Answer:
They provide a source of hydroelectric power.
They provide water for agriculture.
They were an important site for the development of trading cities, such as Augusta.
Step-by-step explanation:
On these rivers, dams should be build which helps in the storage of water and this water is used in order to irrigate the crops. These dams also produced electricity by falling of water on the turbine so hydroelectric power station should be built. It is a site for building trading cities such as Augusta because all the goods comes from other countries received here or sent to other countries from here which makes them a trading city.