Well, this is just a guess, and I'm a 7th Grader, so lets get it. One way the Rivers and Seas could benefit the Roman Empire is, they can prevent attacks, because the Roman Empire was a large, and most likely very hated by many other Empires, and groups. It also is a very good way for economy to grow, because they could do fishing at the rivers, which is a great way to make money, especially as a Poor Citizen!
