The Narmada river in the Peninsular plateau flows westward with a remarkably straight channel. It is because the:

The Narmada river is a unique peninsular river that flows westward through a remarkably straight channel. This linear course is primarily due to its geological setting; it flows through a structural trough or rift valley formed by faulting [3]. Unlike most peninsular rivers that flow eastward following the general tilt of the Deccan Plateau, the Narmada occupies a graben—a depressed block of the Earth's crust bordered by parallel faults—located between the Vindhyan and Satpura ranges [4]. This rift valley is inclined westward, which forces the river to flow toward the Arabian Sea rather than the Bay of Bengal. The tectonic control of this fault-guided valley prevents the river from developing typical meanders, resulting in its characteristic straight channel pattern [2]. While it does form a boundary between the Central Highlands and the Deccan Plateau, the structural rift valley is the direct cause of its straight westward flow.

Sources

1. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 3: The Drainage System of India > Narmada River > p. 20
2. [3] CONTEMPORARY INDIA-I ,Geography, Class IX . NCERT(Revised ed 2025) > Chapter 3: Drainage > The Narmada Basin > p. 21
3. [4] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Drainage System > River Systems of the Peninsular Drainage > p. 24
4. [2] INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Drainage System > THE PENINSULAR DRAINAGE SYSTEM > p. 23