The river system of an area is called drainage. The area drained by a single river system is called the drainage basin.
Benefits of River:
(i) Rivers provide water for survival and growth of all organisms.
(ii) Rivers Provided ideal conditions for the early man to lead a settled life.
(iii) Rivers have built flood plains, deltas and provide fertile soil for agriculture.
(iv) Water from rivers is used for drinking, irrigation and for generating hydro-electricity.
(v) Man is able to supplement his food supply with the fish in the rivers. Rivers also serve as natural waterways.
(vi) World's earnest civilization developed in the river valleys, e.g., Nile Valley civilization, Indus Valley civilization, etc. River Valleys are the world's best agricultural lands, and are densely populated regions.