Question

Which two Peninsular rivers flow through trough?

Answer 1

Hint:Indian drainage system is broadly divided into two types- Himalayan rivers and Peninsular rivers. Consisting of the Ganga, Brahmaputra and Indus basin, Himalayan rivers are youthful and perennial in nature. On the other hand, Peninsular rivers are older than Himalayan rivers and are more superimposed in nature.

Complete answer:Having a smaller basin size than the Himalayan rivers, the Peninsular rivers are rain fed and non- perennial in nature. Major peninsular rivers include Kaveri ,Krishna, Mahanadi, Narmada, Tapi , Godavari etc. Most peninsular rivers are east flowing. Narmada and Tapi are the only two major peninsular rivers that empty into the Arabian sea.
The Western Ghats act as a water divide between east flowing river and west flowing river.

To attempt this question, let us look at the three major geological or events that have shaped the peninsular drainage.
1.Subsidence of the western flank of the peninsula , leading to its subsequent submergence below the sea level.
2.The peninsular block slightly tilted from north west to south east.
3.Emergence of the Himalayas which led to the northern flank of peninsular being subjected to subsidence. This resulted in trough faulting.

Narmada and Tapi are the rivers that flow through these troughs.
Narmada originates in Amarkantak hills and flows in the rift valley created by faulting. Narmada basin covers parts of Madhya Pradesh and Gujarat. It has short tributaries which join it at right angles. It flows in the rift valley between Satpura and Vindhya ranges.

Tapi originates in Satpura ranges and its basins cover parts of Madhya Pradesh, Gujarat and Maharashtra. Though shorter than Narmada, Tapi also flows in the troughs of Peninsular plateau.

Therefore, the correct answer is Narmada and Tapi.

Note:While Narmada and Tapi are major rivers that flow from east to west, there are other small rivers like Sabarmati, Mahi, Bharatpuza and Periyar which flow from east to west.Another fact to remember is that as these rivers flow through hard rocks of the peninsular plateau, these rivers have fixed courses with low alluvial deposits.