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Postdoctoral Fellows


Dr. Juan S. Acero Triana

Dr. Acero Triana completed his PhD in Ag & Bio Engineering with a concentration in Computational Science and Engineering at UIUC (US) and an MSc in Applied Hydrometeorology at RSHU (RU). He joined the Department of Environmental Sciences in 2020, where his research studies ecohydrological processes across highly managed agroecosystems and lake-watershed interactions integrating numerical models and data analytics tools. The ultimate goal of his research is to develop robust decision support systems that help decision-makers and stakeholders to assess management alternatives aimed at enhancing watershed ecosystem services under climate and land-use change scenarios.


Dr. Sandra Armengol Vall

I am a Postdoctoral Scholar at the Department of Environmental Sciences, University of California Riverside. My research is aimed at gaining knowledge and understanding in the use of chemical and isotopic tracers in hydrogeology. My main areas of expertise include the use of conventional chemical techniques, geochemical modelling and geostatistics to identify the groundwater provenance in aquifers and to study water-soil interactions including salinization processes.

I have five years of experience in analyzing groundwater chemistry and collecting rainwater samples. I worked in groundwater related issues in Spain (Onyar River Basin, Llobregat River Basin) and North (Iberá Estuary) and Central (Matanza-Riachuelo River Basin) Argentina. I have planned and conducted many surveys, including building a rainwater monitoring network for a 2300 km2 basin.


Dr. Lin Chen 

Co-advised by Dr. Jirka Šimunek and Dr. Scott Bradford

Lin Chen is a postdoctoral researcher at the Department of Environmental Sciences, working with Dr. Jirka Šimunek, Dr. Scott Bradford, and Dr. Hoori Ajami. Lin’s post-doc research is to develop a watershed scale model to simulate the coupling of water flow and contaminant transport in surface water, vadose zone, and groundwater. Lin completed his PhD at the University of Montreal, where he utilized a combination of field work and numerical modeling to quantify the surface energy components for different land cover types and to investigate impacts of subsurface water flow on the thermal stability of roads and highways built on permafrost.


Dr. Sanghyun Lee

Sanghyun Lee is a postdoctoral scholar in the Department of Environmental Sciences at the University of California, Riverside, working with Dr. Hoori Ajami. He completed his PhD in the Department of Agricultural and Biological Engineering with a Computational Science and Engineering concentration at University of Illinois at Urbana-Champaign. His research interests are focused on surface and subsurface hydrology, sediment fate and transport, analyses of geospatial data, development, and integration of hydrologic models, algorithms, and analyses of ecosystem responses under environment changes. His overall goal is to foster a better understanding of the hydrological processes that are likely to determine the fate of our physical environment by adopting and integrating emerging technologies. 


Dr. Julio César Pachón Maldonado

Co-advised by Dr. Daniel Hirmas

Julio completed his B.S. in Science of Natural & Environmental Systems at Cornell University in 2014, worked with an NGO in tanzania for a year, and finally earned a Ph.D. at the University of Florida in 2021 in Soil and Water Sciences with Dr. Allan Bacon studying soil microaggregation across wide spatial areas in the U.S. and Africa. Julio's continuous goal is to improve long term management of natural resources by enhancing our understanding of the development of soil structure and its impacts on biogeochemical cycles. Currently, as a Postdoctoral Scholar with Dr. Hoori Ajami and Dr. Daniel Hirmas, Julio is working towards improving our understanding of bedrock driven processes on developing preferential flow paths.

Yusen photo.jpg

Dr. Yusen Yuan 

Yusen Yuan is a postdoctoral researcher at the Department of Environmental Sciences, University of California Riverside. His research expertise is in eco-hydrology and isotope geochemistry. In his previous work, Yusen set up and optimized two isotope-based eco-hydrology models. Currently, Yusen is working on quantifying evapotranspiration processes in agricultural ecosystems of Central Valley using a combination of water 18O/2H isotopes and numerical modeling. The goal of his research is to better understand plant water use and groundwater recharge processes in agricultural ecosystems of Central Valley.

Graduate Students

Alyssa Duro

Co-advised by Dr. Daniel Hirmas

Alyssa earned her BS in Environmental Sciences from the University of California, Riverside in 2020, then continued her studies at UCR as a PhD student in pedology. Her dissertation work aims to quantitatively and objectively describe the spatial distribution of soil properties using multi stripe laser triangulation, proximally-sensed hyperspectral imaging, and high resolution photography in order to understand the mechanisms underlying soil structure and related soil functions including carbon storage and hydraulic properties.


Eric Wineteer

As an Environmental Sciences PhD student at UC Riverside, I use remotely sensed data to constrain hydrologic models and better understand groundwater recharge. In my previous position as a consulting engineer, I developed improved statistical downscaling techniques to predict the impact of climate change on water quality, and its implications for infrastructure planning. I have extensive experience in high performance computing, particularly in parallel programming with Python. I recived my B.S. in Civil Engineering and my M.S. in Environmental Engineering from the Northeastern University. 


Clarissa Carretta

Co-advised by Dr. Daniel Hirmas

I am a Junior Specialist providing support to the labs of Hoori Ajami and Daniel Hirmas at the Department of Environmental Sciences, University of California Riverside. I graduated from UCR in 2021 with my BS of Geology and have had the privilege of spending my gap year continuing the research I began in my undergrad. Since 2020, my main project has been on the creation of the NEON-NRCS Dataset to link soil morphological descriptions from NEON sites across the United States to lab data. I also assist with field campaigns, perform standard lab analyses of soil and water properties, and help out with whatever tasks need to be done around the lab!


Vaishnavi Varikuti

Co-advised by Dr. Daniel Hirmas

I earned my BS degree in Agricultural Sciences from Acharya N.G. Ranga Agricultural University, India. After graduation, I was highly aspired to study abroad and thus joined South Dakota State University, Brookings to get my MS degree in Plant Sciences. I worked with Dr. Sandeep Kumar and Dr. Navreet K. Mahal on a project focusing on understanding the response of perennial grass-legume intercropping to soil health parameters on marginal lands. As a PhD student in the Department of Environmental Sciences at UCR under the supervision of Drs. Daniel Hirmas and Hoori Ajami, my research is focused on understanding the effects of interactions between roots, soil, and bedrock on the evolution of soil hydraulic properties, distribution of soil chemical and physical properties, and hydrological functioning of the critical zone.



William Scott Burgess  

BS in Mathematics, Digital Agricultural Fellow (2021-2022)


Maxim Shapovalov 

BS in Earth & Planetary Sciences (2021-2022)

Dr. Adam Schreiner- McGraw

Postdoctoral Fellow (2018-2021)


Now: Research Hydrologist, USDA ARS Missouri 


Kiarash Ehsani


MS in Environmental Sciences (2019-2020)


Aarushi Jha 

MS in Environmental Sciences (2018-2020)

Thesis Title: Application of a Semi-Distributed Hydrologic Model to Understand Hydrologic Flux Partitioning of an Arid, Highly Managed Watershed


Jacob Palmer

M.Eng in Chemical and Environmental Engineering

Now: PhD Student at Texas State University, San Marco


Dr. Conrad Wasko

Visiting scholar, University of Melbourne


Dr. Clare Stephens

Visiting scholar, University of New South Wales

  • Kelly Perez (2019): (UCR, undergraduate researcher, groundwater monitoring)

  • Carly Pierce (2018): (UCR, undergraduate researcher, Land cover change)

  • Mohamed Eissa (2017): (UCR, undergraduate researcher, Semi-distributed modeling)

  • Kyle Fructuoso (2017): (UCR, undergraduate researcher, Seawater intrusion)

  • Austin Fimbres (2017): (UCR, undergraduate researcher, Stream flow analysis)

  • Huihai Wang (2017): (UCR, undergraduate researcher, Hydrologic modeling)

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