Tuesday, February 22, 2011

Remotely India # 6: Chambal River - Badlands ...And Bad Men n Women

Geology and Livelihoods - 8

In the alluvial Gangetic plains, the rivers that catch everyone's eye are the Yamuna and the Ganga with their source in the high Himalayas and their standing in Indian society as the holiest of India's many holy rivers.

But the alluvial Himalayan foreland is also fed by rivers originating in the Indian craton (continental crust formed in early earth history) on the high northern flanks of the Narmada rift zone. These cratonic rivers flow north northeastwards and join the Yamuna or Ganga.The map below shows Himalayan and Cratonic rivers flowing into the north Indian foreland basin.


Source: R.Sinha et al 2009

The Chambal is the largest of these cratonic rivers. From source to its confluence with the Yamuna it is about a 1000 km long. It flows over both the Deccan Basalts and Proterozoic Vindhyan strata and contributes significant amount of sediment to the foreland basin.

The Chambal river badlands is a late Pleistocene-Holocene degradational landscape. In the image below the badlands can be recognized by the closely spaced dendritic network of gullies. The location is just west of the town of Morena in Madhya Pradesh.


Rivers and their associated floodplains go through aggradational and degradational phases. In an aggradational phase the river is carrying a large sediment load and flooding results in deposition of this sediment in the flood affected areas. This periodic deposition builds up or aggrades the floodplain.

Conditions may change. For example during longer wet periods and increased rain intensity river discharge increases. Sediment is not deposited locally but is carried out of the system to the sea.  In these conditions rivers incise or cut into their own deposits. The river channel becomes situated in a deep valley detached from its floodplain. Starved of sediment, the floodplain degrades as erosion along the main channel and smaller streams cuts gully and ravines forming badlands.

Below is a pictorial representation of this process.


 Source: Gibling et al 2005

Sedimentological and stratigraphic analysis of facies and dating of sediment by Optical Stimulated Luminesence along the Ganga, Yamuna and some cratonic tributaries suggest (Ref) that in this region badland formation coincided with the intensification of the south west Indian monsoon at the end of the Last Glacial Maximum around 15 thousand years ago and likely continues today, amplified over the last couple of millenia by intense human reworking of the landscape.

Another mechanism that may initiate a phase of river incision is tectonic uplift and tilting of the region. Tectonic upwarp may steepen stream gradients increasing their erosive power. That mechanism has been invoked by some to explain phases of incision of the Yamuna and the Chambal. However many researchers have pointed out that late Pleistocene - Holocene river incision episodes in basins of varied tectonic settings from Nepal , Bangladesh and northern India all coinciding with monsoon resurgence points to a regional climatic control.

Ravined badlands border long stretches of the Chambal as seen in the image above but also occur along the Yamuna, Betwa and Sengur rivers. The incised main channel of the river and the ravines expose older sediment. In these older sediments, earlier degradational and aggradational episodes can be recognized and coincide with fluctuations in monsoon intensity interpreted from coeval Arabian sea cores containing variations in pollen abundance which records variation in terrestrial vegetation and planktonic foraminiferal abundance which records oceanic upwellings related to monsoonal circulation.

These badlands and incised channels of the Yamuna, Chambal and other smaller cratonic rivers have given geologists a priceless opportunity to study the interplay between fluvial processes and climatic changes mainly the influence of the Indian monsoon on sedimentary processes over the last hundred thousand years.

I am leading into a different topic for the rest of the post- a somewhat warped installment of my long running series Geology and livelihoods, the reason being that in the Chambal region for long centuries people have developed a parallel economy based on dacoity. Some of India's most infamous outlaws have operated from this region. Dongar-Baturi, Pana, Sultan, Man Singh, Amritlal, Lakhan, Gabbra and Putli Bai (the first documented women dacoit of the Chambal), Kallan and more recently the notorious Nirbhay Gujjar (in photo, source).. the list is long.

The reasons are many and the badlands and ravines play an important role through history. They are situated close to the power centers of ancient north India, Delhi and the kingdoms of Rajasthan. Rebels used to retreat and hide in its byzantine gullies and engage in guerrilla warfare. That metamorphosed over time to looting and making a living that way, a culture of highway banditry developed.

From ancient times to recent, people took to being outlaws for different reasons. Droughts which are common in this region drove many to desperation. A rigid caste system often ignited inter caste violence and initiated revenge cycles that lasted generations. The rugged terrain meant that farming land was scarce and land disputes escalated to murderous outbursts and often a point of no return. 

The background was always the gullied landscape in which the outlaws could escape and hide from their enemies and the law.

Annie Zaidi surveying this region has found out that dacoity has changed with the times. These days gangs earn a livelihood not by old fashioned looting and raids on villages and travelers but by kidnappings for ransom and protection rackets.

Geology influences this new economy too. At the fringes of the alluvial badlands outcrop Archean granites and gneisses, Proterozoic marbles, limestones and sandstones and the Deccan Basalts,all of which are extensively quarried, often illegally.

These quarries are in remote areas and gangs extort protection pay from owners in exchange of safety.

Chambal geology, both recent and ancient has sustained illegal livelihoods for centuries.

Interactive:


View Larger Map

See: Geology and livelihoods

2 comments:

  1. Happened to pass through from Gwalior to Agra on train. You cross over at a point a little north east of your map.
    The river bed was full of ant-hill type of formations

    ReplyDelete
  2. Yes, that's a good description of the landform.. north of Gwalior is where the badlands start.. Morena which I mentioned is the heart of badland country :)

    ReplyDelete