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As climate change alters precipitation patterns, stakeholders will need to understand how performance of green stormwater infrastructure (GSI) could change in response. As an alternative to using on-site monitoring, which may not always feasible, we propose that changes in performance could be tracked using annual rainfall measures (e.g., maximum daily rainfall per year). We estimated performance of GSI in 17 U.S. cities using rainfall measures by establishing linear relationships with specific performance metrics (e.g., frequency of discharge). Prediction accuracy was evaluated in 2 cities for the period 2020 to 2060 by comparing performance predicted from rainfall trends from regional climate models (RCMs) with simulated performance in SWMM using the same RCMs as input. Findings suggest that tracking rainfall measures can provide insight into the hydrologic performance of green infrastructure by predicting the direction of change, as well as, the magnitude within 25% to 50% percent change. [ABSTRACT FROM AUTHOR]

Extreme weather events have increased due to climate change. Bioretention basins can effectively alleviate urban flooding by short-term water retention. Reclaimed water (RW) is considered an alternative water resource during water shortages. In this study, the abilities for waterlogging tolerance of four herbaceous flowers (angelonia, narrow-leaf zinnia, celosia, and medallion flower) are investigated to screen suitable ornamental plants for bioretention basins, and the influence of RW on the plants is also evaluated. All plants were treated with 10 days of waterlogging (electrical conductivity (EC) of tap water = 110.0 μS·cm−1) followed by a seven-day recovery. Angelonia (Angelonia salicariifolia Humb. & Bonpl) was not affected by waterlogging and showed the best performance, judged from the ornamental quality, photosynthesis rate, and leaf malondialdehyde (MDA) among the tested flowers. Photosynthesis of the narrow-leaf zinnia (Zinnia angustifolia Kunth) decreased during waterlogging but soon recovered after being drained. Celosia (Celosia argentea L.) and medallion flower (Melampodium paludosum Kunth) were significantly affected by waterlogging and did not recover after drainage, in terms of responses to both external and physiological reactions. Moreover, waterlogging by the simulated RW (EC = 542.4 μS·cm−1) did not have negative impacts on angelonia and narrow-leaf zinnia, due to the reduced leaf malondialdehyde concentration of angelonia and retarded the decline in the net photosynthesis rate of narrow-leaf zinnia. Thus, RW could be used as an alternative irrigation water resource for bioretention basins during the dry season to maintain plant growth.

Stormwater runoff is one of the main contributors to stream impairment in the United States and is primarily treated using best management practices (BMPs). One of the problems with BMPs (e.g., bioretention basins) is that the media used in bioretention basins are not well evaluated, including the optimal composition and physical characteristics. The objective of this research is to evaluate the use of rubber chips as a possible supplemental BMP media because of their light weight and availability. Four types of rubber-chip-mediated soil mixtures were tested, i.e., 100% rubber chips and 50% rubber chips mixed with 50% of either silty loam soil, sand, or compost. Results indicate that a 50/50 mix of rubber chips and sand could treat contaminants in highway runoff efficiently, but lacked the best qualities for plant growth and may require addition of compost. Based on both physical and chemical properties of the media mixture, compost rubber (CR) and silty loam rubber (SLR) were found to be the best as BMP media. Tests on physical properties of BMP media can generate critical information about the media. The methodology used in this study may be used to test physical properties of other BMP media. [ABSTRACT FROM AUTHOR]

Vegetation type alters surface hydrology and nitrogen (N) cycling by partitioning evapotranspiration (ET) and drainage, but has not been fully utilized for this purpose in the design of urban rain gardens. Replicated treatments of three vegetation types (prairie, shrub, and turfgrass) commonly planted in rain gardens, as well as bare soil (control), were evaluated 1 year after establishment in 12, free-drainage bioretention cells designed to specifications for residential rain gardens in the Midwestern United States. Water and N budgets were calculated to assess differences in ET, drainage, soil moisture, and N transport following three stormwater applications in July, August, and October of 2006. Evaporative demand was also estimated as potential or reference ET during the study period using Hamon, Priestley-Taylor, and FAO Penman-Monteith models. Results show that after 1 year of establishment, vegetation type changed the water budgets of rain gardens thus altering their provisioning of ecosystem services via observed tradeoffs between daytime evaporative cooling (ET), stormwater storage, N-load reduction, soil and plant N retention, and groundwater recharge (drainage). Vegetation effects on hydrology and N transport were most significant when evaporative demand was high during the middle of the growing season. Observed changes in ET, drainage, soil moisture, and N transport support the incorporation of different vegetation types into conceptual and numerical models of rain gardens to assess ecological outcomes and tradeoffs at a variety of spatiotemporal scales. [ABSTRACT FROM AUTHOR]

Extreme weather events have increased due to climate change. Bioretention basins can effectively alleviate urban flooding by short-term water retention. Reclaimed water (RW) is considered an alternative water resource during water shortages. In this study, the abilities for waterlogging tolerance of four herbaceous flowers (angelonia, narrow-leaf zinnia, celosia, and medallion flower) are investigated to screen suitable ornamental plants for bioretention basins, and the influence of RW on the plants is also evaluated. All plants were treated with 10 days of waterlogging (electrical conductivity (EC) of tap water = 110.0 μS·cm−1) followed by a seven-day recovery. Angelonia (Angelonia salicariifolia Humb. & Bonpl) was not affected by waterlogging and showed the best performance, judged from the ornamental quality, photosynthesis rate, and leaf malondialdehyde (MDA) among the tested flowers. Photosynthesis of the narrow-leaf zinnia (Zinnia angustifolia Kunth) decreased during waterlogging but soon recovered after being drained. Celosia (Celosia argentea L.) and medallion flower (Melampodium paludosum Kunth) were significantly affected by waterlogging and did not recover after drainage, in terms of responses to both external and physiological reactions. Moreover, waterlogging by the simulated RW (EC = 542.4 μS·cm−1) did not have negative impacts on angelonia and narrow-leaf zinnia, due to the reduced leaf malondialdehyde concentration of angelonia and retarded the decline in the net photosynthesis rate of narrow-leaf zinnia. Thus, RW could be used as an alternative irrigation water resource for bioretention basins during the dry season to maintain plant growth. [ABSTRACT FROM AUTHOR]