carrier to organize having that carriers cell phones and then investigate the site options for actual radio signal.
3) if there is a local building with internet then you could consider a point-to-point system. For a local internet need to investigate how to access that network – sometimes it is easy (eg School, sympathetic property owner) other times the network owner (eg County Water Agency) is challenging to get to the right person and permission to install at top of building. Then need to map the Line of Sight for the radio waves – in valleys its tricky.

One narrow valley I installed in – the property owner knew where there was a narrow alley for Verizon Cellphone – its where he could get his Cellphone to work. And we installed a Verizon system in that alley – which was very unique as almost nobody uses Verizon CDMA systems

Regards

[Author]

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