Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Breakthrough discovery finally shows that rain can really move mountains

Breakthrough discovery finally shows that rain can really move mountains



Dr, Byron A. Adams, Greater Himalayas, Central Bhutan

First and corresponding author Dr. Byron A. Adams in the steep terrain of the Greater Himalayas, Central Bhutan. Credit: Photo by co-author Professor Kelin X Whipple

A groundbreaking technique that captures exactly how mountains bend to the will of the raindrops has helped solve a long-standing scientific riddle.

The dramatic effect of precipitation on the development of mountainous landscapes is widely discussed among geologists, but new research led by University of Bristol and was published today in Scientific progress, clearly calculates its impact and promotes our understanding of how peaks and valleys have evolved over millions of years.

Its findings, which focused on the most powerful mountain range – the Himalayas – also pave the way for predicting the possible impact of climate change on landscapes and, in turn, human life.

Main author Dr. Byron Adams, Royal Society Dorothy Hodgkin Fellow at the University’s Cabot Institute for the Environment, said: “It may seem intuitive that more rain can shape mountains by causing rivers to cut into rocks faster. But scientists have also believed that rain can degrade a landscape fast enough to essentially ‘suck’ the rocks out of the ground and effectively pull mountains up very quickly.

Wang Chu, southwestern Bhutan

Looking upstream within a tributary of Wang Chu, southwestern Bhutan. Credit: Dr. Byron A. Adams

“Both of these theories have been debated for decades because the measurements needed to prove them are so meticulously complicated. That is what makes this discovery such an exciting breakthrough, as it strongly supports the notion that atmospheric and solid earth processes are closely linked. ”

Although there is no shortage of scientific models aimed at explaining how the Earth works, the greater challenge may be to make good enough observations to test which ones are most accurate.

The study was based in the central and eastern Himalayas of Bhutan and Nepal because this region of the world has become one of the most developed landscapes for erosion rate studies. Dr. Together with partners from Arizona State University (ASU) and Louisiana State University, Adams used cosmic clocks in sand grains to measure the rate at which rivers erode the rocks beneath them.

“When a cosmic particle from outer space reaches the earth, it is likely to hit grains of sand on slopes when transported towards rivers. When this happens, some atoms within each grain of sand can be transformed into a rare element. By counting how many atoms of this element are present in a bag of sand, we can calculate how long the sand has been there and therefore how quickly the landscape has been eroded, ”said Dr. Adams.

Paro Valley, western Bhutan

Ta Dzong overlooking the Paro Valley, western Bhutan. Credit: Dr. Byron A. Adams

“Once we have erosion rates from the entire mountain range, we can compare them with variations in river stiffness and rain. However, such a comparison is very problematic because each data point is very difficult to produce and the statistical interpretation of all data together is complicated. ”

Dr. Adams overcame this challenge by combining regression techniques with numerical models of how rivers erode.

“We tested a large number of numerical models to reproduce the observed erosion rate pattern over Bhutan and Nepal. In the end, only one model was able to accurately predict the measured erosion rates, ”said Dr. Adams.

“This model allows us, for the first time, to quantify how precipitation affects erosion rates in uneven terrain.”

Research partner Professor Kelin Whipple, professor of geology at ASU, said: “Our findings show how critical it is to take precipitation into account when assessing patterns of tectonic activity using topography, and also provide an important step forward in addressing , how much slip rate tectonic defects can be controlled by climate-driven surface erosion. ”

The study results also have important implications for land use management, infrastructure maintenance and hazards in the Himalayas.

In the Himalayas, there is the ever-present risk that high erosion rates could drastically increase sedimentation behind dams and jeopardize critical hydropower projects. The results also suggest that higher rainfall could undermine slopes and increase the risk of mudslides or landslides, some of which may be large enough to dam the river and create a new danger – lake eruptions.

Dr. Adams added: “Our data and analysis provide an effective tool for estimating erosion patterns in mountainous landscapes such as the Himalayas and can thus provide invaluable insight into the dangers affecting hundreds of millions of people living in and at the foot of these mountains. . ”

The research was funded by the Royal Society, the UK Natural Environmental Research Council (NERC) and the National Science Foundation (NSF) in the United States.

Based on this important research, Dr. Adams currently how landscapes react after major volcanic eruptions.

“This new frontier for modeling landscape development also sheds new light on volcanic processes. With our groundbreaking techniques for measuring erosion rates and rock properties, we will be able to better understand how rivers and volcanoes have affected each other in the past, ”said Dr. Adams.

“This will help us more accurately predict what is likely to happen after future volcanic eruptions and how we deal with the consequences for communities living nearby.”

Reference: October 16, 2020, Scientific progress.




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