Chang Liao

Chang Liao
Pacific Northwest National Laboratory | PNNL · Atmospheric Sciences and Global Change Division

Doctor of Philosophy

About

9
Publications
5,383
Reads
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42
Citations
Introduction
Chang Liao currently works at the Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory. Chang does research in Ecology, Hydrology and Remote Sensing. Their current project is 'Modeling lateral groundwater drainage using a hill slope method.'
Additional affiliations
August 2017 - present
Pacific Northwest National Laboratory
Position
  • PhD Student
January 2014 - May 2014
Purdue University
Position
  • Research Assistant
August 2012 - May 2017
Purdue University
Position
  • Research Assistant
Education
August 2012 - June 2017
Purdue University
Field of study
  • Ecosystems Modeling
September 2009 - June 2011
Chinese Academy of Sciences
Field of study
  • Quantitative Remote Sensing and Ecology
September 2009 - June 2011
Wuhan University
Field of study
  • Remote Sensing and Photogrammetry

Publications

Publications (9)
Preprint
Full-text available
Coastal backwater effects are caused by the downstream water level increase as the result of elevated sea level, 10 high river discharge and their compounding influence. Such effects have crucial impacts on floods in densely populated regions but have not been well represented in large-scale river models used in Earth System Models (ESMs), partly d...
Article
Full-text available
Runoff is a critical component of the terrestrial water cycle, and Earth system models (ESMs) are essential tools to study its spatiotemporal variability. Runoff schemes in ESMs typically include many parameters so that model calibration is necessary to improve the accuracy of simulated runoff. However, runoff calibration at a global scale is chall...
Article
Watershed delineation and flow direction representation are the foundations of streamflow routing in spatially distributed hydrologic modeling. A recent study showed that hexagon-based watershed discretization has several advantages compared to the traditional Cartesian (latitude-longitude) discretization, such as uniform connectivity and compatibi...
Article
The representation of physical processes in earth system models is often constrained and simplified by details of the underlying numerical model. Ocean, atmosphere, ice, land and river dynamics are typically discretised over incompatible computational grids, and are coupled together via ‘lossy’ interpolation schemes. In this work, we describe an al...
Article
Spatial discretization is the cornerstone of all spatially-distributed numerical simulations including watershed hydrology. Traditional square grid spatial discretization has several limitations including inability to represent adjacency uniformly. In this study, we developed a watershed delineation model (HexWatershed) based on the hexagon grid sp...
Article
Full-text available
Arctic terrestrial ecosystems are very sensitive to the global climate change due to the large storage of soil organic carbon and the presence of snow, glacier and permafrost, which respond directly to near surface air temperature that has warmed in the Arctic by almost twice as much as the global average. These ecosystems play a significant role i...
Article
This study uses a spatially distributed surface hydrology model to investigate the role of snowmelt in stream discharge for the Tanana Flats Basin in interior Alaska. The Parameter ESTimation code is used to calibrate the model with observed stream discharge data. The model was further evaluated using remote sensing-based snow cover product and in...
Article
This study uses a three-dimensional groundwater flow model to investigate groundwater dynamics and groundwater-surface water (GW-SW) interactions considering the effects of permafrost distribution for the Tanana Flats Basin in interior Alaska. The Parameter ESTimation (PEST) code is used to calibrate the model with observed stream discharge data. A...
Article
Full-text available
Droughts dramatically affect plant production of global terrestrial ecosystems. To date, quantification of this impact remains a challenge because of the complex plant physiological and biochemical processes associated with drought. Here, this study incorporates a drought index into an existing process-based terrestrial ecosystem model to estimate...

Questions

Questions (5)
Question
I have seen this many times and I know we need to manually modify the boundary and stream networks in some cases.
However, i have never seen a publication specifically discusses this issue.
Serious answer only, please.
Question
We always need data to evaluate model, but often we are encountered with limited data.
What are the statregy we can take to conduct the evaluation in this case?
I will list some common methods below and will also welcome contributions.
Thanks.
Question
In (surface) hydrology, one usual step is watershed delineation based on DEM.
DEM has different resolution. Usually the high resolution will generate "better" or more "realistic" stream lines?
How can we quantitatively describe the quality of watershed delineation?
What metrics can I use to compare the stream line differences between a few delineations using different DEMs with different resolutions?
Ideally, if the DEM is fine enough, there should one of the metrics indicating how much they overlap with actual stream line.
My current idea is to calculate the total area of two polylines. The closer they are, the smaller the area should be.
The figure is used for illustration only.
Question
I am assuming decomposition is far more complex than simple decay (radioactive isotope). Because decomposition includes physical, chemical and all other processes.
Question
I am interested in the global water budget uncertainty. Specifically, I want to quantify each component in the figure from here:
So I need some expert discussions on what are the current state of research on these component estimate.
And what might be missing here? Sea ice?
Any good publications related are welcome.
Thanks for contribution.

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Cited By

Projects

Projects (4)
Project
Run coupled land-river-ocean simulation using the variable resolution (2km-50km) unified mesh.
Project
This is the litter component of the three-dimensional water and carbon cycle model.
Project
I am expanding my regional 3D ecosystem model to global scale with lots of improvements! Please tune in the regional scale project first.