It wasn’t what they came there to do, but a group of architects, designers and engineers that came to Kibera in Kenya last year have discovered a problem many Kenyans didn’t even knew was so serious. They could now end up saving millions of lives.

Between 500,000 and 1 million people likely live in Kibera – an informal settlement along the banks of the Nairobi River in Kenya’s capital. The river overflows twice a year, flooding the neighbouring sites and ruining the lives of the Kibera residents but, up until the Kounkuey Design Initiative (KDI) came there in 2015, no one knew that the river wasn’t the real reason so much was being destroyed. “It wasn’t something that we set out to deal with,” says executive director and co-founder Chelina Odbert. “Flooding really found us.”

From March to August 2015, KDI conducted lengthy interviews in 1,000 Kibera households, used cellphone mapping software to carefully gather data about past floods, documented local preparation and relief tactics, logged flood-related damages and deaths, captured locational photographs, uploaded information into geographic information system – GIS – software, and traced routes of hundreds of poorly placed drainage channels running through Kibera.

Analyzing the data, the KDI team discovered, to everyone’s surprise, that up to 50 percent of households at the top of Kibera experienced flooding during the rainy seasons —almost the same proportion as those living at the bottom, despite a 190-foot (58-meter) difference in elevation. “For us, it showed that flooding wasn’t just happening from the river, but it was also because of the major drainage channels coming down from the roads,” KDI volunteer engineer Anna Collins explains.

The team quickly recognized that Nairobi’s recent blitz of road construction, which greatly increased the amount of flat surfaces in the region but only included a few drainage channels funneling toward Kibera, was contributing to the flooding. “People assume that the flooding problem comes from the river, but to see how much of that comes from the drainage — this data brings to light so many problems that wouldn’t be intuitive,” Odbert says. He adds that the robust data sets and resulting detailed maps have allowed KDI to advocate for county-level flood prevention strategies by bolstering partnerships between KDI and Nairobi public works departments to identify inefficient drainage channels and determine practical solutions for flood prevention. “I think the reason there’s been so much success in working with the local government is because it’s clear that KDI has been able to provide information that [the local government] can’t,” Odbert says.

KDI is now partnering with local government and nonprofits to provide flood preparedness workshops for residents. Each workshop they do, the team says, reveals newer insights into the troubles facing the residents of Kibera, and provides newer solutions they didn’t think would’ve helped before.

Read more about this initiative here.