QRC members lead and participate in a wide range of disciplinary and interdisciplinary research projects from the study of past earth climates and glaciations to shifts in the geographic distributions and evolution of vegetation and faunal communities, to the evolution and dispersals of the genus Homo and the increasing scales of human modification of earth environments through the Holocene. QRC provides a venue for meeting and collaborating with scholars across Quaternary disciplines. We are also fortunate to be able to provide seed funding and small grants for member research projects. We are especially happy to support grad student and junior scholar research activities, much of which leads to larger, external funding from agencies like the National Science Foundation.
The geomorphic legacy of outburst floods: does boulder deposition from megaflooding control erosional patterns in the eastern Himalaya?
Abstract: The eastern Himalaya holds evidence for hundreds of temporary glacial and landslide dam impoundments throughout the Quaternary. Holocene glacial moraine dams at the Namche Barwa massif are thought to have impounded large lakes, producing megafloods (discharge >106 m3/s) after dam failure. These large, infrequent floods have been proposed as mechanisms of intense erosion during deglaciation in the Quaternary on the Yarlung-Siang River, however, their depositional footprint remains unexplored. Deposition from these floods in the form of boulders may feed back into erosional processes, controlling how and where sediment can move in the river during annual flows This project will assess the depositional impact of Quaternary megafloods within the Siang main channel from a paleohydraulic perspective. We will pair field measurements of boulder bars and channel widths with depth-averaged 2D numerical simulations of megafloods over 3D topography to explore the stability of these features in the channel and the implications for long-term river incision. We target boulder bars because recent numerical modelling of a historic landslide dam-break outburst flood down the Yarlung-Siang River suggests that large boulders can be deposited during outburst floods in unexpected areas. Boulders can exert a first-order control on sediment transport in coarse-grained systems by armoring the bed, increasing surface roughness, and extracting momentum from the flow. Boulders deposited during an outburst flood potentially control erosional and depositional patterns within the river if they are too large to be moved during average annual and peak flows. There are many large boulder bars in unexpected areas along the Siang River (i.e. at cut banks on meander bends where erosion is expected) suggesting they are not a product of average annual or peak flows. We will travel to the Siang River in Arunachal Pradesh, India in November 2019 to make field measurements of grain size and lithology of several out of place boulder bars in the Siang River. We will then use numerical modelling to simulate 2D hydraulic characteristics of two Quaternary megafloods to explore sediment transport dynamics at these boulder bars, validating these models with our field observations. Combined, field observations and numerical simulations will allow us to see what percent of these boulder bars can be moved during megafloods. Our results will begin to explore the lasting impact these large infrequent floods have on the Siang River and the surrounding hillslopes.