Explainer: Egypt fears losing water supply to Ethiopia mega-dam

Ministers from Egypt, Sudan and Ethiopia are holding talks over disputes related to the world’s longest river.
 
Egypt, which depends on the Nile for water, is worried about a dam being built upstream by Ethiopia.
 
The $5bn dam will be the largest in Africa and Ethiopia wants it to produce electricity for 70 percent of its population.
 
But Egypt, which relies on the Nile for 90 percent of its water supply, fears the dam would divert enough water to destroy half of the country’s farmland.
 
Al Jazeera’s Bernard Smith explains.