Education
2008 - Present: Graduate student, University of Pennsylvania,
Department of Earth and Environmental Sciences
2003 - 2008: BSE in Geological Engineering, Princeton University,
Department of Civil and Environmental Engineering
Thesis: “Urbanization, Aerosols, and Precipitation Modification in
Beijing”
Modeling sedimentary
transport in step-pool streams
Step-pool bedform topography is characterized by protruding steps of
large interlocking boulders alternating along the longitudinal profile
of a river channel with pooled depressions containing finer
material. Previous studies suggest that the jamming of large
boulders into channel-spanning arched structures is the primary
mechanism governing step formation and destruction. To
explore
this idea, I am currently setting up flume experiments in the
University of Pennsylvania Sediment
Dynamics Laboratory to create a scaled-version of
step-pool topography. I am also
working on a granular-based cellular model of sediment-transport in
step-pool streams based on the idea that grain-grain interactions
dominate and turbulent fluid effects are negligible.
Predictions
from laboratory and computer modeling are being compared to bedform
geometries observed in the field, such as at Hickory Run in White
Haven, PA.
Cresheim Creek, Philadelphia:
Compare the photos from before and after. Boulders definitely
moved!
July 7, 2009
July 17, 2009
Nonlinear dynamics of rice
pile avalanches.
The angular nature of rice grain geometry causes grains to lock
together, forming variously sized meta-stable steps in the elevation
profile. Random variations in locking structures produce
fluctuations in the critical angle for slope failure, resulting in
fluctuations in rice transport rate over a wide range of scales –
despite a steady input of rice. The power-law fluctuations in
rice transport through avalanching can serve as an analogue for
sediment-transporting systems in general, where wild fluctuations in
sediment transport often arise from the internal nonlinear dynamics of
the system. I am currently analyzing data from rice
pile
experiments performed at the St. Anthony Falls Laboratory to study the
effect of non-linear transport dynamics on the preservation and
destruction of external signals produced by a variation in rice feed
rate.
Evolution of sandy bedforms and connection to hyporheic exchange
Bedforms
develop at a wide range of scales in response to streamflow conditions.
These bedforms in turn influence the exchange of streamwater
solutes with groundwater (hyporheic exchange). To study the
evolution of sandy bedforms and their effect on hyporheic exchange, we
are engaged in an NSF-funded research project with Northwestern
University and the USGS to study the bedforms and solute exchange in
Clear Run, Wilmington, NC. I have been working on characterizing
the evolution of these bedforms by analyzing a series of time-lapse
photographs produced during a recent field campaign at Clear Run.
The video below shows the evolution of the bedforms through a
small flood stimulated by a controlled dam release.
Time lapse video of Clear Run bedforms during experimental flood,
9/18/09. Frame interval is 30 seconds, video shows 10 frames per
second. Field of view length ~3 meters.
