The idea that the Ghaggar-Hakra was fed by Himalayan sources has been contradicted by recent geophysical research, which shows that the Ghaggar-Hakra system, although having greater discharge in Harappan times which was enough to sustain human habitation, was not sourced by the glaciers and snows of the Himalayas, but rather by a system of perennial monsoon-fed rivers. Geologist Liviu Giosan of the Woods Hole Oceanographic Institution and his team showed that in contrast to all Himalayan rivers in the region that dug out wide valleys in their own sediments as the monsoon declined, no such valley exists between the Sutlej and the Yamuna, demonstrating that neither the Ghaggar-Hakra nor any other Sarasvati candidate in that region had a Himalayan source. Late Holocene aridification subsequently reduced the Ghaggar-Hakra to the seasonal river it is today.