Early Career Spotlight

Gen Li

Tell us about yourself:

My name is Gen Li. I am currently a postdoc fellow at Caltech, working with Mike Lamb, Woody Fischer, and Jean-Philippe Avouac on several projects looking at the interaction between surface processes, mountain building, and the global carbon cycle. Before moving to Caltech, I was a postdoctoral scholar at UCLA, working with Seulgi Moon on studying how topographic stress affects surface processes. I obtained my Ph.D. in Earth Sciences from the University of Southern California, working with Josh West on understanding the role of large earthquakes in mountain belt evolution, landscape denudation, and the carbon cycle. I did my undergraduate at Nanjing University, China, where I worked on quantifying the carbon budget in the Yangtze river basin under the supervision of professors Junfeng Ji and Jiedong Yang.

 

What is your research about?

I am broadly interested in the dynamic processes that cycle elements, materials, and fluids in the Earth system. My current research focuses on three themes: (1) mountain building and erosion in tectonically active areas; (2) sediment production and transport across landscapes; and (3) the global carbon cycle. Some of my projects include mapping and analyzing earthquake-triggered landslides using remote imagery and geospatial techniques to quantify the magnitude of landslide-induced erosion, developing numerical models to simulate the long-term evolution of mountain belt under the competition between erosion and uplift caused by earthquakes, field studies of grain size compositions of landslide and riverbed sediments, fieldwork to collect river water and sediment samples to understand fluvial transport of sediment and carbon, and laboratory work to characterize organic matter in sediments. I have done fieldwork across diverse landscapes from high mountains to lowland rivers, including remote areas in the U.S., China, and the Nepal Himalayas.

 

 What excites you about your research?

What excites me most is the multi- and inter-disciplinary nature of my research, which provides me a valuable opportunity to resonate with researchers across different fields. During my Ph.D., when I worked on mountain building over earthquake cycles, I got excited that we could use knowledge and tools from geophysics and seismology to solve problems in geomorphology, and I learned tremendously from my geophysicist friends. On the other side, I found geomorphology fascinating that it acts as the nexus connecting plate tectonics and the global carbon cycle, the two fundamental processes that make Earth a habitable planet and our home in the universe.

 

What broader importance does your research have for society?

There are two aspects on which my research may impact society. Firstly, my work advances our understanding of landslide hazards in mountainous communities, as well as landslide-induced cascading hazards such as aggradation and flooding. My research outcomes can be used to develop predictive models of landslide hazards from hillslope to regional scales, which is crucial for decision makers to mitigate hazards. Secondly, my work help to evaluate how human activities impact natural geomorphic processes, the global carbon cycle, and consequently the climate system. It allows me to evaluate the intrinsic behaviors of geomorphic systems, through working in remote areas such as the Himalayas where the human perturbation is limited. My studies in populated areas help evaluate the influences of human activities on Earth surface processes. For example, my prior work shows that dam building in the Yangtze has created a short-term transient atmospheric carbon sink through the sequestration of organic carbon, whose magnitude is comparable to the organic carbon burial in the Bengal Fan (Li et al., 2015).

 

What inspired you to pursue a career in Earth science?

My earliest interest in Earth Science stems from rivers. I grew up in eastern China, where the Huai river joins the Yangtze river. Rivers played a big role in my early life as a child: I enjoyed river boating as my favorite outdoor activity, but have also feared the river when big floods influenced the life of people in my hometown. I got further inspired from my undergraduate experience at Nanjing University. Prof. Ji showed me the beauty of working on rivers and how we could combine geochemistry, hydrology, and geomorphology to understand the geological cycling of elements and sediment. Importantly, our research allowed me to boat on rivers! Prof. Yang introduced me to the ‘uplift-weathering’ hypothesis (Raymo et al., 1988), that mountain uplift could drive changes in climate system through erosion and weathering. This really attracted me and made me realize the importance of surface processes and geomorphology not only on their own but also in the broad context of Earth Science. A final motivation was the catastrophic 2008 Wenchuan earthquake, which caused a significant loss of human life. Landslides are a major hazard associated with the Wenchuan earthquake, and the cascading hazards induced by co-seismic landslides are still occurring today. Mitigating seismic hazards, especially those from earthquake-triggered landslides, relies on a better understanding of sediment production and transport in steep mountains, and I wish I can make some contribution to such important topics.

 

What are you looking to do after you complete your PhD or postdoc?

I plan to pursue a career in scientific research and work at universities/research institutions.

 

Given unlimited funding and access to resources, what is your dream project that you would pursue?

That would definitely be boating on every river in the world, collecting sediment and water samples and hydraulic data, and later measuring those samples in the laboratory. From this, we can depict the dynamic cycling of materials and chemicals in the Earth surface system. We can also know the answers to many fundamental, yet unanswered, questions in Earth Science and geomorphology. For example, what is the grain size distribution of all sediment particles transported by rivers? What is the radiocarbon age, and the associated residence time, of all organic carbon molecules in the world? What is the highest denudation rate on Earth and where does it occur? This would also help to map hot spots undergoing active surface processes and geochemical cycles and to delineate areas that would experience major hazards associated with sediment and/or hydrology.

 

 What else do you do?  Any hobbies or interests outside of work?

Outside of work, I like playing the Rubik’s Cube. It is interesting that the very first reason that made me a cube player is that the winter in Nanjing, the city where I did my undergraduate, was so cold that I really wanted to exercise my hands and fingers to keep warm. Nowadays, I always try to bring my cube with me every time I travel.

 

You can follow Gen’s research here: https://scholar.google.com/citations?user=-kkO4HEAAAAJ&hl=en


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File

Gen Li on a October 2015 field trip to the Nepalese Himalaya to study landslides caused by the 2015 Gorkha earthquake. The background shows fresh co-seismic landslides in a valley near Kathmandu.