The cold desert in Ladakh once experienced a large flood that rose to more than 30-metre above the present-day river level, claimed a study, and that there are possibilities of serious flooding in the region in the future.
Why Ladakh is likely to be prone to major floods in the future
According to a press release from the Ministry of Science and Technology, “Scientists have shown that the cold desert of Ladakh Himalaya once experienced large floods that rose much above the present-day river level. It implies that in the scenario of global warming when the higher Himalaya regions are expected to respond dramatically, flood frequency in Ladakh may increase, which may call for serious urban and rural planning.”
Large floods naturally occur in India’s major rivers due to melting snow and glaciers and yearly monsoon during summer. These floods impact lives and economy of many people in the country who are settled in flood-prone regions.
What are the different types of floods?
There are different types of floods like those triggered by glacial/landslide lake outbursts, cloud bursts and excessively strong monsoon. Due to a variety of reasons behind these floods, there is a large amount of uncertainty in flood prediction models.
The study said that “an instrumental record of these floods is of ~100 years is not enough to understand the natural ramp of flood occurrences in the Himalayas, and therefore archive going deep into time is required”.
What the study is about?
Under the aegis of the Wadia Institute of Himalayan Geology at Dehradun, an autonomous institute of the Department of Science and Technology, a team of students and scientists went to “the tough terrains of Zanskar and Indus drained Himalaya and looked minutely into geological signatures of past floods in Ladakh region that date between 15-3 thousand years before present”.
This study that was recently published in the Geological Society of America Bulletin said that flood leaves a stack of fine sand and silts at places along its channel where the flood energy drastically reduces’
It said that wider segments of river valleys, confluences, behind rock embayments which are called Slack Water Deposits (SWDs) are located at several locations along the Zanskar and Indus rivers.
These deposits were counted vertically for the number of floods and were dated using technology called Optically Stimulated Luminescence (OSL) and Accelerator Mass Spectrometry of 14C. The flood deposits were also analysed for their source.
The active flood plains nearer to the river were also utilised by human beings, possibly as camping sites and cooking as indicated by the presence of hearths at several locations and levels of flood deposits, the study found.