Gravel geometry of the Indus river unravel its paleoclimatic history

Gravel geometry of the Indus river unravel its paleoclimatic history
CHANDIGARH–Researchers from Wadia Institute of Himalayan Geology
(WIHG), Dehradun, an autonomous institute under the Department of
Science and Technology, Government. of India, have traced the paleoclimatic
history of the Indus River in Ladakh Himalaya with the help of
geometric data from overlapping gravels of channel fills.
They studied the discharge during periods in which the river
experienced an increase in land elevation, due to the deposition of
sediment) and its incision.
River Terraces are ubiquitous in mountains that nourish and help
sustain past, present, and future human societies. These terraces are
part of valley-wide aggradations, which has been studied extensively
in Himalaya to understand the processes driving such a periodic
increase in river valley land elevation and incision. Scientists are
still debating whether wetter climate intervals with increased
rainfall and glacial melting promote river aggradation through
increased discharge and enhanced sediment load, or instead, is it
during drier conditions when aggradation occurs through increased
sediment to water ratio.
The researchers studied the discharge during periods of established
river aggradation and incision of the Indus River, Ladakh Himalaya
over late Quaternary (the current and most recent of the three periods
in the geologic time scale). They used geometric data from overlapping
gravels of channel fills to calculate paleodischarges during net river
aggradation at 47–23 ka (thousand years),and preserved slack water
deposits (SWDs) at 14–10 ka to constrain paleodischarges that occurred
during net river incision.
They observed that the aggradation in the Himalayan rivers occurred in
glacial-interglacial transient warm climatic conditions (33–21 ka and
17–14 ka) when the sediment budget in the rivers increased just after
the glacial events.
Their study published in the journal Geomorphology shows that
aggradation took place in the Indus River when sediment to water ratio
was higher during MIS-3 (Marine isotope stages (MIS), marine
oxygen-isotope stages, are alternating warm and cool periods in the
Earth’s paleoclimate, deduced from oxygen isotope data reflecting
changes in temperature derived from data from deep-sea core samples)
and incision initiated when sediment to water ratio reduced during
post-glacial climatically wet phase (early Holocene).

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SK Vyas

SK Vyas

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