What are some differences in the topography of ancient Mesopotamia and today's Iraq?

Mesopotamia was much larger than present-day Iraq: it also covered a great part of Syria and Lebanon. Secondly, the coast bordering the Persian Gulf was some 50 miles more inland than it is today. Thirdly, the river Eufrates (today 'tamed' through all kinds of water works) was then a wild and often fast-flowing river, infamous for its unpredictable floodings of the surrounding countryside. As in many other parts of the Middle East and North Africa, the countryside of Iraq that is today mostly bare was then covered by often large forests and savannas.