Hydrologic Performance of Green Infrastructure across Climate Regions

As a climate change adaptation strategy, numerous countries worldwide have implemented Green Infrastructure (GI) to attenuate the volume of stormwater runoff. The primary objective of this thesis is to compare the performance of seven GI types across six climate zones within the contiguous United States, categorized by the IPCC climate regions. The EPA Storm Water Management Model (SWMM) was used to simulate the following seven GI types: (1) bioretention cells, (2) infiltration trenches, (3) permeable pavement, (4) rain barrels, (5) vegetative swales, (6) rain gardens, and (7) green roofs. Additionally, the Python Stormwater Management Model (PySWMM) was incorporated into the analysis framework to conducte the simulations using a combination of random parameter values within a specified range that represents the characteristics of GI. The percentage of GI implementation was studied included runoff (m³) and peak flow rates (m³/s) at the catchment and outlet, respectively. Permeable pavement performed best with a runoff volume reduction around 50% and a peak flow reduction of roughly 60%. Green roofs were effective in reducing runoff and lowering peak flow rates by approximately 30%. Bioretention cells and rain gardens ranked third, reducing runoff volume by about 24% and lowering peak flow rates by approximately 22%. Infiltration trenches came next, reducing runoff volume by about 22% and peak flow rates by 20%. Rain barrels and vegetative swales were seldom effective. Vegetative swales reduced peak flow by 15% but had minimal impact on volume, decreasing it by less than 1%. Rain barrels were similarly ineffective, with reductions of less than 3% for both performance metrics. The effectiveness of GI is significantly influenced by the climatic characteristics of a region. For permeable pavement and green roofs, their performance declines notably in moist regions, with the order of performance as follows: Cool temperature regions outperform warm temperature regions, and warm regions outperform tropical regions. Vegetative swales consistently exhibit inferior performance in the tropical and moist (TM) region. In contrast, the overall results for bioretention cells, infiltration trenches, rain barrels, and rain gardens do not exhibit significant changes across various climate regions.