Which one of the following is the correct sequence of the following topographical features found from upper to lower course of a river ?

The topographical features of a river change systematically from its source to its mouth. In the upper course, characterized by steep gradients and vertical erosion, features like waterfalls and rapids are prominent [t1][t4]. As the river enters the middle and lower courses, the gradient decreases and lateral erosion increases, leading to the formation of meanders [t7]. Over time, intensive erosion at meander loops can cause them to disconnect from the main channel, forming oxbow lakes [c2][t3]. Finally, in the lower course, the river reaches its mouth where it meets the sea. Here, features such as deltas or estuaries are formed due to reduced velocity and tidal influence [t3][t4][t5]. Therefore, the correct sequence from upper to lower course is Rapids (upper), Ox-bow lake (middle/lower), and Estuary (mouth).

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 16: Fluvial Landforms and Cycle of Erosion > Oxbow Lake > p. 200