With more and more people moving to cities, informal settlements are expected to grow. When floods hit these unplanned places, it can be disastrous, as we often don’t know much about them. Crucial questions often remain difficult to answer, like how many people live there, what are the buildings made of, and could they withstand a flood?

In the township of Alexandra in Johannesburg, the BBC’s Nomsa Maseko visits a project using drones and artificial intelligence to help authorities prevent the worst impacts of flooding. And in Porto Alegre in the south of Brazil, we hear how an innovative digital map helped the emergency response – and will soon be available to all for free across the world.

This programme was first broadcast in 2024. You can email us at theclimatequestion@bbc.com

Guests: Rodrigo Rocha, Partner at the Responsive Cities Institute, Porto Alegre Dr Caroline Gevaert, Associate Professor at the International Institute for Geo-Information Science and Earth Observation, University of Twente Nomsa Maseko, the BBC’s South Africa Correspondent

Presenter: Jordan Dunbar Producer: Osman Iqbal Researcher: Octavia Woodward Sound mix: Tom Brignell Editors: Sophie Eastaugh and Simon Watts

Image: Reuters