"Open design of a fixed probe for water quality monitoring in rivers and lakes" is the bachelor project of an EPFL student, Nils Bonfils, which is done within the Biodesign project and supervised by Robin Scheibler.
The aim of this project is to set up a prototype measurement station in the Sorge (a small river near the EPFL) to collect some data about the water and the environmental conditions. And also make the work reproducible so that someone, somewhere else could also build one to collect data about a specific river or lake. That's why there also is a GitHub for the project, where there are guidlines on how to build your own, these guidlines where made based on my own experience of building such a device.
The data collected is for my prototype restrained to the temperature of the water, the turbidity of the water, the ambient temperature, the barometric pressure and taking a photo of the water. One could easily imagine that can be extended to collect more data related to pollution of the water like the conductivity or pH. But it's for simplicity sake and to get a prototype working until the due date that there are only 5 different type of data collect (which seems enough for a prototype). And one must not forget that this project is started from scratch !
What is this project useful for ?
For now, basically nothing really interresting, but as mentioned in the intro, it's a prototype and the application of such a device are potentially interresting, like extending the work and change or add more sensors to collect data related to other parameters that are useful for you. Also this could be nice in some countries where governements aren't willing to spend money in water monitoring, and you don't need to spend 10'000$ to get a proffesional probe like the ones the used in the State of Geneva (Nils had the chance to meet Stephane Odriozola who works there, see his post on the Biodesign blog), maybe a scientific team could build few of those probe and check in some rivers if the water is polluted and/or dirty.
This project is the frame of something that could become really improved if peoples contribute to it, also this project is part of of the Biodesign project which for now the "main" project is to detect Arsenic in water with a bacteria, and the collecting system has to be manually done, it could be interesting to automate it by maybe integrating these kind of measurments in a more advanced version of such a probe.
Developpement from scratch
This project starts from scratch meaning that at first there was just an idea. The idea of this emerged between Sachiko, Robin and Nils, at first Robin and Sachiko presented the Biodesign project to Nils and they came to the idea that, as the collecting of sample for the bacteria measurements is not highly developped as well as the recording of the data, it would be interresting to automate some part of it.
So the came idea of having some kind of probe on the field that would do the measurements and sending data through internet, but as for the bacteria there are specific protocols and other things, it was more reasonable to start with measurements that are easier to make, like the temperature of the water (etc... ). So that's where the idea of such a probe came from.
"Open design of a fixed probe for water quality monitoring in rivers and lakes" is the bachelor project of an EPFL student Nils Bonfils which is done within the Biodesign project and supervised by Robin Scheibler. The goal is to set a fixed measurement station on Sorge river at EPFL. It will collect different water-related and environment-related data and then send them through the internet to a server to be stored there, and then maybe displayed with a web interface. The core of the station is a raspberry pi that will be used to interface with the different components like the temperature probe. The advantages of using raspberry pi in such project is firstly its low power consumption (roughly 2 to 3 W  ). The there are other advantages like easy backup storage and internet connexion through USB (like usb dongle for 3g/4g) and there also is an ease of use with the ssh connexion which provide a direct inteface to acces the raspberry pi, update the code, etc...
These are the parameters that will be mesured by the station. Rpi GPIO
- Turbidity of water -> adc hook up for reading from sensor - python code to read from adc - need to add a 10k resistor from data to gnd
- Photo of the water -> arduino camera
- Barometric pressure -> Used Sensor (BMP180) Datasheet of the sensor BMP180 circuit hook up BMP python lib
- Temperature of the air + water (available at hackuarium) -> waterproof sensor(DS18B20) - useful python library (needed to change /boot/config.txt though) - ada fruit DS18B circuit hook up (the resistor is 4.7 or 10k Ohms)
These are parameters related to the project that will not be measured for simplicity sake, but it could be interresting to have them on an upgrade of the project (bigger station, needs to measure other things).
Tutorial to connect ADC to raspberry pi 
- SD card shield
- GSM shield -> sparkfun - ebay - arduino official
- GSM click -> octanis wiki - useful command sequence - some doc on at commands - configure serial on RPi - Set CTS pin HIGH and RTS pin LOW to get proper communication
Battery and power management
- RPi shield that can schedule shutdown and wakeup Witty Pi
- Power management: LiPo Rider from SeeedStudio (at hackuarium) wiki page
- Laboratory of ecohydrology at EPFL has a project for herbicide monitoring in the Chamberonne catchment where meteorological and flow data are available.
- Flood monitor in the Flood Network.