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Research

Research

The Han NBS Lab advances ecosystem restoration by leveraging nature-based solutions (NBS) to develop resilient, long-term strategies for environmental challenges. Our goal is to create sustainable ecosystems that benefit both people and the planet.

Our interdisciplinary research integrates biology, ecology, hydrology, pedology, and engineering. We focus on using natural infrastructure in ecological engineering design, emphasizing nature’s capacity for self healing. Our methods include field trials, lab experiments, and spatial modeling.

Innovative Research for Real-World Environmental Solutions

At the Han NBS Lab, our research spans several key areas that apply nature-based strategies to solve pressing environmental challenges

  • In-stream and riparian best management practices enhance water quality in disturbed aquatic environments by restoring natural functions in streams and riparian zones.
  • Regenerative Agriculture uses nature-based products to improve soil health on degraded croplands and rangelands, supporting resilient food systems.
  • Sustainable Land Management integrates natural processes to boost biodiversity and ecological function in low-quality or abandoned environments.
  • Emerging Contaminant Studies aim to understand and mitigate how human waste and wastewater impact ecosystems and public health.
Five members of the Han NBS Lab posing for a photograph.

Han NBS Lab members as of Spring 2025.

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Current Projects

Professional Services Grant, Department of Environmental Quality
July 2025 - June 2026

In partnership with DEQ’s Solid Waste and Land Management Divisions, this project, conducted at the Norman Landfill Environmental Research Site (NLERS), evaluates the dynamics of PFAS movement in response to rainfall through an unlined landfill. This project delivers:

  • Laboratory data on samples analyzed for total fluorine as well as 40 types of PFAS
  • Data analysis conducted to assess the impact of precipitation intensity on PFAS concentrations
  • A final report and presentation to DEQ staff

This masters-level thesis project will contribute to our understand of contaminant dispersal and is expected to result in a peer-reviewed publication.

Sydney Nordquist standing next to landfill leachate collection well.

Sydney Nordquist standing next to landfill leachate collection well.


Faculty Start-Up Project | University of Oklahoma
August 2024 – May 2026

Funded by Dr. Lori Han through faculty start-up support, this graduate research project explores the use of Eastern Redcedar biochar—produced from an invasive tree species in Oklahoma—as a nature-based filter for removing excess nitrate and phosphate from natural waters.

The project has three primary goals:

  • Establish a baseline dataset of Eastern Redcedar biochar properties
  • Evaluate its effectiveness in removing nutrients from aquatic environments
  • Investigate whether amendments (e.g., iron or microbial inoculants) enhance its water treatment performance

This masters-level thesis project will contribute to sustainable water management practices and is expected to result in a peer-reviewed publication.

Jessica Burke standing next to her experimental columns.

Jessica Burke standing next to her experimental columns.


Student Support Agreement | Grand River Dam Authority (GRDA)
August 2024 - May 2026

In collaboration with the Grand River Dam Authority, this graduate research project investigates how forest thinning and prescribed fire affects the ecological health of bottomland hardwood forests in the Neosho Bottoms of Northeastern Oklahoma. These floodplain areas, once cleared for agriculture and later abandoned, have become overrun with invasive-like tree species.

The project focuses on three key goals:

  1. Enhance biodiversity by reducing green ash and box elder dominance in disturbed forest areas
  2. Improve soil health through prescribed fire to support plant growth and ecosystem recovery
  3. Restore ecosystem function by increasing species diversity and improving plant-soil interactions

This masters-level thesis project will contribute to sustainable forest management practices and is expected to result in a peer-reviewed publication.

Nitu Adhikari (left) and Nethmi Wickrama Gunarathne (right) taking GPS coordinates and tagging trees.

Nitu Adhikari (left) and Nethmi Wickrama Gunarathne (right) taking GPS coordinates and tagging trees.


Centers of Excellence for Stormwater Control Infrastructure Technologies Grant Program | Environmental Protection Agency (EPA)

August 2025 - May 2027

The nature of this master's-level thesis project is to develop an GIS-based decision support tool capable of to determining the viability of potential sites within rural Great Plains communities for the construction of GSI. This assessment will utilize multi-criteria based site evaluations that account for priority issues as well as social and economic dimensions. This project will use a combination of pre-existing GIS datasets and community surveys to gather sufficient information for our tool to rank order suggested practices.

The project has three primary goals:

  1. The development of a GIS method capable of carrying out multi-criteria site assessments

  2. Community involvement aimed at gathering information on which factors need greater weight in site assessment

  3. Performing a pilot test of the tool on a smaller scale, largely focused on a subset of small rural communities in Oklahoma and Kansas

This project will contribute to the establishment of a technology-based methodology to support local communities, and is expected to result in a peer-reviewed publication.


Oklahoma Water Survey | University of Oklahoma

August 2025 – May 2027

This master’s-level thesis project for the Oklahoma Water Survey builds upon work by Andrea Tavera, M.S., a former student of Dr. Jason Vogel, who developed a stormwater model aimed at mitigating peak runoff flow using Low Impact Development (LID) techniques. In collaboration with municipal officals, the current study evaluates the performance of the as-built system compared to the original model predictions implemented at the neighborhood scale.

The project includes three core components:

  1. Monitoring selected locations for flow, water quality, and infiltration rates
  2. Conducting onsite topographical surveys to document deviations between design and implementation                                                                                      
  3. Refining and calibrating the InfoDrainage model the site to compare originally predicted versus as-built performance of the site

This research will contribute to the innovative use of LID for flood control and is expected to result in a peer-reviewed publication.

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Past Projects

Professional Services Grant | Oklahoma Department of Environmental Quality
Dec 2024 – June 2025

In partnership with DEQ’s Solid Waste and Land Management Divisions, this project evaluates the risk of PFAS contamination from landfill leachate to Oklahoma’s groundwater. The project delivers:

  • A prioritized list of landfill sites for PFAS assessment
  • Statewide guidance for PFAS groundwater sampling
  • An implementation plan for the Norman Landfill Environmental Research Site
  • A final report and presentation to DEQ staff

This work began as an undergraduate honors thesis and will continue as a graduate research project in July 2026.

Seed Funding | Data Institute for Societal Challenges (DISC)
Feb. 2024 – Feb. 2025

This undergraduate research project, supported by DISC, focused on preparing the GIS database needed to adapt the Prioritize, Target, and Measure Application (PTMApp) - a watershed modeling tool originally developed in Minnesota—for use in Oklahoma.

The project involved acquiring and generating key natural resource GIS layers to support future applications of PTMApp in agricultural landscapes, helping to identify optimal locations for best management practices (BMPs). Technical support was provided by Houston Engineering, Inc., one of the tool’s original developers.

The project successfully produced a complete input dataset, laying the groundwork for future modeling and pursuing external funding opportunities.