Tectonic movement causes erosion in Himalayas: research

Dec 12 - Geologists have found that erosion in the Himalayas is actually due to the ground movement rather than the climate. The recent findings that question the effect of precipitation on the mountains on erosion in the Himalayas have been published in this month’s issue of Nature, a noted science magazine.

D.W Burbank, of the Department of Geological Sciences at the University of California, who headed the research in the Himalayan region, has found no significant link between precipitation and erosion in the Himalayas. The geologists have instead suggested upward tectonic (geological) movement as driving the erosion process.

Tank Ojha, working geologist, who was also a part of the research, told The Kathmandu Post that the studies began after the scientists wanted to further understand the erosion process in the mountains of Nepal.

“Was there a connectivity of the rate of erosion to monsoon or weather change? Is climate responsible for the rate of erosion in the regions of Nepal? These were some of the questions that needed to be answered,” said Ojha.

After signing a memorandum of understanding (MoU) with the Department of Hydrology and Meteorology, the scientists placed 40 meteorological stations along the Marshyangdi River in 1999 to examine the erosion. The stations measured things like precipitation, air temperature and humidity.

“However, what was found was that in places where there was high precipitation, the erosion was less,” added Ojha. For instance, in regions like Dharapani to Chami, the yearly average rainfall is 125 millimetres while the erosion rate was measured to be six millimetres. However, in the lower Narayangadh area, the annual average rainfall is over 450 millimetres while erosion was two millimetres.

So what triggered the erosion? It was then that the geologists discovered that the trans-Himalayan ranges were more active than the lesser Himalayas. Previously, experts thought that the regions of the lesser Himalayas on the border area of the Indian peninsula were more active.
The groundbreaking findings have shown that it was this tectonic movement around the trans-Himalayas (higher Himals) that was resulting in erosion. The movement meant that the higher portion of the mountains was eroding because of the pressure of collision.