1.   Syria is vulnerable to Turkey damming the water of the upper Euphrates for irrigation and agricultural schemes.

2.   The concrete-slab backyard, crumbling into shards, abuts a creek bed that has been dry for years, ever since the water was dammed upstream.

3.   The leaves began backing up, damming the water which rotted the wood behind and under the gutters.

4.   Then came New York City, with the power to condemn certain riverside settlements so it could dam the water and divert it for its swelling population.