Car Wipers Used to Measure Rainfall, Improve Flood Prediction and Prevention

Car windshield wipers could help scientists gain a better read on rainfall distribution, leading to better flood prediction and prevention, among other things.

Led by German scientists, the initiative is designed around GPS-equipped cars known as "RainCars," which the researchers hope to use as a complement to the nation's sparsely distributed rain gauges.

"If moving cars could be used to measure rainfall the network density could be improved dramatically," project-leader Uwe Haberlandt of the University of Hannover said in a statement.

In order to test their idea, the scientists placed cars with different wiper systems under a rain machine that could be adjusted to simulate everything from a drizzle to a downpour.

The first experiment included a person manually adjusting the wiper speed based on windshield visibility. This proved to be relatively unreliable, however. The second experiment, in contrast, relied on optical sensors found in many of today's cars in order to automate the wipers based on the amount of rainfall. This option proved to be the most accurate.

"The optical sensors measure the rain on the windshield in a more direct and continuous manner so, currently, they would be the better choice for rain sensors in cars," Haberlandt said.

The researchers then tested the effects of car movement on the rainfall measurements by placing the sensors on a rotating device designed to simulate car speed under the rain simulator.

Still, the scientists admit there are still other variables that could affect their measurements, including wind, spray from other cars or protection from trees or other objects.

According to Haberlandt, "the value of using moving cars to measure rainfall is not about a higher accuracy of rainfall measurements but about a much higher number of measurement points."

Already the team is working to apply the technology in Hanover where cars are being used to measure the rainfall there.

"There are some volunteers, a taxi company and a car company involved in the field experiments. We certainly would like to have some more people engaged."

The study was published in the open access journal of the European Geosciences Union.