Originally published in our July 2020 newsletter (Issue 5)
Yanyan Cheng is a hydrologist and land surface modeler working on complex energy-water-land dynamics. She is currently a Postdoc at the Pacific Northwest National Laboratory (PNNL) in the Atmospheric Sciences and Global Change division. She earned a PhD in hydrology and water resources engineering from the University of Wyoming in 2018.
Yanyan’s research focuses on the development and application of hydrological and land surface models to explore the complex interactions among land use and land cover changes (LULCC), vegetation dynamics, and hydrology in agro-ecosystems. During her PhD, she developed a physically-based, distributed, hyper-resolution hydrologic model named “PFPMod” to investigate how preferential flow influences hydrological behaviors in tropical catchments (e.g., Panama). This work was the first attempt to explicitly incorporate preferential flow into hydrological models at catchment scales and has been featured in American Geophysical Union (AGU) Magazine Eos as an AGU Research Spotlight. She further applied PFPMod to examine the effects of land use dependent preferential flow on water provisioning in the Panama Canal Watershed.
Her current research at PNNL aims at improving the capability of land surface models to represent key missing vegetation types (e.g., perennial bioenergy crops) and hydrological processes (e.g., preferential flow) to investigate water, energy, and carbon cycle dynamics associated with LULCC across various scales. Recently, she has implemented two new perennial bioenergy crops (Miscanthus and switchgrass) into one of the most widely used land surface models, the Community Terrestrial System Model (CTSM; formerly known as the Community Land Model [CLM]) with comprehensive validation against site-level measurements, which constitutes the first attempt to explicitly simulate perennial bioenergy crops in CTSM (https://github.com/ESCOMP/CTSM/releases/tag/ctsm1.0.dev097). The local-scale results indicate that these two high-yield perennial crops assimilate more CO2 while demand less nutrients and water than traditional annual crops, which are promising alternatives for biofuel feedstocks. With this enhancement, CTSM becomes one of the first land surface models that can evaluate how energy technology advances (such as potential future biofuel expansion) could influence the complex energy-water-land-climate dynamics at local, regional, and global scales.
She also comprehensively validated CTSM over the Contiguous United States (CONUS) during the historical period against various datasets to examine the capability of CTSM in simulating water and carbon cycle dynamics at regional scales, with a particular focus on identifying model shortcomings related to model structure, parameterization, and agricultural management practices, which could inform future model development. Working with colleagues at PNNL and NCAR, her most recent work focuses on developing an integrated multi-sector and multi-scale modeling framework (Global Change Assessment Model [GCAM]-Demeter-CTSM) to investigate how future biofuel expansion could influence water availability and quality over the CONUS.
Yanyan is co-convening an AGU session on Advances in Understanding Impacts of Land Use and Land Cover Change in a Changing Climate Using Earth System Records and Models this year. The session’s conveners sincerely welcome the MSD community’s submissions and collaborations.
– Cheng, Y. et al. (2019). Parameterizing perennial bioenergy crops in Version 5 of the Community Land Model based on site-level observations in the Central Midwestern United States, Journal of Advances in Modeling Earth Systems
– Cheng, Y. et al. (2018), Land use dependent preferential flow paths affect hydrological response of steep tropical lowland catchments with saprolitic soils, Water Resources Research.
– Cheng, Y. et al. (2017), Earthworms and tree roots: A model study of the effect of preferential flow paths on runoff generation and groundwater recharge in steep, saprolitic, tropical lowland catchments, Water Resources Research.
– Cheng, Y. et al. (2019), Characterization of sudden and sustained base flow jump hydrologic behavior in the humid seasonal tropics of the Panama Canal Watershed, Hydrological Processes.