PhD Final Defense – Laura Gray
- Event Type
- Seminar/Symposium
- Sponsor
- Civil and Environmental Engineering
- Location
- Civil and Environmental Engineering Building Room 3017
- Date
- Dec 9, 2025 1:00 pm
- Views
- 3
- Originating Calendar
- CEE Seminars and Conferences
Impacts of Ground-Based Green Stormwater Infrastructure on Surface Hydroclimatology
Advisors: Associate Professor Ashlynn Stillwell & Assistant Professor Lei Zhao
Abstract
Climate change impacts are becoming increasingly consequential in cities, particularly as more
of the human population moves to urban environments. Issues with urban flooding, urban heat
stress and temperature extremes, and aging infrastructure have become more common for cities
across the globe, with policymakers and planners struggling to keep up with strategies to address
these concerns. Different climate adaptation tactics have been devised to combat some of these
concerns, but there is often uncertainty about how different tactics will address issues in a
particular location and context. Green stormwater infrastructure (GSI) is one such adaptation
strategy, which promotes stormwater management in a manner that mimics the natural
hydrologic cycle through enhanced infiltration and evapotranspiration. While a promising
strategy, GSI's performance across different locations and background climates is not well
understood, nor are its potential impacts on a regional level from a hydroclimatic standpoint.
This dissertation aims to bridge these scientific gaps by quantifying the hydroclimatic impacts of
vegetated, ground-based GSI in U.S. cities utilizing an Earth system model (ESM), and by
providing context on the suitability of implementation across different locations and climates.
Objective 1 develops and implements a parameterization of ground-based GSI (in the form of
rain gardens) into the urban land component of the global Community Earth System Model
(CESM), examining initial runoff reduction performance in a fine-resolution (~10 km) current
period simulation. The rain garden parameterization is validated using existing data on
evapotranspiration and infiltration data from modeled and observed rain gardens. Objective 1
also examines general hydrologic impacts due to GSI implementation, and finds strong
contributions of background climate to GSI performance. Utilizing the same set of simulations as
in Objective 1, Objective 2 builds on this parameterization by examining additional
hydroclimatic impacts of the “rain garden,” such as temperature decreases, changes in humidity,
and impacts to human perception of temperature. Based on the compensating effects of humidity
and temperature, Objective 2 illustrates that human perceptions of temperature will likely be
unaffected due to implementation. Objective 2 also examines contributions of background
climate and urban morphology to thermal impacts, and finds that many suburban areas see
greater impacts than do their urban core counterparts. Lastly, to provide further context on
broader impacts from GSI adoption, Objective 3 utilizes the CESM's coupling capabilities to
examine how widespread rain garden implementation affects the regional hydroclimate. In this
objective, the same fine resolution as the previous objectives (~10 km) is used, but the
atmospheric component of the CESM is active, allowing for examination of the impacts of landatmosphere
interactions on GSI-induced hydroclimatic changes. Results from Objective 3
demonstrate varying impacts to hydroclimatological and surface parameters and emphasize the
complexity of implementing nature-based strategies such as GSI.
The overall findings in this dissertation advance knowledge on rain garden suitability across
diverse locations and climates from both hydrologic and thermal perspectives. The research
presented here builds on previous studies completed on the local and mesoscale levels, and
provides insight into land and atmospheric interactions resulting from urban development.
Understanding how climate adaptation strategies such as GSI affect the surface hydroclimate
across climates and morphologies has important policy and planning implications, and the results
presented here illustrate the need for context-specific consideration.