Answer:
The two meanings of turbulent
Step-by-step explanation:
One meaning of the adjective Turbulent = Characterized by conflict, disorder, or confusion, not controlled or calm. When related to the noun air or water it means moving unsteadily or violently.
In these lines the author uses the analogy of water (stream) with humans to describe the downward-flowing (water seeks for the lowest point; humanity seeks for surviving) evacuees that could become a disordered and violent human conflict.