CHAPTER 3 DRAINAGE The term drainage describes the river system of an area. Look at the physical map. You will notice that small streams flowing from different directions come together to form the main river, which ultimately drains into a large water body such as a lake or a sea or an ocean. The area drained by a single river system is called a drainage basin. A closer observation on a map will indicate that any elevated area, such as a mountain or an upland, separates two drainage basins. Such an upland is known as a water divide (Figure 3.1). Figure 3.1 : Water Divide DO YOU KNOW? The world’s largest drainage basin is of the Amazon river. FIND OUT Which river has the largest basin in India? DRAINAGE SYSTEMS IN INDIA The drainage systems of India are mainly controlled by the broad relief features of the subcontinent. Accordingly, the Indian rivers are divided into two major groups: • the Himalayan rivers; and • the Peninsular rivers. Apart from originating from...