The refugees are displaced and urgently need international aid.
Tips
history
The phrase draws on 《汉书·薛广德传》: 关东困极,人民流离 — describing peasants driven from their homes by hardship. 'Displacement due to catastrophe' has been its meaning for two thousand years.
usage
Almost always for mass catastrophe: war, famine, natural disaster, political upheaval. Heavy, serious register — not for someone who's just had to move apartments.