Ethiopia says its huge dam upstream on the Nile will generate electricity for millions. But downstream countries like Sudan and Egypt are worried about what it’ll mean for their water supply.

We get the details from two BBC reporters: Kalkidan Yibeltal, in Ethiopia's capital Addis Ababa and Jaidaa Taha, in Egypt’s capital Cairo.

We also take a look at disagreements over the Mekong River in Asia. It runs through Myanmar, Laos, Thailand, Cambodia, and Vietnam. Brian Eyler is from a foreign affairs think tank, the Stimson Centre, and has written a book on it. Email: whatintheworld@bbc.co.uk WhatsApp: +44 0330 12 33 22 6 Presenters: Hannah Gelbart Producers: Emily Horler and Alex Rhodes Editor: Verity Wilde and Simon Peeks