Elephant breach of electric fence monitoring system
Pilot project at the Bandipur national park
Solar or other cable based fences are widely used in the prevention of human elephant conflict, but they are often subject to damage by elephants as you can see in the above video. While it is difficult to prevent elephants from attempting to break the fence, it is entirely possible to monitor the fence status remotely, and get an immediate warning whenever a fence breach is in progress. In such a case, sensors placed on the fence’s pole can sense when there is pushing, shaking or bending of the pole. This information is used to send an alert with long range wireless communication. When an alert is received by the Forest Department, quick response teams can be sent to chase back the elephant and repair the fence before it gets breached further. We propose a low cost scalable early warning system placed on fences around the human settlements in the regions affected by HEC. The tech being developed is completely open source, which means anyone can take the designs, modify if necessary and replicate for their area. We successfully conducted an initial field test of this technology in the Bandipur Tiger Reserve and will be implementing a pilot project of installing our sensors for more than 2 km at the same location. This work was supported by IUCN as part of the European Union funded CITES-MIKE project “Asia Wildlife Law Enforcement and Demand Management Project: MIKE Programme Sub-regional Support in South Asia and Southeast Asia”.
Tech Overview
In this project sensor nodes are placed securely on the poles of the solar electric fences around forest reserves as you can see in the image above. These sensors send a signal whenever the pole’s angle with respect to the ground is changed significantly. This can be due to animals pushing at and trying to cross the fence, or similar behavior by people trying to vandalize it. The signal that is sent when this happens can alert the authorities of this, and a quick response can be made. All the sensors in the radius of 2–3 multiple km send a warning wirelessly to a gateway on a tower using narrow-band communication. The gateway then forwards this information over to a central server using the mobile network. The authorized stakeholders can then receive a notification of the location of the source of the alert over SMS and a cross platform mobile app. Additionally, they can view the log of alerts and the current status on this mobile app. The image below illustrates this.
For in depth details of the open source tech being used please visit docs.appiko.org/fence-monitor
Field Testing
As mentioned earlier, the deployment for this project would be done at the Bandipur Tiger reserve. We visited the Tiger reserve with the intention of ascertaining from the forest department an ideal location for this pilot project and conducting the test of our sensor prototypes at this location to check for their performance.
The forest department officials suggested installing the fence tilt sensors on the electric fence that is present about 1 km (line of sight) from the premises of the Bandipur offices (base station). This electric fence protects saplings of trees that the forest department grows and is routinely encroached by elephants.
Location scouting
The location of the electric fence is shown approximately with the blue markers on the map below.
The length of the fence is a bit more than 2 km with poles steel poles holding up the electric wire present every 5–6 m. Right before our visit some poles were damaged by elephants and can be seen in the images below.
We installed our two of our sensors on two points marked 1 and 2 in the maps above. They were installed at a bent angle so that they kept sending the alert signal.
We kept track of the communication from these two units all the way to the base station. Here on the ground we were able to reliably get packets from the sensor at location 2 but unreliably from sensor at location 1. This can be seen in the -107 dBm signal received from the car at the base station.
We then tested the communication from the top of an unused tower next to the post office, which is the green marker on the map. From a vantage point at the height of about 16 m, we were able to reliably get packets from both the sensors. The signal strength was about -95 to -100 dBm from both the sensors, which means we have about 20 dBm link budget left. This tower can house the gateway and the building next to it can provide the intermittent mains power supply and house the battery. In the images below you can see Prithvi near the top of the tower and the view from the tower.
Also there is a BSNL network tower within the base camp to provide mobile connectivity to the gateway. With this we demonstrated that Appiko’s technology is working reliably in the field for the particular electric fence of forest department’s interest. Going ahead we plan to deploy around 150 sensors on this electric fence surrounding the forest department’s plantation.
