Uruk, according to the Gilgamesh Epic, was approached by boat. The people dug all these canals/irrigation ditches and then went around by boat. The "city" was the cultivated area in those times.
When the river was high, water could be captured in the ditches and used to irrigate.
They still have these irrigation ditches all over the place in Iraq, and we have lost soldiers who drove into these canals and drowned.
Fishermen along the rivers live in houses made of woven reeds--giant baskets. These are right next to the water and probably are replaced frequently. I saw a picture of one of these houses in the Metropolitan Museum of Art.
The Mesopotamian Noah, Unapishtim, was warned by a god named Ea/Enki who whispered to the walls of his house that a flood was coming. It was a reed house, the epic specifies. The houses are still the same thousands of years later.
Technically, the walls told Unapishtim the flood was coming. My students always think this is crazy until I explain that the god Ea/Enki has divided loyalties.
He isn't supposed to tell man about the flood because that would be disloyal to the gods, but he wants to warn man.
He defends his breach of confidence to the other gods by "explaining" that he only told the walls, not Unapishtim.
Clearly, he is being disingenuous. Ea/Enki was the god of waters and was known for his slyness. Water is sly and two-faced in Mesopotamia--just like Ea/Enki. Water gives you life and also takes it.
When people ask Unapishtim (Mesopotamian Noah) why he is building a boat, he tells them (on the advice of Ea) to say that Enlil is mad at him so he has to move to the sea, but "on you he will rain down an abundant harvest of bran and wheat."
Ea is very two-faced, and this pun illustrates his dual nature. Bran and wheat can also mean rain down misfortune and sorrow in their language.
Ea is like those later Greek oracles who always speak the truth, but people don't understand.
At the end of the story, the other gods turn against Enlil who convinced them to send the flood. He isn't allowed to eat the food sacrificed because he brought the flood.
The gods are not all-knowing. They are shocked by the flood and hide behind their walls in heaven "like dogs."
I've read where some speculate that the god enki was in fact the comet Encke.
Now, after the 1991 Gulf War, Saddam was mad at the Marsh Arabs and drained their swamp. When the draining was complete, it revealed an impact crater dated to 2200-2300BC and coincides with a worldwide tree-ring incident. Below is an article covering this discovery.
Disaster That Stuck The Ancients
"Today's crater lies on what would have been shallow sea 4,000 years ago, and any impact would have caused devastating fires and flooding."
"The catastrophic effect of these could explain the mystery of why so many early cultures went into sudden decline around 2300 BC."