Research Topics

Soil Moisture

In-situ & satellite soil moisture data analysis through “soil moisture signatures” for understanding hydrologic processes.

Catchment Hydrology

Understanding catchment functions using hydrologic signatures & perceptual models analysis.

California

Investigating California’s local water issues, e.g., rain-on-snow, and marine debris.

Soil moisture


A signature-based approach to quantify soil moisture dynamics under contrasting land-uses

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Model diagnostic tools for soil moisture data (‘soil moisture signatures‘) has been increasingly developed. However, the soil moisture signatures have been tested under limited types of land-uses, which must be a strong control factor on the dynamics. Then, my question becomes, Are soil moisture signatures useful to describe the different dynamics under contrasting land-uses? We summarized 9 soil moisture signature behaviors for 12 different land-use types.

Advisor: Dr. H. McMillan

High-frequency multi-depth soil moisture observation for detecting preferential flow

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(Under construction)

USGS Powell Center project, PI: Dr. Matthias Sprenger, Dr. Pamela Sullivan, Dr. John Nimmo, Dr. Tianfan Xu

Forest Flows: Understanding how water flows through the land and plants in forests

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(Under construction)

PI: Dr. Dean Meason

Catchment Hydrology


How do hydrologists perceive watersheds? A survey on perceptual models

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Our team is investigating on how hydrologists perceive watershed systems by analyzing their conceptual illustrations in literature. Such illustrations are called ‘perceptual models,’ and are often used as blueprints of computational models. We explore the best guidelines to create perceptual models for the better knowedge sharing in hydrology.

PI: Dr. H. McMillan

A framework to predict hydrologic processes at continental scales

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Our team suggest hydrologic signature, a metrics that represent watershed dynamics,  as a new approach to estimate dominant processes. We investigate the links between hydrologic signatures and watershed process using large-scale streamflow dataset from the U.S., U.K., Brazil, and Australia.

PI: Dr. H. McMillan, Funded by NSF

Rainfall infiltration reaches the groundwater table despite thick clay layers in humid tropical forests in Sumatra, Indonesia

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Our team has conducted research on rainfall-runoff processes in humid tropics. Despite the presence of thick clayey soil layers, typically known for being impermeable, our team has found that groundwater tables respond quickly with large magnitudes in Indonesia, even in hillslopes with such soil characteristics. Through fieldwork and modeling, we have identified soil aggregation as the possible mechanism that allows for large infiltration flux in the soil layer.

These findings shed light on the behavior of rainfall infiltration in humid tropical forests, where previous studies were lacking. They will serve as a useful foundation for modeling hydrological processes in this area.

PI: Dr. T. Sayama, Funded by Kaken

California



Snowmelt processes in the National Water Model during extreme Atmospheric River events

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National Water Model (NWM) is a hydrologic model that simulates the streamflow over the entire continental United States. The project aims to assess and improve the prediction of rapid snowmelt caused by Rain-on-Snow events in the Sierra Nevada and Cascade mountains by NWM.

I worked on reviewing literature, compiling hydro-climatic data, and analyzing the soil moisture data. Moreover, I created a real-time webmap to visualize the rain-on-snow risks to inform decision-makers.

Advisor: Dr. H. McMillan, Dr. Ming Pan, Dr. Ty Brandt, Dr. Edwin Sumargo, Dr. Forest Cannon at CW3E, Funded by NOAA

Missing the main load? Quantifying marine debris loadings from storm drain and river margin sources in the San Diego River

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Debris from rivers is a major contaminant in the San Diego coastal areas. The project team is conducting fieldwork, laboratory, and modeling works in the San Diego River watershed to quantify and identify the source of marine debris. I supervise three undergraduate students and leading a fieldwork module in the project.

PI: Dr. H. McMillan, Dr. Trent Biggs, Funded by NOAA

Canyon flow analysis with particle velocity imagery (PIV) technique in San Diego

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Traditional measurements of river flow rates require contact with the flow. With the PIV (particle image velocimetry) technique, we can obtain the river surface’s 2-D velocity field without entering the river. PIV cross-correlates the particle in sequential images of the flowing river surface. Out group aims to assess the effectiveness and uncertainties of the PIV technique in small rivers (the river width around less than 10 metres).

I supervised two undergraduate students on the setting up field sites, implementing the fieldwork, and analyzing the data with PIV.

PI: Dr. H.McMillan