Floods are one of the most dangerous kinds of natural disasters in world. Just in the United States, where we have early warnings and infrastructure to evacuate, 116 people were killed in floods in 2017. The problem is much worse in places where flooding is more common, and where early warning systems are lacking. In 2000, 347 Cambodians were killed in floods, and the total population of Cambodia is only about 1/20th of the United States. Now, a low-cost device for detecting floods and warning residents is saving lives.
The project, called Tepmachcha, was developed by the American DAI Maker Lab and the Czech NGO (non-government organization) People in Need. Together, they created an open source kit that costs just $305 and can provide early flood warnings to the people who need them. The kits are built with an Arduino-compatible Seeeduino STalker v3.0 microcontroller development board, an Adafruit FONA 808 cellular breakout board, a Maxbotix sonar module, an XBee radio module, and a solar panel power system.
Once assembled, the Tepmachcha device can be hung from a line above a river or stream, and the sonar will detect when the water level rises. When it does, it notifies a central system operated by People in Need. They, in turn, send out IVR (interactive voice response) calls to people living in the affected area. Most people in Cambodia have cell phones and cell coverage is good, so reaching them isn’t an issue. But, those cell phones rarely support the native Khmer language — and many rural Cambodians can’t read — which necessitates the use of the IVR system. Currently, there are 16 deployed Tepmachcha devices, and the system has 72,000 subscribers.