Bioretention Cell Performance Under Shifting Precipitation Patterns Across the Contiguous United States

Author

Matthew WeathersFollow

Date of Award

5-2021

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental Engineering

Major Professor

Jon M. Hathaway

Committee Members

Anahita Khojandi, John S. Schwartz

Abstract

As climate change produces shifts in precipitation patterns, communities will need to understand how the performance of green stormwater infrastructure (GSI) may be impacted. Bioretention cells are one of the most commonly implemented forms of GSI for their ability to reduce peak discharge and filter pollutants and are a vulnerable component of stormwater infrastructure. Projections in future climate indicate that bioretention cells may be at risk of losing their existing function due to deviations in precipitation frequency and intensity. General circulation models (GCMs) downscaled to regional climate models (RCMs) can provide climate change projections at a high spatial resolution but often have a degree of bias introduced during the downscaling process. As such, an ensemble of 10 regional climate models and 17 locations across the contiguous United States were evaluated to provide the widest range of potential future outcomes. Bioretention cells were modeled using USEPA’s Storm Water Management Model (SWMM) to compare observed and future performances. Observed climate data from 1999 to 2013 were gathered from NOAA’s National Centers for Environmental Information data archive, and simulated future climate data from 2035 to 2049 were gathered from the North American Coordinated Regional Downscaling Experiment data archive. To reduce model bias, simulated future climate data was bias-corrected using the kernel density distribution mapping (KDDM) technique. Median annual rainfall and 99^th percentile rainfall event depths were projected to increase across all 17 locations while median drying period was projected to decrease for 11 locations, indicating fewer events with higher magnitudes of rainfall for a majority of locations. Correspondingly, bioretention cell performance decreased across all 17 locations. Relative percent changes in infiltration loss decreased between 4.0-24.0% across all 17 locations while overflow increased between 0.4-19.6% for 15 locations. Results suggest that bioretention cells in the southern United States are at significant risk of losing their existing function while those in the Midwest and Northeast are at moderate risk. Bioretention cells in the western and northwestern United States performed the best under future climate scenarios but could still lose their existing function if unchanged. Most, if not all, bioretention cells across the contiguous United States will, therefore, require some degree of modification to maintain their existing function in the future. This study provides insight on future regional bioretention cell performance trends that can be used to add resiliency to stormwater infrastructure.

Recommended Citation

Weathers, Matthew, "Bioretention Cell Performance Under Shifting Precipitation Patterns Across the Contiguous United States. " Master's Thesis, University of Tennessee, 2021.
https://trace.tennessee.edu/utk_gradthes/6181