Implementing a LoRAWAN Water Stock Monitoring System in South Africa

TheThings Network

The Things Network Global Team

Posted on 18-09-2020

The Kololo Game Reserve is located near Vaalwater, Limpopo. Because of its location in a rural area, the reserve requires its own water source.

Kololo’s water system consists of three stages: a water well, eight accumulating tanks, and a distribution system of pipes and hoses. The water from the 100m well is pumped over 1 km into the eight 5000ℓ tanks located on a hill. From here, the water is distributed downhill, via gravity, to the lodges.

Measuring levels

Measuring the water levels in both the well and the tanks is important to determine water availability. To assist in this regard, KELLER installed a complete level measurement system in one of the tanks in February 2020. As all eight tanks are connected, the level measured is representative of the level in all the tanks.

Keller LoRa Scheme with The Things Network
Keller LoRa Scheme using The Things Network

Due to Kololo’s size, a wireless IoT (internet of things) solution was needed. However, the reserve’s rural location meant minimal cellular coverage. The chosen solution, therefore, communicates wirelessly via a LoRa (long-range) network.

A typical local LoRa network consists of three basic elements:
1. A digital sensor or gauge
2. A LoRa transmitter
3. A LoRa gateway – the receiver, which is connected to the internet by Ethernet or Wi-Fi.

In the case of Kololo, the LoRa gateway is a Laird Sentrius gateway, and the LoRa transmitters are KELLER’s own ADT1 LoRa modem. A KELLER Series 36XW digital level sensor is connected to the modem, measuring pressure and temperature. The ADT1 retrieves the data from the level sensor and transmits it, together with barometric pressure and air temperature, to the LoRa gateway.

The Things Network’s LoRaWAN Network Server then enables the connectivity, management and monitoring of devices and gateways, and forwards the data to KELLER’s Kolibri Cloud where it is stored.

"Thanks to The Things Network, we were able to create our own wireless micro network in an extremely remote area where no other radio signal such as 3G/4G or other was available", Martijn Smit - Keller.

Data can be viewed in the Kolibri Cloud web app, with additional features including exporting and printing of data, converting data to other units or even tank content calculations, among others.

Scheme of Keller's solution
Scheme of Keller's solution

Installation

Installation and set-up took some time, as it required finding precisely the right transmitting power, without overpowering. Given the location, it would be difficult to return to change batteries, for example. After installation and set-up, the system started measuring every hour. A day later, the data showed a downward sloping chart. Inspection of the difference between two measurements during the night showed a difference of approximately 100ℓ/hour. A leak was the only possible cause. An inspection found that one of the pipe threads was partly pulled out of junction in one of the tanks, causing leakage. Thus, the system proved itself after just one day. Consideration is now being given to extending the system with a KELLER Series 26X digital level sensor for the borehole, in order to monitor basic water stock.

Keller stores the water in eight tanks
Keller stores the water in eight tanks

Kololo’s electricity system

Although Kololo is connected to an electricity network, it has a diesel generator for back-up power. The diesel tanks run the risk of water ingress during refilling. There is also the risk of diesel being stolen, and oftentimes thieves will fill the tanks with water to compensate. For a diesel generator, this can be catastrophic as water in an engine will cause major damage with high repair costs. As a LoRa system cannot measure faster than once every 15 minutes, detecting a change of the diesel level with just a level sensor might not always work if the level is compensated with water to the old level. However, based on conductivity it is possible to detect a change in the mixture. Water is heavier than diesel and has a different conductivity. The change in conductivity therefore represents the presence of water in the diesel tank. Kololo, therefore, opted to install a KELLER Series 36XiW-CTD. This is a digital, combined level and conductivity sensor.

Testing LoRa reception at the measurement spot
Testing LoRa reception at the measurement spot

Conclusion

A level measurement system provides actual data about fluid levels. By storing this data and building up a history, enormous statistical insight can be gained into the consumption and/or malfunctioning of the system. Thus, it can lead to great savings or prevent unnecessary repairs and non-revenue problems. This system can be applied in all fluid level measurements across a variety of industries – game reserves, boreholes, agriculture, petrochemical and many more. Every KELLER sensor with a digital output can be applied in IoT applications.

Want to build your own long-range, low-power IoT solutions? Turn your idea into reality with The Things Network