The Peninsular Drainage System

The Peninsular drainage system is the older of India’s two great drainage systems, and its age shows in the landscape. The rivers here flow through broad, largely-graded shallow valleys and have reached a stage of maturity that the younger Himalayan rivers have not. The key to understanding this system is the Western Ghats, which run close to the western coast and act as the water divide. On one side, the major Peninsular rivers discharge into the Bay of Bengal; on the other, small rivulets join the Arabian Sea.

Most of the major Peninsular rivers flow from west to east, with two notable exceptions — the Narmada and the Tapi, which flow westward. The Chambal, the Sind, the Betwa, the Ken and the Son, all originating in the northern part of the Peninsula, belong to the Ganga river system rather than forming independent systems of their own. The other major river systems of the Peninsular drainage are the Mahanadi, the Godavari, the Krishna and the Kaveri.

Peninsular rivers are generally characterised by a fixed course, the absence of meanders and a non-perennial flow of water. The Narmada and the Tapi, which flow through rift valleys, are exceptions to these general features.

Evolution of the Peninsular Drainage System

Three major geological events in the distant past shaped the present drainage systems of Peninsular India.

The first was the subsidence of the western flank of the Peninsula, leading to its submergence below the sea during the early Tertiary period. This event generally disturbed the symmetrical plan of the rivers on either side of the original watershed.

The second was the upheaval of the Himalayas, when the northern flank of the Peninsular block was subjected to subsidence and consequent trough faulting. The Narmada and the Tapi flow in these trough faults and fill the original cracks with their detritus materials. This is why these rivers lack alluvial and deltaic deposits.

The third was a slight tilting of the Peninsular block from the northwest to the southeast direction, which gave orientation to the entire drainage system towards the Bay of Bengal during the same period.

River Systems of the Peninsular Drainage

There are a large number of river systems in the Peninsular drainage. A brief account of the major ones follows.

The Mahanadi rises near Sihawa in the Raipur district of Chhattisgarh and runs through Odisha to discharge its water into the Bay of Bengal. It is 851 km long, and its catchment area spreads over 1.42 lakh sq. km. Some navigation is carried on in the lower course of this river. Fifty-three per cent of its drainage basin lies in Madhya Pradesh and Chhattisgarh, while 47 per cent lies in Odisha.

The Godavari is the largest Peninsular river system and is also called the Dakshin Ganga. It rises in the Nasik district of Maharashtra and discharges its water into the Bay of Bengal. Its tributaries run through the states of Maharashtra, Madhya Pradesh, Chhattisgarh, Odisha and Andhra Pradesh. It is 1,465 km long, with a catchment area spreading over 3.13 lakh sq. km. Of this, 49 per cent lies in Maharashtra, 20 per cent in Madhya Pradesh and Chhattisgarh, and the rest in Andhra Pradesh. Its tributaries include the Penganga and the Indravati. …