Chang Liao

Earth Scientist

Institute of Atmospheric Physics, CAS

Beijing, China

I am an Earth Scientist at the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS) in Beijing, China. Prior to joining CAS in 2026, I worked as an Earth Scientist and Postdoctoral Research Associate at the Pacific Northwest National Laboratory (PNNL). I received my Ph.D. in Earth, Atmospheric, and Planetary Sciences from Purdue University.

The overarching goal of my research is to establish flexible, operational, and scalable modeling frameworks to investigate and predict global water, carbon, and energy cycle dynamics under changing climates and extreme events.

Research Interests

Land Surface & Earth System Modeling: Kilometer-scale land surface simulations, coupled water-carbon dynamics, and soil hydrology.
Mesh-Independent Hydrology & River Routing: Unstructured Centroidal Voronoi Tessellations (MPAS) and hexagonal grid frameworks for multi-scale flow direction and river networks.
Compound Flooding & Hydro-Climate Extremes: Two-way coupled river-coastal hydrodynamic modeling and uncertainty quantification in extreme events.
High-Performance Computing (HPC): Developing scalable Earth system models and parallel scientific software in C++, Fortran, and Python.

news

Oct 13, 2026	Our paper “An unstructured Voronoi mesh framework for large-scale hydrologic and land surface models” was accepted by the Journal of Advances in Modeling Earth Systems (JAMES).
Apr 13, 2026	Our paper “Systematic evaluation of atmospheric forcing, surface datasets, and mesh effects on Kilometer-Scale land surface and river modeling” was published in Journal of Hydrology.
Apr 13, 2026	Our paper “Influence of plateau, slope, and valley on soil hydrology during the dry season in a Central Amazon old-growth forest” was published in Vadose Zone Journal.
Feb 16, 2026	Our paper “ELM-MOSART-DOC: A Large-Scale Riverine Dissolved Organic Carbon Model and Its Application Over the United States” was published in the Journal of Advances in Modeling Earth Systems (JAMES).
Jan 01, 2026	I joined the Institute of Atmospheric Physics, Chinese Academy of Sciences (CAS) in Beijing, China as an Earth Scientist, leading the development and application of three-dimensional kilometer-scale land surface models.

selected publications

JAMES
An Unstructured Voronoi Mesh Framework for Large-Scale Hydrologic and Land Surface Models

Chang Liao, Darren Engwirda, Donghui Xu, Tian Zhou, Zeli Tan, and 1 more author

Journal of Advances in Modeling Earth Systems, 2026

Accepted

Abs Bib

Accurate representation of river networks and land surface heterogeneity is crucial for improving the performance of continental-to-global hydrologic and land surface models (LSMs). Traditional approaches rely on either coarse-resolution grids, which may oversimplify complex terrain and limit the accurate representation of key processes, or computationally demanding full-domain high-resolution meshes. This study introduces a novel framework for generating Hydrologic Refined Meshes (HRMs) that seamlessly integrates crucial land surface features, including river networks, watershed boundaries, and lake boundaries, into the mesh generation process within the Model for Prediction Across Scales (MPAS) architecture.
@article{liao2026unstructured, title = {An Unstructured {Voronoi} Mesh Framework for Large-Scale Hydrologic and Land Surface Models}, author = {Liao, Chang and Engwirda, Darren and Xu, Donghui and Zhou, Tian and Tan, Zeli and Leung, L. Ruby}, journal = {Journal of Advances in Modeling Earth Systems}, year = {2026}, note = {Accepted}, }
ESSD
Discrete Global Grid System-Based Flow Routing Datasets in the Amazon and Yukon Basins

Chang Liao, Darren Engwirda, Matthew G. Cooper, M. Li, and Y. Fang

Earth System Science Data, 2025

Abs DOI Bib HTML

Discrete Global Grid systems (DGGs) are emerging spatial data structures widely used to organize geospatial datasets across scales. This study pioneers the development of new flow routing datasets using Icosahedral Snyder Equal Area (ISEA) DGGs and a novel mesh-independent flow direction model for the tropical Amazon River Basin and the Arctic Yukon River Basin.
@article{liao2025dggs, title = {Discrete Global Grid System-Based Flow Routing Datasets in the {Amazon} and {Yukon} Basins}, author = {Liao, Chang and Engwirda, Darren and Cooper, Matthew G. and Li, M. and Fang, Y.}, journal = {Earth System Science Data}, year = {2025}, doi = {10.5194/essd-2023-398}, }
GMD
Representing Lateral Groundwater Flow From Land to River in Earth System Models

Chang Liao, L. Ruby Leung, Yilin Fang, Teklu Tesfa, and Robinson Negron-Juarez

Geoscientific Model Development, 2025

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Lateral groundwater flow (LGF) is an important hydrologic process in controlling water table dynamics. In this study, we developed a hillslope-based lateral groundwater flow model based on Darcy’s equation and coupled it to the land component (ELM) and river component (MOSART) of the Energy Exascale Earth System Model (E3SM).
@article{liao2025representing, title = {Representing Lateral Groundwater Flow From Land to River in Earth System Models}, author = {Liao, Chang and Leung, L. Ruby and Fang, Yilin and Tesfa, Teklu and Negron-Juarez, Robinson}, journal = {Geoscientific Model Development}, volume = {18}, number = {14}, pages = {4601--4624}, year = {2025}, doi = {10.5194/gmd-18-4601-2025}, }
JAMES
Evaluation of Flow Routing on the Unstructured Voronoi Meshes in Earth System Modeling

Chang Liao, Donghui Xu, Matthew G. Cooper, Tian Zhou, Darren Engwirda, and 5 more authors

Journal of Advances in Modeling Earth Systems, 2025

Abs Bib

Flow routing is a fundamental process of Earth System Models’ river components. This study extends the river component of the Energy Exascale Earth System Model (E3SM) to unstructured Voronoi meshes and evaluates the model’s performance in simulating river discharge and water depth across Arctic, temperate, and tropical watersheds.
@article{liao2025evaluation, title = {Evaluation of Flow Routing on the Unstructured {Voronoi} Meshes in Earth System Modeling}, author = {Liao, Chang and Xu, Donghui and Cooper, Matthew G. and Zhou, Tian and Engwirda, Darren and Bisht, Gautam and Li, Hong-Yi and Li, Lingcheng and Feng, Dongyu and Leung, L. Ruby}, journal = {Journal of Advances in Modeling Earth Systems}, year = {2025}, }
JAMES
Topological Relationship-Based Flow Direction Modeling: Mesh-Independent River Networks Representation

Chang Liao, Tian Zhou, Donghui Xu, Matthew G. Cooper, Darren Engwirda, and 2 more authors

Journal of Advances in Modeling Earth Systems, 2023

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Accurately representing river networks in spatially distributed hydrologic models is sensitive to model resolution. We developed a topological relationship-based river network representation method using graph theory algorithms to simplify vector networks and reconstruct conceptual river networks across structured and unstructured meshes.
@article{liao2023topological, title = {Topological Relationship-Based Flow Direction Modeling: Mesh-Independent River Networks Representation}, author = {Liao, Chang and Zhou, Tian and Xu, Donghui and Cooper, Matthew G. and Engwirda, Darren and Li, Hong-Yi and Leung, L. Ruby}, journal = {Journal of Advances in Modeling Earth Systems}, volume = {15}, number = {3}, pages = {e2022MS003089}, year = {2023}, doi = {10.1029/2022MS003089}, }
JOSS
PyFlowline: A Mesh-Independent River Network Generator for Hydrologic Models

Chang Liao, Matthew G. Cooper, Donghui Xu, Tian Zhou, Gautam Bisht, and 1 more author

Journal of Open Source Software, 2023

Abs DOI Bib HTML PDF Code

PyFlowline is an open-source Python package that generates mesh-independent river networks. With PyFlowline, hydrologic modelers can generate conceptual river networks at various spatial resolutions for both structured and unstructured computational meshes.
@article{liao2023pyflowline, title = {{PyFlowline}: A Mesh-Independent River Network Generator for Hydrologic Models}, author = {Liao, Chang and Cooper, Matthew G. and Xu, Donghui and Zhou, Tian and Bisht, Gautam and Leung, L. Ruby}, journal = {Journal of Open Source Software}, volume = {8}, number = {91}, pages = {5446}, year = {2023}, doi = {10.21105/joss.05446}, }
JAMES
Topological Relationship-Based Flow Direction Modeling: Stream Burning and Depression Filling

Chang Liao, Tian Zhou, Donghui Xu, Zeli Tan, Gautam Bisht, and 4 more authors

Journal of Advances in Modeling Earth Systems, 2023

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This follow-up study presents a novel DEM processing approach for flow direction modeling consisting of a topological relationship-based hybrid breaching-filling stream burning method and a modified depression removal method for rivers and hillslopes across arbitrary mesh systems.
@article{liao2023streamburning, title = {Topological Relationship-Based Flow Direction Modeling: Stream Burning and Depression Filling}, author = {Liao, Chang and Zhou, Tian and Xu, Donghui and Tan, Zeli and Bisht, Gautam and Cooper, Matthew G. and Engwirda, Darren and Li, Hong-Yi and Leung, L. Ruby}, journal = {Journal of Advances in Modeling Earth Systems}, volume = {15}, number = {7}, pages = {e2022MS003487}, year = {2023}, doi = {10.1029/2022MS003487}, }
AWR
Advances in Hexagon Mesh Based Flow Direction Modeling

Chang Liao, Tian Zhou, Donghui Xu, Richard Barnes, Gautam Bisht, and 6 more authors

Advances in Water Resources, 2022

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Watershed delineation and flow direction representation are the foundations of streamflow routing in hydrologic modeling. In this study, we explored approaches such as spatial resampling and hybrid breaching-filling stream burning techniques to improve watershed delineation using HexWatershed in the Columbia River basin.
@article{liao2021advances, title = {Advances in Hexagon Mesh Based Flow Direction Modeling}, author = {Liao, Chang and Zhou, Tian and Xu, Donghui and Barnes, Richard and Bisht, Gautam and Li, Hong-Yi and Tan, Zeli and Tesfa, Teklu and Duan, Zhuoran and Engwirda, Darren and Leung, L. Ruby}, journal = {Advances in Water Resources}, volume = {160}, pages = {104099}, year = {2022}, doi = {10.1016/j.advwatres.2021.104099}, }
EMS
Watershed Delineation on a Hexagonal Mesh Grid

Chang Liao, Teklu Tesfa, Zhuoran Duan, and L. Ruby Leung

Environmental Modelling & Software, 2020

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We developed a watershed delineation model (HexWatershed) based on hexagonal grid spatial discretization to overcome the limitations of Cartesian grids, such as non-uniform adjacency, showing significant advantages for spatially distributed hydrologic simulations.
@article{liao2020watershed, title = {Watershed Delineation on a Hexagonal Mesh Grid}, author = {Liao, Chang and Tesfa, Teklu and Duan, Zhuoran and Leung, L. Ruby}, journal = {Environmental Modelling \& Software}, volume = {130}, pages = {104702}, year = {2020}, doi = {10.1016/j.envsoft.2020.104702}, }