The town of Hasankeyf, Turkey, will soon be only a memory. From her front door, Fatima Salkan has a sweeping view of the fruit trees, historic ruins and tidy stone compounds that run along this stretch of the Tigris River in southeastern Turkey. She tries her best not to look off in the distance, to the right. The town on the horizon, still under construction, is where she will move when the valley is flooded by a downstream hydropower dam. “Do you see all these old places?” she asks in Kurdish. “We are the owner, but today we are homeless.”...