The Evolution of Peninsular Drainage System
Three major geological events in the distant past have shaped the present drainage systems of Peninsular India: (i) Subsidence of the western flank of the Peninsula leading to its submergence below the sea during the early tertiary period. Generally, it has disturbed the symmetrical plan of the river on either side of the original watershed. (ii) An upheaval of the Himalayas when the northern flank of the peninsular block was subjected to subsidence and the consequent trough faulting. The Narmada and The Tapi flow in trough faults and fill the original cracks with their detritus materials. Hence, there is a lack of alluvial and deltaic deposits in these rivers. (iii) Slight tilting of the peninsular block from northwest to the southeastern direction gave orientation to the entire drainage system towards the Bay of Bengal during the same period.
- Peninsula Rivers are much older than the Himalayan Rivers.
- The peninsular drainage is mostly Concordant except for few rivers in the Upper Peninsula region.
- They are non-perennial rivers with an utmost release in the rainy season.
- The peninsular rivers have reached the mature stage and have almost reached their base level.
- The rivers are characterized by broad and superficial valleys.
- The river banks have gentle slopes except for a limited track where faulting forms steep sides.
- The main water divide in peninsular rivers is formed by the Western Ghats, which run from north to south close to the western coast.