In a recent issue of PNAS. Use a combination of high resolution topographic data, geomorphologic analysis and sediment dating to establish a chronology of the evolution of fluvial landforms of the Indus and its tributaries. The Harappan civilization over a 600 year period from around 4500 B.P (before present) to about 3900 B.P flourished in this region and then went into decline with urban centers abandoned and populations moving eastwards towards the Himalayan foothills and the Gangetic plains. Goisan et.al's work - and there is also independent evidence for this - shows that this 600 year period was a kind of a Goldilocks period. The region became arid, but not too arid. Indus and its tributaries get water from two climatic regimes, the summer monsoons from the Arabian sea and winter rains from the northwesterly winter disturbances bringing moisture from the Mediterranian, Caspian and Black sea region.
We report morphologic and chronologic evidence indicating that fluvial landscapes in Harappan. Endurance High Sierras Full Episodes. The Harappan or Indus Civilization. National Academy of Sciences. The Indo-Aryan Migration Debate, Oxford University. Fluvial landscapes of the Harappan. Fluvial landscapes of the Harappan civilization. We report morphologic and.
Most of the sediment load of these rivers is generated during the heavy erosion that takes place in the Himalayas during the summer monsoons. When rivers carry and deposit sediment along their course they are said to be in an aggradational mode i.e.
The stream bed and the surrounding floodplains get raised as more and more sediment is deposited. Over much of the earliest part of the Holocene, the Indus and its tributaries were aggradational. Malayalam Poetry.
Then the monsoons weakened and the sediment load reduced. Winter rains falling as snow though kept river discharge active. Rivers without sediment or less sediment incise or cut into their own deposits.
So, by mid Holocene all these rivers had developed a characterized profile of incised valleys and river terraces marking the original river bed and broad surrounding plains that because of reduced rainfall were less prone to severe flooding. Giosan et.al suggest that the Harappan people took advantage and adapted to these circumstances. Jpop Mp3 Album S on this page. There are Harappan and even pre-Harappan sites within these incised valleys of the Indus and its tributaries like the Beas and the Sutlej. This suggests that incision had occurred in the early Holocene and agriculture evolved to take advantage of manageable floods and a perennial water supply within the valleys and adjoining plains.
After around 3900 B.P. The aridification intensified. The agricultural heartland of this civilization was along the Ghaggar/Hakra river, located between the Sutlej and the Yamuna. This river was monsoonal fed and would have been perennial until then.