[The Conversation Africa] More than 11,000 people have been killed and tens of thousands are missing following the catastrophic dam collapse in the eastern Libyan city of Derna on 12 September. The dam collapse came after an extreme storm, Storm Daniel, slammed into the north African country. The Conversation Africa's Moina Spooner asked water resources and engineering expert Nadhir Al-Ansari, who has researched the design and safety of dams, to provide insights into the disaster.