Internally-driven, transient incision from river capture: Sutlej River,
western Himalaya
Abstract
Topographic features are commonly interpreted to represent interactions
between tectonic and climate-driven processes. However, recent work has
highlighted how drainage reorganization from river capture may produce
landscapes that resemble those generated by changing tectonic conditions
and emphasized the importance of developing tools and metrics to
identify the source of landscape transience (Yang et al., 2015; Whipple
et al., 2017). While few studies have sought to estimate the rates and
magnitudes of increased transient incision resulting from river capture
(e.g. Prince et al., 2011, Yanites et al., 2013), the ability to
quantify river capture-related incision is vital to improve our
characterization of landscape responses to transience. This work tests
the hypothesis that the observed incision and distribution of
knickpoints in the Sutlej river network of the western Himalaya is the
result of an ongoing transient response to a large-scale river capture
event that occurred in the late Pleistocene. A combination of
topographic analyses using digital elevation models, knickpoint
propagation modeling, 1-D numerical incision modeling, and landscape
evolution modeling are used in conjunction with new and existing
field-derived data (e.g. cosmogenic radionuclide-derived erosion rates
and (U-Th)/He and fission track thermochronology) to quantify the
magnitude and timing of the transient landscape response. Redistribution
of drainage area and the subsequent enhancement of incision along the
Sutlej may explain the increased amounts of Himalayan detritus delivered
to the Indus fan since 5 Ma (Clift and Blusztajn, 2005). Similar
large-scale river capture events proposed throughout the Himalaya (e.g.
Garzione et al., 2003; Van Der Beek et al., 2018), suggest that capture
events may be a regional phenomenon inherent to the Himalayan orogen and
imply that river capture may be an important contributor to the
distribution of sediment along collisional margins.