Oxford Flood Network

The Oxford Flood network is a project to monitor river and stream levels throughout the City of Oxford and to react to the changes in levels. The first part of the project involved the design and development of a reliable sensor that could operate outdoors in all weather while reliably measuring the level of the water. The method for measuring the water level that was chosen is ultrasonic, this was seen to be a method that would create a small, low cost and reliable sensor that would not need to be regularly maintained.

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The sensor has been through a number of iterations, the first prototype was the product of the first Sushack hackday held in Oxford in November 2013. This spent a short few weeks under a bridge before its batteries died. The second sensor included a custom designed PCB, high energy battery, single transducer ultrasonic sensor and temperature sensor. This was housed in a IP55 rated junction box attached to the steel bridge using magnets and a safety line to catch it if it got knocked from its position.

The sensor transmitted its readings at regular intervals to a Raspberry Pi running a Node-Red flow that pushed the data out to a number of cloud based systems to capture the data. This sensor was mostly successful, but being an indoor spec sensor it wasn’t reliable in damp conditions. The third iteration of the design went on to use a proper weatherproof ultrasonic sensor from the same manufacturer and was also a direct replacement. A few minor changes were also made to the PCB to aid building, addressing and testing the sensors.

At present a number of new sensors are being built and deployed across Oxford as part of a TV Whitespace trial being run by Love Hz.

The design files and firmware for the sensor has been made available for others to build their own sensors, with build instructions available here.

The latest version of the sensor is is a small enclosure with built in mounting points to make attachment to various locations easier.

 

 

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As part of the testing the sensors are subjected to freezing conditions in a domestic freezer with temperatures lower than -15C. The sensors are also put into a bowl of water to ensure there are no leaks in the enclosure itself and the holes that have been machined for the sensors.

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