measuring river depth

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Graham Eddy

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Aug 22, 2020, 11:30:58 AM8/22/20
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i measure river depth using an off-the-shelf product - the hardware is usable but i replaced the windoze app by writing a simple weewx service. a differential pressure sensor has RF connection to a controller (supports up to 8 sensors). the receiver passes a record of latest sensor values over serial interface every 5 secs or so and the weewx service picks them up

"Aquagauge Differential Pressure Water Level Sensor with Receiver /Display
this went off the market for a while but seems to be back on again

the pressure probe has been secured onto river bottom by the high-tech method of tying it to a brick and shoving it under a big tree root. it has a lead up to the transmitter box that contains batteries as power supply - they last about 6 months. the receiver/controller needs external power and serial connection to computer (i use serial/usb dongle).
handy hint: put the transmitter higher than flood level. i didn’t and my first transmitter was shorted :-( weather-proof is not water-proof

writing the weewx service was quite straightfoward. it has a thread that reads/parses records and queues the values (up to 8 sensors, remember) so that the next LOOP callback by weewx engine inserts them into the packet. the service is configured to map each sensor to a weewx data_type and unit

service implementation: see https://github.com/g-eddy/weewx-aqua.
my configuration in weewx.conf is

[Aquagauge]
    port = /dev/aqua
    speed = 2400
    #open_attempts_max = 4
    #open_attempts_delay = 2
    #open_attempts_delay_long = 1800
    [[0]]
        data_type = riverLevel
        unit = mm
so it is providing data_type ‘riverLevel’ from raw numbers in mm
(i use udev to create the constant device file i want, rather than default /dev/ttyUSB0 or similar that can change)

in my weather station i am using a vantage pro2 with its driver, which produces LOOP records about every 2.7 seconds. the aquagauge controller provides records about every 5 secs, so something is waiting in the queue about every second LOOP record. but that’s okay because weewx accumulates the values for the duration of the reporting cycle and they end up summarised in the ARCHIVE record and saved to database

i am saving ‘riverLevel’ in a database column and running reports off it e.g. tag $day.riverLevel.max.
in extensions.py i have put ‘riverLevel’ in ‘group_length’, and in weewx.conf i have set ‘group_length = cm’ because i want graphs by default to report ‘riverLevel' in cm

weather list

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Aug 22, 2020, 8:21:40 PM8/22/20
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Graham,

I note that sensor transmits on 433 MHz. Could one just use an SDR receiver instead of passing through their own receiver box —> to computer?

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Graham Eddy

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Aug 23, 2020, 1:57:21 AM8/23/20
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you read my mind. i placed an order for an SDR-RTL dongle yesterday! no doubt i will share my pain in the forum...

Chris Alemany

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Aug 23, 2020, 5:37:40 PM8/23/20
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This is fantastic! I just installed a pond and stream in the front yard and would love to be able to monitor the depth of it. Could you provide a parts/supply list for the sensor, transmitter and receiver?

Cheers
Chris

Graham Eddy

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Aug 23, 2020, 11:56:03 PM8/23/20
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the hardware supplier i used is at https://www.electrosense.com.au. as i mentioned, they removed this specific product from sale for a while but it appears to be back again. the transmitter is pretty robust - if the case is full of water then giving it a shake, blow dry, some new batteries and a bit of a rest makes it comes good, but my other transmitter (flow meter sensor) didn't survive being submerged for a few weeks

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p q

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Aug 24, 2020, 12:15:41 AM8/24/20
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Why measure from the bottom of the body of water when you can measure from the top? Do you care how deep it is or where the top of the water is?



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Graham Eddy

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Aug 24, 2020, 2:37:00 AM8/24/20
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for me, both: fish and flood. fish also care about the river temp

i was waiting for ultrasonic to be raised. i didn’t pursue that option because i didn't want to build my own (eg arduino and a cheap sensor) and the commercially available ones here are either offline datalogger or hideously expensive (usually both). though i might have more options if i can use SDR to break into closed system wireless displays, of which there are plenty

vince

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Aug 24, 2020, 8:50:04 PM8/24/20
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On Sunday, August 23, 2020 at 2:37:40 PM UTC-7, Chris Alemany wrote:
This is fantastic! I just installed a pond and stream in the front yard and would love to be able to monitor the depth of it. Could you provide a parts/supply list for the sensor, transmitter and receiver?


Isn't this typically just done with a waterproof ds18b20 and a nodeMCU cheap arduino that has wifi ?   Heck you could set the arduino to deep sleep and only collect data every minute or three I think, couldn't you ?  That water temperature is not going to change much over time. 

Jason Harrop

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Sep 9, 2020, 7:33:40 PM9/9/20
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electrosense emailed back saying they no longer sell their Aquagauge.  lots of options for diy submerged pressure gauges though.

A problem with a submerged pressure gauge for me is that it might get washed away in a flood.  So I'm exploring ultrasonic and lidar.  Ultrasonic tends to have limited range, though https://www.maxbotix.com/Ultrasonic_Sensors/MB7066.htm claims 10m.   

weather list

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Sep 9, 2020, 7:57:59 PM9/9/20
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There is a Maxbotix extension already available for WeeWx.

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Jason Harrop

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Sep 20, 2020, 8:47:33 PM9/20/20
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Thanks for the heads up, definitely a point in its favour!
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