Geology of Rivers

Today begins a festival of 10-days called Godavari Dussehra. Unfortunately, the priest communities of Trimbakeshwar and Nashik are the only ones who are carrying forward this tradtion, and not many locals are aware of this. We at ‘Reconnecting with Godavari’ take these ten days as an opportunity to unravel multiple facets of a river.

Let us begin by understanding the ‘Geology of Rivers’ and the geological characteristics of Godavari.

“Geology is a stream of science which deals with the physical structure and substance of the earth, their history, and the processes which act on them.”

Rivers being an integral component of the physical structure of the earth, its history, and processes which are transforming the earth, are one of the primary areas of investigation in the discipline of geology. Rivers are the carriers of water from different sources, they can originate in a lake, through a spring or melting of ice caps on the mountains. Usually, the rivers begin to flow as a small stream and gradually becomes bigger with the addition of water from other sources (like natural springs, rainfall, tributaries, etc.). Near the source, the rivers flow quickly through the steep sloping sections, washing away gravel and mud, thus leaving a rocky riverbed.

One can see all these attributes in the Godavari, originating of Brahmagiri Mountain, as well. Once it reaches the plains, the Godavari starts to take its shape by twisting and turning and becomes a meandering river. As visible the stretch of the Godavari flowing through the city of Nashik.The entire Godavari River Basin is bounded by hills – Satmala Hills in the North, Ajanta Range and Mahadeo Hills in the South, Eastern Ghats, and the Western Ghats. In addition to this, the drainage basin of the river is undulating. The Godavari River Basin is divided into 12 sub-basins, these are – the Upper Godavari (from the source to its confluence with Manjira), the Pravara, the Purna, the Manjira, the Middle Godavari (from its confluence with Manjira to its confluence with the Pranhita), the Maner, the Penganga, the Wardha, the Pranhita, the Lower Godavari (from its confluence with the Pranhita up to the Sea), the Indravati, and the Sabari.

The geological composition of the Godavari River Basin is described in the excerpt below from the book Hydrology and Water Resources of India by Sharad K. Jain, Pushpendra K. Agrawal, and Vijay P. Singh –

“The upper reaches of the Godavari drainage basin are occupied by the Deccan Traps containing minerals, hypersthene, augite, diopside, enstatite, magnetite, epidote, biotite, zircon, rutile, apatite and chlorite. The middle part of the basin is principally Archean granites and Dharwars composed of phyllites, quartzites, amphiboles and granites. The downstream part of the middle basin is occupied mainly by the Cuddapah and Vindhyan metasediments and rocks of the Gondwana group. The Cuddapahs and Vindhyan are quartzites, sandstones, shales, limestones and conglomerates. The Gondwanas are principally detritals with some thick coal seams. The Eastern Ghats dominate the lower part of the drainage basin and are formed mainly from the Khondalites which include quartz- feldspar- garnet- silllimanite gneisses, quartzite, calc-granulites and charnockites. In the coastal region the tertiary Rajahmundry sandstones crop out.

The western edge of the basin is an almost unbroken line formed by the Sahyadri range of the Western Ghats from 600 to 2,100m height. It has the heaviest rainfall and the dampest climate in the basin. Hardly 50 to 60 km east of the Ghats lie the sparsely cultivated and undulating plains of the Deccan, with a dry climate. The interior of the basin is a plateau, the greater part of which is at an elevation of 300 to 600m with its general slope eastwards. Great undulating plains, divided from each other by flat topped ranges of hills, are the chief characteristics of this plateau.

The Eastern Ghats which form the eastern boundary of the peninsula are not well-defined or continuous as the Sahyadri range on the west. They rise from the plains of East Godavari and Visakhapatnam to the level of the table land of Jeypore. The northern boundary of the basin comprises a series of table-lands varying from 600 to 1,200m in elevation, which have withstood the effect of ages of denudation better than the terrain to the north and south of them. To the south, lie great stretches of plain at an elevation of more than 300m interspersed with and surrounded by hill ranges, some bare and rocky, but generally covered with forests and scrub jungles. The delta of Godavari consists of a wide belt of river borne alluvium formed by deposits at the mouth of the river over the ages. The process of silting at the mouth of the river is still continuing and the delta is gradually extending into the sea.” (2007: 675-676)

Further, the principal soil types in the Godavari Basin are – Black Soils, Red Soils, Laterites and Lateritic Soils, Alluvium, Mixed Red and Black Soils and Red and Yellow Soils, and Saline and Alkaline Soils.

So, this was Godavari through a geological perspective. Let us meet again tomorrow with a different outlook.

Shilpa Dahake | Facebook

 

Reference:

Jain, Sharad K, Agarwal, Pushpendra K, Singh, Vijay P. 2007. Hydrology and Water Resources of India. Netherlands: Springer

Image Source:

http://india-wris.nrsc.gov.in/wrpinfo/images/e/ee/Godavari_basin.png

News Reporter
I am an architect turned anthropologist. After finishing my Masters in Anthropology from University of Pune, I was working with Gokhale Institute of Politics and Economics, Pune under a project funded by UNICEF and Integrated Child Development Scheme, Government of Maharashtra. During which I was stationed in Nandurbar District of Maharashtra (which is predominantly a tribal region) as a Field Research officer. Currently, I am a doctoral candidate in Department of Humanities and Social Sciences, Indian Institute of Science Education and Research Mohali, India. My current research explores the interaction of the cultural-religious, the political-economic and the ecological dimensions of the river in Nashik city in Maharashtra. Broadly, investigating how the multiple perspectives of a natural resource overlap, contradict, challenge and support each other, thus shaping the urban landscape and producing socio-spatial inequalities.

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