Risks and hazards

Forecasting rain more accurately using telephones


The Rain Cell, or Rain Measurement from Cellular phone networks, project is based on an innovative, ‘green’ concept to address climate and social issues by measuring rainfall and anticipating the risks of a flood or drought, making use of the mobile telephone networks.

The method uses a simple idea: rain attenuates the signals sent out across the network from one antenna to another. These fluctuations can be measured to determine precipitation at any point in the network, potentially in real time. The advantage lies in making use of a quality infrastructure, set up and maintained by the telephone operators.

The principle has been studied since the 2000s by teams of Dutch, Israeli, French and German researchers but had never been tested in a tropical zone. Yet it is in countries in the Global South that the method would be the most valuable, in that the ground measurement networks are insufficient and that hydro-climatic risks are constantly rising, especially in the fast-growing metropolitan centres.

Working with operator Telecel Faso, a pilot site was set up to validate quantitative rainfall estimates using microwave links over the mobile phone networks for the first time in Africa.
The results of the Rain Cell concept validation process in Ouagadougou, through comparison with rain gauges and the Xport radar, demonstrate that detection (95% success rate) and quantification (global bias under 10%) of rain using operational microwave links are excellent. The data provided by Telecel Faso can be used to measure rainfall at time intervals of just 5 minutes. At this very fine scale, consistency with radar information is very good.

On the back of this success, the project led to an international workshop from 30 March to 2 April 2015, bringing together 90 participants from 18 countries, including many of IRD’s partners in West Africa and several international organisations. 

Converting the try

Applied to an entire telephone network, the method would provide high-resolution rainfall maps in real time at city, country or watershed level.
There are plenty of potential applications:

Africa offers enormous potential for developing the method at regional scale and making the concept operational. However, other regions of the world could benefit from these developments and potential partners have already come forward in Asia and South America

To develop Rain Cell applications and make the most of the concept, partnerships need to be formed between telephone operators, R&D teams and users. This is something that the IRD teams and their partners intend to work on in the future.